Increase In Extreme Precipitation Research Articles

Projection of extreme precipitation induced by Arctic amplification over the Northern Hemisphere

Numerous attempts have been made to understand the connection between extreme weather and Arctic amplification (AA), and it is still disputed whether the mechanism is the elongation and deceleration of planetary-scale waves. In this study, we provide further evidence that the Arctic’s rapid warming is influencing extreme precipitation in the Northern Hermisphere based on observation and model outputs, and elucidate the underlying dynamic mechanisms. We find that AA has a significant positive correlation with extreme precipitation, both in the past (1901–2018) and in the future (by 2100). Moreover, observations reveal that, with the enhancement of AA since the mid-1980s, the planetary-scale wave amplitude has increased significantly at 0.66°/decade. This is associated with a negative Northern Hemisphere annular mode and an increased duration of weather patterns, resulting in more extreme precipitation events. Under Shared Socioeconomic Pathways SSP585 scenario, extreme precipitation increases by 8.7% along with wave amplitude increase of 7.9° by 2100.

Global climate shift in 1970s causes a significant worldwide increase in precipitation extremes

The shift in climate regimes around 1970s caused an overall enhancement of precipitation extremes across the globe with a specific spatial distribution pattern. We used gridded observational-reanalysis precipitation dataset and two important extreme precipitation measures, namely Annual Maximum Daily Precipitation (AMDP) and Probable Maximum Precipitation (PMP). AMDP is reported to increase for almost two-third of the global land area. The variability of AMDP is found to increase more than its mean that eventually results in increased PMP almost worldwide, less near equator and maximum around mid-latitudes. Continent-wise, such increase in AMDP and PMP is true for all continents except some parts of Africa. The zone-wise analysis (dividing the globe into nine precipitation zones) reveals that zones of ‘moderate precipitation’ and ‘moderate seasonality’ exhibit the maximum increases in PMP. Recent increased in pole-ward heat and moisture transport as a result of Arctic Amplification may be associated with such spatial redistribution of precipitation extremes in the northern hemisphere.

Record summer rains in 2019 led to massive loss of surface and cave ice in SE Europe

Abstract. Glaciers worldwide are shrinking at an accelerated rate as the climate changes in response to anthropogenic influence. While increasing air temperature is the main factor behind glacier mass and volume loss, variable patterns of precipitation distribution also play a role, though these are not as well understood. Furthermore, while the response of surface glaciers (from large polar ice sheets to small alpine glaciers) to climatic changes is well documented and continuously monitored, little to nothing is known about how cave glaciers (perennial ice accumulations in rock-hosted caves) react to atmospheric warming. In this context, we present here the response of cave and surface glaciers in SE Europe to the extreme precipitation events occurring between May and July 2019 in SE Europe. Surface glaciers in the northern Balkan Peninsula lost between 17 % and 19 % of their total area, while cave glaciers in Croatia, Greece, Romania and Slovenia lost ice at levels higher than any recorded by instrumental observations during the past decades. The melting was likely the result of large amounts of warm water delivered directly to the surface of the glaciers, leading to rapid reduction in the area of surface glaciers and the thickness of cave glaciers. As climate models predict that such extreme precipitation events are set to increase in frequency and intensity, the presence of cave glaciers in SE Europe and the paleoclimatic information they host may be lost in the near future. Moreover, the same projected continuous warming and increase in precipitation extremes could pose an additional threat to the alpine glaciers in southern Europe, resulting in faster-than-predicted melting.

U.S. Extreme Precipitation Weather Types Increased in Frequency During the 20th Century

AbstractExtreme precipitation has increased in frequency and intensity across the Conterminous U.S. (CONUS). This trend is expected to continue under future climate change. The cause is a combination of thermodynamic (i.e., warmer temperatures increase the atmospheric moisture content) and dynamic changes (e.g., shifts in cyclone frequency and tracks). It is well‐established that thermodynamic changes will intensify extreme precipitation events, but the impacts of dynamic changes are more uncertain. Extreme events are, per definition, rare and occur in unusual weather situations that are distinctly different from regular day‐to‐day weather. We take advantage of this and identify extreme precipitation‐producing weather patterns (XWTs) for all major watersheds across the CONUS by using a novel algorithm. We show that a set of one to four XWTs per watershed are causing extreme precipitation accumulations. These XWTs can be detected based on their synoptic‐scale fingerprint and are associated with West Coast atmospheric rivers, troughing in the desert Southwest, cutoff lows and troughs in the central and northwestern plains, and tropical cyclones along the Gulf and Atlantic coast. The algorithm is flexible enough to provide reliable results for city to major watershed‐scales and can detect extremes that are unprecedented in the training record. Importantly, this approach allows us to assess long‐term trends in extreme precipitation dynamics and reveal that XWT frequencies increased significantly in most U.S. watersheds during the 20th century indicating that changes in the atmospheric dynamics played an important role in historic extreme precipitation increases.

Assessing the Representation of Synoptic Variability Associated With California Extreme Precipitation in CMIP6 Models

AbstractDays of extreme precipitation over California are evaluated in Coupled Model Intercomparison Project Phase 6 (CMIP6) models and the ERA‐Interim reanalysis. In the current climate, the model spread in composited precipitation on extreme precipitation days is closely related to the magnitude of composited integrated vapor transport (IVT) across models, a proxy for the intensity of atmospheric rivers. Most models underestimate the magnitude of IVT associated with extreme precipitation, according to ERA‐Interim. This is due mostly to the contribution of moisture, which almost all models overestimate, while the contribution of lower‐tropospheric wind speed is generally closer to the reanalyses. Moreover, most models underestimate the variance in the latitude of maxima of numerous variables among days of extreme California precipitation. That is, in the general circulation models there is a lack of diversity in the latitude of the disturbances bringing winter precipitation to California. In the future climate, most models project a decrease in the frequency of southward‐displaced disturbances among California extreme precipitation days. Hence, the greatest increases in extreme precipitation are over northern California. However, the historical underestimate of the latitudinal variance of disturbances calls into question the reliability of these projections. This bias should be especially considered for dynamical downscaling efforts over the region.

Assessment of the European Climate Projections as Simulated by the Large EURO‐CORDEX Regional and Global Climate Model Ensemble

AbstractThis paper analyzes the ensemble of regional climate model (RCM) projections for Europe completed within the EURO‐CORDEX project. Projections are available for the two greenhouse gas concentration scenarios RCP2.6 (22 members) and RCP8.5 (55 members) at 0.11° resolution from 11 RCMs driven by eight global climate models (GCMs). The RCM ensemble results are compared with the driving CMIP5 global models but also with a subset of available last generation CMIP6 projections. Maximum warming is projected by all ensembles in Northern Europe in winter, along with a maximum precipitation increase there; in summer, maximum warming occurs in the Mediterranean and Southern European regions associated with a maximum precipitation decrease. The CMIP6 ensemble shows the largest signals, both for temperature and precipitation, along with the largest inter‐model spread. There is a high model consensus across the ensembles on an increase of extreme precipitation and drought frequency in the Mediterranean region. Extreme temperature indices show an increase of heat extremes and a decrease of cold extremes, with CMIP6 showing the highest values and EURO‐CORDEX the finest spatial details. This data set of unprecedented size and quality will provide the basis for impact assessment and climate service activities for the European region.

Precipitation Characteristics and Future Changes Over the Southern Slope of Tibetan Plateau Simulated by a High‐Resolution Global Nonhydrostatic Model

AbstractCurrent climate model resolution cannot accurately describe the complex topography over the Tibetan Plateau, which limits our understanding of past and future precipitation over this region. This study investigates the daily precipitation characteristics and its future changes over the Tibetan Plateau, especially for the southern slope of Tibetan Plateau (SSTP), by 14‐km Nonhydrostatic ICosahedral Atmospheric Model (NICAM) with explicitly calculated convection for historical and future 30‐years period. By comparing with the satellite Global Precipitation Measurement (GPM), NICAM well reproduces the historical precipitation spatial pattern, seasonal cycle, and the extreme precipitation belt over SSTP, but overestimates precipitation amount by ∼35%. It is found that heavy precipitation probability decreases as elevation becomes higher while the light precipitation generally shows the opposite. For the precipitation changes during June to September from 1979–2008 to 2075–2104, NICAM predicts that mean precipitation will decrease over low‐level SSTP but increase over high‐level SSTP. Nonprecipitation and heavy precipitation probability will increase while light precipitation probability will decrease in the future over SSTP. The extreme precipitation probability and intensity will increase ∼50%/°C and ∼8%/°C over SSTP, and this increase is more obvious as elevation becomes higher. The robust increase of extreme precipitation along the SSTP topography is unique and has not been identified by the climate model simulations before. The strong meridional gradient of specific humidity over SSTP is found to be further enhanced under global warming, and this gradient enhancement is suggested to be responsible for the increase in the extreme precipitation over SSTP.

Spatial-Temporal Distribution of Summer Extreme Precipitation in South China and Response of Tropical Ocean

In the study, the summer extreme precipitation in South China is divided into early rainy season (MJ) and late rainy season (JA). The percentile method (95%) is used to define the extreme precipitation threshold. Based on the international general definition method of extreme precipitation threshold: percentile method (95%), the extreme precipitation thresholds in flood season before and after South China are defined respectively. The total amount and frequency of extreme precipitation in flood season before and after 1979-2014 are calculated in this paper. The change trend of the two indicators is basically the same, and the two indicators have obvious interannual variation and an upward trend. According to the results of wavelet analysis of extreme precipitation frequency, the frequency of extreme precipitation in the first flood season mainly has a period of 3 - 5 years, while the frequency of extreme precipitation in the later flood season has a significant period of 6 - 8 years. The spatial distribution of extreme precipitation before and after the flood season shows that the extreme precipitation in the former flood season is mainly distributed in the central part of Guangdong, the northeast of Guangxi and the western part of Fujian, and the extreme precipitation in the latter flood season mainly occurs in the southern coastal area. The results show that there are different tropical SST regions affecting the extreme precipitation in South China. The former flood season is mainly the tropical Indian Ocean warm SST, and the latter flood season is mainly the tropical Pacific warm SST. The tropical Indian Ocean SST stimulates the anticyclonic anomaly over the South China Sea, which brings the southwest warm and humid air flow into South China, resulting in the increase of extreme precipitation in the first flood season of South China; the tropical Pacific SST stimulates the cyclonic anomaly over the South China Sea, which reduces the water vapor outflow caused by the seasonal northward jump of the subtropical high in South China, resulting in the increase of extreme precipitation in the later flood season of South China.

Response of summer extreme precipitation over East Asia during the mid-Holocene versus future global warming

Changes in extreme precipitation have significant impacts on society and the environment. In recent years, the response of extreme precipitation over East Asia to global warming has received considerable attention; however, few studies have focused on the extreme precipitation in geological warm periods, especially the mid-Holocene—the most recent warm period on the orbital timescale. In this study, the outputs of mid-Holocene, pre-industrial and CO2-induced warming experiments using a coupled climate model (MPI-ESM-P) were employed to examine the changes in extreme precipitation over East Asia in the mid-Holocene and under future warming scenario, respectively. The results show that, during the mid-Holocene, summer extreme precipitation increases over the east of China but decreases over Japan and the surrounding oceans. However, under CO2-induced warming, summer extreme precipitation increases over the southeast of China, Japan, and the surrounding oceans, but decreases over the north of East Asia. Moisture budget analysis shows that these distinct responses come from different changes in moisture and circulation during the two periods. During the mid-Holocene, higher insolation over the Northern Hemisphere leads to a larger ocean–land thermal contrast and a stronger East Asian summer monsoon (EASM). The strengthened EASM brings more moisture to continental East Asia, resulting in an increase in both mean and extreme precipitation. In contrast, the CO2-induced warming facilitates an anomalous heating center in the upper troposphere over the tropical part of Northwestern Pacific ocean, which weakens the EASM. However, enhanced atmospheric moisture counterbalances the effect of the weakened EASM, resulting in more extreme precipitation over the south of East Asia.

Contrasting seasonal changes in total and intense precipitation in the European Alps from 1903 to 2010

Abstract. Changes in precipitation over the European Alps are investigated with the regional climate model MAR (Modèle Atmosphérique Régional) applied with a 7 km resolution over the period 1903–2010 using the reanalysis ERA-20C as forcing. A comparison with several observational datasets demonstrates that the model is able to reproduce the climatology as well as both the interannual variability and the seasonal cycle of precipitation over the European Alps. The relatively high resolution allows us to estimate precipitation at high elevations. The vertical gradient of precipitation simulated by MAR over the European Alps reaches 33% km−1 (1.21 mm d−1 km−1) in summer and 38 % km−1 (1.15 mm d−1 km−1) in winter, on average, over 1971–2008 and shows a large spatial variability. A significant (p value < 0.05) increase in mean winter precipitation is simulated in the northwestern Alps over 1903–2010, with changes typically reaching 20 % to 40 % per century. This increase is mainly explained by a stronger simple daily intensity index (SDII) and is associated with less-frequent but longer wet spells. A general drying is found in summer over the same period, exceeding 20 % to 30 % per century in the western plains and 40 % to 50 % per century in the southern plains surrounding the Alps but remaining much smaller (<10 %) and not significant above 1500 m a.s.l. Below this level, the summer drying is explained by a reduction in the number of wet days, reaching 20 % per century over the northwestern part of the Alps and 30 % to 50 % per century in the southern part of the Alps. It is associated with shorter but more-frequent wet spells. The centennial trends are modulated over the last decades, with the drying occurring in the plains in winter also affecting high-altitude areas during this season and with a positive trend of autumn precipitation occurring only over the last decades all over the Alps. Maximum daily precipitation index (Rx1day) takes its highest values in autumn in both the western and the eastern parts of the southern Alps, locally reaching 50 to 70 mm d−1 on average over 1903–2010. Centennial maxima up to 250 to 300 mm d−1 are simulated in the southern Alps, in France and Italy, as well as in the Ticino valley in Switzerland. Over 1903–2010, seasonal Rx1day shows a general and significant increase at the annual timescale and also during the four seasons, reaching local values between 20 % and 40 % per century over large parts of the Alps and the Apennines. Trends of Rx1day are significant (p value < 0.05) only when considering long time series, typically 50 to 80 years depending on the area considered. Some of these trends are nonetheless significant when computed over 1970–2010, suggesting a recent acceleration of the increase in extreme precipitation, whereas earlier periods with strong precipitation also occurred, in particular during the 1950s and 1960s.

UAV-based evaluation of morphological changes induced by extreme rainfall events in meandering rivers.

Morphological changes, caused by the erosion and deposition processes due to water discharge and sediment flux occur, in the banks along the river channels and in the estuaries. Flow rate is one of the most important factors that can change river morphology. The geometric shapes of the meanders and the river flow parameters are crucial components in the areas where erosion or deposition occurs in the meandering rivers. Extreme precipitation triggers erosion on the slopes, which causes significant morphological changes in large areas during and after the event. The flow and sediment amount observed in a river basin with extreme precipitation increases and exceeds the long-term average value. Hereby, erosion severity can be determined by performing spatial analyses on remotely sensed imagery acquired before and after an extreme precipitation event. Changes of erosion and deposition along the river channels and overspill channels can be examined by comparing multi-temporal Unmanned Aerial Vehicle (UAV) based Digital Surface Model (DSM) data. In this study, morphological changes in the Büyük Menderes River located in the western Turkey, were monitored with pre-flood (June 2018), during flood (January 2019), and post-flood (September 2019) UAV surveys, and the spatial and volumetric changes of eroded/deposited sediment were quantified. For this purpose, the DSAS (Digital Shoreline Analysis System) method and the DEM of Difference (DoD) method were used to determine the changes on the riverbank and to compare the periodic volumetric morphological changes. Hereby, Structure from Motion (SfM) photogrammetry technique was exploited to a low-cost UAV derived imagery to achieve riverbank, areal and volumetric changes following the extreme rainfall events extracted from the time series of Tropical Rainfall Measuring Mission (TRMM) satellite data. The change analyses were performed to figure out the periodic morphodynamic variations and the impact of the flood on the selected meandering structures. In conclusion, although the river water level increased by 0.4–5.9 meters with the flood occurred in January 2019, the sediment deposition areas reformed after the flood event, as the water level decreased. Two-year monitoring revealed that the sinuosity index (SI) values changed during the flood approached the pre-flood values over time. Moreover, it was observed that the amount of the deposited sediments in September 2019 approached that of June 2018.

African Humid Period Precipitation Sustained by Robust Vegetation, Soil, and Lake Feedbacks

AbstractThe African Humid Period (∼11,000–5,000 years before present) was the most recent of several precessionally paced wet intervals during which an increase in the Northern Hemisphere summer incoming solar radiation intensifies the West African Monsoon leading to dramatic changes over northern Africa. However, insolation anomaly alone is not sufficient and feedbacks are essential for further amplification of the monsoon. The most significant feedbacks derive from the land surface, arising from changes to vegetation, soil properties, and distribution of surface water. We show that in contrast to previous studies that have explored the individual impacts of these feedbacks, a modern climate model yields a much greater increase in precipitation in response to their collective effect. Agreement with proxies is improved while the desert‐steppe transition is pushed further northward than in any previous study. In the West African Sahel, intensities of summer daily mean and extreme precipitation increase by 150% and 90%, respectively.

A Comparison of Intra-Annual and Long-Term Trend Scaling of Extreme Precipitation with Temperature in a Large-Ensemble Regional Climate Simulation

AbstractLong-term changes in extreme daily and subdaily precipitation simulated by climate models are often compared with corresponding temperature changes to estimate the sensitivity of extreme precipitation to warming. Such “trend scaling” rates are difficult to estimate from observations, however, because of limited data availability and high background variability. Intra-annual temperature scaling (here called binning scaling), which relates extreme precipitation to temperature at or near the time of occurrence, has been suggested as a possible substitute for trend scaling. We use a large ensemble simulation of the Canadian regional climate model (CanRCM4) to assess this possibility, considering both daily near-surface air temperature and daily dewpoint temperature as scaling variables. We find that binning curves that are based on precipitation data for the whole year generally look like the composite of binning curves for winter and summer, with the lower temperature portion similar to winter and the higher temperature portion similar to summer, indicating that binning curves reflect seasonal changes in the relationship between temperature and extreme precipitation. The magnitude and spatial pattern of binning and trend scaling rates are also quantitatively different, with little spatial correlation between them, regardless of precipitation duration or choice of temperature variable. The evidence therefore suggests that binning scaling with temperature is not a reliable predictor for future changes in precipitation extremes in the climate simulated by CanRCM4. Nevertheless, external forcing does have a discernable influence on binning curves, which are seen to shift upward and to the right in some regions, consistent with a general increase in extreme precipitation.

Hydrological extremes across the Commonwealth of Massachusetts in a changing climate

Study regionThe Commonwealth of Massachusetts, United States. Study focusThe Commonwealth of Massachusetts is projected to experience significant impacts from future climate change and these impacts include but are not limited to increases in extreme precipitation, flooding and droughts. This study investigates the potential impacts of climate change and uncertainties on future floods and low flow conditions in the rivers and streams of Massachusetts. Fourteen downscaled GCM projections under two greenhouse gas concentration pathways (RCP4.5 and RCP8.5) are used as inputs into a distributed hydrological model to obtain future streamflow conditions. New hydrological insights for the regionSeasonal change projections of 100-year flood and a measure of drought (the seven-day, ten-year low flow - Q7,10) are estimated through the near-term (years 2021−2060) and the far-term (years 2060−2099) relative to the base period (years 1981–2016). The median estimates of 100-year flood during winter report a 15 % or higher increases in many watersheds at the far-term. In contrast, flood magnitudes in spring show decreases for most of the watersheds during both near- and far-term. For seven-day, ten-year low flow estimates, largest decreases are projected during the fall and this trend is found to be consistent across future time periods. Two emission scenarios have shown similar trends for most cases although change projections are seen to be more prominent for RCP8.5 when compared to RCP4.5.

Diametrically Opposite Scaling of Extreme Precipitation and Streamflow to Temperature in South and Central Asia

AbstractClausius‐Clapeyron (CC) equation suggests a 6–7% increase in extreme precipitation per degree rise in temperature. Scaling rates of extreme precipitation with temperature at different regions significantly deviate from the CC rate. We find that the daily extreme precipitation scaling is negative over sites in the warmer tropical region of South Asia, as opposed to positive scaling over the cooler subtropics. Daily precipitation scaling tends to break down and becomes negative above a temperature of 23–24°C in all the regions. However, such breakdown disappears for subdaily precipitation extremes, and they continue to increase at high temperatures over both tropics and subtropics. This leads to high positive streamflow‐temperature scaling over small catchments, in contrast to extreme precipitation scaling at a daily scale, which is partly negative. Our analysis highlights an increased threat due to flash flood in a warmer climate, which cannot be fully estimated with the analysis of daily precipitation extremes.

Projected changes in extreme precipitation indices from CORDEX simulations over Ethiopia, East Africa

The projection of precipitation extremes is of significant importance for the reliable management of regional water resources. Thus, this study explores the potential response of the popularly used precipitation extreme indices to the global warming for near future (2011–2040), middle future (2041–2070) and far future (2071–2100) periods, based on the COordinated Regional climate Downscaling EXperiment (CORDEX) Africa experiment outputs over Ethiopia. The results show that the wet (dry) spells were projected to significantly decrease (increase) over most parts of Ethiopia, with relatively longer (shorter) dry (wet) spells projected over the northern parts of Ethiopia. Conversely, the projected changes in extreme precipitation amount above the 95th percentile showed a substantial increase over most parts of Ethiopia, with higher values projected to be in the southern region. The result implies that extreme and heavy precipitation events are likely to be more intense, and could amplify the probability of flood risks, particularly over the southern region. The total and extreme precipitations generally show a strong positive correlation, indicating the increase in extreme precipitation is responsible for the increase in total wet-day precipitation amount in Ethiopia. In general, climate change will have high negative impacts on the dynamics of precipitation patterns over Ethiopia, which could result in more long dry seasons and shorter rainy seasons over most parts of Ethiopia. Thus, the food and water security situation in the region is highly vulnerable due to the projected changes in the intensity and frequency of climate extremes (droughts and floods). However, the increase in precipitation extremes could have the potential to enhance the dry season agricultural productivity of most of the regions in Ethiopia using efficient irrigation systems through excess water harvesting in the rainy season. This can also reduce flood occurrences and hence economic damages. In general, it is of great importance to discuss the socio-economic impacts that could result if increasing precipitation extremes, as well as the increasing (decreasing) trend of maximum length of the dry (wet) spells, continue in the future.

Convection‐Permitting Models Offer Promise of More Certain Extreme Rainfall Projections

AbstractThe future increase in extreme precipitation is likely to have a severe impact on society due to flooding. Previous research has shown the improved representation of precipitation in convection‐permitting models (CPMs), but until now it has not been possible to quantify uncertainties in future changes at convective (<5 km) scales. Here we analyze the first‐ever ensemble of convection‐permitting climate projections run within the UK Climate Projections project. We find that the CPM ensemble shows a significantly stronger intensification of summer hourly precipitation compared to the driving 12 km ensemble, with increases above the Clausius‐Clapeyron relation and natural variability dominating the ensemble spread for extremes. Results suggest that the climate change signal across different CPMs may converge thanks to the more realistic representation of the local storm dynamics. We conclude that CPMs offer the promise of reducing uncertainties for extreme summer precipitation projections due to the better and explicit representation of convection.

Projected Changes in Extreme Precipitation in a 60‐km AGCM Large Ensemble and Their Dependence on Return Periods

AbstractThe dependence of projected changes in extreme precipitation on the return period, as well as on the temporal and spatial scales, is investigated using a large ensemble climate simulation with a 60‐km resolution global atmospheric model. The rate of increase in extreme precipitation is noticeably larger for longer return values in most parts of the world. While thermodynamic contribution to this increase generally follows the Clausius‐Clapeyron relationship for all return periods, dynamic contribution determines the dependence on the return periods. While the dependence on the temporal scales of precipitation has similar characteristics, that on spatial scales is not large. Composites for days with the 100‐year return value show that upward motion is enhanced in the middle and upper troposphere, accompanied by the enhanced horizontal water vapor convergence below. It suggests that an increase in latent heat release due to the water vapor increase plays a significant role in the dynamic contribution.

Estimation of future extreme precipitation changes in Xinjiang based on RegCM4.4 simulations

Based on IPCC mid- and high-greenhouse gas emission scenarios, we have been performed by using a CMIP5 GCM ensemble to drive the high resolution of Regional Climate Model RegCM4.4, and this study has assessed the model ability for simulating extreme precipitation indices and analyzed possible future changes in 2071–2100 under the A2 emissions scenario. Results indicate that RegCM4.4 performs well in the simulation of extreme precipitation indices and RegCM4.4 model can better reproduce the spatial distribution of extreme precipitation in Xinjiang, but this model is less effective in the Tian Shan Mountains due to topography and altitude. Prediction results show the future precipitation extreme simulation of Xinjiang indicates a tendency that the drought in Xinjiang eases relatively, showing a spatial pattern that the precipitation is gradually reduced from the northwest, the southwest to the southeast; RegCM4.4 simulation results show that indices of rainy days (RR1),number of heavy precipitation days (R10mm), maximum 5-day precipitation (RX5day), very wet day precipitation (R95p), and rainstorm rate (R95pTOT) all show an increasing trend that is more obvious in winter. In Xinjiang, the increase in extreme precipitation would not be entirely beneficial. Too much extreme precipitation will not only challenge the carrying capacity of water conservancy facilities and increase the difficulties in managing water resource, but also induce the heavy precipitation-related disasters.

Southward shift of precipitation extremes over south Asia: Evidences from CORDEX data

Analysis of observed Indian Summer Monsoon precipitation reveals more increase in extreme precipitation (in terms of its magnitude) over south India compared to north and central India during 1971–2017 (base period: 1930–1970). In the future, analysis of precipitation from the Coordinated Regional Downscaling Experiment indicates a southward shift of precipitation extremes over South Asia. For instance, the Arabian Sea, south India, Myanmar, Thailand, and Malaysia are expected to have the maximum increase (~18.5 mm/day for RCP8.5 scenario) in mean extreme precipitation (average precipitation for the days with more than 99th percentile of daily precipitation). However, north and central India and Tibetan Plateau show relatively less increase (~2.7 mm/day for RCP8.5 scenario). Analysis of air temperature at 850 mb and precipitable water (RCP4.5 and RCP8.5) indicates an intensification of Indian Ocean Dipole in future, which will enhance the monsoon throughout India. Moisture flux and convergence analysis (at 850 mb) show a future change of the direction of south-west monsoon winds towards the east over the Indian Ocean. These changes will intensify the observed contrast in extreme precipitation between south and north India, and cause more extreme precipitation events in the countries like Myanmar, Thailand, Malaysia, etc.