Journal articles on the topic 'Atmospheric circulation Vietnam Charts'
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1
RAJEEVAN, M., and P. P. BUTALA. "A preliminary study on the variability of post monsoon Tropical cyclone activity over the north Indian Ocean." MAUSAM 41, no. 3 (February 24, 2022): 71–76. http://dx.doi.org/10.54302/mausam.v41i3.2724.
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By the composite method, the long period seasonal mean charts of flow features at 850 hPa and 200 hPa, vertical wind shear and monthly (September) mean charts of SST anomaly for periods with large term activity and small storm activity were constructed to examine the circulation features associated with inter-annual variability of post monsoon (October-December) tropical cyclone activity over the north Indian Ocean. It was found that the prominent circulation features for the periods with small storm activity are: Absence of ITCZ at 850 hPa north of 5°N, weaker upper level subtropical westerlies, southward shift of 200 hPa ridge and relatively larger vertical wind shear over most of the oceanic area. Negative SST anomalies during the month of September also tend to be unfavorable for the formation of storms.
A hypothesis is made for the causes of these circulation changes and SST anomalies. Changes in intensity of monsoon circulation. Cause to develop SST anomalies. These SST anomalies affect the atmosphere by large scale ocean-atmospheric interaction and thus creates an environment favorable or unfavorable for storm development.
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Phan-Van, Tan, Thanh Nguyen-Xuan, Hiep Van Nguyen, Patrick Laux, Ha Pham-Thanh, and Thanh Ngo-Duc. "Evaluation of the NCEP Climate Forecast System and Its Downscaling for Seasonal Rainfall Prediction over Vietnam." Weather and Forecasting 33, no. 3 (April 25, 2018): 615–40. http://dx.doi.org/10.1175/waf-d-17-0098.1.
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Abstract This study investigates the ability to apply National Centers for Environmental Prediction (NCEP) Climate Forecast System (CFS) products and their downscaling by using the Regional Climate Model version 4.2 (RegCM4.2) on seasonal rainfall forecasts over Vietnam. First, the CFS hindcasts (CFS_Rfc) from 1982 to 2009 are used to assess the ability of the CFS to predict the overall circulation and precipitation patterns at forecast lead times of up to 6 months. Second, the operational CFS forecasts (CFS_Ope) and its RegCM4.2 downscaling (RegCM_CFS) for the period 2012–14 are used to derive seasonal rainfall forecasts over Vietnam. The CFS_Rfc and CFS_Ope are validated against the ECMWF interim reanalysis, the Global Precipitation Climatology Centre (GPCC) analyzed rainfall, and observations from 150 meteorological stations across Vietnam. The results show that the CFS_Rfc can capture the seasonal variability of the Asian monsoon circulation and rainfall distribution. The higher-resolution RegCM_CFS product is advantageous over the raw CFS in specific climatic subregions during the transitional, dry, and rainy seasons, particularly in the northern part of Vietnam in January and in the country’s central highlands during July.
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SINGH, M. S. "Upper Air Circulation associated with a Western Disturbance." MAUSAM 14, no. 2 (March 4, 2022): 156–72. http://dx.doi.org/10.54302/mausam.v14i2.5320.
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Upper tropospheric circulation associated with the development of a western disturbance, which was active over India and Pakistan from 28 to 31, December 1960 has been studied with the help of the Asian charts. It was observed that between 26th and 28th a meridional type circulation developed at 300-mb level in the Middle-East and the South-Russian Region. As a result, the upper air trough in the westerlies extended deep into the north, Arabian Sea and a strong northwesterly Jet developed upstream of this trough by the 28th. It was on this day that a feeble western disturbance aolng Makran coast intensified. On the 29th the meridional circulation at 360-mb level was destroyed. Probable causes of these developments in the upper air as well as at the surface have been discussed.
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SASTRY, J. S., and R. S. D'SOUZA. "Oceanography of the Arabian Sea during the southwest monsoon season Part II: Stratification and circulation." MAUSAM 22, no. 1 (November 17, 2021): 23–32. http://dx.doi.org/10.54302/mausam.v22i1.3980.
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The distribution of mass in the Arabian Sea during the southwest monsoon season, 1963 is presented through several vertical sections and spatial distribution charts of the thermosteric anomaly. The circulation patterns in the upper 200 m are derived. The basic feature of circulation is found to be the formation of several cyclonic and anti-cyclonic cells. Upwelling off the southwest coast of India has been explained on a more rational basis than has been assumed hitherto. It is now attributed partly due to the divergence in the current field and partly due to the cyclonic motion around Laccadive and Maldive Island.
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DE, US. "An objective method for forecasting five-day rainfall over Delhi during July and August." MAUSAM 18, no. 3 (April 30, 2022): 355–62. http://dx.doi.org/10.54302/mausam.v18i3.4620.
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The present study is an attempt to evolve a technique for forecasting pentad rainfall over Delhi for the month of July and August. Composite charts for conditions antecedent to excessive and deficient rainfall, during the pentad under consideration, are prepared. The contrasting features of the circulation patterns revealed in these composite charts are taken as guides to picking up crucial station pairs whose relative heights could be taken as representative of the contrasting features. From dot diagrams of rainfall character (as A,' N and S) and pairs of pressure-height co-ordinates the relationship between the predictor and predictant are worked out on the basis of contingency technique. The forecast scheme gives a skill score of. 55.
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ROY, A. K., and N. C. RAI SIRCAR. "On the utility of plotting vectorial changes of upper winds in forecasting developments and progress of Important pressure systems." MAUSAM 6, no. 2 (December 3, 2021): 97–118. http://dx.doi.org/10.54302/mausam.v6i2.4429.
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A study has been made to find the usefulness, for forecasting purposes, of a critical examination of the 24-hour variations in the flow pattern of winds by plotting systematically vectorial changes of upper winds. It is seen that such charts by providing a more definite picture of changes in the circulation pattern of winds, give an insight into the future trend of events in relation to developments of Important synoptic situation, such as, the origin and movements of depressions or of storms in the sea areas, formation of secondaries of western disturbances etc more readily and clearly than what IS possible from a study of two consecutive wind charts.
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DE, U. S., R. N. KESHAVAMURTY, K. S. JOSHI, D. V. VAIDYA, P. V. PILLAI, R. CHELLAPA, and S. K. DAS. "An objective method of weekly rainfall anomaly over central India." MAUSAM 29, no. 1 (February 26, 2022): 397–402. http://dx.doi.org/10.54302/mausam.v29i1.2905.
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The present investigation is an attempt to evolve a technique for forecasting weekly rainfall anomaly over central India (east and west Madhya Pradesh and Vidarbha). Composite circulation anomaly charts for conditions antecedent to active and weak monsoon spells were used as guides to pick up parameters of predictive value, like the zonal wind shear over Peninsula in the lower and middle tropospheres. A relationship using contingency technique has been used to prepare a forecast scheme. Testing of the scheme on independent data yields encouraging results.
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Chen, Tsing-Chang, Shih-Yu Wang, Ming-Cheng Yen, and Adam J. Clark. "Impact of the Intraseasonal Variability of the Western North Pacific Large-Scale Circulation on Tropical Cyclone Tracks." Weather and Forecasting 24, no. 3 (June 1, 2009): 646–66. http://dx.doi.org/10.1175/2008waf2222186.1.
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Abstract The life cycle of the Southeast Asian–western North Pacific monsoon circulation is established by the northward migrations of the monsoon trough and the western Pacific subtropical anticyclone, and is reflected by the intraseasonal variations of monsoon westerlies and trade easterlies in the form of an east–west seesaw oscillation. In this paper, an effort is made to disclose the influence of this monsoon circulation on tropical cyclone tracks during its different phases using composite charts of large-scale circulation for certain types of tracks. A majority of straight-moving (recurving) tropical cyclones appear during weak (strong) monsoon westerlies and strong (weak) trade easterlies. The monsoon conditions associated with straight-moving tropical cyclones are linked to the intensified subtropical anticyclone, while that associated with recurving tropical cyclones is coupled with the deepened monsoon trough. The relationship between genesis locations and track characteristics is evolved from the intraseasonal variation of the monsoon circulation reflected by the east–west oscillation of monsoon westerlies and trade easterlies. Composite circulation differences between the flows associated with the two types of tropical cyclone tracks show a vertically uniform short wave train along the North Pacific rim, as portrayed by the Pacific–Japan oscillation. During the extreme phases of the monsoon life cycle, the anomalous circulation pattern east of Taiwan resembles this anomalous short wave train. A vorticity budget analysis of the strong monsoon condition reveals a vorticity tendency dipole with a positive zone to the north and a negative zone to the south of the deepened monsoon trough. This meridional juxtaposition of vorticity tendency propagates the monsoon trough northward. The interaction of a tropical cyclone with the monsoon trough intensifies the north–south juxtaposition of the vorticity tendency and deflects the tropical cyclone northward. In contrast, during weak monsoon conditions, the interaction between a tropical cyclone and the subtropical high results in a northwestward motion steered by the intensified trade easterlies. The accurate prediction of the monsoon trough and the subtropical anticyclone variations coupled with the monsoon life cycle may help to improve the forecasting of tropical cyclone tracks.
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Tam, Chi-Yung, and Ngar-Cheung Lau. "The Impact of ENSO on Atmospheric Intraseasonal Variability as Inferred from Observations and GCM Simulations." Journal of Climate 18, no. 12 (June 15, 2005): 1902–24. http://dx.doi.org/10.1175/jcli3399.1.
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Abstract The impact of the El Niño–Southern Oscillation (ENSO) on the atmospheric intraseasonal variability in the North Pacific is assessed, with emphasis on how ENSO modulates midlatitude circulation anomalies associated with the Madden–Julian oscillation (MJO) in the Tropics and the westward-traveling patterns (WTP) in high latitudes. The database for this study consists of the output of a general circulation model (GCM) experiment subjected to temporally varying sea surface temperature (SST) forcing in the tropical Pacific, and observational reanalysis products. Diagnosis of the GCM experiment indicates a key region in the North Pacific over which the year-to-year variation of intraseasonal activity is sensitive to the SST conditions in the Tropics. In both the simulated and observed atmospheres, the development phase of the dominant circulation anomaly in this region is characterized by incoming wave activity from northeast Asia and the subtropical western Pacific. Southeastward dispersion from the North Pacific to North America can be found in later phases of the life cycle of the anomaly. The spatial pattern of this recurrent extratropical anomaly contains regional features that are similar to those appearing in composite charts for prominent episodes of the MJO and the WTP. Both the GCM and reanalysis data indicate that the amplitude of intraseasonal variability near the key region, as well as incoming wave activity in the western Pacific and dispersion to the western United States, are enhanced in cold ENSO events as compared to warm events. Similar modulations of the MJO-related circulation patterns in the extratropics by ENSO forcing are discernible in the model simulation. It is inferred from these findings that ENSO can influence the North Pacific intraseasonal activity through its effects on the evolution of convective anomalies in the tropical western Pacific. On the other hand, there is little modification by ENSO of the circulation features associated with the WTP. The combined effect of the MJO and WTP on the intraseasonal circulation in the North Pacific is studied. Based on multiple regression analysis, it is found that the MJO and WTP make comparable contributions to the variability in the midlatitude North Pacific. These contributions may be treated as a linear combination of the anomalies attributed to the MJO and WTP separately.
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Yang, Yiya, Renguang Wu, and Chenghai Wang. "Individual and Combined Impacts of Tropical Indo-Pacific SST Anomalies on Interannual Variation of the Indochina Peninsular Precipitation." Journal of Climate 33, no. 3 (February 1, 2020): 1069–88. http://dx.doi.org/10.1175/jcli-d-19-0262.1.
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AbstractThis study documents interannual rainfall variations over the Indochina Peninsula (ICP) during the rainy season and individual and combined influences of tropical Indo-Pacific sea surface temperature (SST) anomalies. The rainfall variability is large along the west coast in May–June, along the west coast and over the eastern mountains in July–August, and along the central Vietnam coast in September–November. More rainfall in May–June, July–August, and October–November occurs in the La Niña decaying years, La Niña decaying years and/or El Niño developing years, and La Niña developing years, respectively. The May–June rainfall variation along the west coast is associated with equatorial central-eastern Pacific (EP), south Indian Ocean, and western North Pacific SST anomalies. The July–August rainfall variation along the west coast and over the eastern mountains is related to equatorial central Pacific and tropical southeastern Indian Ocean SST anomalies. The October–November rainfall variation along the central Vietnam coast is affected by EP and tropical western Indian Ocean SST anomalies. The EP and tropical western Indian Ocean SST influence is through anomalous Walker circulation. The south Indian Ocean SST influence is via cross-equatorial flows. The tropical southeastern Indian Ocean SST influence is via an anomalous cross-equatorial overturning circulation. The equatorial central Pacific and western North Pacific SST influence is via a Rossby wave–type response. The analysis illustrates the importance of combined effects of regional SST anomalies on the ICP precipitation variation in different stages of the rainy season. Numerical experiments with SST anomalies imposed in different regions confirm the combined effects of the Indo-Pacific SST anomalies on the ICP rainfall variation.
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Thanh Nga, Pham Thi, Pham Thanh Ha, and Vu Thanh Hang. "Satellite-Based Regionalization of Solar Irradiation in Vietnam by k-Means Clustering." Journal of Applied Meteorology and Climatology 60, no. 3 (March 2021): 391–402. http://dx.doi.org/10.1175/jamc-d-20-0070.1.
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AbstractThis study presents the application of k-means clustering to satellite-based solar irradiation in different regions of Vietnam. The solar irradiation products derived from the Himawari-8 satellite, named AMATERASS by the solar radiation consortium under the Japan Science and Technology Agency (JST), are validated with observations recorded at five stations in the period from October 2017 to September 2018 before their use for clustering. High correlations among them enable the use of satellite-based daily global horizontal irradiation for spatial variability analysis and regionalization. With respect to the climate regime in Vietnam, the defined 6-cluster groups demonstrate better agreement with the conventionally classified seven climatic zones rather than the four climatic zones of the Köppen classification. The spatial distribution and seasonal variation in the regionalized solar irradiation reflect interchangeable influences of large-scale atmospheric circulation in terms of the East Asian winter monsoon and the South Asian summer monsoon as well as the effect of local topography. Higher daily averaged solar radiation and its weaker seasonal variation were found in two clusters in the southern region where the South Asian summer monsoon dominates in the rainy season. Pronounced seasonal variability in solar irradiation in four clusters in the northern region is associated with the influence of the East Asian monsoon, resulting in its clear reduction during the winter months.
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GUPTA, DNDAS. "Study of heavy rainfall associated with low pressure microcells over northeast India." MAUSAM 18, no. 1 (April 30, 2022): 101–4. http://dx.doi.org/10.54302/mausam.v18i1.4004.
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Low pressure vortices of small extent or microcells of low pressure are sometimes embedded in the large scale circulation of the lower levels of the atmosphere. These can be located on the surface iecbaric charts plotted on a large scale map by drawing isobars at intervals of 1.0 or 0.5 mb. It is seen that location and movement of these vortices sometimes influence distribution of rainfall over small areas, The spots of heavier rainfall tend to move near to the microcells of low pressure, A II1eso-scale network of observing stations is necessary for precises location of these cells and for study of their movements and influence on rainfall distribution. Results of studies with available observations on some typical days of the monsoon season in 1961 are presented in this paper.
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Girardin, Martin-Philippe, and Jacques Tardif. "Sensitivity of tree growth to the atmospheric vertical profile in the Boreal Plains of Manitoba, Canada." Canadian Journal of Forest Research 35, no. 1 (January 1, 2005): 48–64. http://dx.doi.org/10.1139/x04-144.
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This paper investigates the influence of surface climate and atmospheric circulation on radial growth of eight boreal tree species growing in the Duck Mountain Provincial Forest, Manitoba, Canada. Tree-ring residual chronologies were built, transformed into principal components (PCs), and analysed through correlation and response functions to reveal their associations to climate (temperature, precipitation, and drought data for the period 19121999, as well as local geopotential height data for the period 19481999). Geopotential height correlation and composite charts for the Northern Hemisphere were also constructed. Correlation and response function coefficients indicated that radial growth of all species was negatively affected by temperature-induced drought stresses from the summers previous and current to ring formation. The summer drought stress alone explained nearly 28% of the variance in PC1. Warm spring temperature was also a positive factor for Pinus banksiana Lamb. and Picea glauca (Moench) Voss, but a negative one for all hardwoods. Analyses performed on geopotential height highlighted the importance of the Northern Hemispheric atmospheric circulation in the species' response to climate. The variability within the 500-hPa level over southern Manitoba explained 39% and 58% of the variability in PC1 and PC2, respectively. The relationships were highly significant with the middle and high troposphere during spring and late summer (determinant factor for growing season length) and with the troposphere and stratosphere during summer. The sensitivity of tree growth to atmospheric circulation exceeded the synoptic scale, with a response associated with yearly variations in the amplitude of the mid-tropospheric longwaves.
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Lau, Ngar-Cheung, and Mary Jo Nath. "Model Simulation and Projection of European Heat Waves in Present-Day and Future Climates." Journal of Climate 27, no. 10 (May 9, 2014): 3713–30. http://dx.doi.org/10.1175/jcli-d-13-00284.1.
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Abstract The synoptic behavior of present-day heat waves (HW) over Europe is studied using the GFDL high-resolution atmospheric model (HiRAM) with 50-km grid spacing. Three regions of enhanced and coherent temperature variability are identified over western Russia, eastern Europe, and western Europe. The simulated HW characteristics are compared with those derived from Climate Forecast System Reanalysis products. Composite charts for outstanding HW episodes resemble well-known recurrent circulation types. The HW region is overlain by a prominent upper-level anticyclone, which blocks the passage of synoptic-scale transients. The altered eddy vorticity transports in turn reinforce the anticyclone. The anticyclone is part of a planetary-scale wave train. The successive downstream development of this wave train is indicative of Rossby wave dispersion. Additional runs of HiRAM are conducted for the “time slices” of 2026–35 and 2086–95 in the climate scenario corresponding to representative concentration pathway 4.5 (RCP4.5). By the end of the twenty-first century, the average duration and frequency of HW in the three European sites are projected to increase by a factor of 1.4–2.0 and 2.2–4.5, respectively, from the present-day values. These changes can be reproduced by adding the mean shift between the present and future climatological temperatures to the daily fluctuations in the present-day simulation. The output from a continuous integration of a coupled general circulation model through the 1901–2100 period indicates a monotonic increase in severity, duration, and HW days during the twenty-first century.
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Quadrelli, R., and J. M. Wallace. "Varied Expressions of the Hemispheric Circulation Observed in Association with Contrasting Polarities of Prescribed Patterns of Variability*." Journal of Climate 17, no. 21 (November 1, 2004): 4245–53. http://dx.doi.org/10.1175/jcli3196.1.
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Abstract The low-frequency (>5 day period) variability observed within four different subsets of the climatology (H1, L1, H2, and L2) as defined by the high and low index polarities of the two leading principal components (PCs) of the sea level pressure field is compared, with emphasis on distinctive flow configurations and teleconnection patterns. The analysis is based on wintertime 500-hPa height, sea level pressure, and 1000–500-hPa thickness fields derived from the NCEP–NCAR reanalyses for the period of record, 1958–99. “Spaghetti diagrams” display specified contours for ensembles of individual 10-day mean charts extracted from the four different subsets of the climatology. In L1, 10-day mean maps (weak zonal flow at latitudes ∼55°N) exhibit larger undulations in the barotropic component of the flow than those in H1, implying larger particle displacements and deeper penetration of Arctic air masses, particularly into Europe and the eastern United States. Maps in H2 and L2, separated in accordance with the Pacific–North American (PNA)-like second mode, exhibit quite different kinds of planetary wave patterns. The L2 subset (characterized by a retracted Pacific jet) exhibits greater variability over the Gulf of Alaska and over northern Europe. Cold air outbreaks in Europe occur more frequently in L1 than H1, and over western North America, they occur more frequently in L2 than H2. The cold anomalies associated with low polarities of both PCs are observed more frequently than expected based on linear correlation; within the individual subsets of the climatology there are suggestions of multiple circulation regimes; teleconnection patterns for the subsets of the climatology are also discernibly different. These results constitute evidence of nonnormal or nonlinear behavior of 5- and 10-day mean fields and provide indications of how the intraseasonal variability depends on the mean state of the flow in which it is embedded.
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Sykulski, Patryk, and Zuzanna Bielec-Bąkowska. "Atmospheric fronts over Poland (2006-2015)." Environmental & Socio-economic Studies 5, no. 4 (December 1, 2017): 29–39. http://dx.doi.org/10.1515/environ-2017-0018.
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AbstractThe paper presents the spatial and temporal variations in the occurrence of fronts and days with no fronts over Poland in 2006-2015. The research was based on a database of the atmospheric fronts that moved over five selected stations located in the outermost regions of Poland and in the centre of the country. The database was created as a result of an analysis of synoptic charts from the website of the German weather service (Deutscher Wetterdienst; DWD). As is shown by the results, atmospheric fronts moved over Poland on approximately 65% of days of the year. However, their frequency in the individual regions was almost half of this, ranging from 33-39%. The annual variations in the number of fronts depended largely on the location of a given area and the atmospheric circulation prevailing there. In most years the maximum frequency of occurrence of atmospheric fronts was observed in November-January, and the lowest frequency was seen in February and September. The research confirms that there is a clear predominance of cold fronts, with warm and occluded fronts forming at around half the frequency of cold fronts. One characteristic feature is a decrease in the number of occluded fronts and days with different types of fronts moving from the north of Poland southwards. In the period under study, more than 80% of the sequences of days with atmospheric fronts included up to 6 days, even though there were also cases when fronts passed over Poland on 20 consecutive days.
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Marsiat, I., and J. L. Bamber. "The climate of antarctica in the UGAMP GCM: Sensitivity to topography." Annals of Glaciology 25 (1997): 79–84. http://dx.doi.org/10.3189/s0260305500013835.
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Most spectral general circulation models (GCMs) use an envelope topography to set on land surface elevations. The UK Universities Global Atmospheric Modelling Programme General Circulation Model (UGAMP GCM) uses such a formulation for Antarctica, based on the US Navy 10 are minute charts of the region. In the marginal regions of the continent, an envelope topography consistently overestimates the elevation leading to lower-than-observed surface temperatures. Furthermore, errors in excess of 1000 m exist in the US Navy data, and the UGAMP GCM treats the major ice shelves as sea ice, introducing a 12% reduction in the snow-covered area of the continent. Here, we use a new high-resolution, high-accuracy digital elevation model to improve the representation of Antarctica in the UGAMP GCM. The effect of changing the land–sea mask and the topography on the surface temperature, precipitation and wind held is investigated for both summer and winter runs. Changing the land–sea mask had a dramatic effect on temperature, producing a reduction of 13.3°C for the sector west of the Ross Ice Shelf. Using the new mean topography also introduces substantial differences in temperature, wind speed and precipitation for summer and winter.
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Marsiat, I., and J. L. Bamber. "The climate of antarctica in the UGAMP GCM: Sensitivity to topography." Annals of Glaciology 25 (1997): 79–84. http://dx.doi.org/10.1017/s0260305500013835.
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Most spectral general circulation models (GCMs) use an envelope topography to set on land surface elevations. The UK Universities Global Atmospheric Modelling Programme General Circulation Model (UGAMP GCM) uses such a formulation for Antarctica, based on the US Navy 10 are minute charts of the region. In the marginal regions of the continent, an envelope topography consistently overestimates the elevation leading to lower-than-observed surface temperatures. Furthermore, errors in excess of 1000 m exist in the US Navy data, and the UGAMP GCM treats the major ice shelves as sea ice, introducing a 12% reduction in the snow-covered area of the continent. Here, we use a new high-resolution, high-accuracy digital elevation model to improve the representation of Antarctica in the UGAMP GCM. The effect of changing the land-sea mask and the topography on the surface temperature, precipitation and wind held is investigated for both summer and winter runs. Changing the land�sea mask had a dramatic effect on temperature, producing a reduction of 13.3°C for the sector west of the Ross Ice Shelf. Using the new mean topography also introduces substantial differences in temperature, wind speed and precipitation for summer and winter.
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Nakamura, Hirohiko, Ayako Nishina, and Shoshiro Minobe. "Response of Storm Tracks to Bimodal Kuroshio Path States South of Japan." Journal of Climate 25, no. 21 (November 2012): 7772–79. http://dx.doi.org/10.1175/jcli-d-12-00326.1.
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A large meridional shift of the sea surface temperature front occurs off the south coast of Japan associated with transitions between the large-meander and straight paths of the Kuroshio. Most extratropical cyclones generated in winter near the Kuroshio in the East China Sea pass through the region where the Kuroshio takes either the meander or the straight path. To examine whether such cyclones change their tracks and intensities according to the two states of the path, a new dataset of winter cyclone tracks derived from surface weather charts from the period 1969/70–2008/09 was produced. The composite analysis of cyclone tracks with respect to the meander and straight path states reveals the following: the cyclone track axis for the meander path state is located away from the south coast of Japan with a dispersive tendency, while that for the straight path state is attached to the south coast with a long extending feature. A difference in track between these two states also occurs to the east of Japan over the North Pacific. In addition, this behavior of the cyclone track is shown to be independent of the wintertime atmospheric circulation anomalies around Japan. The development rate of cyclones is 41% faster for the straight path state than the meander path state. Snowfall in Tokyo caused by south-coast cyclones is more frequent for the meander than the straight path state because the former state can act to decrease air temperature in Tokyo.
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Novikov, D. A., Phan Thi Kim Van, Doan Van Tuyen, Do Thi Thu, and Tran Viet Hoan. "New isotope-hydrogeochemical data on the Bang spring (Kuang Binh province, central Vietnam)." Геохимия 64, no. 6 (June 26, 2019): 664–72. http://dx.doi.org/10.31857/s0016-7525646664-672.
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New isotope hydrogeochemical data on two types of thermal water from the Bang spring (Kuang Binh province, central Vietnam) are reported in the work. The first type includes HCO3–Cl–Na–Mg water with extremely low mineralization (44–87 mg/dm3) and pH variations from weakly acidic to weakly alkaline values (5.71–7.84). The second type includes HCO3–Na water with mineralization up to 256–659 mg/dm3 and pH 8.03 to 8.51. The studied types differ significantly in temperature: 24.3–34.5°C in the first type and 62.1–97.1°C in the second type. The analysis of the distribution of oxygen (δ18O) and hydrogen (δD) isotopes carried out for the first time confirms different genetic nature of these hydrogeochemical water types. The first type has an atmospheric genesis (δ18O = –7.3…–6.2‰ and δD = –51.4…–39.3‰), while the second type restricted to the Kien Giang–Bang intersection zone has a deeper source (δ18O = –1.6…–1.3‰ and δD = –22.2…–21.4‰). The tritium (3H) data also point to different circulation times of these waters. The formation time of the HCO3–Cl–Na–Mg waters does not exceed 50 years (3H = 4.3–11.1 ТЕ), while that of HCO3–Na water may reach more than 1000 years (3H = 0.5 ТЕ).
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Lau, Ngar-Cheung, and Mary Jo Nath. "A Model Study of the Air–Sea Interaction Associated with the Climatological Aspects and Interannual Variability of the South Asian Summer Monsoon Development." Journal of Climate 25, no. 3 (February 1, 2012): 839–57. http://dx.doi.org/10.1175/jcli-d-11-00035.1.
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Abstract The climatological characteristics and interannual variations of the development of the South Asian summer monsoon (SASM) in early summer are studied using output from a 200-yr simulation of a coupled atmosphere–ocean general circulation model (CM2.1). Some of the model results are compared with corresponding observations. Climatological charts of the model and observational data at pentadal intervals indicate that both the precipitation and SST signals exhibit a tendency to migrate northward. Enhanced monsoonal precipitation at a given site is accompanied by a reduction in incoming shortwave radiation and intensification of upward latent heat flux, and by oceanic cooling. An extended empirical orthogonal function analysis is used to identify the dates for initiation of the northward march of SASM in individual summers. It is noted that early monsoon development prevails after the mature phase of La Niña events, whereas delayed development occurs after El Niño. Sensitivity experiments based on the atmospheric component of CM2.1 indicate that the effects of SST forcings in the tropical Pacific (TPAC) and Indian Ocean (IO) on monsoon development are opposite to each other. During El Niño events, the atmospheric response to remote TPAC forcing tends to suppress or postpone monsoon development over South Asia. Conversely, the warm SST anomalies in IO, which are generated by the “atmospheric bridge” mechanism in El Niño episodes, lead to accelerated monsoon development. The net result of these two competing effects is an evolution scenario with a timing that is intermediate between the response to TPAC forcing only and the response to IO forcing only.
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Chen, Tsing-Chang, Jenq-Dar Tsay, and Ming-Chang Yen. "Genesis and Development of Spring Rainstorms in Northern Southeast Asia: Southwest China–Northern Indochina and the Northern South China Sea." Monthly Weather Review 145, no. 12 (December 2017): 4949–76. http://dx.doi.org/10.1175/mwr-d-17-0059.1.
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During May and June, the monsoon rainfall in northern Southeast Asia is primarily produced by rainstorms. At the mature stage, these storms, coupled with a midtropospheric subsynoptic-scale trough, produce rainfall ≥50 mm (6 h)−1and exhibit a cyclonic surface vortex. With a scale ~ O(102) km, rainstorms during the period of 1979–2016 are identified with station and satellite observations, along with assimilation data. Several dynamic processes of rainstorm geneses are disclosed by an extensive analysis. 1) Maximum occurrence of rainstorm geneses is located in the midtroposphere of two regions (northern Vietnam–southwestern China and the northern South China Sea), but eventually penetrates downward to the surface. 2) The environment favorable for rainstorm genesis is a southwest–northeast-oriented narrow trough formed by the confluence of the midtropospheric northeasterly around the eastern Tibetan Plateau and the lower-tropospheric monsoon southwesterlies. Because the criterion for Charney–Stern instability is met by the shear flow of this narrow trough, rainstorms are likely initiated by this instability. 3) The majority of rainstorm geneses occurs during the evening over the land and the morning at sea. This timing preference is caused by the modulation of the clockwise rotation of the East Asia continent circulation in response to the diurnal variation of the land–sea thermal contrast. These new findings from this study offer not only a new perspective for the genesis mechanism of the late spring–early summer rainstorms in northern Southeast Asia, but also a new initiative to develop medium-range forecasts for these rainstorms.
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Do Hoai, Nam, Keiko Udo, and Akira Mano. "Downscaling Global Weather Forecast Outputs Using ANN for Flood Prediction." Journal of Applied Mathematics 2011 (2011): 1–14. http://dx.doi.org/10.1155/2011/246286.
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Downscaling global weather prediction model outputs to individual locations or local scales is a common practice for operational weather forecast in order to correct the model outputs at subgrid scales. This paper presents an empirical-statistical downscaling method for precipitation prediction which uses a feed-forward multilayer perceptron (MLP) neural network. The MLP architecture was optimized by considering physical bases that determine the circulation of atmospheric variables. Downscaled precipitation was then used as inputs to the super tank model (runoff model) for flood prediction. The case study was conducted for the Thu Bon River Basin, located in Central Vietnam. Study results showed that the precipitation predicted by MLP outperformed that directly obtained from model outputs or downscaled using multiple linear regression. Consequently, flood forecast based on the downscaled precipitation was very encouraging. It has demonstrated as a robust technology, simple to implement, reliable, and universal application for flood prediction through the combination of downscaling model and super tank model.
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Khoi, Dao Nguyen, and Tadashi Suetsugi. "Hydrologic response to climate change: a case study for the Be River Catchment, Vietnam." Journal of Water and Climate Change 3, no. 3 (September 1, 2012): 207–24. http://dx.doi.org/10.2166/wcc.2012.035.
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The Be River Catchment was studied to quantify the potential impact of climate change on the streamflow using a multi-model ensemble approach. Climate change scenarios (A1B and B1) were developed from an ensemble of four GCMs (general circulation models) (CGCM3.1 (T63), CM2.0, CM2.1 and HadCM3) that showed good performance for the Be River Catchment through statistical evaluations between 15 GCM control simulations and the corresponding time series of observations at annual and monthly levels. The Soil and Water Assessment Tool (SWAT) was used to investigate the impact on streamflow under climate change scenarios. The model was calibrated and validated using daily streamflow records. The calibration and validation results indicated that the SWAT model was able to simulate the streamflow well, with Nash–Sutcliffe efficiency exceeding 0.78 for the Phuoc Long station and 0.65 for the Phuoc Hoa station, for both calibration and validation at daily and monthly steps. Their differences in simulating the streamflow under future climate scenarios were also investigated. The results indicate a 1.0–2.9 °C increase in annual temperature and a −4.0 to 0.7% change in annual precipitation corresponding to a change in streamflow of −6.0 to −0.4%. Large decreases in precipitation and runoff are observed in the dry season.
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SINGH, O. P., B. LAL, and ONKARI PRASAD. "Value addition in district level dynamical forecast during monsoon depressions and storms." MAUSAM 58, no. 1 (November 26, 2021): 1–8. http://dx.doi.org/10.54302/mausam.v58i1.1094.
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ABSTRACT. The trials of district level forecasts yielded encouraging results during 2005 monsoon. The purpose of this paper is to document the methodology followed in the value addition during the periods of monsoon depressions and storms. The focus is on the use of Mean Sea Level (MSL) positions and the 850 hPa circulation features predicted by different model centres, especially the European Centre for Medium-Range Weather Forecasts (ECMWF). The ECMWF-predicted 72 hr MSL position of the monsoon depression centre was found to be significantly correlated to the actual position of the system and the central location of the realized rainfall zone associated with the system. Even the predicted location of the system at 850 hPa by the ECMWF has been found useful in identifying the districts that received heaviest rainfall associated with the monsoon systems.MM5 and T-80 – predicted locations of the system at 850 hPa yielded lower correlations with the location of the actual rainfall zone associated with the system. As ECMWF – predicted rainfall was not available the rainfall predicted by MM5 and T-80 were used in the computations of the correlations with actual rainfall amounts associated with monsoon depressions and storms. The correlations between MM5 and T-80 – predicted average and maximum rainfall associated with systems and corresponding actual were poor. Though it is not difficult to identify the districts that are likely to be affected by the heavy rainfall associated with monsoon depressions/storms, the prediction of exact rainfall amount for each district (beyond heavy, very heavy or exceptionally heavy categories) is difficult from the model outputs which makes such forecasts a very challenging task. Therefore, the value addition using other inputs such as satellite information, synoptic charts, climatology etc. are very useful in the prediction of rainfall amounts associated with monsoon systems.
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SINGH, BIKRAM, and ROHIT THAPLIYAL. "Cloudburst events observed over Uttarakhand during monsoon season 2017 and their analysis." MAUSAM 73, no. 1 (January 15, 2022): 91–104. http://dx.doi.org/10.54302/mausam.v73i1.5084.
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Cloudburst is an extreme weather event characterised by the occurrence of a large amount of rainfall over a small area within a short span of time with a rainfall of 100 mm or more in one hour. It is responsible for flash flood, inundation of low lying areas and landslides in hills causing extensive damages to life and property. During monsoon season 2017 five number of cloudburst events are observed over Uttarakhand and analysed. Self Recording Rain Gauge (SRRG) and 15 minutes interval data from the newly installed General Packet Radio Service (GPRS) based Automatic Weather Station (AWS) are able to capture the cloudburst events over some areas in Uttarakhand. In this paper, an attempt has been made to find out the significant synoptic and thermodynamic conditions associated with the occurrence of the cloudburst events in Uttarakhand. These 5 cases of cloudburst events that are captured during the month of June, July and August 2017 in Uttarakhand are studied in detail. Synoptically, it is observed that the existence of trough at mean sea level from Punjab to head Bay of Bengal running close to Uttarakhand, the movement of Western Disturbance over north Pakistan and adjoining Jammu & Kashmir and existence of cyclonic circulation over north Rajasthan and neighbourhood are favourable conditions. Also, the presence of strong south-westerly wind flow from the Arabian Sea across West Rajasthan and Haryana on upper air charts are found during these events. Thermodynamically, the Convective Available Potential Energy (CAPE) is found to be high (more than 1100 J/Kg) during most of the cases and vertically integrated precipitable water content (PWC) is more than 55mm. The GPRS based AWS system can help in prediction of the cloud burst event over the specified location with a lead time upto half to one hour in association with radar products.
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MADAN, O. P., U. C. MOHANTY, GOPAL IYENGER, R. P. SHIVHARE, ASKAV PRASAD RAO, N. V. SAM, and R. BHATLA. "Off shore trough and very heavy rainfall events along the West Coast of India during ARMEX-2002." MAUSAM 56, no. 1 (January 19, 2022): 37–48. http://dx.doi.org/10.54302/mausam.v56i1.856.
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Arabian Sea Monsoon Experiment (ARMEX) 2O02 was carried out from mid June to mid August to study the presence of off-shore trough (OST) and embedded vortices. Four cases of heavy rainfall along the west coast (rainfall exceeding 12 cm in 24 hour) of India were recorded on 14-16 June, 20-22 June, 26-28 June and 7-10 August 2002. The heavy rainfal1 event of 26-28 June was due to a low pressure system that moved from Bay of Bengal across Madhya Pradesh to Gujarat and adjoining Rajasthan. The other three heavy rainfall events were associated with the off shore trough and /or off shore vortices.
Of the various sea buoys deployed in the Arabian Sea, only one buoy located off Goa, did give hint of an OST both in strong and weak wind conditions. However, surface wind data from other buoys and QSCAT surface wind did not always support the presence of OST. The indications were very subtle and it was found difficult to observe them on the NCMRWF (National Centre for Medium Range Weather Forecasting) analysis or forecast charts. In the present study it has been observed that off shore trough may be observed in weak as well as strong monsoon conditions. However, heavy rainfall events were noticed only when the monsoon current is strong both in the Arabian Sea as well as Bay of Bengal in association with some synoptic systems. In addition, an east-west shear line in wind flow pattern extending from lower to middle or upper tropospheric levels and joining the circulation features in the Arabian Sea and Bay of Bengal has been noticed in all cases of heavy rainfall events. Meso-scale vortices/organized convection systems were also identified during heavy rainfall events on the basis of cloud features noticed in the satellite pictures and TRMM rain rate patterns.
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Khoi, Dao Nguyen, Truong Thao Sam, Nguyen Truong Thao Chi, Do Quang Linh, and Pham Thi Thao Nhi. "Impact of future climate change on river discharge and groundwater recharge: a case study of Ho Chi Minh City, Vietnam." Journal of Water and Climate Change 13, no. 3 (February 9, 2022): 1313–25. http://dx.doi.org/10.2166/wcc.2022.379.
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Abstract Climate change (CC) is likely to have a long-term influence on regional water resources, including surface water and groundwater. Therefore, quantifying the CC influence is indispensable for proper management of water resources. This study scrutinized the influence of CC on river discharge and groundwater recharge (GWR) in Ho Chi Minh City (HCMC), Vietnam, utilizing the Soil and Water Assessment Tool (SWAT). The calibrated SWAT was utilized to simulate the discharge and GWR under projected climate scenarios in reliance on an ensemble of seven General Circulation Models (GCMs) derived from Coupled Model Intercomparison Project Phase 6 (CMIP6) under three Shared Socioeconomic Pathways (SSPs), including SSP1-2.6, SSP2-4.5, and SSP5-8.5. Results pointed out that the climate of HCMC is warmer and wetter in the 21st century. Under the CC influence, the future discharge is envisaged to rise from 0.1 to 4.5% during the near-future period of 2030s (2021–2045), 8.1 to 11.6% during the mid-future period of 2055s (2046–2070), and 7.7 to 19.6% during the far-future period of 2080s (2071–2095) under the three SSP scenarios. In addition, the GWR is prognosticated to have rising trends of 0.9–4.9%, 5.3–7.9%, and 5.7– 13.5% during the near-future, mid-future, and far-future periods, respectively. Furthermore, uncertainties in the discharge and GWR projections connected with SSP scenarios and CMIP6 GCMs are considerable.
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Podnebesnykh, N. V., and I. I. Ippolitov. "LARGE-SCALE ATMOSPHERIC CIRCULATION OVER SIBERIA AT THE END OF XX AND THE BEGINNING OF XXI CENTURIES: A COMPARISON OF DATA OBTAINED ON THE BASIS OF SURFACE SYNOPTIC CHARTS AND THE REANALYSIS." Fundamental and Applied Climatology 2 (2019): 34–44. http://dx.doi.org/10.21513/2410-8758-2019-2-34-44.
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LAL, B., O. P. SINGH, ONKARI PRASAD, S. K. ROY BHOWMIK, S. R. KALSI, and S. K. SUBRAMANIAN. "District level value-added dynamical-synoptic forecast system for rainfall." MAUSAM 57, no. 2 (November 25, 2021): 209–20. http://dx.doi.org/10.54302/mausam.v57i2.468.
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Lkkj & bl ’kks/k&Ik= esa o"kkZ ls lacaf/kr ftyk Lrjh; ekuksa ij vk/kkfjr xfrdh; flukfIVd iwokZuqeku dh Ik)fr vkSj mlds iz;ksxkRed ifj.kkeksa dks izLrqr fd;k x;k gSA blds igys bl rduhd dk mi;ksx o"kZ 2005 dh ekulwu iwoZ dh _rq] nf{k.kh if’peh ekulwu _rq vkSj ekulwu ds Ik’pkr dh _rq ds nkSjku gqbZ ftysokj o"kkZ dk iwokZuqeku yxkus ds fy, fd;k x;k FkkA mDr 2005 ds iwokZuqeku ds fy, Vh-&80],e- ,e- 5] jk"Vªh; e/; vof/k ekSle iwokZuqeku dsUnz ¼,u- lh- ,e- vkj- MCY;w- ,Q-½ ds- bZ- Vh- ,- vkSj Hkkjr ekSle foKku foHkkx esa dk;Z’khy ,e- ,e- 5 xfrdh; fun’kksZa dk lefUor #Ik ls mi;ksx fd;k x;k FkkA iwokZuqeku esa lefUor #Ik ls ;ksxnku nsus okys lHkh fun’kksZa ds ekuksa dk vyx&vyx ewY;kadu djds muls izkIr gq, o"kkZ ds iwokZuqekuksa dk mi;ksx djds xfrdh; iwokZuqeku rS;kj fd;k x;k gSA ifjpkyu y{k.kksa] m/okZ/kj osx] mixzg ls izkIr lwpuk flukfIVd pkVksZa vkSj tyok;q foKku vkfn tSls vU; fun’kksZa dk vkdyu djds xfrdh; iwokZuqekuksa dks eku vk/kkfjr ¼osY;w ,fMM ½ flukfIVd ekSle iwokZuqekuksa esa ifjofrZr fd;k x;k gSA o"kZ 2005 esa fd, x, iwokZuqeku ds vuqHko ls ;g irk pyk gS fd lefUor #Ik ls ;ksxnku nsus okys fun’kksZa ls vyx&vyx izkIr gq, o"kkZ ds iwokZuqekuksa dh fuiq.krk dh rqyuk esa eku&vk/kkfjr ¼osY;w ,fMM ½ xfrdh; flukfIVd iz.kkyh ds 24, 48, 72 ?kaVksa ds ftyk Lrjh; o"kkZ ds iwokZuqeku dgha vf/kd fuiq.krk ls rS;kj fd, tk ldrs gSaA
The paper presents the methodology and trial results of the district level value-added dynamical-synoptic forecast for rainfall. The technique was tried for forecasting districtwise rainfall during Pre-monsoon, Southwest Monsoon and Post monsoon seasons of 2005. The constituent dynamical models were T-80, MM5, ETA of the National Centre for Medium Range Weather Forecasting (NCMRWF) and the MM5 model operational at India Meteorological Department, New Delhi. The dynamical predictions were prepared using the rainfall predictions of the constituent models by assigning different weights. The dynamical predictions were converted into value-added synoptic-weather forecasts by taking into account other inputs like circulation features, vertical velocity, satellite information, synoptic charts and climatology etc. The experience during 2005 has shown that the value-added dynamical-synoptic system can produce 24, 48, 72 hours district level rainfall forecast of greater skill than the skills of the constituent models.
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Jeong, J. H., D. I. Lee, C. C. Wang, S. M. Jang, C. H. You, and M. Jang. "Environment and morphology of mesoscale convective systems associated with the Changma front during 9–10 July 2007." Annales Geophysicae 30, no. 8 (August 22, 2012): 1235–48. http://dx.doi.org/10.5194/angeo-30-1235-2012.
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Abstract. To understand the different environment and morphology for heavy rainfall during 9–10 July 2007, over the Korean Peninsula, mesoscale convective systems (MCSs) that accompanied the Changma front in two different regions were investigated. The sub-synoptic conditions were analysed using mesoscale analysis data (MANAL), reanalysis data, weather charts and Multi-functional Transport Satellite (MTSAT-IR) data. Dual-Doppler radar observations were used to analyse the wind fields within the precipitation systems. During both the case periods, the surface low-pressure field intensified and moved northeastward along the Changma front. A low-level warm front gradually formed with an east-west orientation, and the cold front near the low pressure was aligned from northeast to southwest. The northern convective systems (meso-α-scale) were embedded within an area of stratiform cloud north of the warm front. The development of low-level pressure resulted in horizontal and vertical wind shear due to cyclonic circulation. The wind direction was apparently different across the warm front. In addition, the southeasterly flow (below 4 km) played an important role in generating new convective cells behind the prevailing convective cell. Each isolated southern convective cell (meso-β-scale) moved along the line ahead of the cold front within the prefrontal warm sector. These convective cells developed when a strong southwesterly low-level jet (LLJ) intensified and moisture was deeply advected into the sloping frontal zone. A high equivalent potential temperature region transported warm moist air in a strong southwesterly flow, where the convectively unstable air led to updraft and downdraft with a strong reflectivity core.
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Pham Thi Thu, H., C. Amory-Mazaudier, and M. Le Huy. "Sq field characteristics at Phu Thuy, Vietnam, during solar cycle 23: comparisons with Sq field in other longitude sectors." Annales Geophysicae 29, no. 1 (January 4, 2011): 1–17. http://dx.doi.org/10.5194/angeo-29-1-2011.
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Abstract. Quiet days variations in the Earth's magnetic field (the Sq current system) are compared and contrasted for the Asian, African and American sectors using a new dataset from Vietnam. This is the first presentation of the variation of the Earth's magnetic field (Sq), during the solar cycle 23, at Phu Thuy, Vietnam (geographic latitudes 21.03° N and longitude: 105.95° E). Phu Thuy observatory is located below the crest of the equatorial fountain in the Asian longitude sector of the Northern Hemisphere. The morphology of the Sq daily variation is presented as a function of solar cycle and seasons. The diurnal variation of Phu Thuy is compared to those obtained in different magnetic observatories over the world to highlight the characteristics of the Phu Thuy observations. In other longitude sectors we find different patterns. At Phu Thuy the solar cycle variation of the amplitude of the daily variation of the X component is correlated to the F.10.7 cm solar radiation (~0.74). This correlation factor is greater than the correlation factor obtained in two observatories located at the same magnetic latitudes in other longitude sectors: at Tamanrasset in the African sector (~0.42, geographic latitude ~22.79) and San Juan in the American sector (~0.03, geographic latitude ~18.38). At Phu Thuy, the Sq field exhibits an equinoctial and a diurnal asymmetry: – The seasonal variation of the monthly mean of X component exhibits the well known semiannual pattern with 2 equinox maxima, but the X component is larger in spring than in autumn. Depending of the phase of the sunspot cycle, the maximum amplitude of the X component varies in spring from 30 nT to 75 nT and in autumn from 20 nT to 60 nT. The maximum amplitude of the X component exhibits roughly the same variation in both solstices, varying from about ~20 nT to 50 nT, depending on the position into the solar cycle. – In all seasons, the mean equinoctial diurnal Y component has a morning maximum Larger than the afternoon minimum i.e. the equivalent current flow over a day is more southward than northward. During winter, the asymmetry is maximum, it erases the afternoon minimum. At the Gnangara observatory, in Asian Southern Hemisphere, the diurnal Y pattern is opposite and the current flow is more northward. It seems that in the Asian sector, the northern and southern Sq current cells both contribute strongly to the equatorial electrojet. The pattern is different in the African and American sectors where the northern Sq current cell contribution to the equatorial electrojet is smaller than the southern one. These observations can explain the unexpected maximum of amplitude of the equatorial electrojet observed in the Asian sector where the internal field is very large. During winter the Y component flow presents an anomaly, it is always southward during the whole day and there is no afternoon northward circulation.
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Minh, Pham Thi, Bui Thi Tuyet, Tran Thi Thu Thao, and Le Thi Thu Hang. "Application of ensemble Kalman filter in WRF model to forecast rainfall on monsoon onset period in South Vietnam." VIETNAM JOURNAL OF EARTH SCIENCES 40, no. 4 (September 18, 2018): 367–94. http://dx.doi.org/10.15625/0866-7187/40/4/13134.
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This paper presents some results of rainfall forecast in the monsoon onset period in South Vietnam, with the use of ensemble Kalman filter to assimilate observation data into the initial field of the model. The study of rainfall forecasts are experimented at the time of Southern monsoon outbreaks for 3 years (2005, 2008 and 2009), corresponding to 18 cases. In each case, there are five trials, including satellite wind data assimilation, upper-air sounding data assimilation, mixed data (satellite wind+upper-air sounding data) assimilation and two controlled trials (one single predictive test and one multi-physical ensemble prediction), which is equivalent to 85 forecasts for one trial. Based on the statistical evaluation of 36 samples (18 meteorological stations and 18 trials), the results show that Kalman filter assimilates satellite wind data to forecast well rainfall at 48 hours and 72 hours ranges. With 24 hour forecasting period, upper-air sounding data assimilation and mixed data assimilation experiments predicted better rainfall than non-assimilation tests. The results of the assessment based on the phase prediction indicators also show that the ensemble Kalman filter assimilating satellite wind data and mixed data sets improve the rain forecasting capability of the model at 48 hours and 72 hour ranges, while the upper-air sounding data assimilation test produces satisfactory results at the 72 hour forecast range, and the multi-physical ensemble test predicted good rainfall at 24 hour and 48 hour forecasts. The results of this research initially lead to a new research approach, Kalman Filter Application that assimilates the existing observation data into input data of the model that can improve the quality of rainfall forecast in Southern Vietnam and overall country in general.References Bui Minh Tuan, Nguyen Minh Truong, 2013. 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The Third International MAHASRI/HyARC Workshop on Asian Monsoon and Water Cycle, 28-30 August 2013, Da Nang, Viet Nam, 217-224.Richardson L.F., 1922. Weather prediction by numerical process. Cambridge University Press, Cambridge. Reprinted by Dover (1965, New York).Routray, Mohanty U.C., Niyogi D., Rizvi S.R., Osuri K.K., 2008. First application of 3DVAR-WRF data assimilation for mesoscale simulation of heavy rainfall events over Indian Monsoon region. Journal of the Royal Meteorological Society, 1555.Schumacher, R. S., C. A. Davis, 2010. Ensemble-based Forecast Uncertainty Analysis of Diverse Heavy Rainfall Events, 25. Doi: 10.1175/2010WAF2222378.Snyder C., Zhang F., 2003. Assimilation of simulated Doppler radar observations with an Ensemble Kalman filter. Mon. Wea. Rev., 131, 1663.Szunyogh I., Kostelich E.J., Gyarmati G., Kalnay E., Hunt B.R., Ott E., Satterfield E., Yorke J.A., 2008. A local ensemble transform Kalman filter data assimilation system for the NCEP global model. Tellus A., 60, 113-130.Tanaka M., 1992. Intraseasonal oscillation and the onset and retreat dates of the summer monsoon east, southeast Asia and the western Pacific region using GMS high cloud amount data. J. Meteorol. Soc. Japan, 70, 613-628.Tan Tien Tran, Nguyen Thi Thanh, 2011. The MODIS satellite data assimilation in the WRF model to forecast rainfall in the central region. VNU Journal of Science, Natural Sciences and Technology, 27(3S), 90-95.Tao S., Chen L., 1987. A review of recent research on East summer monsoon in China, Monsoon Meteorology. C. P. Changand T. N. Krishramurti, Eds, Oxford University Press, Oxford, 60-92.Tippett M.K., Anderson J.L., Bishop C.H., Hamill T.M., Whitaker J.S., 2003. Ensemble square root filters. Mon. Wea. Rev., 131, 1485.Thuy Kieu Thi, Giam Nguyen Minh, Dung Dang Van, 2013. Using WRF model to forecast heavy rainfall events on September 2012 in Dong Nai River Basin. The Third International MAHASRI/HyARC Workshop on Asian Monsoon and Water Cycle, 28-30 August 2013, Da Nang, Viet Nam, 185-200.Xavier, Chandrasekar, Singh R. and Simon B., 2006. The impact of assimilation of MODIS data for the prediction of a tropical low-pressure system over India using a mesoscale model. International Journal of Remote Sensing 27(20), 4655-4676. https://doi.org/10.1080/01431160500207302. Wang B., 2003. Atmosphere-warm ocean interaction and its impacts on Asian-Australian monsoon variation. J. Climate, 16(8), 1195-1211.Wang B. and Wu R., 1997. Peculiar temporal structure of the South China Sea summer monsoon. J. Climate., 15, 386-396.Wang L., He J., and Guan Z., 2004. Characteristic of convective activities over Asian Australian ”landbridge” areas and its possible factors. Act a Meteorologic a Sinica, 18, 441-454.Wang, B., and Z. Fan, 1999. Choice of South Asian Summer Monsoon Indices. Bull. Amer. Meteor. Sci., 80, 629-638.Webster P.J., Magana V.O., Palmer T.N., Shukla J., Tomas R.A., Yanai M., Yasunari T., 1998. Monsoons: Processes, predictability, and teprospects for prediction, J. Geophys. Res., 103, 14451-14510.Wilks Daniel S., 1997. Statistical Methods in the Atmospheric Sciences. Ithaca New York., 59, 255.Whitaker J.S., Hamill T.M., 2002. Ensemble data assimilation without perturbed observations. Mon. Wea. Rev., 130, 1913.Wu G., Zhang Y., 1998. Tibetan plateau forcing and the timing of the monsoon onset over South Asia and the South China Sea. Mon.Wea.Rev., 126, 913-927.Zhang Z., Chan J.C.L., and Ding Y., 2004. Characteristics, evolution and mechanisms of the summer monsoon onset over Southeast Asia. J.Climatology, 24, 1461-1482.http://weather.uwyo.edu/upperair/sounding.html and http://tropic.ssec.wisc.edu/archive/
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MEHFOOZALI, MEHFOOZ ALI, U. P. SINGH, D. JOARDAR, and NIZAMUDDIN NIZAMUDDIN. "Synoptic study of extremely heavy rainfall events over lower Yamuna catchment : Some cases." MAUSAM 64, no. 2 (December 17, 2021): 265–80. http://dx.doi.org/10.54302/mausam.v64i2.684.
Full textAbstract:
vR;f/kd o"kkZ gksus ds dkj.k HkwL[kyu gksrk gS vDlekr ck<+ vk tkrh gS vkSj Qly dks {kfr igq¡prh gSA lekt] vFkZO;oLFkk vkSj i;kZoj.k ij bldk cgqr nq"izHkko iM+rk gSA i;kZoj.kh; vkSj flukWfIVd fLFkfr;ksa ds mRiUu gksus ls vR;f/kd vFkok cgqr Hkkjh o"kkZ gksus ds dkj.k Hkkjr esa nf{k.k if’peh ekulwu _rq ds nkSjku vf/kdk¡’kr% ck<+ vkrh gSA bl 'kks/k i= esa izeq[k flukWfIVd dkj.kksa dk irk yxkus dk iz;kl fd;k x;k gS tks y?kq vof/k iwokZuqeku ds {ks= esa fodflr iwokZuqeku rduhd vkSj vk/kqfud izs{k.kkRed izkS|ksfxdh ij vk/kkfjr o"kZ 1998&2010 dh vof/k dh bl o"kkZ vkSj ok;qeaMyh; iz.kkfy;ksa ds e/; laca/kksa ds fo’ys"k.k ds ek/;e ls ;equk ds fupys tyxzg.k {ks= ¼,y-okbZ-lh-½ esa vR;f/kd Hkkjh o"kkZ dh ?kVukvksa ds fy, mRrjnk;h gSA bl v/;;u ls ;g irk pyk gS fd bl {ks= esa caxky dh [kkM+h esa fuEu nkc iz.kkfy;ksa dk cuuk izeq[k dkjd gS fuLlansg ;fn LFkkuh; fLFkfr;k¡ izHkkoh gks tSlsa fd xehZ dk c<+uk rks ogk¡ ij Hkkjh o"kkZ gksrh gSA lkekU;r% caxky dh [kkM+h esa fuEu vcnkc iz.kkfy;k¡ ¼pØokr] vonkc] fuEu vonkc {ks= vkfn tSls ¼,y-ih-,l-½ fodflr gqbZ tks if’pe ls mRrjh if’peh fn’kk dh vksj c<+h rFkk ;equk ds fupys tyxzg.k ¼,y-okbZ-lh-½ {ks= esa igq¡phA ,slh ?kVukvksa ds fy, mRrjnk;h mifjru ok;q pØokrh ifjlapj.k ¼lkblj½ ds izHkko ls ogha ij ,y- ih- ,l- Hkh cu ldrk gSA ,slh iz.kkyh ls bDds&nwDds LFkkuksa ij vR;f/kd Hkkjh o"kkZ dh ?kVuk,¡ ¼lkekU;r% iz.kkyh ds nf{k.k if’pe {ks= esa½ vkSj dqN LFkkuksa ij Hkkjh ls cgqr Hkkjh o"kkZ gqbZ ftlds dkj.k ck<+ vkbZA ;fn ;equk ds fupys tyxzg.k ¼,y-okbZ-lh-½ {ks= esa ,y-ih-,l- fuf"Ø; ;k /khek iM+ tkrk gS rks bl izdkj dh o"kkZ dh ?kVukvksa dh laHkkouk c<+ ldrh gSA ,y-ih-,l- ds vkxs c<+us dk lgh iwokZuqeku nsus ds fy, vkj-,l-,e-lh- ¼Hkkjr ekSle foKku foHkkx½ ubZ fnYYkh ds iwoZuqeku :i js[kk ds ,u-MCY;w-ih- mRikn@72] 48 vkSj 24 ?kaVksa ds iou pkVZ lgh lk/ku ik, x, gSaA vR;f/kd o"kkZ dh ?kVukvksa ds iwokZuqeku esa bl izdkj dh lwpuk nsus ls iwokZuqekudrkvksa dks fuf’pr :i ls lgh iwokZuqeku feysxk rkfd ftyk izkf/kdkjh le; jgrs vkink dh rS;kjh ds fy, vko’;d ewyHkwr lqfo/kk,¡ miyC/k djk ldsaA
Extreme rainfall results in landslides, flash flood and crop damage that have major impact on society, the economy and the environment. During southwest monsoon season, flood mostly occurs in India due to extremely or very heavy rain that originates from environmental and synoptic conditions. An attempt has been made to identify the main synoptic reasons, which are responsible for extremely heavy rainfall events over Lower Yamuna catchment (LYC) through the analysis of the relationship between this rainfall and atmospheric systems for the period 1998-2010 based on modern observational technology and developed forecasting technique in the field of short range prediction. The finding of this study show that the major factor have is the arrival of Bay of Bengal low pressure systems in this region, of course if the ascent local conditions such as heat occur, causing the heaviest rains there. The low pressure systems (LPS like, Cyclone, depression, low pressure area etc.) developed generally over Bay of Bengal moved in west to north-westwards direction and reached over the LYC region. Also LPS may be formed in situ under the influence of upper air cyclonic circulation (cycir) responsible for such events. Such system yield extremely heavy rainfall events (generally in the south-west sector of the system) at isolated places and heavy to very heavy rainfall at a few places and there by caused flood situation. The possibility of occurrence of such type of rainfall would be higher if the LPS is either stagnate or slow over LYC region. The NWP products of RSMC (IMD) New Delhi forecast contours / wind charts for 72, 48 & 24 hrs were found good tool for accurate forecast position of the movement of the LPS. Such information certainly facilitate to forecaster in prediction of extreme rainfall events more accurately so that district authorities may set up necessary infrastructures for disaster preparedness in time.
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Lapeña, José Florencio F. "On Research Integrity and Ethical Publication, Authorship and Accreditation." Philippine Journal of Otolaryngology-Head and Neck Surgery 28, no. 2 (December 1, 2013): 4–6. http://dx.doi.org/10.32412/pjohns.v28i2.471.
Full textAbstract:
In 2013, multiple articles reporting the clinical trial of valsartan, an antihypertensive drug of more than US$ 1 billion annual sales from Novartis, were retracted due to data falsification.1,2 These included the Kyoto Heart Study presented by Dr. Hiroaki Matsubara at the European Society of Cardiology 2009 Congress and subsequently published in the European Heart Journal (EHJ).3,4 Aside from retraction of this article by EHJ, the American Heart Association (AHA) also retracted five papers published in three of its journals -- Circulation, Circulation Research, and Hypertension.4 Novartis employees were involved in the conduct and analysis of the Kyoto Heart Study and a second investigator-initiated trial, the Jikei Heart Study,5 although their participation was not acknowledged in publications and presentations of the data, while a Novartis employee who allegedly manipulated statistical data was listed as one of the academic authors, without disclosing the relation with the company.4,6
This scandal has severely damaged scientific integrity in Japan and set the stage for the
“Tokyo Declaration on Research Integrity and Ethical Publication in Science and Medicine in the Asia Pacific Region” adopted at the 2013 Convention of the Asia Pacific Association of Medical Journal Editors (APAME) held in Tokyo from 2 to 4 August 2013, and co-published by Journals linked to APAME and listed in the Index Medicus for the South East Asian Region (IMSEAR) and the Western Pacific Region Index Medicus (WPRIM), including the Philippine Journal of Otolaryngology Head and Neck Surgery, with a Special Announcement in this issue.7
At the core of research integrity and ethical publication is responsible and accountable authorship. The ICMJE "Uniform Requirements for Manuscripts Submitted to Biomedical Journals" has been replaced by the “Recommendations for the Conduct, Reporting, Editing, and Publication of Scholarly Work in Medical Journals.”8 An important change under these new guidelines is an additional criterion for authorship, totaling four (4) instead of three (3) criteria.
The ICMJE recommends that authorship be based on the following 4 criteria:8
Substantial contributions to the conception or design of the work; or the acquisition, analysis, or interpretation of data for the work; AND
Drafting the work or revising it critically for important intellectual content; AND
Final approval of the version to be published; AND
Agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
In addition to being accountable for the parts of the work he or she has done, an author should be able to identify which co-authors are responsible for specific other parts of the work. In addition, authors should have confidence in the integrity of the contributions of their co-authors. One cannot be listed as a co-author for the credit it brings, without being equally accountable in case of discredit. For example, consultant advisers and seniors who would consider adding their names as co-authors of a junior resident, are equally accountable for research misconduct (such as data fabrication, falsification, plagiarism), and cannot lay the blame on one (usually junior) author.
While all those designated as authors should meet all four criteria for authorship, and all who meet the four criteria should be identified as authors, those who do not meet all four criteria should be acknowledged. Hence, it is more appropriate for consultant advisers and seniors who do not meet all four criteria for authorship to be acknowledged in this manner.
Our journal seeks to maintain the highest standards of biomedical publication, and fully supports the APAME Tokyo Declaration on Research Integrity and Ethical Publication in Science and Medicine in the Asia – Pacific Region as well as the ICMJE Recommendations for the Conduct, Reporting, Editing, and Publication of Scholarly Work in Medical Journals. Multiple accreditations and indexing are testimony to these standards.
It was surprising therefore, that a letter from the Commission on Higher Education Journal Accreditation System dated 26 April 2013, which we received 26 May 2013, informed us of our reaccreditation under Category B based on the “recommendation of the panel of evaluators” who “pointed out the need to improve the journal’s refereeing system, regularity of publication/circulation and timeliness.”9
I respectfully responded to these remarks10 stating that:
the Philipp J Otolaryngol Head Neck Surg is one of the few consistently compliant journals accredited by the National Journal Selection Committee of the Philippine Council for Health Research and Development, Department of Science and Technology. Our journal has a reputable loco-regional stature evidenced by international contributions from the USA, Japan, Turkey, Malaysia, India and Brunei, and has consistently been recognized as a benchmark journal by the Philippine Association of Medical Journal Editors and Asia Pacific Association of Medical Journal Editors. It functions as the de facto ASEAN Journal in the field of Otolaryngology Head and Neck Surgery.
It is always regularly published on time, and indexed in the Health Research and Development Network (HERDIN-NeON) supported by the PCHRD-DOST; Philippine Journals On Line (PhilJOL) and Asia Journals On Line (AsiaJOL) supported by the International Network for the Availability of Scientific Publications (INASP); the Western Pacific Region Index Medicus (WPRIM) of the World Health Organization (WHO), APAMED Central and the Index Copernicus™ Journals Master List. It has always met the accreditation criteria of these services. The journal’s online peer review system is used as an example for other local journals, including in National Medical Writing and Reviewing Workshops organized by the PCHRD (2012 Cebu and Davao, 2013 Baguio and Iloilo), in the Philippine National Health Research System Week (2011 Bacolod, 2012 Manila, 2013 Laoag) as well as for regional journals in Medical Writing and Review Workshops held in Brunei, Singapore, Malaysia, Vietnam and Cambodia. Several local and regional journals have been thus assisted by us in their editing and peer review systems.
As a Category A Accredited Research Journal (Batch 1) for 2009 – 2012 per Commission on Higher Education (CHED) Memorandum Order No. 09 s. 2010 and Resolution No. 477-2009, effective December 9, 2009 (signed May 26, 2010), our journal has faithfully complied with all the terms of the JAS, including “acknowledgement in the published journal that the publication thereof was a product of the Journal Accreditation Service project of the Commission on Higher Education” in the inside front cover of every issue. Moreover, we have gone beyond the dissemination requirement by providing a complimentary copy of each issue to every Medical School Library in the Philippines.
I ended by reiterating that our journal “has more than complied with the requirements of the Journal Accreditation Service of the Commission on Higher Education for reaccreditation as a Category A Accredited Research Journal, and beg(ged) the honorable review panel to reconsider its recommendation.”10
It turned out that previously-submitted copies of our journal had been inadvertently misplaced, leading to our downgrade from Category A to B. Expecting full reinstatement, I was surprised to receive a response dated 23 July 2013 on 23 August 2013, informing us that:
“the Technical Evaluators decided to classify the said journal as ‘conditional category A’ pending submission of enhanced volumes with sober and serious formats to project scientific/scholarly image. While refereed journals often contain many graphs and charts, these do not normally include glossy pages (e.g. advertisements) or exciting pictures (e.g. captoons) which noticeably appeared in the issues that you submitted.”11
I again respectfully responded to these remarks by citing12
the International Committee of Medical Journal Editors Recommendations for the Conduct, Reporting, Editing, and Publication of Scholarly Work in Medical Journals (ICMJE Recommendations) updated August 2013, cited 29 August 2013 available at http://www.icmje.org/urm_main.html8
The recommendations have clear guidelines on advertising, and do not forbid exciting pictures and cartoons. Nowhere do they constrain scholarly medical journals to maintain “sober and serious formats to project scientific/scholarly image.” The Philippine Journal of Otolaryngology Head and Neck Surgery is listed among the Journals Following ICMJE Recommendations http://www.icmje.org/journals.html13
The top-tier journals in medicine (BMJ, JAMA, Lancet and NEJM) as well as Science and Nature all have advertising in glossy pages and exciting pictures and cartoons, even on their covers. The same is true for our major journals in the field of Otolaryngology Head and Neck Surgery. I provided the technical panel with copies of the Instructions to Authors of these journals, as well as photographs of actual caricatures from their covers and inside pages. Finally, I also attached an excerpt from: Bennett HJ. Humor in Medicine. South Med J. 2003;96(12)14 for the perusal of the honourable Technical Panel.
As of press time, we have not received a reply from the Technical Panel, but have received advise from the Office of Policy, Planning, Research and Information of the Commission on Higher Education to withhold, in the meantime, our inside front cover acknowledgement that the publication of this issue “was a product of the Journal Accreditation Service project of the Commission on Higher Education.” However, we shall continue to provide a complimentary copy of this issue to every Medical School Library in the Philippines as a valuable service of our Society and Journal as we await the resolution of this situation.
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WICKRAMASINGHE, GMN. "The influence of Nuclear Explosions on the Weather Pattern of Europe and Northern Asia." MAUSAM 20, no. 4 (April 30, 2022). http://dx.doi.org/10.54302/mausam.v20i4.5767.
Full textAbstract:
There were powerful series of atmospheric nuclear explosions in the Novaya Zemlya region of the Arctic autumn and early winter of 1961; and much more powerful series in the same region during the same seasons in 1962. These have been the most powerful so far.
During the above seasons it is noticed that the pressure and circulation pattern of the troposphere and lower stratosphere in Europe and Northern Asia displayed some abnormal features for the time of year during and immediately after each series of nuclear explosions the sea level westerly circulation was weak with low cyclonic activity; but the high level ,westerly circulation was strong with strong cyclonic activity at high levels and intense anticyclonic activity with blocking at sea level and higher levels, often for long periods. This abnormal atmospheric pattern faded between series of explosions, particularly if there was a long interval between the series.
A consequence of this atmospheric pattern has been the development of an extensive cold polar cell over Northern Eurasia by mid-winter of each year. The very cold northerly and easterly winds emitted by this polar cell opposed the warm sea level westerly circulation and prevented the invasion of temperate latitudes by warm fronts. As a consequence the winters were very cold, and the 1962-63 winter was one of the coldest on record.
With the aid of aerologioal charts and available information regarding atmospheric nuclear explosions and their influence on the atmosphere. it has been shown that the series of nuclear explosious played a major role in the evolution of the abnormal atmospheric pattern.
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Ha, Pham Thanh, Hoang Danh Huy, Pham Quang Nam, Jack Katzfey, John McGregor, Nguyen Kim Chi, Tran Quang Duc, Nguyen Manh Linh, and Phan Van Tan. "Implementation of Tropical Cyclone Detection Scheme to CCAM model for Seasonel Tropical Cyclone Prediction over the Vietnam East Sea." VNU Journal of Science: Earth and Environmental Sciences, July 12, 2019. http://dx.doi.org/10.25073/2588-1094/vnuees.4384.
Full textAbstract:
Abstract: This study has selected a vortex tracking algorithm scheme for simulating the activity of tropical cyclone in the Vietnam East Sea by CCAM model. The results show that the CCAM model is able to simulate well the large scale in each month through a reasonable description of the movement rules of the tropical cyclone in the study area. Then, this vortex tracking algorithm scheme was applied to test the seasonal forecast with the outputs of the CCAM model with a resolution of 20km for September 2018 and October 2018. The obtaining results are forecasted quite closely in terms of both quantity and high potential occurrence areas of the tropical cyclone when compared with reality. In particular, for October 2018, although the activity area of the tropical cyclone - YUTU is significantly different from the multi-year average activity position, the seasonal forecast results are obtained from the 120 members of the CCAM model captured this difference. This suggests that it is possible to apply the CCAM model in combination with the selected vortex tracking algorithm scheme for the seasonal forecast of the tropical cyclone over the Vietnam East Sea region in the future.
Keywords: Vortex tracking algorithm scheme, Tropical storm, Tropical cyclone, The Vietnam East Sea.
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Nghia, Bui Phan Quoc, Indrajit Pal, Malay Pramanik, and Rajarshi Dasgupta. "The impact of climate change on drought and its adaptation strategies: findings from general circulation models and households in Tien Giang Province, Vietnam." Climatic Change 175, no. 3-4 (December 2022). http://dx.doi.org/10.1007/s10584-022-03473-1.
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Borm, Jan, Joanna Kodzik, and Sylvie Charbit. "Producing and communicating natural history in the long 18th century: Moravian observations concerning Greenland’s climate in unpublished sources." Polar Record 57 (2021). http://dx.doi.org/10.1017/s0032247421000218.
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Abstract This paper discusses weather observations of Moravian missionaries in Greenland in the long 18th century, placing them in the broader context of their missionary work at Neu-Herrnhut and other stations as well as their comments on the natural world. Some of their climate-related remarks and measurements were published and discussed in print, notably in David Cranz’ History of Greenland and a number of scholarly reviews at the time. These publications are compared to and complemented by data retrieved by the authors from unpublished source material in the Moravian Archives in Herrnhut, Germany, demonstrating that the Moravian diaries can fill in significant gaps in Greenland’s weather charts before systematic measurements were introduced in the 19th century. Their special interest for climate studies is underscored in conclusion, in particular their observations of extreme climate events that can allow us to better characterise the amplitude and geographical extent of such events and to compare them with climate model simulations in order to better understand the respective roles of external (volcanism, solar activity) and internal (atmospheric circulation) forcings and the impacts of potential feedbacks within the ocean–atmosphere system.
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Khoi, D. N., V. T. Nguyen, T. T. Sam, N. T. H. Mai, N. D. Vuong, and H. V. Cuong. "Assessment of climate change impact on water availability in the upper Dong Nai River Basin, Vietnam." Journal of Water and Climate Change, September 13, 2021. http://dx.doi.org/10.2166/wcc.2021.255.
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Abstract On a global scale, climate change is projected to have detrimental impacts on water availability. This situation will become more severe owing to accumulated impacts of climate change and anthropogenic activities. This study aims to investigate climate change impact on water availability in the upper Dong Nai River Basin using the Soil and Water Assessment Tool (SWAT) and Water Evaluation and Planning (WEAP) models. Future rainfall scenarios were downscaled from five different general circulation models under RCP4.5 and RCP8.5 using the Long Ashton Research Station Weather Generator (LARS-WG) tool. Under the climate change impact, annual river discharge in the study region is generally projected to have upward trends in the future, except for the near-future period of 2030s under RCP4.5. In addition, dry-seasonal river discharge is expected to be increased in the future. Considering the baseline condition of water use, there was an annual water shortage of approximately 32.9 × 103 m3, which mostly occurred in the dry season from January to March. Climate change may reduce the water shortage in the study region ranging from 7.0 to 30.1% in the future. Under the combined impacts of climate change and increasing water demand, the water shortage will vary from −18.6 to 6.0% in the future. The results can provide valuable insights to implement appropriate future water resources planning and management in the study region.
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Minh, Pham Thi, Tran Van Son, Tran Thi Mai Hương, Nguyen Thi Hang, and Tu Thi Năm. "Testing of the Multi-Physics Ensemble Kalman filter to Simulate the Track and Intensity of the Typhoon HaiYan (2013)." Science & Technology Development Journal - Science of The Earth & Environment 3, no. 2 (January 6, 2020). http://dx.doi.org/10.32508/stdjsee.v3i2.517.
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This paper presents some experimental results of the multi-physics ensemble Kalman filter method which assimilating the satellite wind data in WRF model to simulate the track and intensity of the typhoon HaiYan (2013). The study conducted two experiments.: (1) Ensemble forecast with multi-physics ensemble Kalman filter assimilates the satellite wind data (CIMSS); (2) multi-physics Ensemble forecast (MPH). The results of atmospheric circulation analysis in the simulation started at 12 UTC (international time) until November 7, 2013, showing that the trend and intensity of the general circulation in the CIMSS test are similar to the real development. So the results of the storm trajectory forecast of CIMSS test at the 48-hour forecast limit onwards are better than the MPH test. Moreover, experimental results based on the results of the 6 simulations for simulation error, the track error in the CIMSS test decreased 14% and 14.3% respectively in the 48-hour forecast period and 72 hours compared with the MPH test, and decreased 14% and 23.9% respectively compared to the global GFS forecast. For storm intensity (Pmin and Vmax), the CIMSS test also resulted in significantly improved errors in the 72-hour forecast period compared to MPH testing. These results confirmed that the assimilation of the satellite wind data into the input field of the model has a positive effect on Haiyan storm intensity and trajectory prediction skills. We may use this research to applying the multi-physics ensemble Kalman filter for forecasting storms affecting Vietnam.
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Hallé, Danielle A. M., Nanna B. Karlsson, Anne Munck Solgaard, and Camilla S. Andresen. "Observationally constrained reconstruction of 19th to mid-20th century sea-ice extent off eastern Greenland." Geological Survey of Denmark and Greenland Bulletin, August 15, 2018, 83–86. http://dx.doi.org/10.34194/geusb.v41.4349.
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Arctic sea ice has a significant impact on the global radiation budget, oceanic and atmospheric circulation and the stability of the Greenland ice sheet (Vaughan et al. 2013). Prior to the era of aircraft and satellite, information on sea-ice extent relied on observations from ships and people living at the coast. This information is a valuable contribution to better understand the history of sea ice. However, the information exists in a range of formats, e.g., sea-ice extent before the late 1800s is typically reported in the literature as an annual index from a single geographical point or as hand-drawn maps. This makes it difficult to assess and compare data across time and space. The combination of digitised historical maps and single-point data makes the information more accessible and provides a record that can help understand the dynamics and processes of the climate and its interactions with the cryosphere (Chapman & Walsh 1993). In this study, maps of sea-ice extent by Koch (1945) were digitised. We use these maps in combination with sea-ice charts from the Danish Meteorological Institute (DMI) and Koch’s sea-ice index from 1820 to 1939, to map estimated sea-ice extent between Iceland and Greenland going back to 1821. This information has not been included in even the most recent databases of Arctic sea ice (Walsh et al. 2015, 2017). Furthermore, we extract time series of sea-ice extent at a number of locations and investigate the relationship between them. Our observation area is along eastern Greenland, between the southern tip of Greenland at 59°46´N northwards to 77°21´N.
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Khoi, Dao Nguyen, Truong Thao Sam, Pham Thi Loi, Bui Viet Hung, and Van Thinh Nguyen. "Impact of climate change on hydro-meteorological drought over the Be River Basin, Viet Nam." Journal of Water and Climate Change, June 21, 2021. http://dx.doi.org/10.2166/wcc.2021.137.
Full textAbstract:
Abstract In this paper, the responses of hydro-meteorological drought to changing climate in the Be River Basin located in Southern Vietnam are investigated. Climate change scenarios for the study area were statistically downscaled using the Long Ashton Research Station Weather Generator tool, which incorporates climate projections from Coupled Model Intercomparison Project 5 (CMIP5) based on an ensemble of five general circulation models (Can-ESM2, CNRM-CM5, HadGEM2-AO, IPSL-CM5A-LR, and MPI-ESM-MR) under two Representative Concentration Pathway (RCP) scenarios (RCP4.5 and RCP8.5). The Soil and Water Assessment Tool model was employed to simulate streamflow for the baseline time period and three consecutive future 20 year periods of 2030s (2021–2040), 2050s (2041–2060), and 2070s (2061–2080). Based on the simulation results, the Standardized Precipitation Index and Standardized Discharge Index were estimated to evaluate the features of hydro-meteorological droughts. The hydrological drought has 1-month lag time from the meteorological drought and the hydro-meteorological droughts have negative correlations with the El Niño Southern Oscillation and Pacific Decadal Oscillation. Under the climate changing impacts, the trends of drought severity will decrease in the future; while the trends of drought frequency will increase in the near future period (2030s), but decrease in the following future periods (2050 and 2070s). The findings of this study can provide useful information to the policy and decisionmakers for a better future planning and management of water resources in the study region.
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Shibani, Abdelfatah H. "Jet Streams as Power Generating Electrical Energy in Libya." Solar Energy and Sustainable Development journal 3, no. 1 (February 15, 2021). http://dx.doi.org/10.51646/jsesd.v3i1.50.
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The supreme wind sources are extremely huge, and according to estimations, these winds can supply Libya with great quantity of electrical energy. Among the examples of contemporary engineering technologies in this field, is to create a new generation of Airborne Wind Turbines. Scientists realized that winds near the Earth’s surface are too weak to provide a regular source of energy due to the presence of aerobic swirls and obstacles, which represent a source of ground friction being the cause of weakening wind power. Some consider that the Earth’s surface is a totally inappropriate place for investing wind energy. As an alternative solution, we start to think about the establishment of wind farms in another place away from the Earth’s surface by developing a new type that can run within the upper-air layers, precisely at jet streams areas. In comparison with fluctuating winds blowing gently near the Earth’s surface, scientists estimate that the energy of jet streams increases a thousand times than that can be gathered from the most powerful winds on high hills. To be able to provide a clear picture of the possibility of energy investment of jet streams, we shall present, across the pages of this paper, an explanation of the topic through the following aspects: How do Airborne Wind Turbines’ trip start, their advantages and difficulties faced, benefits and economic feasibility, General Atmospheric Circulation and jet streams. Since Libya is among the fortunate countries in the world, through which subtropical jet streams pass, we made an analysis and follow-up of daily synoptic charts, which show jet winds’ speed, direction and their altitudes for a period of 60 consecutive months starting from January 1, 2003 until December 31, 2007. Also, an analysis was made of daily observational data of jet winds recorded by Tripoli Upper-air Station during the period from the beginning of March 1987 until the end of February 1989. The paper’s results summarized that jet streams will be in the future one of the important clean energy strategic sources, and can provide a capacity, whose expected intensity is up to 19 kilowatts per square meter. It recommends giving attention to jet streams at the research, experimental and technological levels because research, experimental and technological proficiencies can provide more exciting solutions for energy problems in Libya.