Статті в журналах з теми "Hydroclimat"
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1
Switanek, Matthew B., Peter A. Troch, and Christopher L. Castro. "Improving Seasonal Predictions of Climate Variability and Water Availability at the Catchment Scale." Journal of Hydrometeorology 10, no. 6 (December 1, 2009): 1521–33. http://dx.doi.org/10.1175/2009jhm1073.1.
Повний текст джерелаАнотація:
Abstract In a water-stressed region, such as the southwestern United States, it is essential to improve current seasonal hydroclimatic predictions. Typically, seasonal hydroclimatic predictions have been conditioned by standard climate indices, for example, Niño-3 and Pacific decadal oscillation (PDO). In this work, the statistically unique relationships between sea surface temperatures (SSTs) and particular basins’ hydroclimates are explored. The regions where global SSTs are most correlated with the Little Colorado River and Gunnison River basins’ hydroclimates are located throughout the year and at varying time lags. The SSTs, from these regions of highest correlation, are subsequently used as hydroclimatic predictors for the two basins. This methodology, named basin-specific climate prediction (BSCP), is further used to perform hindcasts. The hydroclimatic hindcasts obtained using BSCP are shown to be closer to the historical record, for both basins, than using the standard climate indices as predictors.
2
Koster, R. D., G. K. Walker, G. J. Collatz, and P. E. Thornton. "Hydroclimatic Controls on the Means and Variability of Vegetation Phenology and Carbon Uptake." Journal of Climate 27, no. 14 (July 10, 2014): 5632–52. http://dx.doi.org/10.1175/jcli-d-13-00477.1.
Повний текст джерелаАнотація:
Abstract Long-term, global offline (land only) simulations with a dynamic vegetation phenology model are used to examine the control of hydroclimate over vegetation-related quantities. First, with a control simulation, the model is shown to capture successfully (though with some bias) key observed relationships between hydroclimate and the spatial and temporal variations of phenological expression. In subsequent simulations, the model shows that (i) the global spatial variation of seasonal phenological maxima is controlled mostly by hydroclimate, irrespective of distributions in vegetation type; (ii) the occurrence of high interannual moisture-related phenological variability in grassland areas is determined by hydroclimate rather than by the specific properties of grassland; and (iii) hydroclimatic means and variability have a corresponding impact on the spatial and temporal distributions of gross primary productivity (GPP).
3
Song, Yougui, Xiulan Zong, Linbo Qian, Huifang Liu, Jibao Dong, Hong Chang, and Mingyu Zhang. "Mineralogical Record for Stepwise Hydroclimatic Changes in Lake Qinghai Sediments Since the Last Glacial Period." Minerals 10, no. 11 (October 28, 2020): 963. http://dx.doi.org/10.3390/min10110963.
Повний текст джерелаАнотація:
Lake Qinghai is sensitive to climatic changes because of its pivotal location between mid-latitude Westerlies and the low-latitude East Asian monsoon. An 18.6 m long drilling core (1Fs) from Lake Qinghai provides new information on the hydroclimatic dynamics since the last glacial period. Here, we present the results of bulk mineral assemblages of this core. X-ray diffraction (XRD) results showed that the bulk minerals of the core sediments consist of major clastic minerals (e.g., quartz, feldspar, muscovite), carbonates (e.g., calcite, aragonite, dolomite), and minor clay minerals (e.g., chlorite). Quartz as an exogenous detrital mineral in lake sediments, its abundance is related to lake level changes resulting from regional climate changes via fluvial/aeolian transportation. Aragonite was precipitated from water solutions or chemical alteration of pre-existing minerals or biogenic mediation, closely related to lake hydroclimate change. Mineral assemblages revealed remarkable stepwise hydroclimatic changes. High quartz content and low calcite without aragonite suggested a cold-wet climate condition under predominant westerlies during the last glacial period from 35 to 25.3 ka. Afterward, quartz decreased and aragonite occasionally appeared, indicating an unstable hydroclimatic condition during the last deglaciation. Since the Early Holocene (11.9–8.2 ka), predominant minerals shifted from terrigenous quartz to authigenic carbonates, suggesting an increasing lake level, possibly due to intensified Asian summer monsoon with increased effective moisture. Aragonite became the primary carbonate mineral, implying a warming and humid hydroclimate environment with a relatively higher lake-level. During the Middle Holocene (8.2–4.2 ka), aragonite showed a decreasing trend indicating a higher lake level with weak evaporation. During the Late Holocene since 4.2 ka, there were lower quartz and aragonite, suggesting a deep lake with a weak summer monsoon. Our quartz and carbonate minerals record provided essential clues to reconstruct hydroclimate change in Lake Qinghai since the last glacial period.
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Markonis, Yannis, and Filip Strnad. "Representation of European hydroclimatic patterns with self-organizing maps." Holocene 30, no. 8 (April 20, 2020): 1155–62. http://dx.doi.org/10.1177/0959683620913924.
Повний текст джерелаАнотація:
Self-organizing maps provide a powerful, non-linear technique of dimensionality reduction that can be used to identify clusters with similar attributes. Here, they were constructed from a 1000-year-long gridded palaeoclimatic dataset, namely the Old World Drought Atlas, to detect regions of homogeneous hydroclimatic variability across the European continent. A classification scheme of 10 regions was found to describe most efficiently the spatial properties of Europe’s hydroclimate. These regions were mainly divided into a northern and a southern subset, linked together with a northwest-to-southeast orientation. Further analysis of the classification scheme with complex networks confirmed the divergence between the northern and southern components of European hydroclimate, also revealing that is not strongly correlated to the Iberian Peninsula. On the contrary, the region covering the British Isles, France and Germany appeared to be linked to both branches, implying links of hydroclimate with atmospheric/oceanic circulation.
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Sang, Yan-Fang, Fubao Sun, Vijay P. Singh, Ping Xie, and Jian Sun. "A discrete wavelet spectrum approach for identifying non-monotonic trends in hydroclimate data." Hydrology and Earth System Sciences 22, no. 1 (January 26, 2018): 757–66. http://dx.doi.org/10.5194/hess-22-757-2018.
Повний текст джерелаАнотація:
Abstract. The hydroclimatic process is changing non-monotonically and identifying its trends is a great challenge. Building on the discrete wavelet transform theory, we developed a discrete wavelet spectrum (DWS) approach for identifying non-monotonic trends in hydroclimate time series and evaluating their statistical significance. After validating the DWS approach using two typical synthetic time series, we examined annual temperature and potential evaporation over China from 1961–2013 and found that the DWS approach detected both the “warming” and the “warming hiatus” in temperature, and the reversed changes in potential evaporation. Further, the identified non-monotonic trends showed stable significance when the time series was longer than 30 years or so (i.e. the widely defined “climate” timescale). The significance of trends in potential evaporation measured at 150 stations in China, with an obvious non-monotonic trend, was underestimated and was not detected by the Mann–Kendall test. Comparatively, the DWS approach overcame the problem and detected those significant non-monotonic trends at 380 stations, which helped understand and interpret the spatiotemporal variability in the hydroclimatic process. Our results suggest that non-monotonic trends of hydroclimate time series and their significance should be carefully identified, and the DWS approach proposed has the potential for wide use in the hydrological and climate sciences.
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Curtis, Scott. "Hydroclimatic Variability at Local, Regional and Global Scales." Water 12, no. 5 (May 23, 2020): 1490. http://dx.doi.org/10.3390/w12051490.
Повний текст джерелаАнотація:
Hydroclimate is non-stationary and varies in often unpredictable ways on local, regional and global scales, which can lead to water insecurity. This editorial relates the advances and challenges in our understanding of the spatio-temporal relationship between climate variability and change and the components of the hydrologic cycle through the lens of six articles, which contributed to the Water Special Issue: Hydroclimatic Variability at Local, Regional and Global Scales. The relationship between the El Niño/Southern Oscillation and precipitation, temperature, and evapotranspiration is examined within the Indian Summer monsoon, gauge-based precipitation datasets are intercompared over Pakistan, trends in precipitation, temperature, and streamflow are investigated in Ethiopia and China, alternate configurations of hydroclimate modeling are assessed over Canada, and finally, future limitations in groundwater supply are presented for Italy.
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Kim, Sinae, Hakkwan Kim, Kyeung Kim, Sang-Min Jun, Soonho Hwang, and Moon-Seong Kang. "Assessing the Hydroclimatic Movement under Future Scenarios Including both Climate and Land Use Changes." Water 13, no. 8 (April 19, 2021): 1120. http://dx.doi.org/10.3390/w13081120.
Повний текст джерелаАнотація:
In this study we simulated the watershed response according to future climate and land use change scenarios through a hydrological model and predicting future hydroclimate changes by applying the Budyko framework. Future climate change scenarios were derived from the UK Earth system model (UKESM1), and future land use changes were predicted using the future land use simulation (FLUS) model. To understand the overall trend of hydroclimatic conditions, the movements in Budyko space were represented as wind rose plots. Moreover, the impacts of climate and land use changes were separated, and the watersheds’ hydroclimatic conditions were classified into five groups. In future scenarios, both increase and decrease of aridity index were observed depending on the watershed, and land use change generally led to a decrease in the evaporation index. The results indicate that as hydroclimatic movement groups are more diversely distributed by region in future periods, regional adaptation strategies could be required to reduce hydroclimatic changes in each region. The results derived from this study can be used as basic data to establish an appropriate water resource management plan and the governments’ land use plan. As an extension of this study, we can consider more diverse land use characteristics and other global climate model (GCMs) in future papers.
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Ghajarnia, Navid, Georgia Destouni, Josefin Thorslund, Zahra Kalantari, Imenne Åhlén, Jesús A. Anaya-Acevedo, Juan F. Blanco-Libreros, et al. "Data for wetlandscapes and their changes around the world." Earth System Science Data 12, no. 2 (May 13, 2020): 1083–100. http://dx.doi.org/10.5194/essd-12-1083-2020.
Повний текст джерелаАнотація:
Abstract. Geography and associated hydrological, hydroclimate and land-use conditions and their changes determine the states and dynamics of wetlands and their ecosystem services. The influences of these controls are not limited to just the local scale of each individual wetland but extend over larger landscape areas that integrate multiple wetlands and their total hydrological catchment – the wetlandscape. However, the data and knowledge of conditions and changes over entire wetlandscapes are still scarce, limiting the capacity to accurately understand and manage critical wetland ecosystems and their services under global change. We present a new Wetlandscape Change Information Database (WetCID), consisting of geographic, hydrological, hydroclimate and land-use information and data for 27 wetlandscapes around the world. This combines survey-based local information with geographic shapefiles and gridded datasets of large-scale hydroclimate and land-use conditions and their changes over whole wetlandscapes. Temporally, WetCID contains 30-year time series of data for mean monthly precipitation and temperature and annual land-use conditions. The survey-based site information includes local knowledge on the wetlands, hydrology, hydroclimate and land uses within each wetlandscape and on the availability and accessibility of associated local data. This novel database (available through PANGAEA https://doi.org/10.1594/PANGAEA.907398; Ghajarnia et al., 2019) can support site assessments; cross-regional comparisons; and scenario analyses of the roles and impacts of land use, hydroclimatic and wetland conditions, and changes in whole-wetlandscape functions and ecosystem services.
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Gallant, A. J. E., A. S. Kiem, D. C. Verdon-Kidd, R. C. Stone, and D. J. Karoly. "Understanding hydroclimate processes in the Murray-Darling Basin for natural resources management." Hydrology and Earth System Sciences 16, no. 7 (July 12, 2012): 2049–68. http://dx.doi.org/10.5194/hess-16-2049-2012.
Повний текст джерелаАнотація:
Abstract. Isolating the causes of extreme variations or changes in the hydroclimate is difficult due to the complexities of the driving mechanisms, but it is crucial for effective natural resource management. In Australia's Murray-Darling Basin (MDB), ocean-atmosphere processes causing hydroclimatic variations occur on time scales from days to centuries, all are important, and none are likely to act in isolation. Instead, interactions between all hydroclimatic drivers, on multiple time scales, are likely to have caused the variations observed in MDB instrumental records. A simplified framework is presented to assist natural resource managers in identifying the potential causes of hydroclimatic anomalies. The framework condenses an event into its fundamental elements, including its spatial and temporal signal and small-scale evolution. The climatic processes that are potentially responsible are then examined to determine possible causes. The framework was applied to a period of prolonged and severe dry conditions occurring in the southern MDB from 1997–2010, providing insights into possible causal mechanisms that are consistent with recent studies. The framework also assists in identifying uncertainties and gaps in our understanding that need to be addressed.
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Duguma, Fekadu Aduna, Fekadu Fufa Feyessa, Tamene Adugna Demissie, and Krystyna Januszkiewicz. "Hydroclimate Trend Analysis of Upper Awash Basin, Ethiopia." Water 13, no. 12 (June 17, 2021): 1680. http://dx.doi.org/10.3390/w13121680.
Повний текст джерелаАнотація:
The Awash River basin is classified into the upper basin, middle basin, and lower basin. The upper basin is the most irrigated and socio-economically important, wherein early and modern agriculture started. This study aimed to assess the upper basin’s hydroclimate variability under climate change from 1991 to 2015 following the county’s land-use policy change. Distinguished topographical settings, namely, lowland, midland, and highland, are used for upper Awash basin hydroclimate trend analysis. Lowland stations revealed a nonsignificant seasonal and annual increasing trend except for the Autumn season. Midland stations showed a decreased seasonal rainfall. Except for Sendafa, the increased station, the highland area exhibited an annual decreasing trend. The Awash-Hombole and Mojo main tributaries are used for the evaluation of basin streamflow. The Awash-Hombole main tributary resulted in annually growing trends during the summer season. Mojo main tributary resulted in a significantly decreasing trend during the spring, summer, and autumn seasons with a 99% level of significance. Therefore, following the basin’s topographic nature, the change of hydroclimatic elements, mainly of the rainfall and streamflow, is observed. Accordingly, its hydroclimate variated by 11 and 38% with precipitation and streamflow, respectively, from the mean value within the study time series.
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St. George, Scott, and Erik Nielsen. "Hydroclimatic Change in Southern Manitoba Since A.D. 1409 Inferred from Tree Rings." Quaternary Research 58, no. 2 (September 2002): 103–11. http://dx.doi.org/10.1006/qres.2002.2343.
Повний текст джерелаАнотація:
AbstractA record of estimated annual (prior August to current July) precipitation derived from a regional bur oak (Quercus macrocarpa Michx.) tree-ring chronology indicates that southern Manitoba's hydroclimate has been relatively stable over the last 200 yr. Although this stability was interrupted briefly by pronounced wet intervals in the late A.D. 1820s and 1850s, hydroclimatic conditions since permanent Euro-Canadian settlement were much less variable and persistent than those prior to A.D. 1790. The reconstruction indicates that the Red River basin experienced extremely dry conditions between A.D. 1670 and 1775, with below-normal precipitation occurring approximately 2 years out of 3. Annual precipitation was estimated at more than two standard deviations below the mean during A.D. 1477, 1485, 1556, 1595, 1612, 1644, 1661, 1743, 1900, and 1980. Comparisons with limnological records from North Dakota and Minnesota suggest that multidecadal fluctuations in regional hydroclimate have been remarkably coherent across the northeastern Great Plains during the last 600 yr. However, individual dry years in the Red River basin were usually associated with larger scale drought across much of the North American interior.
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Bennett, Katrina E., Carl Talsma, and Riccardo Boero. "Concurrent Changes in Extreme Hydroclimate Events in the Colorado River Basin." Water 13, no. 7 (April 1, 2021): 978. http://dx.doi.org/10.3390/w13070978.
Повний текст джерелаАнотація:
Extreme events resulting in catastrophic damage have more than doubled in the last five years, costing hundreds of lives and thousands of homes, and heavily undermining regional economic stability. At present, most of these hydroclimatic extreme events are documented by the media as individual events; however, in scientific terms, many are better understood as concurrent events—concurrent extremes of both temperature and precipitation (e.g., drought, floods). This paper considers concurrent changes in hydroclimate extremes, including heatwaves, drought, flooding, and low flows, in six historical-to-future (1970–1999, 2070–2099) Earth System Model (ESM) climate scenarios for the Colorado River basin. Results indicate that temperature-driven Impacts (heatwaves, drought) have the strongest responses while precipitation-driven Impacts have weaker responses. All Impacts exhibit an increase in magnitude from synoptic to annual time scales, with heatwaves increasing in strength about three times at the annual time scale versus the synoptic, while low flows only increase slightly. Critical watersheds in the Colorado were identified, highlighting the Blue River basin, Uncompahgre, East Taylor, Salt/Verde watersheds, locations of important water infrastructures, water resources, and hydrological research. Our results indicate that concurrent extreme hydroclimate events are projected to increase in the future and intensify within critical regions of the Colorado River basin. Considering extreme hydroclimate events concurrently is an important step towards linking economic and social effects of these events and their associated instabilities on a regional scale.
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Deshpande, Ajinkya G., Thomas W. Boutton, Ayumi Hyodo, Charles W. Lafon та Georgianne W. Moore. "Bottomland hardwood forest growth and stress response to hydroclimatic variation: evidence from dendrochronology and tree ring Δ<sup>13</sup>C values". Biogeosciences 17, № 22 (19 листопада 2020): 5639–53. http://dx.doi.org/10.5194/bg-17-5639-2020.
Повний текст джерелаАнотація:
Abstract. Wetland forests around the world have been reduced to a small proportion of their original expanse due to changing climatic conditions and intensification of human land use activities. As a case in point, the Columbia bottomland hardwood forests along the Brazos–Colorado coastal basin on the Gulf coast of Texas are currently threatened by an increasingly erratic hydroclimate in the form of both extreme floods and droughts and by urban expansion. In this study, we use dendrochronology and tree ring carbon isotopes to understand the effect of changing hydroclimatic conditions on the functional attributes of these forests. We examined the tree rings of Quercus nigra at four sites within the Columbia bottomlands, of which one site experiences frequent and prolonged flooding, while the other three are less flood prone. The objectives of this study were to (i) understand the impact of hydroclimatic variation on radial growth, using tree ring width analysis, (ii) assess the magnitude of physiological stress inflicted by extreme hydroclimatic conditions, using tree ring Δ13C measurements as a proxy, and (iii) evaluate the relationship between tree ring width and Δ13C values. Radial growth across the landscape was influenced most strongly by the midgrowing season climate, while the early growing season climate had the strongest effect on Δ13C. Growth inhibition was minimal, and tree ring Δ13C values were not affected in trees at the wetter site under extreme hydrological conditions such as droughts or floods. In addition, trees at the wet site were less sensitive to precipitation and showed no response to higher temperatures. In contrast, trees at the three drier sites experienced growth inhibition and had lower tree ring Δ13C values during dry periods. Our results indicate more favorable growing conditions and lower stress in trees growing under wetter hydrological conditions. Management and conservation strategies dependent on site-specific conditions are critical for the health of these wetland forests under a rapidly changing hydroclimate. This study provides the first dendrochronological baseline for this region and a better understanding of favorable conditions for the growth and health of these forests, which can assist in management decisions such as streamflow regulation and conservation plans.
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Tejedor, Ernesto, Nathan J. Steiger, Jason E. Smerdon, Roberto Serrano-Notivoli, and Mathias Vuille. "Global hydroclimatic response to tropical volcanic eruptions over the last millennium." Proceedings of the National Academy of Sciences 118, no. 12 (March 8, 2021): e2019145118. http://dx.doi.org/10.1073/pnas.2019145118.
Повний текст джерелаАнотація:
Large tropical volcanic eruptions can affect the climate of many regions on Earth, yet it is uncertain how the largest eruptions over the past millennium may have altered Earth’s hydroclimate. Here, we analyze the global hydroclimatic response to all the tropical volcanic eruptions over the past millennium that were larger than the Mount Pinatubo eruption of 1991. Using the Paleo Hydrodynamics Data Assimilation product (PHYDA), we find that these large volcanic eruptions tended to produce dry conditions over tropical Africa, Central Asia and the Middle East and wet conditions over much of Oceania and the South American monsoon region. These anomalies are statistically significant, and they persisted for more than a decade in some regions. The persistence of the anomalies is associated with southward shifts in the Intertropical Convergence Zone and sea surface temperature changes in the Pacific and Atlantic oceans. We compare the PHYDA results with the stand-alone model response of the Community Earth System Model (CESM)-Last Millennium Ensemble. We find that the proxy-constrained PHYDA estimates are larger and more persistent than the responses simulated by CESM. Understanding which of these estimates is more realistic is critical for accurately characterizing the hydroclimate risks of future volcanic eruptions.
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Räsänen, Timo A., Ville Lindgren, Joseph H. A. Guillaume, Brendan M. Buckley, and Matti Kummu. "On the spatial and temporal variability of ENSO precipitation and drought teleconnection in mainland Southeast Asia." Climate of the Past 12, no. 9 (September 21, 2016): 1889–905. http://dx.doi.org/10.5194/cp-12-1889-2016.
Повний текст джерелаАнотація:
Abstract. The variability of the hydroclimate over mainland Southeast Asia is strongly influenced by the El Niño–Southern Oscillation (ENSO), which has been linked to severe droughts and floods that profoundly influence human societies and ecosystems alike. Although the significance of ENSO is well understood, there are still limitations in the understanding of its effects on hydroclimate, particularly with regard to understanding the spatio-temporal characteristics and the long-term variation of its effects. Therefore we analysed the seasonal evolution and spatial variations in the effect of ENSO on precipitation over the period of 1980–2013 and the long-term variation in the ENSO teleconnection using tree-ring-derived Palmer drought severity indices (PDSIs) for the March–May season that span over the time period 1650–2004. The analyses provided an improved understanding of the seasonal evolution of the precipitation anomalies during ENSO events. The effects of ENSO were found to be most consistent and expressed over the largest areal extents during March–May of the year when the ENSO events decay. On a longer timescale, we found that ENSO has affected the region's March–May hydroclimate over the majority (95 %) of the 355-year study period and that during half (52 %) of the time ENSO caused a significant increase in hydroclimatic variability. The majority of the extremely wet and dry March–May seasons also occurred during ENSO events. However, considerable variability in ENSO's influence was revealed: the spatial pattern of precipitation anomalies varied between individual ENSO events, and the strength of ENSO's influence was found to vary through time. Given the high variability in ENSO teleconnection that we described and the limitations of the current understanding of the effects of ENSO, we suggest that the adaptation to ENSO-related extremes in hydroclimate over mainland Southeast Asia needs to recognise uncertainty as an inherent part of adaptation, must go beyond "predict and control", and should seek adaptation opportunities widely within society.
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Downs, Peter W., and Philip J. Soar. "Determining the dynamics of coarse bedload transport using passive indirect monitoring: time-dependent variability at event to inter-annual scales." E3S Web of Conferences 40 (2018): 05014. http://dx.doi.org/10.1051/e3sconf/20184005014.
Повний текст джерелаАнотація:
The dynamics of coarse bedload transport in rivers is governed by multiple hierarchical factors including catchment-scale controls on sediment production, annually variable hydroclimatic driving of segment-scale sediment supply, and reach-scale factors related to the interaction of hydraulic forces with channel morphology. Exploring hydroclimatic drivers can beneficially utilise passive sensors to record coarse bedload transport over extended time periods and in previously unattainable resolution. For the River Avon (Devon, UK), five-minute coarse bedload frequency data collected using seismic impact plates inherently records the instantaneous variability of bedload transport intensity, patterns of event-scale hysteresis and selective path transport, and the influence of inter-event supply variations. Converting a four-year record of impacts into loads via a probabilistic, data-driven model illustrates the combined influence of hydroclimate and sedimentology on bedload at the inter-annual scale. Despite highly variable water years, the results indicate that ‘bar-building flows’ consistently achieve the peak efficiency for coarse bedload transport whereas bankfull flows are relatively ineffective. Further, annual sediment rating curves combine both supply and transport limiting phases. Sediment transport forecasting is thus sensitive to both flow year type and antecedent controls on sediment supply, with implications for advancing sustainable solutions in river management.
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Cavagnaro, David B., Scott W. McCoy, Matthew A. Thomas, Jaime Kostelnik, and Donald N. Lindsay. "The spatial distribution of debris flows in relation to observed rainfall anomalies: Insights from the Dolan Fire, California." E3S Web of Conferences 415 (2023): 04003. http://dx.doi.org/10.1051/e3sconf/202341504003.
Повний текст джерелаАнотація:
A range of hydrologic responses can be observed in steep, recently burned terrain, which makes predicting the spatial distribution of large debris flows challenging. Studies from rainfall-induced landslides in unburned areas show evidence of hydroclimatic tuning of landslide triggering, such that the spatial distribution of events is best predicted by the observed rainfall anomaly relative to climatic norms rather than by absolute rainfall. In this paper, we test whether the spatial distribution of debris flows in response to rainfall can be similarly predicted by rainfall anomaly. The 520 km2 Dolan Fire burn scar in Monterey County, California, USA, spans a sharp hydroclimatic gradient and experienced a widespread storm in January 2021 that triggered floods and debris flows, providing a natural experiment in which to test this hypothesis. In this study, we use remote and field methods to map debris-flow response and examine its spatial heterogeneity. Together with rainfall data, our mapping reveals that the observed anomalies in peak 15-min rainfall intensity (I15) relative to the intensity of the 1-yr return interval storm predict debris-flow occurrence better than the absolute peak I15. Our findings indicate that debris-flow processes and threshold rainfall required for debris-flow initiation may be tuned to local hydroclimate.
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Stager, J. Curt, Brendan Wiltse, Brian F. Cumming, Timothy C. Messner, Joshua Robtoy, and Sidney Cushing. "Hydroclimatic and cultural instability in northeastern North America during the last millennium." PLOS ONE 16, no. 3 (March 26, 2021): e0248060. http://dx.doi.org/10.1371/journal.pone.0248060.
Повний текст джерелаАнотація:
Long-term, large-scale perspectives are necessary for understanding climate variability and its effects on ecosystems and cultures. Tree ring records of the Medieval Climate Anomaly (MCA) and Little Ice Age (LIA) have documented major hydroclimatic variability during the last millennium in the American West, but fewer continuous, high-resolution hydroclimate records of the MCA-LIA period are available for eastern North America, particularly during the transition from the MCA to the LIA (ca. A.D. 1250–1400). Diatoms (micro-algae with silica cell walls) in sediment cores from three Adirondack (NY, USA) lakes and a hiatus in a wetland peat deposit in the Adirondack uplands provide novel insights into the late Holocene hydroclimate history of the Northeast. These records demonstrate that two of the region’s most extreme decadal-scale droughts of the last millennium occurred ca. A.D. 1260–1330 and ca. A.D. 1360–1390 during a dry-wet-dry (DWD) oscillation in the Adirondacks that contributed to forest fires and desiccation of wetlands in New York and Maine. The bimodal drying was probably related to more extreme droughts farther west and coincided with major events in Iroquoian and Abenaki cultural history. Although the causes of the DWD oscillation in the Adirondacks remain uncertain, changing sea-surface temperatures and solar variability are likely to have played a role.
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Marshall, Adrienne, Van Butsic, and John Harte. "The Phenology of Wilderness Use: Backcountry Recreation in a Changing Climate." Weather, Climate, and Society 10, no. 2 (January 26, 2018): 209–23. http://dx.doi.org/10.1175/wcas-d-17-0087.1.
Повний текст джерелаАнотація:
Abstract Phenology studies are a critical tool for identifying the ways that changing climate affects species and ecosystems. Here, a phenological framework was used to assess the sensitivity of human behavior to temperature and hydroclimate variables that are likely to change as temperatures warm under twenty-first-century climate change. The timing of visitation to wilderness areas of the Sierra Nevada was used as a case study. Visitation timing was assessed using a backcountry permit database and data collected from weblogs or blogs. Mean, earliest, and latest visitation dates were regressed against temperature, streamflow, and snowpack variables: seasonally averaged air temperatures, snow water equivalent (SWE) in spring months, center of timing (CT), and total annual flow. Mean visitation was sensitive to CT, total annual flow, April and May SWE, and spring and summer temperatures, with visitors advancing 0.20–0.28 days for each day advance in CT and 3.7 to 5.7 days for each degree Celsius increase in summer temperatures. Visitors appear to be partially sensitive to both hydroclimate and temperature, suggesting that visitation may occur earlier as spring snow decreases, but also that because of this partial sensitivity, visitors may interact with ecosystems in a different phenological stage as the climate warms. Managers of these areas should plan for changing timing of visitation and should also consider ways that visitors interacting with different hydroclimatic and ecosystem conditions may influence management strategies.
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Wernicke, J., J. Grießinger, P. Hochreuther та A. Bräuning. "Variability of summer humidity during the past 800 years on the eastern Tibetan Plateau inferred from δ<sup>18</sup>O of tree-ring cellulose". Climate of the Past 11, № 2 (24 лютого 2015): 327–37. http://dx.doi.org/10.5194/cp-11-327-2015.
Повний текст джерелаАнотація:
Abstract. We present an 800-year δ18O chronology from the eastern part of the Tibetan Plateau (TP). The chronology dates back to AD 1193 and was sampled in AD 1996 from living Juniperus tibetica trees. This first long-term tree-ring-based δ18O chronology for eastern Tibet provides a reliable archive for hydroclimatic reconstructions. Highly significant correlations were obtained with hydroclimatic variables (relative humidity, vapour pressure, and precipitation) during the summer season. We applied a linear transfer model to reconstruct summer season relative humidity variations over the past 800 years. More moist conditions prevailed during the termination of the Medieval Warm Period while a systematic shift during the Little Ice Age is not detectable. A distinct trend towards more dry conditions since the 1870s is apparent. The moisture decline weakened around the 1950s but still shows a negative trend. The mid-19th century humidity decrease is in good accordance with several multiproxy hydroclimate reconstructions for south Tibet. However, the pronounced summer relative humidity decline is stronger on the central and eastern TP. Furthermore, the relative humidity at our study site is significantly linked to the relative humidity at large parts of the TP. Therefore, we deduce that the reconstructed relative humidity is mostly controlled by local and mesoscale climatic drivers, although significant connections to the higher troposphere of west-central Asia were observed.
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Flack, Anna L., Anthony S. Kiem, Tessa R. Vance, Carly R. Tozer, and Jason L. Roberts. "Comparison of published palaeoclimate records suitable for reconstructing annual to sub-decadal hydroclimatic variability in eastern Australia: implications for water resource management and planning." Hydrology and Earth System Sciences 24, no. 12 (November 29, 2020): 5699–712. http://dx.doi.org/10.5194/hess-24-5699-2020.
Повний текст джерелаАнотація:
Abstract. Knowledge of past, current, and future hydroclimatic risk is of great importance. However, like many other countries, Australia's observed hydroclimate records are at best only ∼ 120 years long (i.e. from ∼ 1900 to the present) but are typically less than ∼ 50 years long. Therefore, recent research has focused on developing longer hydroclimate records based on palaeoclimate information from a variety of different sources. Here we review and compare the insights emerging from 11 published palaeoclimate records that are relevant for annual to sub-decadal hydroclimatic variability in eastern Australia over the last ∼ 1000 years. The sources of palaeoclimate information include ice cores, tree rings, cave deposits, and lake sediment deposits. The published palaeoclimate information was then analysed to determine when (and where) there was agreement (or uncertainty) about the timing of wet and dry epochs in the pre-instrumental period (1000–1899). The occurrence, frequency, duration, and spatial extent of pre-instrumental wet and dry epochs was then compared to wet and dry epochs since 1900. The results show that instrumental records (∼ 1900–present) underestimate (or at least misrepresent) the full range of rainfall variability that has occurred, and is possible, in eastern Australia. Even more disturbing is the suggestion, based on insights from the published palaeoclimate data analysed, that 71 % of the pre-instrumental period appears to have no equivalent in the instrumental period. This implies that the majority of the past 1000 years was unlike anything encountered in the period that informs water infrastructure, planning, and policy in Australia. A case study, using a typical water storage reservoir in eastern Australia, demonstrates that current water resource infrastructure and management strategies would not cope under the range of pre-instrumental conditions that this study suggests has occurred. When coupled with projected impacts of climate change and growing demands, these results highlight some major challenges for water resource management and infrastructure. Though our case study location is eastern Australia, these challenges, and the limitations associated with current methods that depend on instrumental records that are too short to realistically characterise interannual to multi-decadal variability, also apply globally.
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Wu, Hongbao, Xuexia Wang, Hongwei Shui, Hasbagan Ganjurjav, Guozheng Hu, Quanhong Lin, Xiaobo Qin, and Qingzhu Gao. "Spatiotemporal Variations of Water Stable Isotope Compositions in Nujiang Headwaters, Qinghai-Tibetan Plateau." Sustainability 12, no. 16 (August 18, 2020): 6654. http://dx.doi.org/10.3390/su12166654.
Повний текст джерелаАнотація:
The variations of the stable isotope compositions in water provide critical information on hydroclimatic mechanisms. The climatological and hydrological processes in the Nujiang headwaters in the central Qinghai–Tibetan Plateau are extremely complex and are controlled by alternating continental/local recycled and maritime moisture. However, previous studies have only derived limited data from different types of water in the Nujiang headwaters. Therefore, aiming to understand the sources of stable oxygen (δ18O) and hydrogen (δ2H) isotopes’ compositional variability and how these are related to hydroclimatic processes, we measured δ18O and δ2H values from surface waters, snow and precipitation across the Nujiang headwaters from April to September 2018. We found higher δ18O (−13.7‰), δ2H (−101.8‰) and deuterium excess (d-excess; 7.6‰) values in the non-monsoon season and lower values in the summer monsoon season. Our findings indicated that the δ18O and δ2H compositions were significantly affected by different moisture sources in this region. The slope (6.66) and intercept (−14.90) of the surface water line (SWL: δ2H = 6.66 δ18O − 14.90, R2 = 0.98) were lower than those of the local meteoric water line (LMWL: δ2H = 9.50 δ18O + 41.80, R2 = 0.99) and global meteoric water line (GMWL), indicating that precipitation was the primary water vapor source for surface water, and evaporation was the dominant hydrological process for the Nujiang headwaters. In general, δ18O and δ2H tended to be negatively correlated with precipitation and air temperature. In addition, δ18O and δ2H values in the Nagqu River were inversely correlated with the intensity of discharge, highlighting a precipitation-driven isotope-discharge pattern. Our findings provide a theoretical basis for the hydroclimatic mechanisms occurring in the Nujiang headwaters and further augment our understanding of the southern–middle–northern hydroclimate in the Qinghai–Tibetan Plateau.
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Lahijani, H. A. K., H. Abbasian, A. Naderi Beni, S. A. G. Leroy, S. Haghani, P. Habibi, M. Hosseindust, et al. "Sediment distribution pattern of the South Caspian Sea: possible hydroclimatic implications." Canadian Journal of Earth Sciences 56, no. 6 (June 2019): 637–53. http://dx.doi.org/10.1139/cjes-2017-0239.
Повний текст джерелаАнотація:
The south Caspian subbasin extends from the foot of the Alborz Mountains to the deepest part of Caspian Sea. The lithological background and tectonic setting of the study area primarily control the deposition of thick sedimentary sequences of the basin, while hydroclimatic processes exert secondary impacts on the sediment distribution pattern. To evaluate past hydroclimatic changes, short sediment cores were retrieved from the continental shelf and upper slope of the south Caspian Sea and were treated for basic sedimentological properties and mineralogy. The results show that the sediments are composed of terrigenous, biogenic, and chemical components. The chemical component has a significant signature in the internal structure of the sediment, which reflects degradation of organic material due to a succession of aerobic and anaerobic conditions. Aerobic conditions reflect the extreme climatic conditions that lead to formation of well-oxygenated deep water in lowstands and extremely cold winters, when dense oxygenated water is allowed to touch the bottom sediments. The sediment distribution pattern demonstrates three distinctive areas in the southern continental margin with different organic matter and carbonate content. Fluvial inputs and wave hydrodynamics control the sediment properties and their distribution pattern in the upper shelf, while in deeper parts, the dynamics of water stratification and its temporal and long-term variations, relating to climate and water level changes, determine sediment composition. Overall, the sedimentary distribution pattern is a result of their sources in the catchment basin and the hydroclimate of the Caspian Sea.
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Pakdel-Khasmakhi, Hadis, Majid Vazifedoust, Dev Raj Paudyal, Sreeni Chadalavada, and Md Jahangir Alam. "Google Earth Engine as Multi-Sensor Open-Source Tool for Monitoring Stream Flow in the Transboundary River Basin: Doosti River Dam." ISPRS International Journal of Geo-Information 11, no. 11 (October 25, 2022): 535. http://dx.doi.org/10.3390/ijgi11110535.
Повний текст джерелаАнотація:
Understanding the effects of global change and human activities on water supplies depends greatly on surface water dynamics. A comprehensive examination of the hydroclimatic variations at the transboundary level is essential for the development of any adaptation or mitigation plans to deal with the negative effects of climate change. This research paper examines the hydroclimatic factors that contribute to the desiccation of the Doosti Dam’s basin in the transboundary area using multisensor satellite data from the Google Earth Engine (GEE) platform. The Mann–Kendall and Sens slope estimator test was applied to the satellite datasets to analyse the spatial and temporal variation of the hydroclimate variables and their trend over the transboundary area for 18 years from 2004 to 2021 (as the dam began operating in 2005). Statistical analysis results showed decreasing trends in temperature and an increase in rainfall with respect to station-observed available data. Evapotranspiration and irrigated area development followed the increasing pattern and a slight decrease in snow cover. The results confirmed a large expansion of the irrigated area, especially during the winter growing season. The increase in irrigated cultivated areas during both winter and summer seasons is possibly the main reason for the diversion of water to meet the irrigation requirements of the developed agriculture areas. The approach followed in this study could be applied to any location around the globe to evaluate the hydrological conditions and spatiotemporal changes in response to climate change, trend analysis and human activities.
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Khand, Kul, and Gabriel B. Senay. "Land Cover Change Effects on Stormflow Characteristics across Broad Hydroclimate Representative Urban Watersheds in the United States." Water 14, no. 14 (July 19, 2022): 2256. http://dx.doi.org/10.3390/w14142256.
Повний текст джерелаАнотація:
Urban development alters stormflow characteristics and is associated with increasing flood risks. The long-term evaluation of stormflow characteristics that exacerbate floods, such as peak stormflow and time-to-peak stormflow at varying levels of urbanization across different hydroclimates, is limited. This study investigated the long-term (1980s to 2010s) effects of increasing urbanization on key stormflow characteristics using observed 15 min streamflow data across six broad hydroclimate representative urban watersheds in the conterminous United States. The results indicate upward trends in peak stormflow and downward trends in time-to-peak stormflow at four out of six watersheds. The watershed in the Great Plains region had the largest annual increasing (decreasing) percent change in peak stormflow (time-to-peak stormflow). With the current change rates, peak stormflow in the Great Plains region watershed is expected to increase by 55.4% and have a 2.71 h faster time-to-peak stormflow in the next decade.
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Lücke, Andreas, Sebastian Kock, Holger Wissel, Julio J. Kulemeyer, Liliana C. Lupo, Frank Schäbitz, and Karsten Schittek. "Hydroclimatic record from an Altiplano cushion peatland (24°S) indicates large-scale reorganisation of atmospheric circulation for the late Holocene." PLOS ONE 17, no. 11 (November 10, 2022): e0277027. http://dx.doi.org/10.1371/journal.pone.0277027.
Повний текст джерелаАнотація:
The hydroclimate of South America is characterized by the South American summer monsoon (SASM), a tropical atmospheric circulation that induces a summer precipitation regime, and the Southern Hemisphere Westerlies (SHW), an extratropical atmospheric circulation that induces a winter precipitation regime. Stretched between these two systems is a NW-SE-oriented region dominated by descending air masses, resulting in the South American subtropical dry zone (SASDZ), also known as the arid diagonal. We investigated the Cerro Tuzgle cushion peatland (CTP) located on the Argentine Altiplano, north of the present-day SASDZ. Previous work revealed that the CTP was consistently in the SASM regime during the last 2900 cal yr BP. Here, we extend the CTP record to the middle Holocene covering the last 7200 cal yr BP to gain further knowledge of the Holocene development of the SASM and potential modulations of the SASDZ. The prominent feature of the entire record is a distinct and lasting transition centred around 3100 cal yr BP characterized by declining minerogenic content, increasing organic carbon content, rising stable carbon isotope values of organic matter and cellulose, and increasing stable oxygen isotope values of cellulose. We interpret this specific proxy pattern as a hydroclimatic transition towards less arid conditions at the CTP after 3100 cal yr BP. The transition corresponds with the end of the continuous Holocene strengthening of the SASM between 3500 cal yr BP and 3000 cal yr BP indicated by proxy records from north and east of the CTP. The CTP does not reflect this strengthening of the SASM and rather exhibits a threshold response indicating the effective establishment of the SASM summer precipitation regime at 24°S. This suggests that moisture supply during a more arid middle Holocene was provided by isotopically depleted precipitation, while moisture supply after the transition originated from isotopically enriched SASM summer precipitation. Concurrent hydroclimatic changes in the SHW winter precipitation regime south of the SASDZ are documented in a distinct lake level rise of Laguna Aculeo (33°50´S) around 3200 cal yr BP. These coinciding hydrological changes of the SASM and the SHW precipitation regimes indicate larger scale reorganisations of atmospheric circulation components, potentially connected to major modulations of the SASDZ. Thus, our CTP record sheds light on the middle to late Holocene development of the SASM at its southern limit and corroborates connections between the tropical and extratropical hydroclimate of South America.
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Morales, Mariano S., Edward R. Cook, Jonathan Barichivich, Duncan A. Christie, Ricardo Villalba, Carlos LeQuesne, Ana M. Srur, et al. "Six hundred years of South American tree rings reveal an increase in severe hydroclimatic events since mid-20th century." Proceedings of the National Academy of Sciences 117, no. 29 (July 6, 2020): 16816–23. http://dx.doi.org/10.1073/pnas.2002411117.
Повний текст джерелаАнотація:
South American (SA) societies are highly vulnerable to droughts and pluvials, but lack of long-term climate observations severely limits our understanding of the global processes driving climatic variability in the region. The number and quality of SA climate-sensitive tree ring chronologies have significantly increased in recent decades, now providing a robust network of 286 records for characterizing hydroclimate variability since 1400 CE. We combine this network with a self-calibrated Palmer Drought Severity Index (scPDSI) dataset to derive the South American Drought Atlas (SADA) over the continent south of 12°S. The gridded annual reconstruction of austral summer scPDSI is the most spatially complete estimate of SA hydroclimate to date, and well matches past historical dry/wet events. Relating the SADA to the Australia–New Zealand Drought Atlas, sea surface temperatures and atmospheric pressure fields, we determine that the El Niño–Southern Oscillation (ENSO) and the Southern Annular Mode (SAM) are strongly associated with spatially extended droughts and pluvials over the SADA domain during the past several centuries. SADA also exhibits more extended severe droughts and extreme pluvials since the mid-20th century. Extensive droughts are consistent with the observed 20th-century trend toward positive SAM anomalies concomitant with the weakening of midlatitude Westerlies, while low-level moisture transport intensified by global warming has favored extreme rainfall across the subtropics. The SADA thus provides a long-term context for observed hydroclimatic changes and for 21st-century Intergovernmental Panel on Climate Change (IPCC) projections that suggest SA will experience more frequent/severe droughts and rainfall events as a consequence of increasing greenhouse gas emissions.
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Başağaoğlu, Hakan, Debaditya Chakraborty, and James Winterle. "Reliable Evapotranspiration Predictions with a Probabilistic Machine Learning Framework." Water 13, no. 4 (February 22, 2021): 557. http://dx.doi.org/10.3390/w13040557.
Повний текст джерелаАнотація:
Evapotranspiration is often expressed in terms of reference crop evapotranspiration (ETo), actual evapotranspiration (ETa), or surface water evaporation (Esw), and their reliable predictions are critical for groundwater, irrigation, and aquatic ecosystem management in semi-arid regions. We demonstrated that a newly developed probabilistic machine learning (ML) model, using a hybridized “boosting” framework, can simultaneously predict the daily ETo, Esw, & ETa from local hydroclimate data with high accuracy. The probabilistic approach exhibited great potential to overcome data uncertainties, in which 100% of the ETo, 89.9% of the Esw, and 93% of the ETa test data at three watersheds were within the models’ 95% prediction intervals. The modeling results revealed that the hybrid boosting framework can be used as a reliable computational tool to predict ETo while bypassing net solar radiation calculations, estimate Esw while overcoming uncertainties associated with pan evaporation & pan coefficients, and predict ETa while offsetting high capital & operational costs of EC towers. In addition, using the Shapley analysis built on a coalition game theory, we identified the order of importance and interactions between the hydroclimatic variables to enhance the models’ transparency and trustworthiness.
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Maxbauer, Daniel P., Mark D. Shapley, Christoph E. Geiss, and Emi Ito. "Holocene climate recorded by magnetic properties of lake sediments in the Northern Rocky Mountains, USA." Holocene 30, no. 3 (November 21, 2019): 479–84. http://dx.doi.org/10.1177/0959683619887418.
Повний текст джерелаАнотація:
We present two hypotheses regarding the evolution of Holocene climate in the Northern Rocky Mountains that stem from a previously unpublished environmental magnetic record from Jones Lake, Montana. First, we link two distinct intervals of fining magnetic grain size (documented by an increasing ratio of anhysteretic to isothermal remanent magnetization) to the authigenic production of magnetic minerals in Jones Lake bottom waters. We propose that authigenesis in Jones Lake is limited by rates of groundwater recharge and ultimately regional hydroclimate. Second, at ~8.3 ka, magnetic grain size increases sharply, accompanied by a drop in concentration of magnetic minerals, suggesting a rapid termination of magnetic mineral authigenesis that is coeval with widespread effects of the 8.2 ka event in the North Atlantic. This association suggests a hydroclimatic response to the 8.2 ka event in the Northern Rockies that to our knowledge is not well documented. These preliminary hypotheses present compelling new ideas that we hope will both highlight the sensitivity of magnetic properties to record climate variability and attract more work by future research into aridity, hydrochemical response, and climate dynamics in the Northern Rockies.
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Seager, Richard, and Robert J. Burgman. "Medieval hydroclimate revisited." PAGES news 19, no. 1 (March 2011): 10–12. http://dx.doi.org/10.22498/pages.19.1.10.
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Cudennec, Christophe, Alexander Gelfan, Liliang Ren, and Mohamed Slimani. "Hydrometeorology and Hydroclimate." Advances in Meteorology 2016 (2016): 1–4. http://dx.doi.org/10.1155/2016/1487890.
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Morales, Mariano S., Doris B. Crispín-DelaCruz, Claudio Álvarez, Duncan A. Christie, M. Eugenia Ferrero, Laia Andreu-Hayles, Ricardo Villalba, et al. "Drought increase since the mid-20th century in the northern South American Altiplano revealed by a 389-year precipitation record." Climate of the Past 19, no. 2 (February 20, 2023): 457–76. http://dx.doi.org/10.5194/cp-19-457-2023.
Повний текст джерелаАнотація:
Abstract. Given the short span of instrumental precipitation records in the South American Altiplano, longer-term hydroclimatic records are needed to understand the nature of climate variability and to improve the predictability of precipitation, a key natural resource for the socioeconomic development in the Altiplano and adjacent arid lowlands. In this region grows Polylepis tarapacana, a long-lived tree species that is very sensitive to hydroclimatic changes and has been widely used for tree-ring studies in the central and southern Altiplano. However, in the northern sector of the Peruvian and Chilean Altiplano (16–19∘ S) still exists a gap of high-resolution hydroclimatic data based on tree-ring records. Our study provides an overview of the temporal evolution of the late-spring–mid-summer precipitation for the period 1625–2013 CE at the northern South American Altiplano, allowing for the identification of wet or dry periods based on a regional reconstruction from three P. tarapacana chronologies. An increase in the occurrence of extreme dry events, together with a decreasing trend in the reconstructed precipitation, has been recorded since the 1970s in the northern Altiplano within the context of the last ∼4 centuries. The average precipitation over the last 17 years stands out as the driest in our 389-year reconstruction. We reveal a temporal and spatial synchrony across the Altiplano region of dry conditions since the mid-1970s. Independent tree-ring-based hydroclimate reconstructions and several paleoclimatic records based on other proxies available for the tropical Andes record this synchrony. The influence of El Niño–Southern Oscillation (ENSO) on the northern Altiplano precipitation was detected by our rainfall reconstruction that showed past drier conditions in our study region associated with ENSO warm events. The spectral properties of the rainfall reconstruction showed strong imprints of ENSO variability at decadal, sub-decadal, and inter-annual timescales, in particular from the Pacific NIÑO 3 sector. Overall, the recent reduction in precipitation in comparison with previous centuries, the increase in extreme dry events and the coupling between precipitation and ENSO variability reported by this work is essential information in the context of the growing demand for water resources in the Altiplano. This study will contribute to a better understanding of the vulnerability and resilience of the region to the projected evapotranspiration increase for the 21st century associated with global warming.
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Steiger, Nathan J., and Jason E. Smerdon. "A pseudoproxy assessment of data assimilation for reconstructing the atmosphere–ocean dynamics of hydroclimate extremes." Climate of the Past 13, no. 10 (October 27, 2017): 1435–49. http://dx.doi.org/10.5194/cp-13-1435-2017.
Повний текст джерелаАнотація:
Abstract. Because of the relatively brief observational record, the climate dynamics that drive multiyear to centennial hydroclimate variability are not adequately characterized and understood. Paleoclimate reconstructions based on data assimilation (DA) optimally fuse paleoclimate proxies with the dynamical constraints of climate models, thus providing a coherent dynamical picture of the past. DA is therefore an important new tool for elucidating the mechanisms of hydroclimate variability over the last several millennia. But DA has so far remained untested for global hydroclimate reconstructions. Here we explore whether or not DA can be used to skillfully reconstruct global hydroclimate variability along with the driving climate dynamics. Through a set of idealized pseudoproxy experiments, we find that an established DA reconstruction approach can in principle be used to reconstruct hydroclimate at both annual and seasonal timescales. We find that the skill of such reconstructions is generally highest near the proxy sites. This set of reconstruction experiments is specifically designed to estimate a realistic upper bound for the skill of this DA approach. Importantly, this experimental framework allows us to see where and for what variables the reconstruction approach may never achieve high skill. In particular for tree rings, we find that hydroclimate reconstructions depend critically on moisture-sensitive trees, while temperature reconstructions depend critically on temperature-sensitive trees. Real-world DA-based reconstructions will therefore likely require a spatial mixture of temperature- and moisture-sensitive trees to reconstruct both temperature and hydroclimate variables. Additionally, we illustrate how DA can be used to elucidate the dynamical mechanisms of drought with two examples: tropical drivers of multiyear droughts in the North American Southwest and in equatorial East Africa. This work thus provides a foundation for future DA-based hydroclimate reconstructions using real-proxy networks while also highlighting the utility of this important tool for hydroclimate research.
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Linderholm, Hans W., Marie Nicolle, Pierre Francus, Konrad Gajewski, Samuli Helama, Atte Korhola, Olga Solomina, et al. "Arctic hydroclimate variability during the last 2000 years: current understanding and research challenges." Climate of the Past 14, no. 4 (April 10, 2018): 473–514. http://dx.doi.org/10.5194/cp-14-473-2018.
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Abstract. Reanalysis data show an increasing trend in Arctic precipitation over the 20th century, but changes are not homogenous across seasons or space. The observed hydroclimate changes are expected to continue and possibly accelerate in the coming century, not only affecting pan-Arctic natural ecosystems and human activities, but also lower latitudes through the atmospheric and ocean circulations. However, a lack of spatiotemporal observational data makes reliable quantification of Arctic hydroclimate change difficult, especially in a long-term context. To understand Arctic hydroclimate and its variability prior to the instrumental record, climate proxy records are needed. The purpose of this review is to summarise the current understanding of Arctic hydroclimate during the past 2000 years. First, the paper reviews the main natural archives and proxies used to infer past hydroclimate variations in this remote region and outlines the difficulty of disentangling the moisture from the temperature signal in these records. Second, a comparison of two sets of hydroclimate records covering the Common Era from two data-rich regions, North America and Fennoscandia, reveals inter- and intra-regional differences. Third, building on earlier work, this paper shows the potential for providing a high-resolution hydroclimate reconstruction for the Arctic and a comparison with last-millennium simulations from fully coupled climate models. In general, hydroclimate proxies and simulations indicate that the Medieval Climate Anomaly tends to have been wetter than the Little Ice Age (LIA), but there are large regional differences. However, the regional coverage of the proxy data is inadequate, with distinct data gaps in most of Eurasia and parts of North America, making robust assessments for the whole Arctic impossible at present. To fully assess pan-Arctic hydroclimate variability for the last 2 millennia, additional proxy records are required.
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Brázdil, Rudolf, Andrea Kiss, Jürg Luterbacher, David J. Nash, and Ladislava Řezníčková. "Documentary data and the study of past droughts: a global state of the art." Climate of the Past 14, no. 12 (December 11, 2018): 1915–60. http://dx.doi.org/10.5194/cp-14-1915-2018.
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Abstract. The use of documentary evidence to investigate past climatic trends and events has become a recognised approach in recent decades. This contribution presents the state of the art in its application to droughts. The range of documentary evidence is very wide, including general annals, chronicles, memoirs and diaries kept by missionaries, travellers and those specifically interested in the weather; records kept by administrators tasked with keeping accounts and other financial and economic records; legal-administrative evidence; religious sources; letters; songs; newspapers and journals; pictographic evidence; chronograms; epigraphic evidence; early instrumental observations; society commentaries; and compilations and books. These are available from many parts of the world. This variety of documentary information is evaluated with respect to the reconstruction of hydroclimatic conditions (precipitation, drought frequency and drought indices). Documentary-based drought reconstructions are then addressed in terms of long-term spatio-temporal fluctuations, major drought events, relationships with external forcing and large-scale climate drivers, socio-economic impacts and human responses. Documentary-based drought series are also considered from the viewpoint of spatio-temporal variability for certain continents, and their employment together with hydroclimate reconstructions from other proxies (in particular tree rings) is discussed. Finally, conclusions are drawn, and challenges for the future use of documentary evidence in the study of droughts are presented.
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Foroozan, Zeynab, Jussi Grießinger, Kambiz Pourtahmasi та Achim Bräuning. "501 Years of Spring Precipitation History for the Semi-Arid Northern Iran Derived from Tree-Ring δ18O Data". Atmosphere 11, № 9 (22 серпня 2020): 889. http://dx.doi.org/10.3390/atmos11090889.
Повний текст джерелаАнотація:
In semi-arid regions of the world, knowledge about the long-term hydroclimate variability is essential to analyze and evaluate the impact of current climate change on ecosystems. We present the first tree-ring δ18O based hydroclimatic reconstruction for northern semi-arid Iran spanning the period 1515–2015. A highly significant correlation between tree-ring δ18O variations of juniper trees and spring (April–June) precipitation reveals a major influence of spring water availability during the early growing season. The driest period of the past 501 years occurred in the 16th century while the 18th century was the wettest, during which the overall highest frequency of wet year events occurred. A gradual decline in spring precipitation is evident from the beginning of the 19th century, pointing to even drier climate conditions. The analysis of dry/wet events indicates that the frequency of years with relatively dry spring increased over the last three centuries, while the number of wet events decreased. Our findings are in accordance with historical Persian disaster records (e.g., the severe droughts of 1870–1872, 1917–1919; severe flooding of 1867, the 1930s, and 1950). Correlation analyses between the reconstruction and different atmospheric circulation indices revealed no significant influence of large-scale drivers on spring precipitation in northern Iran.
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Theissen, Kevin M., Thomas A. Hickson, Ashley L. Brundrett, Sarah E. Horns, and Matthew S. Lachniet. "A record of mid- and late Holocene paleohydroclimate from Lower Pahranagat Lake, southern Great Basin." Quaternary Research 92, no. 2 (April 17, 2019): 352–64. http://dx.doi.org/10.1017/qua.2019.11.
Повний текст джерелаАнотація:
AbstractWe present a continuous, sediment core-based record of paleohydroclimate spanning ~5800 cal yr BP to recent from Lower Pahranagat Lake (LPAH), a shallow, alkaline lake in southern Nevada. We apply stable isotopes (δ18O and δ13C) from fine-fraction authigenic carbonate, which are sensitive recorders of hydroclimatic variability in this highly evaporative region. Additional geochemical proxies (total organic carbon, C/N, and total inorganic carbon) provide supporting information on paleoecological change in and around the lake. Our data suggest progressively wetter conditions starting at the later part of the middle Holocene and extending into the late Holocene (~5500–3350 cal yr BP) followed by a millennial-scale dry period from ~3150 to 1700 cal yr BP. This latter interval encompasses the ‘Late Holocene dry period’ (LHDP) reported by other investigators, and our data help refine the area affected in this episode. Our data also show evidence for a series of century-scale fluctuations in regional hydroclimate, including wet and dry intervals between 2350 and 1600 cal yr BP, and drier conditions over the past few centuries. Paleohydroclimate trends in the LPAH record show correspondence with those from the central Great Basin to the north, suggesting that both areas were subject to similar climatic forcings.
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Brown, Casey, Robyn Meeks, Yonas Ghile, and Kenneth Hunu. "Is water security necessary? An empirical analysis of the effects of climate hazards on national-level economic growth." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 371, no. 2002 (November 13, 2013): 20120416. http://dx.doi.org/10.1098/rsta.2012.0416.
Повний текст джерелаАнотація:
The influence of climate and the role of water security on economic growth are topics of growing interest. Few studies have investigated the potential role that climate hazards, which water security addresses, and their cumulative effects have on the growth prospects for a country. Owing to the relatively stationary spatial patterns of global climate, certain regions and countries are more prone to climate hazards and climate variability than others. For example, El Nino/Southern Oscillation patterns result in greater hydroclimatic variability in much of the tropics than that experienced at higher latitudes. In this study, we use a precipitation index that preserves the spatial and temporal variability of precipitation and differentiates between precipitation maxima (e.g. floods) and minima (e.g. droughts). The index is a more precise instrument for hydroclimate hazards than that used in any previous studies. A fixed effects, for year and country, regression model was developed to test the influence of climate variables on measures of economic growth and activity. The results indicate that precipitation extremes (i.e. floods and droughts) are the dominant climate influences on economic growth and that the effects are significant and negative. The drought index was found to be associated with a highly significant negative influence on gross domestic product (GDP) growth, while the flood index was associated with a negative influence on GDP growth and lagged effects on growth. The flood index was also found to have a negative effect on industrial value added in contemporary and lagged regressions. Temperature was found to have little significant effect. These results have important implications for economic projections of climate change impacts. Perhaps more important, the results make clear that hydroclimatic hazards have measurable negative impacts, and thus lack of water security is an impediment to growth. In addition, adaptation strategies should recognize the importance of managing hazards given the identification of precipitation extremes as the key climate influence on historical GDP growth.
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Chegini, Taher, Hong-Yi Li, and L. Leung. "HyRiver: Hydroclimate Data Retriever." Journal of Open Source Software 6, no. 66 (October 27, 2021): 3175. http://dx.doi.org/10.21105/joss.03175.
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Seager, Richard, Nicholas Graham, Celine Herweijer, Arnold L. Gordon, Yochanan Kushnir, and Ed Cook. "Blueprints for Medieval hydroclimate." Quaternary Science Reviews 26, no. 19-21 (October 2007): 2322–36. http://dx.doi.org/10.1016/j.quascirev.2007.04.020.
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Singh, Ram, Kostas Tsigaridis, Allegra N. LeGrande, Francis Ludlow, and Joseph G. Manning. "Investigating hydroclimatic impacts of the 168–158 BCE volcanic quartet and their relevance to the Nile River basin and Egyptian history." Climate of the Past 19, no. 1 (January 27, 2023): 249–75. http://dx.doi.org/10.5194/cp-19-249-2023.
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Abstract. The Ptolemaic era (305–30 BCE) is an important period of Ancient Egyptian history known for its material and scientific advances, but also intermittent political and social unrest in the form of (sometimes widespread) revolts against the Ptolemaic elites. While the role of environmental pressures has long been overlooked in this period of Egyptian history, ice-core-based volcanic histories have identified the period as experiencing multiple notable eruptions, and a repeated temporal association between explosive volcanism and revolt has recently been noted. Here we analyze the global and regional (Nile River basin) hydroclimatic response to a unique historical sequence of four large and closely timed volcanic eruptions (first a tropical one, followed by three extratropical northern hemispheric events) between 168 and 158 BCE, a particularly troubled period in Ptolemaic history for which we now provide a more detailed hydroclimatic context. The NASA (National Aeronautics and Space Administration) GISS (Goddard Institute for Space Studies) ModelE2.1 Earth system model simulates a strong radiative response with a radiative forcing (top of atmosphere) of −7.5 W m−2 (following the first eruption) and −2.5 W m−2 (after each of the three remaining eruptions) at a global scale. Associated with this, we observe a global surface cooling of the order of 1.5 ∘C following the first (tropical) eruption, with the following three extratropical eruptions extending the cooling period for more than 15 years. Consequently, this series of eruptions is observed to constrain the northward migration of the inter-tropical convergence zone (ITCZ) during the Northern Hemisphere summer monsoon season, and major monsoon zones (African, South Asian, and East Asian) were seen to experience a suppression of rainfall of >1 mm d−1 during the monsoon (JJAS) season averaged for 2 years after each eruption. A substantial suppression of the Indian and North African summer monsoon (over the Nile River headwater region) was seen to strongly affect the modeled river flow in the catchment and discharge at river mouth. River mass flow over the basin was observed to decrease by 29 % and 38 % relative to an unperturbed (non-volcanic) annual mean flow in the first and second year, respectively, after the first (i.e., tropical) eruption. A moderate decrease ranging between 5 % and 18 % was observed after the third and fourth (extratropical) eruptions. These results indicate, in sum, that the first eruption likely produced a strong hydroclimate response, with the following extratropical eruptions prolonging this. These results also support the recently hypothesized association between ice-core-based signals of explosive volcanism and hydroclimatic variability during the Ptolemaic era, including the suppression of the agriculturally critical Nile summer flooding.
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Wernicke, J., J. Grießinger, P. Hochreuther та A. Bräuning. "Variability of summer humidity during the past 800 years on the eastern Tibetan Plateau inferred from δ<sup>18</sup>O of tree-ring cellulose". Climate of the Past Discussions 10, № 4 (15 серпня 2014): 3327–56. http://dx.doi.org/10.5194/cpd-10-3327-2014.
Повний текст джерелаАнотація:
Abstract. We present an 800 years long δ18O chronology from the eastern part of the Tibetan Plateau (TP). The chronology dates back to 1193 AD and was sampled in 1996 AD from living Juniperus tibetica trees. The chronology is unique for eastern Tibet and provides a reliable archive for hydroclimatic reconstructions. Highly significant correlations were obtained with air moisture (relative humidity, vapour pressure and precipitation) during the summer season. We applied a linear transfer model to reconstruct the summer season relative humidity variation over the past 800 years. We identified more moist conditions at the termination of the Medieval Warm Period, an oscillating air humidity around the mean during the Little Ice Age and a sudden decrease of relative humidity since the 1870s. The late 19th century humidity decrease is in good accordance with several multiproxy hydroclimate reconstructions for south Tibet. On the other hand, since the end of the 19th century strong evidences for an increase in humidity on the northern TP is exhibited. Spatial correlation analysis with the North Atlantic Oscillation index (NAO) and the sea surface temperature (SST) of Niño region 3.4 reveal a weak and nonstationary relationship to the δ18O chronology. Instead, spatial correlations expose a dominating convective influence to the relative humidity reconstruction. Furthermore, wavelength analysis reveal good agreements between the significant cyclicities in our δ18O chronology and several moisture sensitive proxy archives.
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Ivory, Sarah J., Margaret W. Blome, John W. King, Michael M. McGlue, Julia E. Cole, and Andrew S. Cohen. "Environmental change explains cichlid adaptive radiation at Lake Malawi over the past 1.2 million years." Proceedings of the National Academy of Sciences 113, no. 42 (October 3, 2016): 11895–900. http://dx.doi.org/10.1073/pnas.1611028113.
Повний текст джерелаАнотація:
Long paleoecological records are critical for understanding evolutionary responses to environmental forcing and unparalleled tools for elucidating the mechanisms that lead to the development of regions of high biodiversity. We use a 1.2-My record from Lake Malawi, a textbook example of biological diversification, to document how climate and tectonics have driven ecosystem and evolutionary dynamics. Before ∼800 ka, Lake Malawi was much shallower than today, with higher frequency but much lower amplitude water-level and oxygenation changes. Since ∼800 ka, the lake has experienced much larger environmental fluctuations, best explained by a punctuated, tectonically driven rise in its outlet location and level. Following the reorganization of the basin, a change in the pacing of hydroclimate variability associated with the Mid-Pleistocene Transition resulted in hydrologic change dominated by precession rather than the high-latitude teleconnections recorded elsewhere. During this time, extended, deep lake phases have abruptly alternated with times of extreme aridity and ecosystem variability. Repeated crossings of hydroclimatic thresholds within the lake system were critical for establishing the rhythm of diversification, hybridization, and extinction that dominate the modern system. The chronology of these changes closely matches both the timing and pattern of phylogenetic history inferred independently for the lake’s extraordinary array of cichlid fish species, suggesting a direct link between environmental and evolutionary dynamics.
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Liu, Zhongfang, Yanlin Tang, Zhimin Jian, Christopher J. Poulsen, Jeffrey M. Welker, and Gabriel J. Bowen. "Pacific North American circulation pattern links external forcing and North American hydroclimatic change over the past millennium." Proceedings of the National Academy of Sciences 114, no. 13 (March 13, 2017): 3340–45. http://dx.doi.org/10.1073/pnas.1618201114.
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Land and sea surface temperatures, precipitation, and storm tracks in North America and the North Pacific are controlled to a large degree by atmospheric variability associated with the Pacific North American (PNA) pattern. The modern instrumental record indicates a trend toward a positive PNA phase in recent decades, which has led to accelerated warming and snowpack decline in northwestern North America. The brevity of the instrumental record, however, limits our understanding of long-term PNA variability and its directional or cyclic patterns. Here we develop a 937-y-long reconstruction of the winter PNA based on a network of annually resolved tree-ring proxy records across North America. The reconstruction is consistent with previous regional records in suggesting that the recent persistent positive PNA pattern is unprecedented over the past millennium, but documents patterns of decadal-scale variability that contrast with previous reconstructions. Our reconstruction shows that PNA has been strongly and consistently correlated with sea surface temperature variation, solar irradiance, and volcanic forcing over the period of record, and played a significant role in translating these forcings into decadal-to-multidecadal hydroclimate variability over North America. Climate model ensembles show limited power to predict multidecadal variation in PNA over the period of our record, raising questions about their potential to project future hydroclimatic change modulated by this circulation pattern.
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Ault, Toby R., Julia E. Cole, Jonathan T. Overpeck, Gregory T. Pederson, Scott St. George, Bette Otto-Bliesner, Connie A. Woodhouse, and Clara Deser. "The Continuum of Hydroclimate Variability in Western North America during the Last Millennium." Journal of Climate 26, no. 16 (August 6, 2013): 5863–78. http://dx.doi.org/10.1175/jcli-d-11-00732.1.
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Abstract The distribution of climatic variance across the frequency spectrum has substantial importance for anticipating how climate will evolve in the future. Here power spectra and power laws (β) are estimated from instrumental, proxy, and climate model data to characterize the hydroclimate continuum in western North America (WNA). The significance of the estimates of spectral densities and β are tested against the null hypothesis that they reflect solely the effects of local (nonclimate) sources of autocorrelation at the monthly time scale. Although tree-ring-based hydroclimate reconstructions are generally consistent with this null hypothesis, values of β calculated from long moisture-sensitive chronologies (as opposed to reconstructions) and other types of hydroclimate proxies exceed null expectations. Therefore it may be argued that there is more low-frequency variability in hydroclimate than monthly autocorrelation alone can generate. Coupled model results archived as part of phase 5 of the Coupled Model Intercomparison Project (CMIP5) are consistent with the null hypothesis and appear unable to generate variance in hydroclimate commensurate with paleoclimate records. Consequently, at decadal-to-multidecadal time scales there is more variability in instrumental and proxy data than in the models, suggesting that the risk of prolonged droughts under climate change may be underestimated by CMIP5 simulations of the future.
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Seyedhashemi, Hanieh, Jean-Philippe Vidal, Jacob S. Diamond, Dominique Thiéry, Céline Monteil, Frédéric Hendrickx, Anthony Maire, and Florentina Moatar. "Regional, multi-decadal analysis on the Loire River basin reveals that stream temperature increases faster than air temperature." Hydrology and Earth System Sciences 26, no. 9 (May 17, 2022): 2583–603. http://dx.doi.org/10.5194/hess-26-2583-2022.
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Abstract. Stream temperature appears to be increasing globally, but its rate remains poorly constrained due to a paucity of long-term data and difficulty in parsing effects of hydroclimate and landscape variability. Here, we address these issues using the physically based thermal model T-NET (Temperature-NETwork) coupled with the EROS semi-distributed hydrological model to reconstruct past daily stream temperature and streamflow at the scale of the entire Loire River basin in France (105 km2 with 52 278 reaches). Stream temperature increased for almost all reaches in all seasons (mean =+0.38 ∘C decade−1) over the 1963–2019 period. Increases were greatest in spring and summer, with a median increase of + 0.38 ∘C (range =+0.11 to +0.76 ∘C) and +0.44 ∘C (+0.08 to +1.02 ∘C) per decade, respectively. Rates of stream temperature increases were greater than for air temperature across seasons for the majority of reaches. Spring and summer increases were typically greatest in the southern part of the Loire basin (up to +1 ∘C decade−1) and in the largest rivers (Strahler order ≥5). Importantly, air temperature and streamflow could exert a joint influence on stream temperature trends, where the greatest stream temperature increases were accompanied by similar trends in air temperature (up to +0.71 ∘C decade−1) and the greatest decreases in streamflow (up to −16 % decade−1). Indeed, for the majority of reaches, positive stream temperature anomalies exhibited synchrony with positive anomalies in air temperature and negative anomalies in streamflow, highlighting the dual control exerted by these hydroclimatic drivers. Moreover, spring and summer stream temperature, air temperature, and streamflow time series exhibited common change points occurring in the late 1980s, suggesting a temporal coherence between changes in the hydroclimatic drivers and a rapid stream temperature response. Critically, riparian vegetation shading mitigated stream temperature increases by up to 0.16 ∘C decade−1 in smaller streams (i.e. < 30 km from the source). Our results provide strong support for basin-wide increases in stream temperature due to joint effects of rising air temperature and reduced streamflow. We suggest that some of these climate change-induced effects can be mitigated through the restoration and maintenance of riparian forests.
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Seftigen, Kristina, Hugues Goosse, Francois Klein, and Deliang Chen. "Hydroclimate variability in Scandinavia over the last millennium – insights from a climate model–proxy data comparison." Climate of the Past 13, no. 12 (December 18, 2017): 1831–50. http://dx.doi.org/10.5194/cp-13-1831-2017.
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Abstract. The integration of climate proxy information with general circulation model (GCM) results offers considerable potential for deriving greater understanding of the mechanisms underlying climate variability, as well as unique opportunities for out-of-sample evaluations of model performance. In this study, we combine insights from a new tree-ring hydroclimate reconstruction from Scandinavia with projections from a suite of forced transient simulations of the last millennium and historical intervals from the CMIP5 and PMIP3 archives. Model simulations and proxy reconstruction data are found to broadly agree on the modes of atmospheric variability that produce droughts–pluvials in the region. Despite these dynamical similarities, large differences between simulated and reconstructed hydroclimate time series remain. We find that the GCM-simulated multi-decadal and/or longer hydroclimate variability is systematically smaller than the proxy-based estimates, whereas the dominance of GCM-simulated high-frequency components of variability is not reflected in the proxy record. Furthermore, the paleoclimate evidence indicates in-phase coherencies between regional hydroclimate and temperature on decadal timescales, i.e., sustained wet periods have often been concurrent with warm periods and vice versa. The CMIP5–PMIP3 archive suggests, however, out-of-phase coherencies between the two variables in the last millennium. The lack of adequate understanding of mechanisms linking temperature and moisture supply on longer timescales has serious implications for attribution and prediction of regional hydroclimate changes. Our findings stress the need for further paleoclimate data–model intercomparison efforts to expand our understanding of the dynamics of hydroclimate variability and change, to enhance our ability to evaluate climate models, and to provide a more comprehensive view of future drought and pluvial risks.
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Shi, Xiaogang, Stephen J. Déry, Pavel Ya Groisman, and Dennis P. Lettenmaier. "Relationships between Recent Pan-Arctic Snow Cover and Hydroclimate Trends." Journal of Climate 26, no. 6 (March 15, 2013): 2048–64. http://dx.doi.org/10.1175/jcli-d-12-00044.1.
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Abstract Using the Variable Infiltration Capacity (VIC) land surface model forced with gridded climatic observations, the authors reproduce spatial and temporal variations of snow cover extent (SCE) reported by the National Oceanic and Atmospheric Administration (NOAA) Northern Hemisphere weekly satellite SCE data. Both observed and modeled North American and Eurasian snow cover in the pan-Arctic have statistically significant negative trends from April through June over the period 1972–2006. To diagnose the causes of the pan-Arctic SCE recession, the authors identify the role of surface energy fluxes generated in VIC and assess the relationships between 15 hydroclimatic indicators and NOAA SCE observations over each snow-covered sensitivity zone (SCSZ) for both North America and Eurasia. The authors find that surface net radiation (SNR) provides the primary energy source and sensible heat (SH) plays a secondary role in observed changes of SCE. As compared with SNR and SH, latent heat has only a minor influence on snow cover changes. In addition, these changes in surface energy fluxes resulting in the pan-Arctic snow cover recession are mainly driven by statistically significant decreases in snow surface albedo and increased air temperatures (surface air temperature, daily maximum temperature, and daily minimum temperature), as well as statistically significant increased atmospheric water vapor pressure. Contributions of other hydroclimate variables that the authors analyzed (downward shortwave radiation, precipitation, diurnal temperature range, wind speed, and cloud cover) are not significant for observed SCE changes in either the North American or Eurasian SCSZs.
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Newman, Andrew J., Naoki Mizukami, Martyn P. Clark, Andrew W. Wood, Bart Nijssen, and Grey Nearing. "Benchmarking of a Physically Based Hydrologic Model." Journal of Hydrometeorology 18, no. 8 (August 1, 2017): 2215–25. http://dx.doi.org/10.1175/jhm-d-16-0284.1.
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Abstract The concepts of model benchmarking, model agility, and large-sample hydrology are becoming more prevalent in hydrologic and land surface modeling. As modeling systems become more sophisticated, these concepts have the ability to help improve modeling capabilities and understanding. In this paper, their utility is demonstrated with an application of the physically based Variable Infiltration Capacity model (VIC). The authors implement VIC for a sample of 531 basins across the contiguous United States, incrementally increase model agility, and perform comparisons to a benchmark. The use of a large-sample set allows for statistically robust comparisons and subcategorization across hydroclimate conditions. Our benchmark is a calibrated, time-stepping, conceptual hydrologic model. This model is constrained by physical relationships such as the water balance, and it complements purely statistical benchmarks due to the increased physical realism and permits physically motivated benchmarking using metrics that relate one variable to another (e.g., runoff ratio). The authors find that increasing model agility along the parameter dimension, as measured by the number of model parameters available for calibration, does increase model performance for calibration and validation periods relative to less agile implementations. However, as agility increases, transferability decreases, even for a complex model such as VIC. The benchmark outperforms VIC in even the most agile case when evaluated across the entire basin set. However, VIC meets or exceeds benchmark performance in basins with high runoff ratios (greater than ~0.8), highlighting the ability of large-sample comparative hydrology to identify hydroclimatic performance variations.
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DeMott, Laura M., and Christopher A. Scholz. "Lacustrine carbonate tufa facies of Winnemucca Dry Lake Basin, Nevada, U.S.A." Journal of Sedimentary Research 90, no. 12 (December 31, 2020): 1804–28. http://dx.doi.org/10.2110/jsr.2020.004.
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ABSTRACT Lacustrine carbonate tufa deposits are common in present-day lakes and dry pans of the western United States, and large-scale deposits (> 100 m high) are found throughout the subbasins of Pleistocene Lake Lahontan. This study presents a depositional model for very well exposed tufa in Winnemucca Dry Lake, a subbasin of Lake Lahontan, that incorporates new observations of tufa growth over length scales of 10–4–102 m. Tufa depositional facies are defined on the basis of outcrop morphology and texture. Deposits were mapped using satellite imagery and field observations. Tufa facies and volumes were quantified for seven tufa exposures across the basin using digital outcrop and elevation models from aerial images acquired from a small uncrewed aerial system (sUAS). Tufa thin sections were examined using transmitted-light petrography and scanning electron microscopy and combined with measurements of porosity and permeability to define small-scale facies characteristics. Both porosity and permeability are highly variable across textures; average values for both (ϕ = 29%, k = 5.5 D) indicate that all tufa types may exhibit excellent reservoir properties. The age and distribution of these facies across the basin are directly linked to hydroclimate and variations in lake level. The most important controls on tufa distribution at the basin scale are basin hydrology and pathways of groundwater inflow. Groundwater flow into the basin is largely concentrated along the western flexural margin along the contact between volcanic and volcaniclastic bedrock and alluvial sediments, rather than concentrated along the border fault margin, in contrast to other models which predict strong fault control of tufa occurrence. Microbially influenced tufa textures and morphologies are the most volumetrically significant tufas in the basin, composing between 77% and 100% of tufa volume at individual exposures; these are inferred to form during times when lake waters were warmer and levels higher, while physico-chemical processes dominate during early tufa formation, and generally in colder waters and under conditions of lower lake level. Deposition of tufas is a result of combined physical, chemical, and biological factors that are directly related to the basin geology and hydroclimate; however, the importance of each controlling factor is highly variable both spatially and temporally, complicating the development of effective and predictive depositional models. This case study describes tufa deposition intrinsically linked to basinal hydroclimatic histories, and understanding these relationships may assist in predicting volumes, physical properties, and stacking patterns of petroleum reservoir facies in lacustrine basins.