Journal articles on the topic 'Precipitation variability Indonesia'
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Belgaman, Halda A., Kimpei Ichiyanagi, Rusmawan Suwarman, Masahiro Tanoue, Edvin Aldrian, Arika I. D. Utami, and Sheila D. A. Kusumaningtyas. "Characteristics of seasonal precipitation isotope variability in Indonesia." Hydrological Research Letters 11, no. 2 (2017): 92–98. http://dx.doi.org/10.3178/hrl.11.92.
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Alsepan, Givo, and Shoshiro Minobe. "Relations between Interannual Variability of Regional-Scale Indonesian Precipitation and Large-Scale Climate Modes during 1960–2007." Journal of Climate 33, no. 12 (June 15, 2020): 5271–91. http://dx.doi.org/10.1175/jcli-d-19-0811.1.
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AbstractRegional-scale precipitation responses over Indonesia to major climate modes in the tropical Indo–Pacific Oceans, namely canonical El Niño, El Niño Modoki, and the Indian Ocean dipole (IOD), and how the responses are related to large-scale moisture convergences are investigated. The precipitation responses, analyzed using a high-spatial-resolution (0.5° × 0.5°) terrestrial precipitation dataset for the period 1960–2007, exhibit differences between the dry (July–September) and wet (November–April) seasons. Canonical El Niño strongly reduces precipitation in central to eastern Indonesia from the dry season to the early wet season and northern Indonesia in the wet season. El Niño Modoki also reduces precipitation in central to eastern Indonesia during the dry season, but conversely increases precipitation in western Indonesia in the wet season. Moisture flux analysis indicates that corresponding to the dry (wet) season precipitation reduction due to the canonical El Niño and El Niño Modoki anomalous divergence occurs around the southern (northern) edge of the convergence zone when one of the two edges is located near the equator (10°S–15°N) associated with their seasonal migration. This largely explains the seasonality and regionality of precipitation responses to canonical El Niño and El Niño Modoki. IOD reduces precipitation in southwestern Indonesia in the dry season, associated with anomalous moisture flux divergence. The seasonality of precipitation response to IOD is likely to be controlled by the seasonality of local sea surface temperature anomalies in the eastern pole of the IOD.
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Wati, T., T. W. Hadi, A. Sopaheluwakan, and L. M. Hutasoit. "Evaluation gridded precipitation datasets in Indonesia." IOP Conference Series: Earth and Environmental Science 893, no. 1 (November 1, 2021): 012056. http://dx.doi.org/10.1088/1755-1315/893/1/012056.
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Abstract This preliminary study evaluates ten gridded precipitation datasets in Indonesia, namely APHRODITE, CMORPH, CHIRPS, GFD, SA-OBS, TMPA 3B42 v7, PERSIAN-CDR at 0.25°, moreover GSMaP_NRT V06, GPM-IMERG (Early-Run) V06, and MSWEP V2 at 0.1» in the period of 2003 to 2015. The evaluation focuses on time series bias using metrics such as Mean Error, Coefficient of Variation, Relative Change (Variability), and Kolmogorov-Smirnov test (KS-test) at daily, monthly, seasonal, and annual time scales. The statistical relationship between the precipitation datasets with reference observational data use Taylor diagrams for evaluating the relative skill of the precipitation dataset. The study aims to evaluate the uncertainty of the precipitation datasets compared to rain gauge datasets. Time series bias of SA-OBS and MSWEP have the nearest value to zero as the best score. The relative skill of monthly rainfall based on rainfall typical shows that MSWEP outperformed in regions A and B, GPM-IMERG in C region. GPM-IMERG's relative skill is outperformed than other datasets at annual time scale in Region A and B, while TMPA 3B42 in Region C. The application of existing precipitation datasets is essential to cope with the limitation of rain gauge observations. This study implicates the development of precipitation products in the Indonesia region.
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Good, Stephen P., Kaiyu Guan, and Kelly K. Caylor. "Global Patterns of the Contributions of Storm Frequency, Intensity, and Seasonality to Interannual Variability of Precipitation." Journal of Climate 29, no. 1 (December 22, 2015): 3–15. http://dx.doi.org/10.1175/jcli-d-14-00653.1.
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Abstract Interannual variation in precipitation totals is a critical factor governing the year-to-year availability of water resources, yet the connection between interannual precipitation variability and underlying event- and season-scale precipitation variability remains unclear. In this study, tropical and midlatitude precipitation characteristics derived from extensive station records and high-frequency satellite observations were analyzed to attribute the fraction of interannual variability arising as a result of individual variability in precipitation event intensity, frequency, and seasonality, as well as the cross-correlation between these factors at the global scale. This analysis demonstrates that variability in the length of the wet season is the most important factor globally, causing 52% of the total interannual variability, while variation in the intensity of individual rainfall events contributes 31% and variability in interstorm wait times contributes only 17%. Spatial patterns in the contribution of each of these intra-annual rainfall characteristics are informative, with regions such as Indonesia and southwestern North America primarily influenced by seasonality, while regions such as the eastern United States, central Africa, and the upper Amazon basin are strongly influenced by storm intensity and frequency. A robust cross-correlation between climate characteristics is identified in the equatorial Pacific, revealing an increased interannual variability over what is expected based on the variability of individual events. This decomposition of interannual variability identifies those regions where accurate representation of daily and seasonal rainfall statistics is necessary to understand and correctly model rainfall variability at longer time scales.
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Margini, Nastasia F., Wasis Wardoyo, and Nadjadji Anwar. "Variability of Discharge Inflow in Wonorejo Reservoir, Indonesia." IOP Conference Series: Earth and Environmental Science 999, no. 1 (March 1, 2022): 012014. http://dx.doi.org/10.1088/1755-1315/999/1/012014.
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Abstract Discharge variability such as frequency and magnitude at certain seasons has the main control on the hydrological behavior of the river. This means a better understanding of discharge variability for reservoir inflow it can be used to manage water reservoir manajement more effectively during the wet year we can use more water, and during the dry season water saving must be done. This flow discharge variation was investigated using data for 18 years from 2003 to 2020 using data on the daily inflow gate of the Wonorejo Reservoir. This study was used to examine the Standardized Precipitation Index (SPI) and statistical methods in the form of average annual discharge, standard deviation (SD), and coefficient of variation (CV) were used to determine the relationship between rain and discharge that occurred. The results of this study show the variability of the discharge for wet, normal and dry years, as well as the distribution of, and changes in the stream flow record. This study is very valuable in order to know the trend of seasonal discharge that occurs, the estimated highest and lowest discharge, as well as the annual discharge cycle in the context of water resources management. Thus, the inflow discharge of the Wonorejo Reservoir from January 2003 to December 2020 shows that each time series follows a normal distribution with a probability percentage of a wet year and a dry year of 41% while a normal year is 11%.
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Mulsandi, Adi, Ardhasena Sopaheluwakan, Akhmad Faqih, Rahmat Hidayat, and Yonny Koesmaryono. "EVALUASI PERFORMA INDEKS MONSUN AUSMI DAN WNPMI DI WILAYAH INDONESIA." Jurnal Sains & Teknologi Modifikasi Cuaca 22, no. 2 (December 29, 2021): 61–70. http://dx.doi.org/10.29122/jstmc.v22i2.4705.
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Intisari Iklim di wilayah Indonesia sangat dipengaruhi oleh aktivitas monsun Asia-Australia. Variabilitas kedua sistem monsun tersebut dapat direpresentasikan dengan baik masing-masing oleh indeks monsun Australian Summer Monsoon Index (AUSMI) dan Western North Pacific Monsoon Index (WNPMI). Saat ini, BMKG secara operasional menggunakan indeks AUSMI dan WNPMI untuk memonitor aktivitas monsun di wilayah Indonesia sebagai bahan prakiraan musim. Meskipun banyak literatur menyatakan bahwa wilayah Indonesia merupakan bagian dari sistem monsun Asia-Australia, namun kondisi topografi lokal yang kompleks berpotensi memodifikasi sirkulasi monsun sehingga perlu dikaji performa kedua indeks tersebut sebelum digunakan secara operasional. Penelitian ini dilakukan untuk menguji performa indeks monsun AUSMI dan WNPMI dalam menggambarkan variasi antartahunan (interannual), variasi dalam musim (intraseasonal), dan siklus tahunan (annual cycle) hujan monsun Indonesia. Hasil penelitian mengungkapkan bahwa kedua indeks memiliki performa yang sangat baik hanya di wilayah dimana indeks tersebut didefinisikan namun kurang baik untuk wilayah Indonesia seperti yang ditunjukan oleh nilai koefisien korelasi yang tidak signifikan dari hasil uji statistik antara kedua indeks dengan curah hujan dari Global Precipitation Climatology Project (GPCP) pada periode 1981-2010. Selain itu, kedua indeks juga memperlihatkan karakteristik siklus tahunan yang berbeda dengan karakteristik siklus tahunan hujan wilayah Jawa sebagai wilayah kunci monsun Indonesia. Hasil ini mengindikasikan perlunya pendefinisian indeks sendiri untuk memonitor aktivitas monsun di wilayah Indonesia. Abstract The climate of Indonesia is strongly affected by the Asian-Australian monsoon system. The variability of the two monsoon systems can be well represented by the Western North Pacific Monsoon Index (WNPMI) and the Australian Summer Monsoon Index (AUSMI) respectively. For producing seasonal forecast, BMKG uses the WNPMI and AUSMI monsoon index to monitor monsoon activity in Indonesia. Although most literature states that the Indonesian region is part of the Asian-Australian monsoon system, the complex local topography may modify the monsoon circulation. Hence, it is necessary to assess the performance of the two indices before they are operationally used. This study was conducted to evaluate the performance of the AUSMI and WNPMI monsoon indices in describing the annual cycle, intraseasonal and interannual variability of the Indonesian monsoon rainfall. The results revealed that the two indices only performed very well in the areas where the index was defined but lack of skill for the Indonesian region because of insignificant linear correlation based on a statistical significance test between the two indices and the Global Precipitation Climatology Project (GPCP) rainfall in the 1981-2010 period. In addition, both monsoon indices and Java rainfall showed different characteristics of the annual cycle. These results indicate that it is necessary to define a specific index for monitoring monsoon activity in Indonesia.
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Fanin, Thierry, and Guido R. van der Werf. "Precipitation–fire linkages in Indonesia (1997–2015)." Biogeosciences 14, no. 18 (September 15, 2017): 3995–4008. http://dx.doi.org/10.5194/bg-14-3995-2017.
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Abstract. Over the past decades, fires have burned annually in Indonesia, yet the strength of the fire season is for a large part modulated by the El Niño Southern Oscillation (ENSO). The two most recent very strong El Niño years were 2015 and 1997. Both years involved high incidences of fire in Indonesia. At present, there is no consistent satellite data stream spanning the full 19-year record, thereby complicating a comparison between these two fire seasons. We have investigated how various fire and precipitation datasets can be merged to better compare the fire dynamics in 1997 and 2015 as well as in intermediary years. We combined nighttime active fire detections from the Along Track Scanning Radiometer (ATSR) World Fire Atlas (WFA) available from 1997 until 2012 and the nighttime subset of the Moderate-Resolution Imaging Spectroradiometer (MODIS) sensor from 2001 until now. For the overlapping period, MODIS detected about 4 times more fires than ATSR, but this ratio varied spatially. Although the reasons behind this spatial variability remain unclear, the coefficient of determination for the overlapping period was high (R2 = 0. 97, based on monthly data) and allowed for a consistent time series. We then constructed a rainfall time series based on the Global Precipitation Climatology Project (GPCP, 1997–2015) and the Tropical Rainfall Measurement Mission Project (TRMM, 1998–2015). Relations between antecedent rainfall and fire activity were not uniform in Indonesia. In southern Sumatra and Kalimantan, we found that 120 days of rainfall accumulation had the highest coefficient of determination with annual fire intensity. In northern Sumatra, this period was only 30 days. Thresholds of 200 and 305 mm average rainfall accumulation before each active fire were identified to generate a high-incidence fire year in southern Sumatra and southern Kalimantan, respectively. The number of active fires detected in 1997 was 2.2 times higher than in 2015. Assuming the ratio between nighttime and total active fires did not change, the 1997 season was thus about twice as severe as the one in 2015. Although large, the difference is smaller than found in fire emission estimates from the Global Fire Emissions Database (GFED). Besides different rainfall amounts and patterns, the two-fold difference between 1997 and 2015 may be attributed to a weaker El Niño and neutral Indian Ocean Dipole (IOD) conditions in the later year. The fraction of fires burning in peatlands was higher in 2015 compared to 1997 (61 and 45 %, respectively). Finally, we found that the non-linearity between rainfall and fire in Indonesia stems from longer periods without rain in extremely dry years.
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Leemhuis, C., and G. Gerold. "The impact of the warm phase of ENSO (El Niño Southern Oscillation) events on water resource availability of tropical catchments in Central Sulawesi, Indonesia." Advances in Geosciences 6 (February 16, 2006): 217–20. http://dx.doi.org/10.5194/adgeo-6-217-2006.
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Abstract. Precipitation anomalies caused by the warm phase (El Niño) of the ENSO cycle lead to a strong decrease of water resources in South-East Asia. The aim of this work is to study the impact of warm phase ENSO caused precipitation anomalies on the water balance of a mesoscale tropical catchment in Central Sulawesi, Indonesia using a scenario analysis. We applied statistically generated precipitation anomalies caused by warm phase ENSO events on a validated hydrological model of the Palu River catchment (2694 km2) to investigate the implications of the generated ENSO scenarios on the total annual water balance, the annual discharge regime and the discharge variability. Moreover we analysed the influence of various catchment characteristics during warm phase ENSO conditions on the discharge variability through a comparison of different sub-catchment types. The results of the scenario analysis proved a severe decline of the annual discharge rate during warm phase ENSO conditions and an increase of the overall discharge variability.
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Rahmad, R., and M. A. Wirda. "Long-term Spatiotemporal Trend Analysis of Precipitation and Temperature in Citarum Watershed, Indonesia." IOP Conference Series: Earth and Environmental Science 930, no. 1 (December 1, 2021): 012038. http://dx.doi.org/10.1088/1755-1315/930/1/012038.
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Abstract Analyzing meteorological variables such as precipitation and temperature can give valuable information regarding past and future climate variability. Citarum Watershed is one of the world’s most threatened watersheds and the most degraded on Indonesia’s Java Island. The Indonesian government regards it as the most strategically important river basin territory because it supplies 80 percent of the surface water supply to Jakarta. This study aims to analyze the precipitation and temperature trend in the Citarum Watershed. This study is preliminary research and intends to provide a better insight into the impacts of climate change on water availability in the tropical region. The detection was carried out with the use of a Mann-Kendall with Sen’s slope. The results indicated that there are significant increasing trends of precipitation during the wet season. Whereas the increasing trend in temperature exhibits for all stations in the basin. The highest increasing trend is in Bandung City, the city with the highest urbanization rate in Indonesia. It is widely acknowledged that rising urbanization will have a considerable impact on the worldwide land warming trend.
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Qian, Jian-Hua, Andrew W. Robertson, and Vincent Moron. "Interactions among ENSO, the Monsoon, and Diurnal Cycle in Rainfall Variability over Java, Indonesia." Journal of the Atmospheric Sciences 67, no. 11 (November 1, 2010): 3509–24. http://dx.doi.org/10.1175/2010jas3348.1.
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Abstract Using a high-resolution regional climate model—the Abdus Salam International Centre for Theoretical Physics Regional Climate Model version 3 (RegCM3)—and station and satellite observations, the authors have studied the spatial heterogeneity of climate variability over Java Island, Indonesia. Besides the well-known anomalous dry conditions that characterize the dry and transition seasons during an El Niño year, analysis of regional model output reveals a wet mountainous south versus dry northern plains in precipitation anomalies associated with El Niño over Java during the peak rainy season. Modeling experiments indicate that this mountains/plains contrast is caused by the interaction of the El Niño–induced monsoonal wind anomalies and the island/mountain-induced local diurnal cycle of winds and precipitation. During the wet season of El Niño years, anomalous southeasterly winds over the Indonesian region oppose the climatological northwesterly monsoon, thus reducing the strength of the monsoon winds over Java. This weakening is found to amplify the local diurnal cycle of land–sea breezes and mountain–valley winds, producing more rainfall over the mountains, which are located closer to the southern coast than to the northern coast. Therefore, the variability of the diurnal cycle associated with this local spatial asymmetry of topography is the underlying cause for the heterogeneous pattern of wet south/dry north rainfall anomalies during El Niño years. It is further shown that the mean southeasterly wind anomalies during December–February of El Niño years result from more frequent occurrence of a quiescent monsoon weather type, during which the strengthened sea-breeze and valley-breeze convergence leads to above normal rainfall over the mountains.
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Liebmann, Brant, Martin P. Hoerling, Chris Funk, Ileana Bladé, Randall M. Dole, Dave Allured, Xiaowei Quan, Philip Pegion, and Jon K. Eischeid. "Understanding Recent Eastern Horn of Africa Rainfall Variability and Change." Journal of Climate 27, no. 23 (December 1, 2014): 8630–45. http://dx.doi.org/10.1175/jcli-d-13-00714.1.
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Abstract Observations and sea surface temperature (SST)-forced ECHAM5 simulations are examined to study the seasonal cycle of eastern Africa rainfall and its SST sensitivity during 1979–2012, focusing on interannual variability and trends. The eastern Horn is drier than the rest of equatorial Africa, with two distinct wet seasons, and whereas the October–December wet season has become wetter, the March–May season has become drier. The climatological rainfall in simulations driven by observed SSTs captures this bimodal regime. The simulated trends also qualitatively reproduce the opposite-sign changes in the two rainy seasons, suggesting that SST forcing has played an important role in the observed changes. The consistency between the sign of 1979–2012 trends and interannual SST–precipitation correlations is exploited to identify the most likely locations of SST forcing of precipitation trends in the model, and conceivably also in nature. Results indicate that the observed March–May drying since 1979 is due to sensitivity to an increased zonal gradient in SST between Indonesia and the central Pacific. In contrast, the October–December precipitation increase is mostly due to western Indian Ocean warming. The recent upward trend in the October–December wet season is rather weak, however, and its statistical significance is compromised by strong year-to-year fluctuations. October–December eastern Horn rain variability is strongly associated with El Niño–Southern Oscillation and Indian Ocean dipole phenomena on interannual scales, in both model and observations. The interannual October–December correlation between the ensemble-average and observed Horn rainfall 0.87. By comparison, interannual March–May Horn precipitation is only weakly constrained by SST anomalies.
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Pratiwi, Nila Ardhyarini H., Mahawan Karuniasa, and Djoko Santoso Abi Suroso. "Exploring Historical and Projection of Drought Periods in Cirebon Regency, Indonesia." E3S Web of Conferences 68 (2018): 02007. http://dx.doi.org/10.1051/e3sconf/20186802007.
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Climate hazards that affect drought could have an impact on agricultural production. Cirebon Regency as one of West Java's food supply areahas experienced hydrological drought because ofclimate variability. Hence, there were many rice fieldswhich lack of water sources for irrigation and resulted in crop failure. Accordingly, this study aims to explore the historical and projection of drought periods as well as the severity of droughts in Cirebon Regency, Indonesia. Interpretation of weather and climate data and Standardized Precipitation Index (SPI) were employed for methods of this studyby using rainfall data only. Based on baseline data (1986-2017) from Jatiwangi Meteorological Stationand Global Circulation Model (GCM) projection simulation (2020-2045) under the Representative Concentration Pathways (RCP) 4.5 scenario, the SPI analysis results show that the drought periodsare predicted to shift in the future with increasing drought severity. This study concludes that climate variability that affects future dry rainfall will still happen in uncertain month periods.Therefore, climatic information is needed in the vulnerable area to reduce the potential impactsthat will occur in the future.
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Xu, Qi, Zhaoyong Guan, Dachao Jin, and Dingzhu Hu. "Regional Characteristics of Interannual Variability of Summer Rainfall in the Maritime Continent and Their Related Anomalous Circulation Patterns." Journal of Climate 32, no. 14 (June 19, 2019): 4179–92. http://dx.doi.org/10.1175/jcli-d-18-0480.1.
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Abstract Using the NCEP–NCAR reanalysis and Global Precipitation Climatology Project monthly rainfall, we have investigated the regional features of interannual variations of rainfall in the Maritime Continent (MC) and their related anomalous atmospheric circulation patterns during boreal summer by employing the rotated empirical orthogonal function (REOF) analysis. Our results demonstrate that the rainfall variabilities in the MC are of very striking regional characteristics. The MC is divided into four independent subregions on the basis of the leading REOF modes; these subregions are located in central-eastern Indonesia (subregion I), the oceanic area to the west of Indonesia (subregion II+V), the part of the warm pool in the equatorial western Pacific Ocean (subregion III), and Guam (subregion IV+VI).The anomalous precipitation in different subregions exhibits different variation periodicities, which are associated with different circulation patterns as a result of atmospheric response to different sea surface temperature anomaly (SSTA) patterns in the tropical Indo-Pacific sector. It is found that rainfall anomalies in subregion I are induced by the Pacific ENSO, whereas those in subregion II+V are dominated by a triple SSTA pattern with positive correlations in the MC and negative correlation centers in the tropical Pacific and tropical Indian Ocean. Rainfall anomalies in subregion III mainly resulted from an SSTA pattern with negative correlations in the eastern MC and positive correlations in the western equatorial Pacific east of the MC. A horseshoe SSTA pattern in the central Pacific is found to affect the precipitation anomalies in subregion IV+VI. All of the results of this study are helpful for us to better understand both the climate variations in the MC and monsoon variations in East Asia.
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Runtunuwu, Eleonora, and Akihiko Kondoh. "ASSESSING GLOBAL CLIMATE VARIABILITY UNDER COLDEST AND WARMEST PERIODS AT DIFFERENT LATITUDINAL REGIONS." Indonesian Journal of Agricultural Science 9, no. 1 (October 25, 2016): 7. http://dx.doi.org/10.21082/ijas.v9n1.2008.7-18.
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Effect of climate change on water balance will play a key role in the biosphere system. To study the global climate change impact on water balance during 95-year period (1901-1995), long-term grid climatic data including global mean monthly temperature and precipitation at 0.5 x 0.5 degree resolution were analysed. The trend and variation of climate change, the time series of monthly air temperature and precipitation data were aggregated into annual arithmetic means for two extreme periods (1901-1920 and 1990-1995). The potential evapotranspiration (Eo) was calculated using Thornthwaite method.<br />The changes in mean annual value were obtained by subtracting the maximum period data from 1990 to 1995 (Max) with the minimum period data from 1901 to 1920 (Min). The results revealed that over 95-year period, mean global air temperature increased by 0.57oC. The temperature increase varied greatly in Asia, with more than 3.0oC, especially at 45-70oN, as well over the northern part of America (60-65oN) and Europe (55- 75oN). In low latitude across Asia, Africa, and South America, the variation was less than 1.5oC. In 80-85ºN region, the variation was relatively small and at higher latitudes it increased<br />significantly. Precipitation varied temporally and spatially. In the 40-45ºN and 40-45ºS regions, increasing precipitation of more than 100 mm occurred during the June-August and<br />September-November, especially in the northern hemisphere. The Eo increase of 2000 mm during 95 years occurred in the tropical northern America, middle Africa, and South-East Asia. A grid in Central Java of Indonesia showed that the Eo increase of 2500 mm during 95 years resulted in the decrease of growing period by 100 days. In coping with climate change, adjustment of cropping calendar is imperative.
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Runtunuwu, Eleonora, and Akihiko Kondoh. "ASSESSING GLOBAL CLIMATE VARIABILITY UNDER COLDEST AND WARMEST PERIODS AT DIFFERENT LATITUDINAL REGIONS." Indonesian Journal of Agricultural Science 9, no. 1 (October 25, 2016): 7. http://dx.doi.org/10.21082/ijas.v9n1.2008.p7-18.
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Effect of climate change on water balance will play a key role in the biosphere system. To study the global climate change impact on water balance during 95-year period (1901-1995), long-term grid climatic data including global mean monthly temperature and precipitation at 0.5 x 0.5 degree resolution were analysed. The trend and variation of climate change, the time series of monthly air temperature and precipitation data were aggregated into annual arithmetic means for two extreme periods (1901-1920 and 1990-1995). The potential evapotranspiration (Eo) was calculated using Thornthwaite method.<br />The changes in mean annual value were obtained by subtracting the maximum period data from 1990 to 1995 (Max) with the minimum period data from 1901 to 1920 (Min). The results revealed that over 95-year period, mean global air temperature increased by 0.57oC. The temperature increase varied greatly in Asia, with more than 3.0oC, especially at 45-70oN, as well over the northern part of America (60-65oN) and Europe (55- 75oN). In low latitude across Asia, Africa, and South America, the variation was less than 1.5oC. In 80-85ºN region, the variation was relatively small and at higher latitudes it increased<br />significantly. Precipitation varied temporally and spatially. In the 40-45ºN and 40-45ºS regions, increasing precipitation of more than 100 mm occurred during the June-August and<br />September-November, especially in the northern hemisphere. The Eo increase of 2000 mm during 95 years occurred in the tropical northern America, middle Africa, and South-East Asia. A grid in Central Java of Indonesia showed that the Eo increase of 2500 mm during 95 years resulted in the decrease of growing period by 100 days. In coping with climate change, adjustment of cropping calendar is imperative.
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Moron, Vincent, Andrew W. Robertson, and Rizaldi Boer. "Spatial Coherence and Seasonal Predictability of Monsoon Onset over Indonesia." Journal of Climate 22, no. 3 (February 1, 2009): 840–50. http://dx.doi.org/10.1175/2008jcli2435.1.
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Abstract The seasonal potential predictability of monsoon onset during the August–December season over Indonesia is studied through analysis of the spatial coherence of daily station rainfall and gridded pentad precipitation data from 1979 to 2005. The onset date, defined using a local agronomic definition, exhibits a seasonal northwest-to-southeast progression from northern and central Sumatra (late August) to Timor (mid-December). South of the equator, interannual variability of the onset date is shown to consist of a spatially coherent large-scale component, together with local-scale noise. The high spatial coherence of onset is similar to that of the September–December seasonal total, while postonset amounts averaged over 15–90 days and September–December amount residuals from large-scale onset show much less spatial coherence, especially across the main islands of monsoonal Indonesia. The cumulative rainfall anomalies exhibit also their largest amplitudes before or near the onset date. This implies that seasonal potential predictability over monsoonal Indonesia during the first part of the austral summer monsoon season is largely associated with monsoon onset, and that there is much less predictability within the rainy season itself. A cross-validated canonical correlation analysis using July sea surface temperatures over the tropical Pacific and Indian Oceans (20°S–20°N, 80°–280°E) as predictors of local-scale onset dates exhibits promising hindcast skill (anomaly correlation of ∼0.80 for the spatial average of standardized rain gauges and ∼0.70 for standardized gridded pentad precipitation data).
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Yusnaini, Helmi, Ravidho Ramadhan, Marzuki Marzuki, Ayu Putri Ningsih, Hiroyuki Hashiguchi, Toyoshi Shimomai, Mutya Vonnisa, Harmadi Harmadi, Wiwit Suryanto, and Sholihun Sholihun. "Statistical Comparison of IMERG Precipitation Products with Optical Rain Gauge Observations over Kototabang, Indonesia." JURNAL ILMU FISIKA | UNIVERSITAS ANDALAS 14, no. 1 (November 28, 2021): 10–20. http://dx.doi.org/10.25077/jif.14.1.10-20.2022.
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Satellite-based precipitation estimates play a crucial role in many hydrological and numerical weather models, especially to overcome the scarcity of rain gauge data. Globally gridded rainfall product from Integrated Multi-Satellite Retrievals for Global Precipitation Measurement (GPM) (IMERG) has been used in a wide range of hydrological applications. However, the IMERG is inherently prone to errors and biases. This study evaluated the performance of the IMERG-Final run (IMERG-F) product to estimate rainfall in a mountainous area of Sumatra. Validation was carried out using optical rain gauge (ORG) data for 15 years (2002-2016), at Kototabang, West Sumatra, Indonesia. In general, IMERG-F overestimated rainfall in all time scales. The longer the time scale was, the better the performance of IMERG-F we obtained. This feature was indicated by all quantities of continuous and categorical statistical matrices used. The performance of IMERG-F was lower than in other areas of the Maritime Continent, except for the probability of detection (POD) value. IMERG-F could detect rain very well, including for daily and hourly data, but the false alarm rate (FAR) was also relatively high. Such high FAR value may indicate a significant small-scale spatial rainfall variability in mountainous area of Sumatra.
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Olchev, A., A. Ibrom, O. Panferov, D. Gushchina, P. Propastin, H. Kreilein, T. June, A. Rauf, G. Gravenhorst, and A. Knohl. "Response of CO<sub>2</sub> and H<sub>2</sub>O fluxes of a mountainous tropical rain forest in equatorial Indonesia to El Niño events." Biogeosciences Discussions 12, no. 6 (March 16, 2015): 4405–31. http://dx.doi.org/10.5194/bgd-12-4405-2015.
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Abstract. The possible impact of El Niño–Southern Oscillation (ENSO) events on the main components of CO2 and H2O fluxes in a pristine mountainous tropical rainforest growing in Central Sulawesi in Indonesia is described. The fluxes were continuously measured using the eddy covariance method for the period from January 2004 to June 2008. During this period, two episodes of El Niño and one episode of La Niña were observed. All these ENSO episodes had moderate intensity and were of Central Pacific type. The temporal variability analysis of the main meteorological parameters and components of CO2 and H2O exchange showed a very high sensitivity of Evapotranspiration (ET) and Gross Primary Production (GPP) of the tropical rain forest to meteorological variations caused by both El Niño and La Niña episodes. Incoming solar radiation is the main governing factor that is responsible for ET and GPP variability. Ecosystem Respiration (RE) dynamics depend mainly on the air temperature changes and are almost insensitive to ENSO. Changes of precipitation due to moderate ENSO events did not cause any notable effect on ET and GPP, mainly because of sufficient soil moisture conditions even in periods of anomalous reduction of precipitation in the region.
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Sok, Rachna. "Typical Rainfall Distribution Pattern of Flood Event Caused by Tropical Cyclone at Bima City, West Nusa Tenggara, Indonesia." Journal of the Civil Engineering Forum 5, no. 1 (January 17, 2019): 1. http://dx.doi.org/10.22146/jcef.34604.
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Tropical cyclones are the most serious meteorological phenomena that hit Bima city in December 2016. The strong winds and heavy precipitation associated with a typhoon significantly affect the weather in this city. The impact of a tropical cyclone on precipitation variability in Bima is studied using rainfall data for analyzing hourly rainfall distribution pattern during the event. Depend on the geographic situation and climate characteristic, the hourly rainfall distribution pattern of one area is different to others area. The research aims to analyze hourly rainfall distribution pattern in the form of the rainfall intensity distribution. This research is conducted using one automatic rainfall gauge in Bima city, West Nusa Tenggara province that obtained from Regional Disaster Management Agency (BPBD). The results showed that two events of rainfall were recorded. The first rainfall event was on 20th to 21st December 2016 with a total rainfall 191.4 mm. The second rainfall event occurred on 22nd to 23rd December 2016 with a total rainfall 126.2 mm. The rainfall distribution pattern has rainfall intensity peak at 45% of duration with cumulative rainfall reached 70%. It was found there is no common pattern of temporal rainfall distribution for rainfall induced by tropical cyclones.
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Henke, L. M. K., F. H. Lambert, and D. J. Charman. "Was the Little Ice Age more or less El Niño-like than the Mediaeval Climate Anomaly? Evidence from hydrological and temperature proxy data." Climate of the Past Discussions 11, no. 6 (November 26, 2015): 5549–604. http://dx.doi.org/10.5194/cpd-11-5549-2015.
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Abstract. The El Niño-Southern Oscillation (ENSO), an ocean–atmosphere coupled oscillation over the equatorial Pacific, is the most important source of global climate variability on inter-annual time scales. It has substantial environmental and socio-economic consequences such as devastation of South American fish populations and increased forest fires in Indonesia. The instrumental ENSO record is too short for analysing long-term trends and variability, hence proxy data is used to extend the record. However, different proxy sources have produced varying reconstructions of ENSO, with some evidence for a temperature–precipitation divergence in ENSO trends over the past millennium, in particular during the Mediaeval Climate Anomaly (MCA; AD 800–1300) and the Little Ice Age (LIA; AD 1400–1850). This throws into question the stability of the modern ENSO system and its links to the global climate, which has implications for future projections. Here we use a new statistical approach using EOF-based weighting to create two new large-scale ENSO reconstructions derived independently from precipitation proxies and temperature proxies respectively. The method is developed and validated using pseudoproxy experiments that address the effects of proxy dating error, resolution and noise to improve uncertainty estimations. The precipitation ENSO reconstruction displays a significantly more El Niño-like state during the LIA than the MCA, while the temperature reconstruction shows no significant difference. The trends shown in the precipitation ENSO reconstruction are relatively robust to variations in the precipitation EOF pattern. However, the temperature reconstruction suffers significantly from a lack of high-quality, favourably located proxy records, which limits its ability to capture the large-scale ENSO signal. Further expansion of the palaeo-database and improvements to instrumental, satellite and model representations of ENSO are needed to fully resolve the discrepancies found among proxy records.
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Drumond, A. R. M., and T. Ambrizzi. "Inter ENSO variability and its influence over the South American monsoon system." Advances in Geosciences 6 (February 1, 2006): 167–71. http://dx.doi.org/10.5194/adgeo-6-167-2006.
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Abstract. Previous studies have discussed the interannual variability of a meridional seesaw of dry and wet conditions over South America (SA) associated to the modulation of the South Atlantic Convergence Zone (SACZ). However, they did not explore if the variability inter ENSO (El Niño Southern Oscillation) can be related to the phase changes of this dipole. To answer this question, an observational work was carried out to explore the atmospheric and Sea Surface Temperature (SST) conditions related to the same ENSO signal and to opposite dipole phases. Rotated Empirical Orthogonal Function (REOF) analysis was applied over normalized Chen precipitation seasonal anomalies in order to find the dipole mode in the Austral Summer (December to February). The fourth rotated mode, explaining 6.6% of the total variance, consists of positive loading over the SACZ region and negative loading over northern Argentina. Extreme events were selected and enhanced activity of SACZ during the Summer season (SACZ+) was identified in nine years: five during La Niña events (LN) and two in El Niño episodes (EN). On the other hand, inhibited manifestations of this system (SACZ-) were identified in seven years: four in EN and two during LN. Power spectrum analysis indicated that the interannual variability of the precipitation dipole seems to be related to the low frequency and to the quasi-biennial part of ENSO variability. The ENSO events with the same signal can present opposite phases for the dipole. The results suggest that the displacement of the convection over Indonesia and western Pacific can play an important role to modulate the seesaw pattern.
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Olchev, A., A. Ibrom, O. Panferov, D. Gushchina, H. Kreilein, V. Popov, P. Propastin, et al. "Response of CO<sub>2</sub> and H<sub>2</sub>O fluxes in a mountainous tropical rainforest in equatorial Indonesia to El Niño events." Biogeosciences 12, no. 22 (November 24, 2015): 6655–67. http://dx.doi.org/10.5194/bg-12-6655-2015.
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Abstract. The possible impact of El Niño–Southern Oscillation (ENSO) events on the main components of CO2 and H2O fluxes between the tropical rainforest and the atmosphere is investigated. The fluxes were continuously measured in an old-growth mountainous tropical rainforest in Central Sulawesi in Indonesia using the eddy covariance method for the period from January 2004 to June 2008. During this period, two episodes of El Niño and one episode of La Niña were observed. All these ENSO episodes had moderate intensity and were of the central Pacific type. The temporal variability analysis of the main meteorological parameters and components of CO2 and H2O exchange showed a high sensitivity of evapotranspiration (ET) and gross primary production (GPP) of the tropical rainforest to meteorological variations caused by both El Niño and La Niña episodes. Incoming solar radiation is the main governing factor that is responsible for ET and GPP variability. Ecosystem respiration (RE) dynamics depend mainly on the air temperature changes and are almost insensitive to ENSO. Changes in precipitation due to moderate ENSO events did not have any notable effect on ET and GPP, mainly because of sufficient soil moisture conditions even in periods of an anomalous reduction in precipitation in the region.
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Auliyani, D., and N. Wahyuningrum. "Rainfall variability based on the Climate Hazards Group InfraRed Precipitation with Station Data (CHIRPS) in Lesti watershed, Java Island, Indonesia." IOP Conference Series: Earth and Environmental Science 874, no. 1 (October 1, 2021): 012003. http://dx.doi.org/10.1088/1755-1315/874/1/012003.
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Sittichok, Ketvara, and Chaiyapong Thepprasit. "Differences of Precipitation Characteristics among GCMs over Southeast Asia under AR6 Climate Change Scenarios." ASEAN Journal of Scientific and Technological Reports 25, no. 1 (March 3, 2022): 11–23. http://dx.doi.org/10.55164/ajstr.v25i1.244632.
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Southeast Asia is known globally as a highly vulnerable climate change region. Precipitation is the primary factor that impacts livelihood in this region due to recurring flood and drought incidents. Variables projections under climate change can be made using General Circulation Models (GCMs). An investigation of projected precipitation with the new phase of the model experiment, the Sixth Assessment Report (AR6), is worth to be considered. This study investigates the spatial distributions of variability, trend and conditions (wet/dry) of precipitations generated using 10 GCMs over the SEA under AR6 with four scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8). Three statistical methods, coefficient of variation (CV), Mann-Kendall test (MK) and standardized anomaly index (SAI), were calculated by grid cells. Significant differences among GCMs could be seen in the results. High precipitation variation with CV was indicated around the southern part of Indonesia and the Philippines oceans for six models, whereas only one model (MRI-ESM2) returned strong variation for mainland countries. A decreasing precipitation trend during the historical period could be observed in mainland countries with four GCMs. However, the SSP3-7.0 and SSP5-8.5 of most models presented precipitation increment. The extremely wet and dry ratio to all other years was calculated. Highly wet years higher than 10% were indicated in SSP5-8.5 with MPI-ESM1 occurring in most areas of the region, whereas other models gave 6-10% of highly wet occurrence. Drought situation occurred higher than 10% and could be seen with only three models with small areas under all scenarios. returned strong variation for mainland countries. A decreasing precipitation trend during the historical period could be observed in mainland countries with four GCMs. However, the SSP3-7.0 and SSP5-8.5 of most models presented precipitation increment. The extremely wet and dry ratio to all other years was calculated. Highly wet years higher than 10% were indicated in SSP5-8.5 withMPI-ESM1 occurring in most areas of the region, whereas other models gave 6-10% of highly wet occurrence. Drought situation occurred higher than 10% and could be seen with only three models with small areas under all scenarios.
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Hermawan, Eddy, Sandro W. Lubis, Teguh Harjana, Anis Purwaningsih, Risyanto Risyanto, Ainur Ridho, Dita Fatria Andarini, Dian Nur Ratri, and Retno Widyaningsih. "Large-Scale Meteorological Drivers of the Extreme Precipitation Event and Devastating Floods of Early-February 2021 in Semarang, Central Java, Indonesia." Atmosphere 13, no. 7 (July 11, 2022): 1092. http://dx.doi.org/10.3390/atmos13071092.
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Unusually long duration and heavy rainfall from 5 to 6 February 2021 caused widespread and devastating floods in Semarang, Central Java, Indonesia. The heavy rainfall was produced by two mesoscale convective systems (MCSs). The first MCS developed at 13Z on 5 February 2021 over the southern coast of Sumatra and propagated towards Semarang. The second MCS developed over the north coast of Semarang at 18Z on 5 February 2021 and later led to the first peak of precipitation at 21Z on 5 February 2021. These two MCSs eventually merged into a single MCS, producing the second peak of precipitation at 00Z on 6 February 2021. Analysis of the moisture transport indicates that the strong and persistent north-westerly wind near the surface induced by CENS prior to and during the event created an intensive meridional (southward) tropospheric moisture transport from the South China Sea towards Semarang. In addition, the westerly flow induced by low-frequency variability associated with La Nina and the tropical depression over the North of Australia produced an intensive zonal (eastward) tropospheric moisture transport from the Indian Ocean towards Semarang. The combined effects of the zonal and meridional moisture transport provided favorable conditions for the development of MCSs, and hence extreme rainfall over Semarang. These results provide useful precursors for extreme weather-driven hazard prediction in Semarang and the surrounding regions in the future.
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Sintorini, Margareta Maria. "Pengaruh Iklim terhadap Kasus Demam Berdarah Dengue." Kesmas: National Public Health Journal 2, no. 1 (August 1, 2007): 11. http://dx.doi.org/10.21109/kesmas.v2i1.279.
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Penyakit demam berdarah dengue (DBD) telah menjadi penyakit endemik di kota-kota besar di Indonesia. Ramalan Intergovernmental Panel on Climate Change tahun 1996 menyebutkan insidens DBD di Indonesia dapat meningkat tiga kali lipat pada tahun 2070. Tujuan penelitian ini untuk membuat model di- namika sistem dengan analisis ekologi untuk mengetahui dinamika kejadian DBD dalam kaitan dengan pola variablitas iklim di DKI Jakarta. Rancangan penelitian digunakan adalah ecologic study dengan uji hipotesis, permodelan, simulasi, dan intervensi. Wawancara terhadap 844 responden untuk mengetahui tingkat pengetahuan, sikap, dan perilaku (PSP) masyarakat. Pengukuran faktor iklim meliputi curah hujan, suhu, kelembaban, intensitas cahaya, dan kadar CO2. Aspek vektor yang diukur adalah angka hinggap per jam nyamuk Aedes (AHJ) dan nyamuk istirahat per rumah (NIR). Hasil penelitian menunjukkan kasus DBD dipengaruhi curah hujan (p:0,000..), suhu lingkungan (p:0,000..), kelembaban ruang (p:0,003), kelembaban lingkungan (p:0,000..), AHJ Aedes (p:0,016), NIR Aedes (p:0,000..) dan pengetahuan masyarakat (p:0,008). Disimpulkan, faktor iklim yang paling berpengaruh terhadap kasus DBD adalah curah hujan, suhu dan kelembaban serta pengetahuan masyarakat yang rendah. Sedangkan AHJ Aedes dapat dijadikan indikator kenaikan kasus DBD.Kata kunci: Demam berdarah dengue, perubahan iklimAbstractDengue hemorrhagic fever (DHF) has become endemic in many big cities in Indonesia. It was predicted by Intergovernmental Panel on Climate Change, that in 1996 the DHF in Indonesia in 2070 would be tripled. The objective of this research is to make a system dynamic model using ecological analysis to identify the dynamic of DHF cases related to the pattern of the climate variability in Jakarta. This research uses the design of ecological study with hypothesis testing, modeling, simulation, and intervention. Respondents of 844 households were interviewed to explore their knowledge, attitude and practice (KAP) regarding DHF using a standard questionnaire. Precipitation, humidity, light intensity and CO2 concentration were determined per week. AHJ (Man Landing Rate) and NIR (resting habit) were determined for Aedes population density. The results indicate that the DHF cases all are influenced by precipitation (0.000), temperature ambient (0.000), indoor humidity (0.003), outdoor humidity (0.000), AHJ (0.016), NIR (0.000), and knowledge (0.008). The most influencial climate factor to the DHF cases are precipitation, temperature, humidity and the low level of the community knowledge.Key words: Dengue hemorrhagic fever, climate change
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Hasibuan, A. M., E. Randriani, I. N. A. Wicaksono, Dani, and T. J. Santoso. "Local-adapted and high-yield varieties for sustainable Robusta coffee farming: Evidence from South Sumatera, Indonesia." IOP Conference Series: Earth and Environmental Science 974, no. 1 (January 1, 2022): 012130. http://dx.doi.org/10.1088/1755-1315/974/1/012130.
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Abstract Climate change causes an adverse impact on the coffee plantation as it directly influences the productivity and quality of coffee products. For the adaptation strategy, using superior variety is often considered an important step because it has potential attributes such as high yield and quality, and is more tolerant to certain environmental shocks. This study aims to analyze the environmental adaptability and financial feasibility of local Robusta coffee varieties. This study used data from field observations, surveys, and interviews of key informants in Ogan Komering Ulu Regency, South Sumatera, Indonesia from 2018-2021. Data were analyzed descriptively. Results showed that three local clones have high adaptability in the study site, even in a high precipitation rate. The varieties are financially feasible to be adopted by farmers, even though on a small scale. Sensitivity analysis with the scenario of decreasing the yield or increasing operational cost as the impact of climate variability about 10 percent showed the lower feasibility indicators (NPV, IRR, and Net B/C), but still higher than the minimum threshold so that still feasible and profitable for farmers. Hence, the three local clones are the potential to be developed for sustainable Robusta coffee plantations.
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Li, Gen, Shang-Ping Xie, and Yan Du. "Monsoon-Induced Biases of Climate Models over the Tropical Indian Ocean*." Journal of Climate 28, no. 8 (April 7, 2015): 3058–72. http://dx.doi.org/10.1175/jcli-d-14-00740.1.
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Abstract Long-standing biases of climate models limit the skills of climate prediction and projection. Overlooked are tropical Indian Ocean (IO) errors. Based on the phase 5 of the Coupled Model Intercomparison Project (CMIP5) multimodel ensemble, the present study identifies a common error pattern in climate models that resembles the IO dipole (IOD) mode of interannual variability in nature, with a strong equatorial easterly wind bias during boreal autumn accompanied by physically consistent biases in precipitation, sea surface temperature (SST), and subsurface ocean temperature. The analyses show that such IOD-like biases can be traced back to errors in the South Asian summer monsoon. A southwest summer monsoon that is too weak over the Arabian Sea generates a warm SST bias over the western equatorial IO. In boreal autumn, Bjerknes feedback helps amplify the error into an IOD-like bias pattern in wind, precipitation, SST, and subsurface ocean temperature. Such mean state biases result in an interannual IOD variability that is too strong. Most models project an IOD-like future change for the boreal autumn mean state in the global warming scenario, which would result in more frequent occurrences of extreme positive IOD events in the future with important consequences to Indonesia and East Africa. The Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) characterizes this future IOD-like projection in the mean state as robust based on consistency among models, but the authors’ results cast doubts on this conclusion since models with larger IOD amplitude biases tend to produce stronger IOD-like projected changes in the future.
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Stubenrauch, C. J., A. Chédin, G. Rädel, N. A. Scott, and S. Serrar. "Cloud Properties and Their Seasonal and Diurnal Variability from TOVS Path-B." Journal of Climate 19, no. 21 (November 1, 2006): 5531–53. http://dx.doi.org/10.1175/jcli3929.1.
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Abstract Eight years of cloud properties retrieved from Television Infrared Observation Satellite-N (TIROS-N) Observational Vertical Sounder (TOVS) observations aboard the NOAA polar orbiting satellites are presented. The relatively high spectral resolution of these instruments in the infrared allows especially reliable cirrus identification day and night. This dataset therefore provides complementary information to the International Satellite Cloud Climatology Project (ISCCP). According to this dataset, cirrus clouds cover about 27% of the earth and 45% of the Tropics, whereas ISCCP reports 19% and 25%, respectively. Both global datasets agree within 5% on the amount of single-layer low clouds, at 30%. From 1987 to 1995, global cloud amounts remained stable to within 2%. The seasonal cycle of cloud amount is in general stronger than its diurnal cycle and it is stronger than the one of effective cloud amount, the latter the relevant variable for radiative transfer. Maximum effective low cloud amount over ocean occurs in winter in SH subtropics in the early morning hours and in NH midlatitudes without diurnal cycle. Over land in winter the maximum is in the early afternoon, accompanied in the midlatitudes by thin cirrus. Over tropical land and in the other regions in summer, the maximum of mesoscale high opaque clouds occurs in the evening. Cirrus also increases during the afternoon and persists during night and early morning. The maximum of thin cirrus is in the early afternoon, then decreases slowly while cirrus and high opaque clouds increase. TOVS extends information of ISCCP during night, indicating that high cloudiness, increasing during the afternoon, persists longer during night in the Tropics and subtropics than in midlatitudes. A comparison of seasonal and diurnal cycle of high cloud amount between South America, Africa, and Indonesia during boreal winter has shown strong similarities between the two land regions, whereas the Indonesian islands show a seasonal and diurnal behavior strongly influenced by the surrounding ocean. Deeper precipitation systems over Africa than over South America do not seem to be directly reflected in the horizontal coverage and mesoscale effective emissivity of high clouds.
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Ismail, Ismail, Ali Torabi Haghighi, Hannu Marttila, Uun Kurniawan, Oka Karyanto, and Bjørn Kløve. "Water table variations on different land use units in a drained tropical peatland island of Indonesia." Hydrology Research 52, no. 6 (October 28, 2021): 1372–88. http://dx.doi.org/10.2166/nh.2021.062.
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Abstract Restoration and water table control on peatlands to limit fire risk are national priorities in Indonesia. The present study was initiated at Padang Island, Sumatra, to increase understanding on peatland hydrology in the tropic. At the pilot site, water table and precipitation were monitored at different stations. The results show variation in water table depths (WTDs) over time and space due to spatial and temporal variability in rain intensity and drainage networks. In part of the island, large-scale drainage for plantations led to deep WTD (−1.8 m) and high WTD recession rates (up to 3.5 cm/day). Around villages, farm-scale drainages had a smaller impact with a lower recession rate (up to 1.8 cm/day) and shallow WTD, typically below −0.4 m, the threshold for sustainable peatland management in Indonesia. The recession rates levelled off at 1.0 cm/day near the drained forest/plantation and at 0.5 cm/day near the farm. Deeper layers had much lower specific yield (Sy), 0.1 at −1.5 m depth, compared with top peat soils with Sy up to 0.3. Proximity to drainages extended discharge flow to deeper layers. The results highlighted the severity of peatland drainage impact on most coastal zones of Padang Island, which have intensive drainage networks.
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Schollaen, K., C. Karamperidou, P. Krusic, E. Cook, and G. Helle. "ENSO flavors in a tree-ring δ<sup>18</sup>O record of <i>Tectona grandis</i> from Indonesia." Climate of the Past 11, no. 10 (October 8, 2015): 1325–33. http://dx.doi.org/10.5194/cp-11-1325-2015.
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Abstract. Indonesia's climate is dominated by the equatorial monsoon system, and has been linked to El Niño-Southern Oscillation (ENSO) events that often result in extensive droughts and floods over the Indonesian archipelago. In this study we investigate ENSO-related signals in a tree-ring δ18O record (1900–2007) of Javanese teak. Our results reveal a clear influence of Warm Pool (central Pacific) El Niño events on Javanese tree-ring δ18O, and no clear signal of Cold Tongue (eastern Pacific) El Niño events. These results are consistent with the distinct impacts of the two ENSO flavors on Javanese precipitation, and illustrate the importance of considering ENSO flavors when interpreting palaeoclimate proxy records in the tropics, as well as the potential of palaeoclimate proxy records from appropriately selected tropical regions for reconstructing past variability of. ENSO flavors.
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Gitima, Ginjo, Abiyot Legesse, and Dereje Biru. "Assessing The Impacts of Climate Variability on Rural Households in Agricultural Land Through The Application of Livelihood Vulnerability Index." Geosfera Indonesia 6, no. 1 (April 30, 2021): 96. http://dx.doi.org/10.19184/geosi.v6i1.20718.
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Climate variability adversely affects rural households in Ethiopia as they depend on rain-fed agriculture, which is highly vulnerable to climate fluctuations and severe events such as drought and pests. In view of this, we have assessed the impacts of climate variability on rural household’s livelihoods in agricultural land in Tarchazuria district of Dawuro Zone. A total of 270 samples of household heads were selected using a multistage sampling technique with sample size allocation procedures of the simple random sampling method. Simple linear regression, the standard precipitation index, the coefficient of variance, and descriptive statistics were used to analyze climatic data such as rainfall and temperature. Two livelihood vulnerability analysis approaches, such as composite index and Livelihood Vulnerability Index-Intergovernmental Panel on Climate Change (LVI-IPCC) approaches, were used to analyze indices for socioeconomic and biophysical indicators. The study revealed that the variability patterns of rainfall and increasing temperatures had been detrimental effects on rural households' livelihoods. The result showed households of overall standardized, average scores of Wara Gesa (0.60) had high livelihood vulnerability with dominant major components of natural, physical, social capital, and livelihood strategies to climate-induced natural hazards than Mela Gelda (0.56). The LVI-IPCC analysis results also revealed that the rural households in Mela Gelda were more exposed to climate variability than Wara Gesa and slightly sensitive to climate variability, considering the health and knowledge and skills, natural capitals, and financial capitals of the households. Therefore, interventions including road infrastructure construction, integrated with watershed management, early warning information system, providing training, livelihood diversification, and SWC measures' practices should be a better response to climate variability-induced natural hazards.
Keywords: Households; Livelihood Vulnerability Index; climate variability; Tarchazuria District
Copyright (c) 2021 Geosfera Indonesia and Department of Geography Education, University of Jember
This work is licensed under a Creative Commons Attribution-Share A like 4.0 International License
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Wirasatriya, Anindya, Raden Dwi Susanto, Joga Dharma Setiawan, Fatwa Ramdani, Iskhaq Iskandar, Abd Rasyid Jalil, Ardiansyah Desmont Puryajati, Kunarso Kunarso, and Lilik Maslukah. "High Chlorophyll-a Areas along the Western Coast of South Sulawesi-Indonesia during the Rainy Season Revealed by Satellite Data." Remote Sensing 13, no. 23 (November 28, 2021): 4833. http://dx.doi.org/10.3390/rs13234833.
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The southern coast of South Sulawesi-Indonesia is known as an upwelling area occurring during dry season, which peaks in August. This upwelling area is indicated by high chlorophyll-a (Chl-a) concentrations due to a strong easterly wind-induced upwelling. However, the investigation of Chl-a variability is less studied along the western coast of South Sulawesi. By taking advantages of remote sensing data of Chl-a, sea surface temperature, surface wind, and precipitation, the present study firstly shows that along the western coast of South Sulawesi, there are two areas, which have high primary productivity occurring during the rainy season. The first area is at 119.0° E–119.5° E; 3.5° S–4.0° S, while the second area is at 119.0° E–119.5° E; 3.5° S–4.0° S. The maximum primary productivity in the first (second) area occurs in April (January). The generating mechanism of the high primary productivity along the western coast of South Sulawesi is different from its southern coast. The presence of river runoff in these two areas may bring anthropogenic organic compounds during the peak of rainy season, resulting in increased Chl-a concentration.
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Ricaud, P., J. P. Pommereau, J. L. Attié, E. Le Flochmoën, L. El Amraoui, H. Teyssèdre, V. H. Peuch, W. Feng, and M. P. Chipperfield. "Equatorial transport as diagnosed from nitrous oxide variability." Atmospheric Chemistry and Physics 9, no. 21 (November 2, 2009): 8173–88. http://dx.doi.org/10.5194/acp-9-8173-2009.
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Abstract. The mechanisms of transport on annual, semi-annual and quasi-biennial time scales in the equatorial (10° S–10° N) stratosphere are investigated using the nitrous oxide (N2O) measurements of the space-borne ODIN Sub-Millimetre Radiometer from November 2001 to June 2005, and the simulations of the three-dimensional chemical transport models MOCAGE and SLIMCAT. Both models are forced with analyses from the European Centre for Medium-range Weather Forecast, but the vertical transport is derived either from the forcing analyses by solving the continuity equation (MOCAGE), or from diabatic heating rates using a radiation scheme (SLIMCAT). The N2O variations in the mid-to-upper stratosphere at levels above 32 hPa are generally well captured by the models though significant differences appear with the observations as well as between the models, attributed to the difficulty of capturing correctly the slow upwelling associated with the Brewer-Dobson circulation. However, in the lower stratosphere, below 32 hPa, the observed variations are shown to be mainly seasonal with peak amplitude at 400–450 K (~17.5–19 km), totally missed by the models. The minimum N2O in June, out of phase by two months with the known minimum seasonal upwelling associated with the Brewer-Dobson circulation and moreover amplified over the Western Pacific compared to Africa is incompatible with the seasonal change of upwelling evoked to explain the O3 annual cycle in the same altitude range (Randel et al., 2007). Unless the 1.5 ppbv amplitude of N2O annual cycle in the upper troposphere is totally wrong, the explanation of the observed N2O annual cycle of 15 ppbv in the lower stratosphere requires another mechanism. A possible candidate for that might be the existence of a downward time-averaged mass flux above specific regions, as shown by Sherwood (2000) over Indonesia, required for compensating the energy sink resulting from the deep overshooting of cold and heavy air at high altitude over intense convective areas. But, since global models do currently not capture this subsidence, it must be recognised that a full explanation of the observations cannot be provided for the moment. However, the coincidence of the peak contrast between the Western Pacific and Africa with the maximum overshooting volume in May reported by the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar, suggests a strong influence of deep convection on the chemical composition of the tropical lower stratosphere up to 500 K (21 km).
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Islam, M., Andy Chan, Matthew Ashfold, Chel Ooi, and Majid Azari. "Effects of El-Niño, Indian Ocean Dipole, and Madden-Julian Oscillation on Surface Air Temperature and Rainfall Anomalies over Southeast Asia in 2015." Atmosphere 9, no. 9 (September 12, 2018): 352. http://dx.doi.org/10.3390/atmos9090352.
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The Maritime Continent (MC) is positioned between the Asian and Australian summer monsoons zone. The complex topography and shallow seas around it are major challenges for the climate researchers to model and understand it. It is also the centre of the tropical warm pool of Southeast Asia (SEA) and therefore the MC gets extra attention of the researchers. The monsoon in this area is affected by inter-scale ocean-atmospheric interactions such as the El-Niño Southern Oscillation (ENSO), the Indian Ocean Dipole (IOD), and the Madden-Julian Oscillation (MJO). Monsoon rainfall in the MC (especially in Indonesia and Malaysia) profoundly exhibits its variability dependence on ocean-atmospheric phenomena in this region. This monsoon shift often introduces to dreadful events like biomass burning (BB) in Southeast Asia (SEA) in which some led to severe trans-boundary haze pollution events in the past. In this study, the BB episode of 2015 in the MC is highlighted and discussed. Observational satellite datasets are tested by performing simulations with the numerical weather prediction (NWP) model WRF-ARW (Weather Research and Forecast—Advanced research WRF). Observed and model datasets are compared to study the surface air temperature and precipitation (rainfall) anomalies influenced by ENSO, IOD, and MJO. Links amongst these influences have been recognised and the delayed precipitation of the regular monsoon in the MC due to their influence during the 2015 BB episode is explained and accounted for, which eventually led to the intensification of fire and a severe haze.
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Gusyev, Maksym, Akira Hasegawa, Jun Magome, Patricia Sanchez, Ai Sugiura, Hitoshi Umino, Hisaya Sawano, and Yoshio Tokunaga. "Evaluation of Water Cycle Components with Standardized Indices Under Climate Change in the Pampanga, Solo and Chao Phraya Basins." Journal of Disaster Research 11, no. 6 (December 1, 2016): 1091–102. http://dx.doi.org/10.20965/jdr.2016.p1091.
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Drought is a slow-developing disaster of water shortages in water cycle components adversely affecting anthropogenic water use. This study introduces a drought assessment framework of standardized indices in Pampanga (Philippines), Solo (Indonesia), and Chao Phraya (Thailand) basins. We used three existing and developed two new standardized indices to characterize meteorological, agricultural, hydrological and socio-economic droughts. We constructed a 15-arcsec (about 0.45-km) grid block-wise TOP (BTOP) model with multipurpose dam operation at individual river basin using global datasets and calibrated BTOP models with daily river discharge and dam inflow data. The simulated irrigated area is also compared with historical drought damages at each river basin. The calibrated BTOP models were run with bias-corrected MRI-AGCM3.2S precipitation to evaluate droughts under climate change. The calculated standardized indices show similar drought timing of the 1982-1983, 1987-1988, 1991-1992, 1997-1998 and 2002-2003 droughts across three river basins. In addition, the timing of these droughts coincides with historical El Niño-Southern Oscillation (ENSO) cycle events. The projected future climates demonstrate a variability of dam inflows and drought severities between four cases of the worst (RCP8.5) climate change scenario. We conclude that standardized indices are useful tools to characterize droughts at water cycle components.
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Amnuaylojaroen, T., M. C. Barth, L. K. Emmons, G. R. Carmichael, J. Kreasuwun, S. Prasitwattanaseree, and S. Chantara. "Effect of different emission inventories on modeled ozone and carbon monoxide in Southeast Asia." Atmospheric Chemistry and Physics Discussions 14, no. 7 (April 7, 2014): 9345–400. http://dx.doi.org/10.5194/acpd-14-9345-2014.
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Abstract. In order to improve our understanding of air quality in Southeast Asia, the anthropogenic emissions inventory must be well represented. In this work, we apply different anthropogenic emission inventories in the Weather Research and Forecasting Model with Chemistry (WRF-Chem) version 3.3 using MOZART gas-phase chemistry and GOCART aerosols to examine the differences in predicted carbon monoxide (CO) and ozone (O3) surface mixing ratios for Southeast Asia in March and December 2008. The anthropogenic emission inventories include the Reanalysis of the TROpospheric chemical composition (RETRO), the Intercontinental Chemical Transport Experiment-Phase B (INTEX-B), the MACCity emissions (adapted from the Monitoring Atmospheric Composition and Climate and megacity Zoom for the Environment projects), the Southeast Asia Composition, Cloud, Climate Coupling Regional Study (SEAC4RS) emissions, and a combination of MACCity and SEAC4RS emissions. Biomass burning emissions are from the Fire Inventory from NCAR (FINNv1) model. WRF-chem reasonably predicts the 2 m temperature, 10 m wind, and precipitation. In general, surface CO is underpredicted by WRF-Chem while surface O3 is overpredicted. The NO2 tropospheric column predicted by WRF-Chem has the same magnitude as observations, but tends to underpredict NO2 column over the equatorial ocean and near Indonesia. Simulations using different anthropogenic emissions produce only a slight variability of O3 and CO mixing ratios, while biomass burning emissions add more variability. The different anthropogenic emissions differ by up to 20% in CO emissions, but O3 and CO mixing ratios differ by ~4.5% and ~8%, respectively, among the simulations. Biomass burning emissions create a substantial increase for both O3 and CO by ~29% and ~16%, respectively, when comparing the March biomass burning period to December with low biomass burning emissions. The simulations show that none of the anthropogenic emission inventories are better than the others and any of the examined inventories can be used for air quality simulations in Southeast Asia.
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Amnuaylojaroen, T., M. C. Barth, L. K. Emmons, G. R. Carmichael, J. Kreasuwun, S. Prasitwattanaseree, and S. Chantara. "Effect of different emission inventories on modeled ozone and carbon monoxide in Southeast Asia." Atmospheric Chemistry and Physics 14, no. 23 (December 8, 2014): 12983–3012. http://dx.doi.org/10.5194/acp-14-12983-2014.
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Abstract. In order to improve our understanding of air quality in Southeast Asia, the anthropogenic emissions inventory must be well represented. In this work, we apply different anthropogenic emission inventories in the Weather Research and Forecasting Model with Chemistry (WRF-Chem) version 3.3 using Model for Ozone and Related Chemical Tracers (MOZART) gas-phase chemistry and Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) aerosols to examine the differences in predicted carbon monoxide (CO) and ozone (O3) surface mixing ratios for Southeast Asia in March and December 2008. The anthropogenic emission inventories include the Reanalysis of the TROpospheric chemical composition (RETRO), the Intercontinental Chemical Transport Experiment-Phase B (INTEX-B), the MACCity emissions (adapted from the Monitoring Atmospheric Composition and Climate and megacity Zoom for the Environment projects), the Southeast Asia Composition, Cloud, Climate Coupling Regional Study (SEAC4RS) emissions, and a combination of MACCity and SEAC4RS emissions. Biomass-burning emissions are from the Fire Inventory from the National Center for Atmospheric Research (NCAR) (FINNv1) model. WRF-Chem reasonably predicts the 2 m temperature, 10 m wind, and precipitation. In general, surface CO is underpredicted by WRF-Chem while surface O3 is overpredicted. The NO2 tropospheric column predicted by WRF-Chem has the same magnitude as observations, but tends to underpredict the NO2 column over the equatorial ocean and near Indonesia. Simulations using different anthropogenic emissions produce only a slight variability of O3 and CO mixing ratios, while biomass-burning emissions add more variability. The different anthropogenic emissions differ by up to 30% in CO emissions, but O3 and CO mixing ratios averaged over the land areas of the model domain differ by ~4.5% and ~8%, respectively, among the simulations. Biomass-burning emissions create a substantial increase for both O3 and CO by ~29% and ~16%, respectively, when comparing the March biomass-burning period to the December period with low biomass-burning emissions. The simulations show that none of the anthropogenic emission inventories are better than the others for predicting O3 surface mixing ratios. However, the simulations with different anthropogenic emission inventories do differ in their predictions of CO surface mixing ratios producing variations of ~30% for March and 10–20% for December at Thai surface monitoring sites.
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Zhang, Yuhong, Yan Du, and Ming Feng. "Multiple Time Scale Variability of the Sea Surface Salinity Dipole Mode in the Tropical Indian Ocean." Journal of Climate 31, no. 1 (December 15, 2017): 283–96. http://dx.doi.org/10.1175/jcli-d-17-0271.1.
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Abstract In this study, multiple time scale variability of the salinity dipole mode in the tropical Indian Ocean (S-IOD) is revealed based on the 57-yr Ocean Reanalysis System 4 (ORAS4) sea surface salinity (SSS) reanalysis product and associated observations. On the interannual time scale, S-IOD is highly correlated with strong Indian Ocean dipole (IOD) and ENSO variability, with ocean advection forced by wind anomalies along the equator and precipitation anomalies in the southeastern tropical Indian Ocean (IO) dominating the SSS variations in the northern and southern poles of the S-IOD, respectively. S-IOD variability is also associated with the decadal modulation of the Indo-Pacific Walker circulation, with a stronger signature at its southern pole. Decadal variations of the equatorial IO winds and precipitations in the central IO force zonal ocean advection anomalies that contribute to the SSS variability in the northern pole of S-IOD on the decadal time scale. Meanwhile, oceanic dynamics dominates the SSS variability in the southern pole of S-IOD off Western Australia. Anomalous ocean advection transports the fresher water from low latitudes to the region off Western Australia, with additional contributions from the Indonesian Throughflow. Furthermore, the southern pole of S-IOD is associated with the thermocline variability originated from the tropical northwestern Pacific through the waveguide in the Indonesian Seas, forced by decadal Pacific climate variability. A deepening (shoaling) thermocline strengthens (weakens) the southward advection of surface freshwater into the southern pole of S-IOD and contributes to the high (low) SSS signatures off Western Australia.
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Sarathchandraprasad, T., Manish Tiwari, and Padmasini Behera. "South Asian Summer Monsoon precipitation variability during late Pliocene: Role of Indonesian Throughflow." Palaeogeography, Palaeoclimatology, Palaeoecology 574 (July 2021): 110447. http://dx.doi.org/10.1016/j.palaeo.2021.110447.
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Maryunani, Khoiril Anwar. "Microfossil as proxy for palaeoclimate and palaeoceanography." Berita Sedimentologi 47, no. 3 (December 28, 2021): 77–78. http://dx.doi.org/10.51835/bsed.2021.47.3.363.
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Recent global warming has been addressed due to human activity that causes increased greenhouse gases. However, there are inherent uncertainties in the statement, one of them is the level of natural variability inherent in the climate system. Climate data from measuring instruments are not long enough to evaluate climate variability and current climate evolution. Therefore, we need climate data that has a long back span. To get adequate past climate data, we need natural phenomena which are climate dependent. This natural phenomenon provides a proxy record of the climate. This study of proxy data is the foundation of palaeoclimatology and paleoceanography. Microfossils (i.e., foraminifera, palynomorphs, nannofossils) which in geology are used as a standard tool in biostratigraphy for both age determination and paleoenvironment and correlation, can also be used as a proxy for obtaining paleoclimate and paleoceanography data. Using microfossil as a proxy to study past climate and paleoceanography, we need an understanding of the type of proxy data available and methods used in their analysis.In addition to the dating method (biostratigraphy), there are many climate and oceanography parameters that can be obtained from microfossil proxies such as: sea surface temperature (SST), sea surface salinity, (SST) climate (warm, cold, dry, wet), precipitation, productivity, oxygen content and organic carbon level, deep sea current and ventilation/upwelling, thermocline and mixed layer, variability deep water properties, CCD, bathymetry, sea level change and dissolution. The methods to obtain data fall into some categories e.g., faunal/floral displacement, morphology changes, transfer function/modern analog and isotopic content. Another method that can be used is observing microfossil assemblages and link them to ecological changes associated with climate change and its paleoceanography.A paleoclimate and paleoceanography study using microfossil proxies has been conducted in the Cendrawasih bay, Papua, Indonesia. The study shows that climate in the tropical west Pacific margin (Cendrawasih bay) during Late Pleistocene to Holocene shows high variability. There are nineteen climate changes occurred during Holocene. Early Holocene dated as ca. 11,800-year BP marked by rapid warming with SST differences to last glacial is about 4oC. Early to Middle Holocene (ca. 5960-year BP) marked by increasing temperature up to 2oC, interrupted by cooling at ca. 11230-, 8310- and 7120-years BP. At Middle Holocene temperature decreased rapidly and reached its peak at around ca. 3150-year BP. After cooling at ca. 3150-year BP, temperature increased and then decreased with its peak at ca. 1710-year BP. Since ca. 1710-year BP to Recent, temperature shows warming trend. SST from MAT indicates warming environment near to 1.5oC. The warming trend was interrupted by rapid cooling and warming at ca. 300-year BP. This last warming trend indicates that global warming had started before industrial era and rapid cooling, or warming can occur without anthropogenic gases influence. The typical Holocene climate of warm-wet, dry-cold reverse and become warm-dry, cold-wet during ca. 790-370-year BP and then reversed back to preceding state.Semi-restricted basin occurred since last glacial with anaerobic condition and estuarine circulation system. Warming during interstadial 1e-1a, causing reverse water circulation and basin become sub-aerobic with anti-estuarine circulation. A lot of terrestrial organic matter flow to the bay and increase acidity and carbonate dissolution. High sedimentation found occurred during glacial period especially at the end of glacial period. Rapid warming during late glacial to middle Holocene, rising relative sea level and the bay become more open marine with well oxygenated bottom water and high marine productivity. Warm temperature and deeper thermocline depth (~ 250 m) in west Pacific occurred up to ca. 5960-year BP. Decreasing Sea surface temperature at ca. 5960-year BP and drop of relative sea level causing sub-aerobic condition inside bay. The semi-restricted state with sub-aerobic condition occurred up to Recent.Distribution of Sphaeroidinella group in the tropical west Pacific shows strong correlation with thermocline depth and reflect El Niño frequency event. Early middle Holocene dominated by La Niña-like condition and since Middle Holocene (ca. 5960-year BP) frequent El Niño event began to occur.
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Ramadhan, Ravidho, Marzuki Marzuki, Helmi Yusnaini, Robi Muharsyah, Wiwit Suryanto, Sholihun Sholihun, Mutya Vonnisa, Alessandro Battaglia, and Hiroyuki Hashiguchi. "Capability of GPM IMERG Products for Extreme Precipitation Analysis over the Indonesian Maritime Continent." Remote Sensing 14, no. 2 (January 17, 2022): 412. http://dx.doi.org/10.3390/rs14020412.
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Integrated Multi-satellite Retrievals for GPM (IMERG) data have been widely used to analyze extreme precipitation, but the data have never been validated for the Indonesian Maritime Continent (IMC). This study evaluated the capability of IMERG Early (E), Late (L), and Final (F) data to observe extreme rain in the IMC using the rain gauge data within five years (2016–2020). The capability of IMERG in the observation of the extreme rain index was evaluated using Kling–Gupta efficiency (KGE) matrices. The IMERG well captured climatologic characteristics of the index of annual total precipitation (PRCPTOT), number of wet days (R85p), number of very wet days (R95p), number of rainy days (R1mm), number of heavy rain days (R10mm), number of very heavy rain days (R20mm), consecutive dry days (CDD), and max 5-day precipitation (RX5day), indicated by KGE value >0.4. Moderate performance (KGE = 0–0.4) was shown in the index of the amount of very extremely wet days (R99p), the number of extremely heavy precipitation days (R50mm), max 1-day precipitation (RX1day), and Simple Daily Intensity Index (SDII). Furthermore, low performance of IMERG (KGE < 0) was observed in the consecutive wet days (CWDs) index. Of the 13 extreme rain indices evaluated, IMERG underestimated and overestimated precipitation of nine and four indexes, respectively. IMERG tends to overestimate precipitation of indexes related to low rainfall intensity (e.g., R1mm). The highest overestimation was observed in the CWD index, related to the overestimation of light rainfall and the high false alarm ratio (FAR) from the daily data. For all indices of extreme rain, IMERG showed good capability to observe extreme rain variability in the IMC. Overall, IMERG-L showed a better capability than IMERG-E and -F but with an insignificant difference. Thus, the data of IMERG-E and IMERG-L, with a more rapid latency than IMERG-F, have great potential to be used for extreme rain observation and flood modeling in the IMC.
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Song, Qian, Gabriel A. Vecchi, and Anthony J. Rosati. "The Role of the Indonesian Throughflow in the Indo–Pacific Climate Variability in the GFDL Coupled Climate Model." Journal of Climate 20, no. 11 (June 1, 2007): 2434–51. http://dx.doi.org/10.1175/jcli4133.1.
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Abstract The impacts of the Indonesian Throughflow (ITF) on the tropical Indo–Pacific climate, particularly on the character of interannual variability, are explored using a coupled general circulation model (CGCM). A pair of CGCM experiments—a control experiment with an open ITF and a perturbation experiment in which the ITF is artificially closed—is integrated for 200 model years, with the 1990 values of trace gases. The closure of the ITF results in changes to the mean oceanic and atmospheric conditions throughout the tropical Indo–Pacific domain as follows: surface temperatures in the eastern tropical Pacific (Indian) Ocean warm (cool), the near-equatorial Pacific (Indian) thermocline flattens (shoals), Indo–Pacific warm-pool precipitation shifts eastward, and there are relaxed trade winds over the tropical Pacific and anomalous surface easterlies over the equatorial Indian Ocean. The character of the oceanic changes is similar to that described by ocean-only model experiments, though the amplitude of many features in the tropical Indo–Pacific is amplified in the CGCM experiments. In addition to the mean-state changes, the character of tropical Indo–Pacific interannual variability is substantially modified. Interannual variability in the equatorial Pacific and the eastern tropical Indian Ocean is substantially intensified by the closure of the ITF. In addition to becoming more energetic, El Niño–Southern Oscillation (ENSO) exhibits a shorter time scale of variability and becomes more skewed toward its warm phase (stronger and more frequent warm events). The structure of warm ENSO events changes; the anomalies of sea surface temperature (SST), precipitation, and surface westerly winds are shifted to the east and the meridional extent of surface westerly anomalies is larger. In the eastern tropical Indian Ocean, the interannual SST variability off the coast of Java–Sumatra is noticeably amplified by the occurrence of much stronger cooling events. Closing the ITF shoals the eastern tropical Indian Ocean thermocline, which results in stronger cooling events through enhanced atmosphere–thermocline coupled feedbacks. Changes to the interannual variability caused by the ITF closure rectify into mean-state changes in tropical Indo–Pacific conditions. The modified Indo–Pacific interannual variability projects onto the mean-state differences between the ITF open and closed scenarios, rectifying into mean-state differences. These results suggest that CGCMs need to reasonably simulate the ITF in order to successfully represent not just the mean climate, but its variations as well.
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Sachoemar, Suhendar. "VARIABILITY OF SEA SURFACE CHLOROPHYLL-A, TEMPERATURE AND FISH CATCH WITHIN INDONESIAN REGION REVEALED BY SATELLITE DATA." Marine Research in Indonesia 37, no. 2 (March 4, 2015): 75–87. http://dx.doi.org/10.14203/mri.v37i2.25.
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The investigation of sea surface chlorophyll-a (SSC) and sea surface temperature (SST) in relation to fish catch variability within the Indonesian region were conducted by using satellite data of NOAA-AVHRR, SeaWiFs and Aqua MODIS. The investigation focused in the region of the coastal area of Java, Lampung Bay and South Kalimantan as representation of the environment diversities of the Indonesian seas. The result shows that seasonal variation in fish productivity has a strong correlation with SSC variability. High fish productivity corresponded well with high concentration of SSC, and the productivity tended to decrease when the SSC concentration was declined. High SSC variability in the coastal area of Java and Lampung Bay was governed by the upwelling that induced high nutrient load into the sea surface during the southeast monsoon, while in the northern coastal area of Java and South Kalimantan, it was governed by high precipitation ocurring during the northwest monsoon that enhanced the nutrient load through the rivers and coastal discharge.
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Susilokarti, Dyah, Sigit Supadmo Arif, Sahid Susanto, and Lilik Sutiarso. "IDENTIFIKASI PERUBAHAN IKLIM BERDASARKAN DATA CURAH HUJAN DI WILAYAH SELATAN JATILUHUR KABUPATEN SUBANG, JAWA BARAT (Identification of Climate Change Based on Rainfall Data in Southern Part of Jatiluhur, Subang District, West Jawa)." Jurnal Agritech 35, no. 01 (May 4, 2015): 98. http://dx.doi.org/10.22146/agritech.13038.
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Indonesian region is strongly influenced by the monsoon climatic conditions have obvious difference between wetseason and dry season. Climate variability and extreme climate phenomenon that often happens lately caused climatechange. Climate change is characterized by changes in rainfall patterns and its causes shifting early in the season thatmake it difficult to plan cultivation. It is therefore necessary to study the behavior of the climate through rainfall timeseries analysis. Statistical tests performed using the F test and t test. This study aims to identify climate change throughpattern trends, distribution and similarity of rainfall data at different timescales, using rainfall data rainy season (Octoberto March) and the dry season (April to September) year period from 1975 to 2012. Data obtained from 6 (six) graduatedrainfall stations around the study site those are Kalijati, Curugagung, Cinangling, Dangdeur, Subang and Pegaden. Dataare grouped in 10-year period with a 4-year timing differences in accordance with the rules of the moving average. Theperiod 1975 -1984 was indicated as an initial period as a basis to look for changes in rainfall patterns that occur. F testshows there has been a change in the distribution of rainfall in every period than normal period. T test showed there hasbeen a change in the pattern of rainfall in the dry season period from 1987 to 1996. While the rainy season is startingto look at the period from 1995 to 2004. Rainy season and the dry season period (1995-2004) shows a similar patternwith the normal period (1975 -1984) so that it is possible in a certain period of climate change on the location of thecycle is approaching normal conditions.Keywords: Time seriesanalysis,precipitation, climatechange, Subangdistrict ABSTRAKWilayah Indonesia sangat dipengaruhi oleh kondisi iklim monsun yang mempunyai perbedaan yang jelas antaramusim basah dan musim kering.Variabilitas iklim dan adanya fenomena iklim ekstrim yang sering terjadi akhir akhirini menyebabkan terjadinya perubahan iklim. Perubahan iklim ditandai adanya perubahan pola curah hujan yangmenyebabkan terjadinya pergeseran awal musim tanam sehingga sulit membuat perencanaan budidaya tanaman. Olehkarena itu perlu dilakukan kajian prilaku iklim melalui analisis deret waktu curah hujan.Uji statistik dilakukan denganmenggunakan uji F dan uji t. Penelitian ini bertujuan untuk mengidentifikasi terjadinya perubahan iklim melalui polakecenderungan, distribusi dan kesamaan data curah hujan pada rentang waktu yang berbeda, menggunakan data curahhujan musim hujan (Oktober – Maret) dan musim kemarau (April – September) periode tahun 1975 – 2012. Datadiperoleh dari 6 stasiun penakar curah hujan di sekitar lokasi penelitian yaitu stasiun Kalijati, Curug agung, Cinangling,Dangdeur, Subang dan Pegaden. Data dikelompokkan dalam periode 10 tahunan dengan beda waktu 4 tahun sesuaidengan aturanmovingaverage. Periode tahun 1975 -1984 menjadi periode awal sebagai dasar untuk melihat perubahanpola curah hujan yang terjadi. Uji F menunjukkan telah terjadi perubahan distribusi curah hujan disetiap periodedibanding periode normalnya. Uji t menunjukkan telah terjadi perubahan pola curah hujan musim kemarau sejakperiode tahun 1987 – 1996. Sedangkan musim hujan mulai terlihat pada periode tahun 1995 – 2004. Musim hujandan musim kemarau periode (1995-2004) menunjukkan pola yang sama dengan periode normal (1975-1984) sehinggadimungkinkan pada periode tertentu siklus perubahan iklim pada lokasi ini mendekati kondisi normal.Kata kunci: Analisis deret waktu, curah hujan, perubahan iklim, kabupaten Subang
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Rogers, Cassandra Denise Wilks, and Jason Beringer. "Describing rainfall in northern Australia using multiple climate indices." Biogeosciences 14, no. 3 (February 7, 2017): 597–615. http://dx.doi.org/10.5194/bg-14-597-2017.
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Abstract. Savanna landscapes are globally extensive and highly sensitive to climate change, yet the physical processes and climate phenomena which affect them remain poorly understood and therefore poorly represented in climate models. Both human populations and natural ecosystems are highly susceptible to precipitation variation in these regions due to the effects on water and food availability and atmosphere–biosphere energy fluxes. Here we quantify the relationship between climate phenomena and historical rainfall variability in Australian savannas and, in particular, how these relationships changed across a strong rainfall gradient, namely the North Australian Tropical Transect (NATT). Climate phenomena were described by 16 relevant climate indices and correlated against precipitation from 1900 to 2010 to determine the relative importance of each climate index on seasonal, annual and decadal timescales. Precipitation trends, climate index trends and wet season characteristics have also been investigated using linear statistical methods. In general, climate index–rainfall correlations were stronger in the north of the NATT where annual rainfall variability was lower and a high proportion of rainfall fell during the wet season. This is consistent with a decreased influence of the Indian–Australian monsoon from the north to the south. Seasonal variation was most strongly correlated with the Australian Monsoon Index, whereas yearly variability was related to a greater number of climate indices, predominately the Tasman Sea and Indonesian sea surface temperature indices (both of which experienced a linear increase over the duration of the study) and the El Niño–Southern Oscillation indices. These findings highlight the importance of understanding the climatic processes driving variability and, subsequently, the importance of understanding the relationships between rainfall and climatic phenomena in the Northern Territory in order to project future rainfall patterns in the region.
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Syaifullah, M. Djazim, Fikri Nur Muhammad, Ibnu Athoillah, and Samba Wirahma. "ANALISIS VARIABILITAS CURAH HUJAN KOTA MARTAPURA KALIMANTAN SELATAN AKIBAT PERUBAHAN IKLIM." Jurnal Sains & Teknologi Modifikasi Cuaca 15, no. 1 (June 27, 2014): 1. http://dx.doi.org/10.29122/jstmc.v15i1.2650.
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IntisariNegara Indonesia merupakan Negara Kepulauan yang terletak di Khatulistiwa sehingga rentan terhadap perubahan iklim.Curah hujan yang terjadi di suatu tempat dipengaruhi oleh faktor alam dan topografi daerah tersebut. Dengan melihat histori kejadian hujan selama 70 tahun (1915 – 2000) akan mengetahui pola hujan distribusi curah hujan suatu wilayah. Untuk memperoleh hasil tersebut digunakan analisa regresi. Dalam analisa tersebut didapatkan dari tahun 1915 sampai dengan tahun 2000 untuk stasiun di Kota Martapura menunjukan pola kecerendungan kenaikan 4,5898 mm/tahun dengan persamaan regresi Y=4.5898 X-6600.4 with R2=0.0513.AbstractState of Indonesia is a country located on the equator that are vulnerable to climate change. Rainfall (precipitation) that occurs in a place influenced by nature and topography of the area. By knowing historical rainfall events during 70 years (1915-2000) will determine the distribution pattern of rainfall in the area. To obtain the result about distribution pattern used regression analysis. In the regression analysis obtained that from 1915 until 2000 year for station in Martapura shows the rise pattern 4,5898 mm/years with a regression equation Y=4.5898 X-6600.4 with R2=0.0513.
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Parker, Sarah E., Sandy P. Harrison, Laia Comas-Bru, Nikita Kaushal, Allegra N. LeGrande, and Martin Werner. "A data–model approach to interpreting speleothem oxygen isotope records from monsoon regions." Climate of the Past 17, no. 3 (June 4, 2021): 1119–38. http://dx.doi.org/10.5194/cp-17-1119-2021.
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Abstract. Reconstruction of past changes in monsoon climate from speleothem oxygen isotope (δ18O) records is complex because δ18O signals can be influenced by multiple factors including changes in precipitation, precipitation recycling over land, temperature at the moisture source, and changes in the moisture source region and transport pathway. Here, we analyse >150 speleothem records of the Speleothem Isotopes Synthesis and AnaLysis (SISAL) database to produce composite regional trends in δ18O in monsoon regions; compositing minimises the influence of site-specific karst and cave processes that can influence individual site records. We compare speleothem δ18O observations with isotope-enabled climate model simulations to investigate the specific climatic factors causing these regional trends. We focus on differences in δ18O signals between the mid-Holocene, the peak of the Last Interglacial (Marine Isotope Stage 5e) and the Last Glacial Maximum as well as on δ18O evolution through the Holocene. Differences in speleothem δ18O between the mid-Holocene and the Last Interglacial in the East Asian and Indian monsoons are small, despite the larger summer insolation values during the Last Interglacial. Last Glacial Maximum δ18O values are significantly less negative than interglacial values. Comparison with simulated glacial–interglacial δ18O shows that changes are principally driven by global shifts in temperature and regional precipitation. Holocene speleothem δ18O records show distinct and coherent regional trends. Trends are similar to summer insolation in India, China and southwestern South America, but they are different in the Indonesian–Australian region. Redundancy analysis shows that 37 % of Holocene variability can be accounted for by latitude and longitude, supporting the differentiation of records into individual monsoon regions. Regression analysis of simulated precipitation δ18O and climate variables show significant relationships between global Holocene monsoon δ18O trends and changes in precipitation, atmospheric circulation and (to a lesser extent) source area temperature, whereas precipitation recycling is non-significant. However, there are differences in regional-scale mechanisms: there are clear relationships between changes in precipitation and δ18O for India, southwestern South America and the Indonesian–Australian regions but not for the East Asian monsoon. Changes in atmospheric circulation contribute to δ18O trends in the East Asian, Indian and Indonesian–Australian monsoons, and a weak source area temperature effect is observed over southern and central America and Asia. Precipitation recycling is influential in southwestern South America and southern Africa. Overall, our analyses show that it is possible to differentiate the impacts of specific climatic mechanisms influencing precipitation δ18O and use this analysis to interpret changes in speleothem δ18O.
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Nazemosadat, M. J., and H. Ghaedamini. "On the Relationships between the Madden–Julian Oscillation and Precipitation Variability in Southern Iran and the Arabian Peninsula: Atmospheric Circulation Analysis." Journal of Climate 23, no. 4 (February 15, 2010): 887–904. http://dx.doi.org/10.1175/2009jcli2141.1.
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Abstract The influence of the Madden–Julian oscillation (MJO) on daily, monthly, and seasonal precipitation was investigated for southern Iran and the Arabian Peninsula using November–April data for the period of 1979–2005. The positive MJO phase is considered to be the periods for which the enhanced convection center was placed over the south Indonesian–north Australian region. On the other hand, the convection center shifts over the western Indian Ocean tropics and most of the study area as the negative MJO phase prevails. Seasonal precipitation and the frequency of wet events were significantly increased during the negative phase. The ratios of the precipitation amount during the negative phase to the corresponding values during the positive phase were about 1.75–2.75 and 2.75–4.00 for the southwestern and southeastern parts of Iran, respectively. This ratio reached to about 3.00 for Riyadh, 4.20 and 5.50 for Masqat and Doha, 2.10 for Kuwait, and 1.20 for Bahrain. The results of the seasonal and monthly analysis were generally found to be consistent, although because of the smaller sample size the outcomes of the monthly investigations were less statistically significant. While the negative MJO phase does not have a consistent effect on March precipitation over some parts of southern Iran, it has consistently enhanced precipitation over the eastern and southern coasts of the peninsula in Oman, Yemen, and Saudi Arabia. During the negative MJO phase, while enhanced low-level southerly winds transfer a substantial amount of moisture to the study area, upward motion increases in the middle layers of the atmosphere. Synchronized with the prevalence of these rain-bearing southerly winds, the existence of a strong horizontal wind speed gradient at the exit region of the North Africa–Arabian jet enhances precipitation. The jet exit, which was mostly located over Egypt in November, moved westward into the study area in Iran and Saudi Arabia during the rainy period of January–March. The direction of near-surface wind anomalies changed from mostly southeasterly in November to southwesterly in March and April, influencing precipitation pattern during various months of the rainy season. In contrast to the negative phase, an enhanced low-level dry northerly wind and suppressed horizontal wind speed gradient at the jet exits are the main characteristics of atmospheric circulation over the study area during the positive MJO phase. Furthermore, an increased downward air motion at the middle levels of the atmosphere and a significant shortage in precipitation are the other climatic components of the southwest Asian region during such a period.
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Izumo, Takeshi, Clémentde Boyer Montégut, Jing-Jia Luo, Swadhin K. Behera, Sébastien Masson, and Toshio Yamagata. "The Role of the Western Arabian Sea Upwelling in Indian Monsoon Rainfall Variability." Journal of Climate 21, no. 21 (November 1, 2008): 5603–23. http://dx.doi.org/10.1175/2008jcli2158.1.
Full textAbstract:
Abstract The Indian summer monsoon rainfall has complex, regionally heterogeneous, interannual variations with huge socioeconomic impacts, but the underlying mechanisms remain uncertain. The upwelling along the Somalia and Oman coasts starts in late spring, peaks during the summer monsoon, and strongly cools the sea surface temperature (SST) in the western Arabian Sea. They restrict the westward extent of the Indian Ocean warm pool, which is the main moisture source for the monsoon rainfall. Thus, variations of the Somalia–Oman upwelling can have significant impacts on the moisture transport toward India. Here the authors use both observations and an advanced coupled atmosphere–ocean general circulation model to show that a decrease in upwelling strengthens monsoon rainfall along the west coast of India by increasing the SST along the Somalia–Oman coasts, and thus local evaporation and water vapor transport toward the Indian Western Ghats (mountains). Further observational analysis reveals that such decreases in upwelling are caused by anomalously weak southwesterly winds in late spring over the Arabian Sea that are due to warm SST/increased precipitation anomalies over the Seychelles–Chagos thermocline ridge of the southwestern Indian Ocean (and vice versa for years with strong upwelling/weak west Indian summer monsoon rainfall). The latter SST/precipitation anomalies are often related to El Niño conditions and the strength of the Indonesian–Australian monsoon during the previous winter. This sheds new light on the ability to forecast the poorly predicted Indian monsoon rainfall on a regional scale, helped by a proper ocean observing/forecasting system in the western tropical Indian Ocean.