Extreme precipitation events are one of the most dangerous hydrometeorological disasters,often resulting in significant human and socio-economic losses worldwide.It is therefore important to use current global climate...Extreme precipitation events are one of the most dangerous hydrometeorological disasters,often resulting in significant human and socio-economic losses worldwide.It is therefore important to use current global climate models to project future changes in precipitation extremes.The present study aims to assess the future changes in precipitation extremes over South Asia from the Coupled Model Intercomparison Project Phase 6(CMIP6)Global Climate Models(GCMs).The results were derived using the modified Mann-Kendall test,Sen's slope estimator,student's t-test,and probability density function approach.Eight extreme precipitation indices were assessed,including wet days(RR1mm),heavy precipitation days(RR10mm),very heavy precipitation days(RR20mm),severe precipitation days(RR50mm),consecutive wet days(CWD),consecutive dry days(CDD),maximum 5-day precipitation amount(RX5day),and simple daily intensity index(SDII).The future changes were estimated in two time periods for the 21^(st) century(i.e.,near future(NF;2021-2060)and far future(FF;2061-2100))under two Shared Socioeconomic Pathway(SSP)scenarios(SSP2-4.5 and SSP5-8.5).The results suggest increases in the frequency and intensity of extreme precipitation indices under the SSP5-8.5 scenario towards the end of the 21^(st) century(2061-2100).Moreover,from the results of multimodel ensemble means(MMEMs),extreme precipitation indices of RR1mm,RR10mm,RR20mm,CWD,and SDII demonstrate remarkable increases in the FF period under the SSP5-8.5 scenario.The spatial distribution of extreme precipitation indices shows intensification over the eastern part of South Asia compared to the western part.The probability density function of extreme precipitation indices suggests a frequent(intense)occurrence of precipitation extremes in the FF period under the SSP5-8.5 scenario,with values up to 35.00 d for RR1mm and 25.00-35.00 d for CWD.The potential impacts of heavy precipitation can pose serious challenges to the study area regarding flooding,soil erosion,water resource management,food security,and agriculture development.展开更多
Changes of the frequency of precipitation extremes (the number of days with daily precipitation exceeding the 90th percentile of a daily climatology,referred to as R90N) in summer (June-August) over the mid-lower ...Changes of the frequency of precipitation extremes (the number of days with daily precipitation exceeding the 90th percentile of a daily climatology,referred to as R90N) in summer (June-August) over the mid-lower reaches of the Yangtze River are analyzed based on daily observations during 1961-2007.The first singular value decomposition (SVD) mode of R90N is linked to an ENSO-like mode of the sea surface temperature anomalies (SSTA) in the previous winter.Responses of different grades of precipitation events to the climatic mode are compared.It is notable that the frequency of summer precipitation extremes is significantly related with the SSTA in the Pacific,while those of light and moderate precipitation are not.It is suggested that the previously well-recognized impact of ENSO on summer rainfall along the Yangtze River is essentially due to a response in summer precipitation extremes in the region,in association with the East Asia-Pacific (EAP) teleconnection pattern.A negative relationship is found between the East Asian Summer Monsoon (EASM) and precipitation extremes over the mid-lower reaches of the Yangtze River.In contrast,light rainfall processes are independent from the SST and EASM variations.展开更多
Changes in rainfall extremes pose a serious and additional threat to water resources planning and management, natural and artificial oasis stability, and sustainable development in the fragile ecosystems of arid inlan...Changes in rainfall extremes pose a serious and additional threat to water resources planning and management, natural and artificial oasis stability, and sustainable development in the fragile ecosystems of arid inland river basins. In this study, the trend and temporal variation of extreme precipitation are analyzed using daily precipitation datasets at 11 stations over the arid inland Heihe River basin in Northwest China from 1960 to 2011. Eight indices of extreme precipitation are studied. The results show statistically significant and large-magnitude increasing and decreasing trends for most indices, primarily in the Qilian Mountains and eastern Hexi Corridor. More frequent and intense rainfall extremes have occurred in the southern part of the desert area than in the northern portion. In general, the temporal variation in precipitation extremes has changed throughout the basin. Wet day precipitation and heavy precipitation days show statistically significant linear increasing trends and step changes in the Qilian Mountains and Hexi Corridor. Consecutive dry days have decreased obviously in the region in most years after approximately the late 1980s, but meanwhile very long dry spells have increased, especially in the Hexi Corridor. The probability density function indicates that very long wet spells have increased in the Qilian Mountains. The East Asian summer monsoon index and western Pacific subtropical high intensity index possess strong and significant negative and positive correlations with rainfall extremes, respectively. Changes in land surface characteristics and the increase in water vapor in the wet season have also contributed to the changes in precipitation extremes over the river basin.展开更多
The atmospheric water holding capacity will increase with temperature according to Clausius-Clapeyron scaling and affects precipitation.The rates of change in future precipitation extremes are quantified with changes ...The atmospheric water holding capacity will increase with temperature according to Clausius-Clapeyron scaling and affects precipitation.The rates of change in future precipitation extremes are quantified with changes in surface air temperature.Precipitation extremes in China are determined for the 21st century in six simulations using a regional climate model,RegCM4,and 17 global climate models that participated in CMIP5.First,we assess the performance of the CMIP5 models and RCM runs in their simulation of extreme precipitation for the current period(RF:1982-2001).The CMIP5 models and RCM results can capture the spatial variations of precipitation extremes,as well as those based on observations:OBS and XPP.Precipitation extremes over four subregions in China are predicted to increase in the mid-future(MF:2039-58)and far-future(FF:2079-98)relative to those for the RF period based on both the CMIP5 ensemble mean and RCM ensemble mean.The secular trends in the extremes of the CMIP5 models are predicted to increase from 2008 to 2058,and the RCM results show higher interannual variability relative to that of the CMIP5 models.Then,we quantify the increasing rates of change in precipitation extremes in the MF and FF periods in the subregions of China with the changes in surface air temperature.Finally,based on the water vapor equation,changes in precipitation extremes in China for the MF and FF periods are found to correlate positively with changes in the atmospheric vertical wind multiplied by changes in surface specific humidity(significant at the p<0.1 level).展开更多
Extreme precipitation events bring considerable risks to the natural ecosystem and human life.Investigating the spatial-temporal characteristics of extreme precipitation and predicting it quantitatively are critical f...Extreme precipitation events bring considerable risks to the natural ecosystem and human life.Investigating the spatial-temporal characteristics of extreme precipitation and predicting it quantitatively are critical for the flood prevention and water resources planning and management.In this study,daily precipitation data(1957–2019)were collected from 24 meteorological stations in the Weihe River Basin(WRB),Northwest China and its surrounding areas.We first analyzed the spatial-temporal change of precipitation extremes in the WRB based on space-time cube(STC),and then predicted precipitation extremes using long short-term memory(LSTM)network,auto-regressive integrated moving average(ARIMA),and hybrid ensemble empirical mode decomposition(EEMD)-LSTM-ARIMA models.The precipitation extremes increased as the spatial variation from northwest to southeast of the WRB.There were two clusters for each extreme precipitation index,which were distributed in the northwestern and southeastern or northern and southern of the WRB.The precipitation extremes in the WRB present a strong clustering pattern.Spatially,the pattern of only high-high cluster and only low-low cluster were primarily located in lower reaches and upper reaches of the WRB,respectively.Hot spots(25.00%–50.00%)were more than cold spots(4.17%–25.00%)in the WRB.Cold spots were mainly concentrated in the northwestern part,while hot spots were mostly located in the eastern and southern parts.For different extreme precipitation indices,the performances of the different models were different.The accuracy ranking was EEMD-LSTM-ARIMA>LSTM>ARIMA in predicting simple daily intensity index(SDII)and consecutive wet days(CWD),while the accuracy ranking was LSTM>EEMD-LSTM-ARIMA>ARIMA in predicting very wet days(R95 P).The hybrid EEMD-LSTM-ARIMA model proposed was generally superior to single models in the prediction of precipitation extremes.展开更多
In the study of diagnosing climate simulations and understanding the dynamics of precipitation extremes,it is an essential step to adopt a simple model to relate water vapor condensation and precipitation,which occur ...In the study of diagnosing climate simulations and understanding the dynamics of precipitation extremes,it is an essential step to adopt a simple model to relate water vapor condensation and precipitation,which occur at cloudmicrophysical and convective scales,to large-scale variables.Several simple models have been proposed;however,improvement is still needed in both their accuracy and/or the physical basis.Here,we propose a two-plume convective model that takes into account the subgrid inhomogeneity of precipitation extremes.The convective model has three components,i.e.,cloud condensation,rain evaporation,and environmental descent,and is built upon the zero-buoyancy approximation and guidance from the high-resolution reanalysis.Evaluated against the CMIP5 climate simulations,the convective model shows large improvements in reproducing precipitation extremes compared to previously proposed models.Thus,the two-plume convective model better captures the main physical processes and serves as a useful diagnostic tool for precipitation extremes.展开更多
Understanding the responses of precipitation extremes to global climate change remains limited owing to their poor representations in models and complicated interactions with multi-scale systems.Here we take the recor...Understanding the responses of precipitation extremes to global climate change remains limited owing to their poor representations in models and complicated interactions with multi-scale systems.Here we take the record-breaking precipitation over China in 2021 as an example,and study its changes under three different climate scenarios through a developed pseudo-global-warming(PGW)experimental framework with 60-3 km variable-resolution global ensemble modeling.Compared to the present climate,the precipitation extreme under a warmer(cooler)climate increased(decreased)in intensity,coverage,and total amount at a range of 24.3%-37.8%(18.7%-56.1%).With the help of the proposed PGW experimental framework,we further reveal the impacts of the multi-scale system interactions in climate change on the precipitation extreme.Under the warmer climate,large-scale water vapor transport converged from double typhoons and the subtropical high marched into central China,enhancing the convective energy and instability on the leading edge of the transport belt.As a result,the mesoscale convective system(Mcs)that directly contributed to the precipitation extreme became stronger than that in the present climate.On the contrary,the cooler climate displayed opposite changing characteristics relative to the warmer climate,ranging from the large-scale systems to local environments and to the Mcs.In summary,our study provides a promising approach to scientifically assess the response of precipitation extremes to climate change,making it feasible to perform ensemble simulations while investigating the multi-scale system interactions over the globe.展开更多
Global warming has altered the thermodynamic and dynamic environments of climate systems,affecting the biogeochemical processes between the geosphere and atmosphere,which has significant impacts on precipitation extre...Global warming has altered the thermodynamic and dynamic environments of climate systems,affecting the biogeochemical processes between the geosphere and atmosphere,which has significant impacts on precipitation extremes and the terrestrial carbon budget of ecosystems.Existing studies have reported a hook structure for precipitation extreme-temperature relationships but have rarely examined the underlying physical mechanisms.Previous studies have also failed to quantify the impact of precipitation on ecosystem productivity,hindering the assessment of future extreme climatic hazards and potential ecosystem risks.To reveal the thermodynamic driving mechanisms for the formation of global precipitation extremes and ecohydrological effects,this study utilizes over ten multisource datasets(i.e.,satellite,reanalysis,climate model,land surface model,machine learning reconstruction,and flux tower measurements).We first assess the response of water-heat-carbon flux to precipitation extremes and explain the underlying physical mechanisms behind the hook structures in terms of atmospheric thermodynamics and dynamics.Based on outputs from five global climate models(GCMs)under ISIMIP3b,we project future changes in the hook structures as well as their impacts on precipitation extremes.Finally,we discuss the impact of precipitation on the terrestrial carbon budget by using outputs from the CLM4.5 model.The results show that precipitation extremes are usually accompanied by strong exchanges of water and heat and demonstrate a nonlinear relationship between precipitation and ecosystem productivity.The intensity(duration)of extreme precipitation is intensifying(decreasing)over most areas of the globe,whereas three-dimensional precipitation events are becoming more concentrated.Atmospheric dynamics play a key role in shaping the hook structure.The structure is not stable;it shifts under climate change and is projected to result in a 10–40%intensification in precipitation by the end of this century.Moderate levels of precipitation contribute to carbon assimilation in ecosystems,and the response of the carbon budget to precipitation is relatively stable under climate change.展开更多
A comprehensive assessment of representative satellite-retrieved(Integrated Multi-satellite Retrievals for Global Precipitation Measurement(IMERG)and Tropical Rainfall Measuring Mission Multi-satellite Precipitation A...A comprehensive assessment of representative satellite-retrieved(Integrated Multi-satellite Retrievals for Global Precipitation Measurement(IMERG)and Tropical Rainfall Measuring Mission Multi-satellite Precipitation Analysis(TMPA)),reanalysis-based(fifth generation of atmospheric reanalysis by the European Centre for Medium Range Weather Forecasts(ERA5)),and gauge-estimated(Climate Prediction Center(CPC))precipitation products was conducted using the data from 807 meteorological stations across China's Mainland from 2001 to 2017.Error statistical metrics,precipitation distribution functions,and extreme precipitation indices were used to evaluate the quality of the four precipitation products in terms of multi-timescale accuracy and extreme precipitation estimation.When the timescale increased from daily to seasonal scales,the accuracy of the four precipitation products first increased and then decreased,and all products performed best on the monthly timescale.Their accuracy ranking in descending order was CPC,IMERG,TMPA,and ERA5 on the daily timescale and IMERG,CPC,TMPA,and ERA5 on the monthly and seasonal timescales.IMERG was generally superior to its predecessor TMPA on the three timescales.ERA5 exhibited large statistical errors.CPC provided stable estimated values.For extreme precipitation estimation,the quality of IMERG was relatively consistent with that of TMPA in terms of precipitation distribution and extreme metrics,and IMERG exhibited a significant advantage in estimating moderate and heavy precipitation.In contrast,ERA5 and CPC exhibited poor performance with large systematic underestimation biases.The findings of this study provide insight into the performance of the latest IMERG product compared with the widely used TMPA,ERA5,and CPC datasets,and points to possible directions for improvement of multi-source precipitation data fusion algorithms in order to better serve hydrological applications.展开更多
Information about extreme rainfall is lacking in regions of South America and Africa.This study attempts to fill this scientific gap by use of a gridded parameterization for the stochastic weather generator,CLIGEN,to ...Information about extreme rainfall is lacking in regions of South America and Africa.This study attempts to fill this scientific gap by use of a gridded parameterization for the stochastic weather generator,CLIGEN,to map depth-duration-frequency(DDF)relationships.Analysis of 500-year point-scale precipitation time series generated at each grid point allowed maps of return period precipitation to be produced for a se-lection of sixteen durations ranging from 10-min to 1-year and for nine return periods from 2 to 500 years.The generalized extreme value(GEV)probability distribution was fitted for all durations,and given GEV quantiles,an interpolation method was applied to produce maps at 0.1° resolution that better resolve small-scale spatial climate gradients.In addition to uncertainties related to GEV fitting,this study quantifies prediction intervals based on ground validation.This validation was important for identifying biases in CLIGEN,although uncertainties were not always satisfactorily defined due to sampling design and other factors.For daily/multi-day durations,100 stations with daily observations and ≥50-year records were selected for validation against the 0.1° CLIGEN map series,resulting in a median and average absolute error of 13%and 16%,respectively.For sub-daily durations,prediction errors were larger overall.An analogy using available U.S.data established the degree of bias in CUGEN for sub-daily durations,and three records in Brazil with high temporal resolutions were used to confirm that applied bias adjustments resulted in error ranges similar to the daily/multi-day cases.This atlas is freely available for study of extreme precipitation.展开更多
The utility of statistically downscaled data is in its provision of detailed,high-resolution insights,surpassing global models,which is essential for precise assessments of climate impact.This study delves into the ch...The utility of statistically downscaled data is in its provision of detailed,high-resolution insights,surpassing global models,which is essential for precise assessments of climate impact.This study delves into the changes in extreme precipitation across the Tibetan Plateau(TP)and its five subregions,thereby deepening our understanding of climate impacts in the region.Employing NASA Earth Exchange Global Daily Downscaled Climate Projections(NEX-GDDP-CMIP6),which are bias-corrected and statistically downscaled,in conjunction with three gauge-based datasets(CN05.1,CMFD,GMFD)spanning from 1979 to 2014,this study conducts an extensive analysis using eight extreme precipitation indices in the TP.The findings reveal significant spatial disparities in extreme precipitation,with the southern subregion experiencing a sig-nificant increase while the two northern subregions show statistically insignificant changes.NEX-GDDP-CMIP6 performs best in the eastern subregion but fails to capture extreme precipitation characteristics in the southern and western subregions.Averaging over the whole period of 1979-2014(climatology),the NEX-GDDP-CMIP6 dataset performs better on the intensity and persistence indices than on the absolute and relative threshold indices.NEX-GDDP-CMIP6's performance on climate trends is significantly below that of climatology.The NEX-GDDP-CMIP6 dataset has limitations over the TP because of its reliance on the underperforming GMFD reference data.This study provides a comprehensive understanding of the variability of extreme precipitation and disparities among different subregions of the TP,laying a robust scientific groundwork for climate impact studies and future projection in this region.展开更多
Globally,2023 was the warmest observed year on record since at least 1850 and,according to proxy evidence,possibly of the past 100000 years.As in recent years,the record warmth has again been accompanied with yet more...Globally,2023 was the warmest observed year on record since at least 1850 and,according to proxy evidence,possibly of the past 100000 years.As in recent years,the record warmth has again been accompanied with yet more extreme weather and climate events throughout the world.Here,we provide an overview of those of 2023,with details and key background causes to help build upon our understanding of the roles of internal climate variability and anthropogenic climate change.We also highlight emerging features associated with some of these extreme events.Hot extremes are occurring earlier in the year,and increasingly simultaneously in differing parts of the world(e.g.,the concurrent hot extremes in the Northern Hemisphere in July 2023).Intense cyclones are exacerbating precipitation extremes(e.g.,the North China flooding in July and the Libya flooding in September).Droughts in some regions(e.g.,California and the Horn of Africa)have transitioned into flood conditions.Climate extremes also show increasing interactions with ecosystems via wildfires(e.g.,those in Hawaii in August and in Canada from spring to autumn 2023)and sandstorms(e.g.,those in Mongolia in April 2023).Finally,we also consider the challenges to research that these emerging characteristics present for the strategy and practice of adaptation.展开更多
This study comprehensively examines the patterns and regional variation of severe rainfall across the African continent, employing a suite of eight extreme precipitation indices. The analysis extends to the assessment...This study comprehensively examines the patterns and regional variation of severe rainfall across the African continent, employing a suite of eight extreme precipitation indices. The analysis extends to the assessment of projected changes in precipitation extremes using five General Circulation Models (GCMs) from Coupled Model Intercomparison Project Phase 6 (CMIP6) under four Shared Socioeconomic Pathways (SSPs) scenarios at the long-term period (2081-2100) of the 21<sup>st</sup> century. Furthermore, the study investigates potential mechanisms influencing precipitation extremes by correlating extreme precipitation indices with oceanic system indices, specifically Ni?o 3.4 for El Ni?o-Southern Oscillation (ENSO) and Dipole Mode Index (DMI) for the Indian Ocean Dipole (IOD). The findings revealed distinct spatial distributions in mean trends of extreme precipitation indices, indicating a tendency toward decreased extreme precipitation in North Africa, Sahel region, Central Africa and the Western part of South Africa. Conversely, West Africa, East Africa and the Eastern part of South Africa exhibit an inclination toward increased extreme precipitation. The changes in precipitation extreme indices indicate a general rise in both the severity and occurrence of extreme precipitation events under all scenarios by the end of the 21<sup>st</sup> century. Notably, our analysis projects a decrease in consecutive wet days (CWD) in the far-future. Additionally, correlation analysis highlights significant correlation between above or below threshold rainfall fluctuation in East Africa and South Africa with oceanic systems, particularly ENSO and the IOD. Central Africa abnormal precipitation variability is also linked to ENSO with a significant negative correlation. These insights contribute valuable information for understanding and projecting the dynamics of precipitation extreme in Africa, providing a foundation for climate adaptation and mitigation efforts in the region.展开更多
Daily precipitation series at 15 stations in the Beijing metropolitan region(BMR) during 1960–2012 were homogenized using the multiple analysis of series for homogenization method,with additional adjustments based ...Daily precipitation series at 15 stations in the Beijing metropolitan region(BMR) during 1960–2012 were homogenized using the multiple analysis of series for homogenization method,with additional adjustments based on analysis of empirical cumulative density function(ECDF) regarding climate extremes.The cumulative density functions of daily precipitation series,the trends of annual and seasonal precipitation,and summer extreme events during 1960–2012 in the original and final adjusted series at Beijing station were comparatively analyzed to show the necessity and efficiency of the new method.Results indicate that the ECDF adjustments can improve the homogeneity of high-order moments of daily series and the estimation of climate trends in extremes.The linear trends of the regional-mean annual and seasonal(spring,summer,autumn,and winter)precipitation series are-10.16,4.97,-20.04,5.02,and-0.11 mm(10 yr)-1,respectively.The trends over the BMR increase consistently for spring/autumn and decrease for the whole year/summer; however,the trends for winter decrease in southern parts and increase in northern parts.Urbanization affects local trends of precipitation amount,frequency,and intensity and their geographical patterns.For the urban-influenced sites,urbanization tends to slow down the magnitude of decrease in the precipitation and extreme amount series by approximately-10.4% and-6.0%,respectively; enhance the magnitude of decrease in precipitation frequency series by approximately 5.7%; reduce that of extremes by approximately-8.9%; and promote the decreasing trends in the summer intensity series of both precipitation and extremes by approximately 6.8% and51.5%,respectively.展开更多
East Africa is so vulnerable to the impacts of precipitation extremes varying from frequent floods to prolonged droughts.However,systematic regional assessment of precipitation extremes across seasons has received lit...East Africa is so vulnerable to the impacts of precipitation extremes varying from frequent floods to prolonged droughts.However,systematic regional assessment of precipitation extremes across seasons has received little attention,and most previous studies of precipitation extremes have employed many indices and sparse gauge observations giving marginalized details.In this study,we use three precipitation extreme indices to examine the intensity of the highest single-day rainfall record(rx1day),prevalence of very heavy rainfalls(r30mm),and persistence of successive wet days(cwd)at both annual and seasonal scales over recent two decades(1998-2018)based on the Tropical Rainfall Measuring Mission(TRMM)Multisatellite Precipitation Analysis data.The results show that the most intensive and frequent precipitation extremes are noticeable from January to May across the areas extending from Madagascar to the Tanzanian coastal zone.These areas also exhibit patches of significant increasing trends in frequency,duration,and intensity of precipitation extremes annually and seasonally.However,significant declines in frequency and intensity of precipitation extremes are observed from western Ethiopia to Congo-Uganda,especially in June-September.The October-December season witnesses higher interannual variability amounting to overall weak and less significant trends.Further subregional assessment shows overall declining intensity and frequency of precipitation extremes in northern part of the study areas.Mean wetness duration increased,with persistence of moderate wet days and slight reduction of severe events.This study unveils higher susceptibility of the East African region to the widely observed hotspots of precipitation extremes posing threats to food security,water resource,and human well-being.The region should consider upscaling irrigation schemes in addition to planning resilient and supportive infrastructures to withstand the upsurging precipitation extremes,especially along the coastal zone.展开更多
Modification signs in extreme weather events may be directly related to alterations in the thermodynamic panorama of the atmosphere that need to be better understood. This study aimed to make a first interconnection b...Modification signs in extreme weather events may be directly related to alterations in the thermodynamic panorama of the atmosphere that need to be better understood. This study aimed to make a first interconnection between climate extremes and thermodynamic patterns in the city of Rio de Janeiro. Maximum and minimum air temperature and precipitation extreme indices from two surface meteorological stations (ABOV and STCZ) and instability indices based on temperature and humidity from radiosonde observations (SBGL) were employed to investigate changes in the periods 1964-1980 (P1), 1981-2000 (P2), and 2001-2020 (P3). Statistical tests were adopted to determine the significance and magnitude of trends. The frequency of warm (cold) days and warm (cold) nights are increasing (decreasing) in the city. Cold (Warm) extremes are changing with greater magnitude in ABOV (STCZ) than in STCZ (ABOV). In ABOV, there is a significant increase of +84 mm/decade in the rainfall volume associated with severe precipitation (above the 95<sup>th</sup> percentile) and most extreme precipitation indices show an increase in frequency and intensity. In STCZ, there is a decrease in extreme precipitation until the 1990s, and from there, an increase, showing a wetter climate in the most recent years. It is also verified in SBGL that there is a statistically significant increase (decrease) in air temperature of +0.1°C/decade (-0.2°C/decade) and relative humidity of +1.2%/decade (-3%/decade) at the low and middle (high) troposphere. There is a visible rising trend in most of the evaluated instability indices over the last few decades. The increasing trends of some extreme precipitation indices are probably allied to the precipitable water increasing trend of +1.2 mm/decade.展开更多
Based on the daily rainfall data from China Meteorological Administration,the tropical cyclone(TC) best track data from Japan Meteorological Agency,and the NCEP-NCAR reanalysis data from NOAA,regional mean daily pre...Based on the daily rainfall data from China Meteorological Administration,the tropical cyclone(TC) best track data from Japan Meteorological Agency,and the NCEP-NCAR reanalysis data from NOAA,regional mean daily precipitation extreme(RDPE) events over southeastern China(specifically,the Fujian-Jiangxi region(FJR)) and the associated circulation anomalies are investigated.For the summers of 1979-2011,a total of 105 RDPE events are identified,among which 35 are TC-infiuenced(TCIn-RDPE) and 70 are TCfree events(TCFr-RDPE).Distinct differences between these two types of RDPEs are found in both their statistical features and the related circulation patterns.TCFr-RDPEs usually occur in June,while TCInRDPEs mainly take place during July-August.When TCFr-RDPEs happen,a center of the anomalous cyclonic circulation is observed over the FJR,with an anomalous anticyclonic circulation to the south of this region.The warm/moist air flows from the South China Sea(SCS) and western Pacific meet with colder air from the north,forming a narrow convergent belt of water vapor over the FJR.Simultaneously,positive diabatic forcing anomalies are observed over the FJR,whereas negative anomalies appear over both its south and north sides,facilitating the formation and maintenance of the cyclonic circulation anomaly,as well as the upward motion of the atmosphere,over the FJR.When TCIn-RDPEs occur,southeastern China is dominated by a TC-related stronger anomalous cyclonic circulation.An anomalous anticyclonic circulation in the mid and high latitudes north of the FJR exists in the mid and upper troposphere,opposite to the situation during TCFr-RDPE events.Abundant warm/wet air is carried into the FJR from both the Indian Ocean and the SCS,leading to a large amount of latent heat release over the FJR and inducing strong ascending motion there.Furthermore,large differences are also found in the manifestation of Rossby wave energy propagation between these two types of RDPE events.The results of this study are helpful to deepen our understanding of the mechanisms behind these two types of RDPE events.展开更多
The variations of regional mean daily precipitation extreme (RMDPE) events in central China and associated circulation anomalies during June, July, and August (JJA) of 1961-2010 are investigated by using daily in-...The variations of regional mean daily precipitation extreme (RMDPE) events in central China and associated circulation anomalies during June, July, and August (JJA) of 1961-2010 are investigated by using daily in-situ precipitation observations and the NCEP/NCAR reanalysis data. The precipitation data were collected at 239 state-level stations distributed throughout the provinces of Henan, Hubei, and Hunan. During 1961-2010, the 99th percentile threshold for RMDPE is 23.585 mm day-1. The number of RMDPE events varies on both interannual and interdecadal timescales, and increases significantly after the mid 1980s. The RMDPE events happen most frequently between late June and mid July, and are generally associated with anomalous baroclinic tropospheric circulations. The supply of moisture to the southern part of central China comes in a stepping way from the outer-region of an abnormal anticyclone over the Bay of Bengal and the South China Sea. Fluxes of wave activity generated over the northeastern Tibetan Plateau converge over central China, which favors the genesis and maintenance of wave disturbances over the region. RMDPE events typically occur in tandem with a strong heating gradient formed by net heating in central China and the large-scale net cooling in the surrounding area. The occurrence of RMDPE events over central China is tied to anomalous local cyclonic circulations, topographic forcing over the northeast Tibetan Plateau, and anomalous gradients of diabatic heating between central China and the surrounding areas.展开更多
The floods caused by the extreme precipitation in the Yangtze River basin(YRB)and Murray–Darling River basin(MDRB),the largest basins in China and Australia,have significant impacts on the society and regional econom...The floods caused by the extreme precipitation in the Yangtze River basin(YRB)and Murray–Darling River basin(MDRB),the largest basins in China and Australia,have significant impacts on the society and regional economies.Based on the spatial–temporal analysis of the daily precipitation extremes(DPEs)during 1982–2016,we found that for both basins,the whole-basin-type DPEs have the highest proportion and a synchronous DPE interannual variation characteristic exists in the two basins,with the 3-yr running correlation coefficient of the annual DPE days(DPEDs)reaching almost 0.7(significant at the 0.01 level).The El Ni?o–Southern Oscillation(ENSO),which is one of the most significant climate disturbance factors in the world,plays an important role in modulating the variability of the DPEs in the two basins.Singular value decomposition(SVD)analysis revealed that both the YRB and the MDRB’s whole-basin-type DPEs are closely coupled with the procedure that the preceding winter eastern Pacific(EP)-type El Ni?o faded to a central Pacific(CP)-type La Nina.This means that the DPEs in the YRB and MDRB may synchronously occur more frequently when the above process occurs.Owing to the atmosphere–ocean interaction from the east–west dipole sea surface temperature(SST)anomaly pattern,the atmospheric circulation disturbance exhibits a pattern in which the equatorial eastern Pacific region is a mass source anomaly with a higher pressure,drier air,and weaker convection,while the equatorial western Pacific region is a mass sink anomaly with a lower pressure,wetter air,and stronger convection.Moreover,two wave trains that originated from the tropical western Pacific were found to extend to the YRB and MDRB.The interaction between the wave train’s interphase dynamics and water vapor transport disturbance results in the ascent conditions and enhanced water vapor transport,which leads to the synchronous occurrence of DPEs in the YRB and MDRB on an interannual scale.展开更多
In this study,the spatiotemporal variability of trends in extreme precipitation events in Ho Chi Minh City during the period 1980–2017 was analyzed based on several core extreme precipitation indices(Rx1 day,Rx5 day,...In this study,the spatiotemporal variability of trends in extreme precipitation events in Ho Chi Minh City during the period 1980–2017 was analyzed based on several core extreme precipitation indices(Rx1 day,Rx5 day,CDD,CWD,R20 mm,R25 mm,R95 p,and SDII).The nonparametric Mann–Kendall and Sen’s slope methods were used to compute the statistical strength,stability,and magnitude of trends in annual rainfall,as well as the extreme precipitation indices.We found that 64%of the stations had statistically significant upward trends in yearly rainfall,with high magnitudes frequently observed in the northern and southern regions of the city.For the extreme precipitation indices,only SDII and R25 mm showed dominantly significant trends.Additionally,there were increasing trends in the frequency and duration at the southern and central regions of the city during the study period.Furthermore,El Ni?o-Southern Oscillation and Pacific Decadal Oscillation positively correlated with the duration and negatively correlated with the intensity and frequency of extreme precipitation.Thus,water management plans should be adjusted appropriately to reduce the severe impacts of precipitation extremes on communities and ecosystems.展开更多
基金supported by the National Natural Science Foundation of China(42130405)the Innovative and Entrepreneurial Talent Program of Jiangsu Province(R2020SC04)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA2006030201)the Research Fund for International Young Scientists of the National Natural Science Foundation of China(42150410381).
文摘Extreme precipitation events are one of the most dangerous hydrometeorological disasters,often resulting in significant human and socio-economic losses worldwide.It is therefore important to use current global climate models to project future changes in precipitation extremes.The present study aims to assess the future changes in precipitation extremes over South Asia from the Coupled Model Intercomparison Project Phase 6(CMIP6)Global Climate Models(GCMs).The results were derived using the modified Mann-Kendall test,Sen's slope estimator,student's t-test,and probability density function approach.Eight extreme precipitation indices were assessed,including wet days(RR1mm),heavy precipitation days(RR10mm),very heavy precipitation days(RR20mm),severe precipitation days(RR50mm),consecutive wet days(CWD),consecutive dry days(CDD),maximum 5-day precipitation amount(RX5day),and simple daily intensity index(SDII).The future changes were estimated in two time periods for the 21^(st) century(i.e.,near future(NF;2021-2060)and far future(FF;2061-2100))under two Shared Socioeconomic Pathway(SSP)scenarios(SSP2-4.5 and SSP5-8.5).The results suggest increases in the frequency and intensity of extreme precipitation indices under the SSP5-8.5 scenario towards the end of the 21^(st) century(2061-2100).Moreover,from the results of multimodel ensemble means(MMEMs),extreme precipitation indices of RR1mm,RR10mm,RR20mm,CWD,and SDII demonstrate remarkable increases in the FF period under the SSP5-8.5 scenario.The spatial distribution of extreme precipitation indices shows intensification over the eastern part of South Asia compared to the western part.The probability density function of extreme precipitation indices suggests a frequent(intense)occurrence of precipitation extremes in the FF period under the SSP5-8.5 scenario,with values up to 35.00 d for RR1mm and 25.00-35.00 d for CWD.The potential impacts of heavy precipitation can pose serious challenges to the study area regarding flooding,soil erosion,water resource management,food security,and agriculture development.
基金supported by grants from the National Basic Research Program of China(2009CB421401)
文摘Changes of the frequency of precipitation extremes (the number of days with daily precipitation exceeding the 90th percentile of a daily climatology,referred to as R90N) in summer (June-August) over the mid-lower reaches of the Yangtze River are analyzed based on daily observations during 1961-2007.The first singular value decomposition (SVD) mode of R90N is linked to an ENSO-like mode of the sea surface temperature anomalies (SSTA) in the previous winter.Responses of different grades of precipitation events to the climatic mode are compared.It is notable that the frequency of summer precipitation extremes is significantly related with the SSTA in the Pacific,while those of light and moderate precipitation are not.It is suggested that the previously well-recognized impact of ENSO on summer rainfall along the Yangtze River is essentially due to a response in summer precipitation extremes in the region,in association with the East Asia-Pacific (EAP) teleconnection pattern.A negative relationship is found between the East Asian Summer Monsoon (EASM) and precipitation extremes over the mid-lower reaches of the Yangtze River.In contrast,light rainfall processes are independent from the SST and EASM variations.
基金supported by the Key Project of the Chinese Academy of Sciences (Grant No.KZZDEW-04-05)supported by the Australia–China Joint Research Centre on River Basin Management
文摘Changes in rainfall extremes pose a serious and additional threat to water resources planning and management, natural and artificial oasis stability, and sustainable development in the fragile ecosystems of arid inland river basins. In this study, the trend and temporal variation of extreme precipitation are analyzed using daily precipitation datasets at 11 stations over the arid inland Heihe River basin in Northwest China from 1960 to 2011. Eight indices of extreme precipitation are studied. The results show statistically significant and large-magnitude increasing and decreasing trends for most indices, primarily in the Qilian Mountains and eastern Hexi Corridor. More frequent and intense rainfall extremes have occurred in the southern part of the desert area than in the northern portion. In general, the temporal variation in precipitation extremes has changed throughout the basin. Wet day precipitation and heavy precipitation days show statistically significant linear increasing trends and step changes in the Qilian Mountains and Hexi Corridor. Consecutive dry days have decreased obviously in the region in most years after approximately the late 1980s, but meanwhile very long dry spells have increased, especially in the Hexi Corridor. The probability density function indicates that very long wet spells have increased in the Qilian Mountains. The East Asian summer monsoon index and western Pacific subtropical high intensity index possess strong and significant negative and positive correlations with rainfall extremes, respectively. Changes in land surface characteristics and the increase in water vapor in the wet season have also contributed to the changes in precipitation extremes over the river basin.
基金`This study was supported by the National Key Research and Development Program of China(Grant No.2019YFA0606903)the National Natural Science Foundation of China(Grant No.42075162)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDA23090102).
文摘The atmospheric water holding capacity will increase with temperature according to Clausius-Clapeyron scaling and affects precipitation.The rates of change in future precipitation extremes are quantified with changes in surface air temperature.Precipitation extremes in China are determined for the 21st century in six simulations using a regional climate model,RegCM4,and 17 global climate models that participated in CMIP5.First,we assess the performance of the CMIP5 models and RCM runs in their simulation of extreme precipitation for the current period(RF:1982-2001).The CMIP5 models and RCM results can capture the spatial variations of precipitation extremes,as well as those based on observations:OBS and XPP.Precipitation extremes over four subregions in China are predicted to increase in the mid-future(MF:2039-58)and far-future(FF:2079-98)relative to those for the RF period based on both the CMIP5 ensemble mean and RCM ensemble mean.The secular trends in the extremes of the CMIP5 models are predicted to increase from 2008 to 2058,and the RCM results show higher interannual variability relative to that of the CMIP5 models.Then,we quantify the increasing rates of change in precipitation extremes in the MF and FF periods in the subregions of China with the changes in surface air temperature.Finally,based on the water vapor equation,changes in precipitation extremes in China for the MF and FF periods are found to correlate positively with changes in the atmospheric vertical wind multiplied by changes in surface specific humidity(significant at the p<0.1 level).
基金Under the auspices of National Key Research and Development Program of China(No.2017YFE0118100-1)。
文摘Extreme precipitation events bring considerable risks to the natural ecosystem and human life.Investigating the spatial-temporal characteristics of extreme precipitation and predicting it quantitatively are critical for the flood prevention and water resources planning and management.In this study,daily precipitation data(1957–2019)were collected from 24 meteorological stations in the Weihe River Basin(WRB),Northwest China and its surrounding areas.We first analyzed the spatial-temporal change of precipitation extremes in the WRB based on space-time cube(STC),and then predicted precipitation extremes using long short-term memory(LSTM)network,auto-regressive integrated moving average(ARIMA),and hybrid ensemble empirical mode decomposition(EEMD)-LSTM-ARIMA models.The precipitation extremes increased as the spatial variation from northwest to southeast of the WRB.There were two clusters for each extreme precipitation index,which were distributed in the northwestern and southeastern or northern and southern of the WRB.The precipitation extremes in the WRB present a strong clustering pattern.Spatially,the pattern of only high-high cluster and only low-low cluster were primarily located in lower reaches and upper reaches of the WRB,respectively.Hot spots(25.00%–50.00%)were more than cold spots(4.17%–25.00%)in the WRB.Cold spots were mainly concentrated in the northwestern part,while hot spots were mostly located in the eastern and southern parts.For different extreme precipitation indices,the performances of the different models were different.The accuracy ranking was EEMD-LSTM-ARIMA>LSTM>ARIMA in predicting simple daily intensity index(SDII)and consecutive wet days(CWD),while the accuracy ranking was LSTM>EEMD-LSTM-ARIMA>ARIMA in predicting very wet days(R95 P).The hybrid EEMD-LSTM-ARIMA model proposed was generally superior to single models in the prediction of precipitation extremes.
基金National Natural Science Foundation of China(Grant nos.41875050 and 42075146).
文摘In the study of diagnosing climate simulations and understanding the dynamics of precipitation extremes,it is an essential step to adopt a simple model to relate water vapor condensation and precipitation,which occur at cloudmicrophysical and convective scales,to large-scale variables.Several simple models have been proposed;however,improvement is still needed in both their accuracy and/or the physical basis.Here,we propose a two-plume convective model that takes into account the subgrid inhomogeneity of precipitation extremes.The convective model has three components,i.e.,cloud condensation,rain evaporation,and environmental descent,and is built upon the zero-buoyancy approximation and guidance from the high-resolution reanalysis.Evaluated against the CMIP5 climate simulations,the convective model shows large improvements in reproducing precipitation extremes compared to previously proposed models.Thus,the two-plume convective model better captures the main physical processes and serves as a useful diagnostic tool for precipitation extremes.
基金supported by the National Natural Science Foundation of China(42225505)the Beijing Nova Program(Z211100002121100)+2 种基金the National Key Research and Development Program of China(2021YFC3000805)the National Natural Science Foundation of China(U2142204)the Science&Technology Development Fund of Chinese Academy of Meteorological Sciences(CAMS)(2022KJ007)。
文摘Understanding the responses of precipitation extremes to global climate change remains limited owing to their poor representations in models and complicated interactions with multi-scale systems.Here we take the record-breaking precipitation over China in 2021 as an example,and study its changes under three different climate scenarios through a developed pseudo-global-warming(PGW)experimental framework with 60-3 km variable-resolution global ensemble modeling.Compared to the present climate,the precipitation extreme under a warmer(cooler)climate increased(decreased)in intensity,coverage,and total amount at a range of 24.3%-37.8%(18.7%-56.1%).With the help of the proposed PGW experimental framework,we further reveal the impacts of the multi-scale system interactions in climate change on the precipitation extreme.Under the warmer climate,large-scale water vapor transport converged from double typhoons and the subtropical high marched into central China,enhancing the convective energy and instability on the leading edge of the transport belt.As a result,the mesoscale convective system(Mcs)that directly contributed to the precipitation extreme became stronger than that in the present climate.On the contrary,the cooler climate displayed opposite changing characteristics relative to the warmer climate,ranging from the large-scale systems to local environments and to the Mcs.In summary,our study provides a promising approach to scientifically assess the response of precipitation extremes to climate change,making it feasible to perform ensemble simulations while investigating the multi-scale system interactions over the globe.
基金supported by the National Natural Science Foundation of China(Grant No.52009091)the Fundamental Research Funds for the Central Universities(Grant No.2042022kf1221)。
文摘Global warming has altered the thermodynamic and dynamic environments of climate systems,affecting the biogeochemical processes between the geosphere and atmosphere,which has significant impacts on precipitation extremes and the terrestrial carbon budget of ecosystems.Existing studies have reported a hook structure for precipitation extreme-temperature relationships but have rarely examined the underlying physical mechanisms.Previous studies have also failed to quantify the impact of precipitation on ecosystem productivity,hindering the assessment of future extreme climatic hazards and potential ecosystem risks.To reveal the thermodynamic driving mechanisms for the formation of global precipitation extremes and ecohydrological effects,this study utilizes over ten multisource datasets(i.e.,satellite,reanalysis,climate model,land surface model,machine learning reconstruction,and flux tower measurements).We first assess the response of water-heat-carbon flux to precipitation extremes and explain the underlying physical mechanisms behind the hook structures in terms of atmospheric thermodynamics and dynamics.Based on outputs from five global climate models(GCMs)under ISIMIP3b,we project future changes in the hook structures as well as their impacts on precipitation extremes.Finally,we discuss the impact of precipitation on the terrestrial carbon budget by using outputs from the CLM4.5 model.The results show that precipitation extremes are usually accompanied by strong exchanges of water and heat and demonstrate a nonlinear relationship between precipitation and ecosystem productivity.The intensity(duration)of extreme precipitation is intensifying(decreasing)over most areas of the globe,whereas three-dimensional precipitation events are becoming more concentrated.Atmospheric dynamics play a key role in shaping the hook structure.The structure is not stable;it shifts under climate change and is projected to result in a 10–40%intensification in precipitation by the end of this century.Moderate levels of precipitation contribute to carbon assimilation in ecosystems,and the response of the carbon budget to precipitation is relatively stable under climate change.
基金supported by the National Natural Science Foundation of China(Grant No.51979069)the Fundamental Research Funds for the Central Universities(Grant No.B200204029)the National Natural Science Foundation of Jiangsu Province,China(Grant No.BK20211202).
文摘A comprehensive assessment of representative satellite-retrieved(Integrated Multi-satellite Retrievals for Global Precipitation Measurement(IMERG)and Tropical Rainfall Measuring Mission Multi-satellite Precipitation Analysis(TMPA)),reanalysis-based(fifth generation of atmospheric reanalysis by the European Centre for Medium Range Weather Forecasts(ERA5)),and gauge-estimated(Climate Prediction Center(CPC))precipitation products was conducted using the data from 807 meteorological stations across China's Mainland from 2001 to 2017.Error statistical metrics,precipitation distribution functions,and extreme precipitation indices were used to evaluate the quality of the four precipitation products in terms of multi-timescale accuracy and extreme precipitation estimation.When the timescale increased from daily to seasonal scales,the accuracy of the four precipitation products first increased and then decreased,and all products performed best on the monthly timescale.Their accuracy ranking in descending order was CPC,IMERG,TMPA,and ERA5 on the daily timescale and IMERG,CPC,TMPA,and ERA5 on the monthly and seasonal timescales.IMERG was generally superior to its predecessor TMPA on the three timescales.ERA5 exhibited large statistical errors.CPC provided stable estimated values.For extreme precipitation estimation,the quality of IMERG was relatively consistent with that of TMPA in terms of precipitation distribution and extreme metrics,and IMERG exhibited a significant advantage in estimating moderate and heavy precipitation.In contrast,ERA5 and CPC exhibited poor performance with large systematic underestimation biases.The findings of this study provide insight into the performance of the latest IMERG product compared with the widely used TMPA,ERA5,and CPC datasets,and points to possible directions for improvement of multi-source precipitation data fusion algorithms in order to better serve hydrological applications.
文摘Information about extreme rainfall is lacking in regions of South America and Africa.This study attempts to fill this scientific gap by use of a gridded parameterization for the stochastic weather generator,CLIGEN,to map depth-duration-frequency(DDF)relationships.Analysis of 500-year point-scale precipitation time series generated at each grid point allowed maps of return period precipitation to be produced for a se-lection of sixteen durations ranging from 10-min to 1-year and for nine return periods from 2 to 500 years.The generalized extreme value(GEV)probability distribution was fitted for all durations,and given GEV quantiles,an interpolation method was applied to produce maps at 0.1° resolution that better resolve small-scale spatial climate gradients.In addition to uncertainties related to GEV fitting,this study quantifies prediction intervals based on ground validation.This validation was important for identifying biases in CLIGEN,although uncertainties were not always satisfactorily defined due to sampling design and other factors.For daily/multi-day durations,100 stations with daily observations and ≥50-year records were selected for validation against the 0.1° CLIGEN map series,resulting in a median and average absolute error of 13%and 16%,respectively.For sub-daily durations,prediction errors were larger overall.An analogy using available U.S.data established the degree of bias in CUGEN for sub-daily durations,and three records in Brazil with high temporal resolutions were used to confirm that applied bias adjustments resulted in error ranges similar to the daily/multi-day cases.This atlas is freely available for study of extreme precipitation.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program (2019QZKK1001)the Strategic Priority Research Program ofthe Chinese Academy of Sciences (XDA20000000).
文摘The utility of statistically downscaled data is in its provision of detailed,high-resolution insights,surpassing global models,which is essential for precise assessments of climate impact.This study delves into the changes in extreme precipitation across the Tibetan Plateau(TP)and its five subregions,thereby deepening our understanding of climate impacts in the region.Employing NASA Earth Exchange Global Daily Downscaled Climate Projections(NEX-GDDP-CMIP6),which are bias-corrected and statistically downscaled,in conjunction with three gauge-based datasets(CN05.1,CMFD,GMFD)spanning from 1979 to 2014,this study conducts an extensive analysis using eight extreme precipitation indices in the TP.The findings reveal significant spatial disparities in extreme precipitation,with the southern subregion experiencing a sig-nificant increase while the two northern subregions show statistically insignificant changes.NEX-GDDP-CMIP6 performs best in the eastern subregion but fails to capture extreme precipitation characteristics in the southern and western subregions.Averaging over the whole period of 1979-2014(climatology),the NEX-GDDP-CMIP6 dataset performs better on the intensity and persistence indices than on the absolute and relative threshold indices.NEX-GDDP-CMIP6's performance on climate trends is significantly below that of climatology.The NEX-GDDP-CMIP6 dataset has limitations over the TP because of its reliance on the underperforming GMFD reference data.This study provides a comprehensive understanding of the variability of extreme precipitation and disparities among different subregions of the TP,laying a robust scientific groundwork for climate impact studies and future projection in this region.
基金supported by the National Natural Science Foundation of China(42275038)China Meteorological Administration Climate Change Special Program(QBZ202306)。
文摘Globally,2023 was the warmest observed year on record since at least 1850 and,according to proxy evidence,possibly of the past 100000 years.As in recent years,the record warmth has again been accompanied with yet more extreme weather and climate events throughout the world.Here,we provide an overview of those of 2023,with details and key background causes to help build upon our understanding of the roles of internal climate variability and anthropogenic climate change.We also highlight emerging features associated with some of these extreme events.Hot extremes are occurring earlier in the year,and increasingly simultaneously in differing parts of the world(e.g.,the concurrent hot extremes in the Northern Hemisphere in July 2023).Intense cyclones are exacerbating precipitation extremes(e.g.,the North China flooding in July and the Libya flooding in September).Droughts in some regions(e.g.,California and the Horn of Africa)have transitioned into flood conditions.Climate extremes also show increasing interactions with ecosystems via wildfires(e.g.,those in Hawaii in August and in Canada from spring to autumn 2023)and sandstorms(e.g.,those in Mongolia in April 2023).Finally,we also consider the challenges to research that these emerging characteristics present for the strategy and practice of adaptation.
文摘This study comprehensively examines the patterns and regional variation of severe rainfall across the African continent, employing a suite of eight extreme precipitation indices. The analysis extends to the assessment of projected changes in precipitation extremes using five General Circulation Models (GCMs) from Coupled Model Intercomparison Project Phase 6 (CMIP6) under four Shared Socioeconomic Pathways (SSPs) scenarios at the long-term period (2081-2100) of the 21<sup>st</sup> century. Furthermore, the study investigates potential mechanisms influencing precipitation extremes by correlating extreme precipitation indices with oceanic system indices, specifically Ni?o 3.4 for El Ni?o-Southern Oscillation (ENSO) and Dipole Mode Index (DMI) for the Indian Ocean Dipole (IOD). The findings revealed distinct spatial distributions in mean trends of extreme precipitation indices, indicating a tendency toward decreased extreme precipitation in North Africa, Sahel region, Central Africa and the Western part of South Africa. Conversely, West Africa, East Africa and the Eastern part of South Africa exhibit an inclination toward increased extreme precipitation. The changes in precipitation extreme indices indicate a general rise in both the severity and occurrence of extreme precipitation events under all scenarios by the end of the 21<sup>st</sup> century. Notably, our analysis projects a decrease in consecutive wet days (CWD) in the far-future. Additionally, correlation analysis highlights significant correlation between above or below threshold rainfall fluctuation in East Africa and South Africa with oceanic systems, particularly ENSO and the IOD. Central Africa abnormal precipitation variability is also linked to ENSO with a significant negative correlation. These insights contribute valuable information for understanding and projecting the dynamics of precipitation extreme in Africa, providing a foundation for climate adaptation and mitigation efforts in the region.
基金supported by the State Programs of Science and Technology Development(Grant No.2012BAC22B04)the National Natural Science Foundation of China(Grant No.41475078)+1 种基金the National Department Public Benefit Research Foundation of China(Grant No.GYHY201206013)the Science and Technology program of the Institute of Urban Meteorology(Grant No.IUMKY201302PP0102)
文摘Daily precipitation series at 15 stations in the Beijing metropolitan region(BMR) during 1960–2012 were homogenized using the multiple analysis of series for homogenization method,with additional adjustments based on analysis of empirical cumulative density function(ECDF) regarding climate extremes.The cumulative density functions of daily precipitation series,the trends of annual and seasonal precipitation,and summer extreme events during 1960–2012 in the original and final adjusted series at Beijing station were comparatively analyzed to show the necessity and efficiency of the new method.Results indicate that the ECDF adjustments can improve the homogeneity of high-order moments of daily series and the estimation of climate trends in extremes.The linear trends of the regional-mean annual and seasonal(spring,summer,autumn,and winter)precipitation series are-10.16,4.97,-20.04,5.02,and-0.11 mm(10 yr)-1,respectively.The trends over the BMR increase consistently for spring/autumn and decrease for the whole year/summer; however,the trends for winter decrease in southern parts and increase in northern parts.Urbanization affects local trends of precipitation amount,frequency,and intensity and their geographical patterns.For the urban-influenced sites,urbanization tends to slow down the magnitude of decrease in the precipitation and extreme amount series by approximately-10.4% and-6.0%,respectively; enhance the magnitude of decrease in precipitation frequency series by approximately 5.7%; reduce that of extremes by approximately-8.9%; and promote the decreasing trends in the summer intensity series of both precipitation and extremes by approximately 6.8% and51.5%,respectively.
基金Supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(CAS)—CAS Big Earth Data Science Engineering Program(XDA19030401)National Key Research and Development Program of China(2016YFA0600303)。
文摘East Africa is so vulnerable to the impacts of precipitation extremes varying from frequent floods to prolonged droughts.However,systematic regional assessment of precipitation extremes across seasons has received little attention,and most previous studies of precipitation extremes have employed many indices and sparse gauge observations giving marginalized details.In this study,we use three precipitation extreme indices to examine the intensity of the highest single-day rainfall record(rx1day),prevalence of very heavy rainfalls(r30mm),and persistence of successive wet days(cwd)at both annual and seasonal scales over recent two decades(1998-2018)based on the Tropical Rainfall Measuring Mission(TRMM)Multisatellite Precipitation Analysis data.The results show that the most intensive and frequent precipitation extremes are noticeable from January to May across the areas extending from Madagascar to the Tanzanian coastal zone.These areas also exhibit patches of significant increasing trends in frequency,duration,and intensity of precipitation extremes annually and seasonally.However,significant declines in frequency and intensity of precipitation extremes are observed from western Ethiopia to Congo-Uganda,especially in June-September.The October-December season witnesses higher interannual variability amounting to overall weak and less significant trends.Further subregional assessment shows overall declining intensity and frequency of precipitation extremes in northern part of the study areas.Mean wetness duration increased,with persistence of moderate wet days and slight reduction of severe events.This study unveils higher susceptibility of the East African region to the widely observed hotspots of precipitation extremes posing threats to food security,water resource,and human well-being.The region should consider upscaling irrigation schemes in addition to planning resilient and supportive infrastructures to withstand the upsurging precipitation extremes,especially along the coastal zone.
文摘Modification signs in extreme weather events may be directly related to alterations in the thermodynamic panorama of the atmosphere that need to be better understood. This study aimed to make a first interconnection between climate extremes and thermodynamic patterns in the city of Rio de Janeiro. Maximum and minimum air temperature and precipitation extreme indices from two surface meteorological stations (ABOV and STCZ) and instability indices based on temperature and humidity from radiosonde observations (SBGL) were employed to investigate changes in the periods 1964-1980 (P1), 1981-2000 (P2), and 2001-2020 (P3). Statistical tests were adopted to determine the significance and magnitude of trends. The frequency of warm (cold) days and warm (cold) nights are increasing (decreasing) in the city. Cold (Warm) extremes are changing with greater magnitude in ABOV (STCZ) than in STCZ (ABOV). In ABOV, there is a significant increase of +84 mm/decade in the rainfall volume associated with severe precipitation (above the 95<sup>th</sup> percentile) and most extreme precipitation indices show an increase in frequency and intensity. In STCZ, there is a decrease in extreme precipitation until the 1990s, and from there, an increase, showing a wetter climate in the most recent years. It is also verified in SBGL that there is a statistically significant increase (decrease) in air temperature of +0.1°C/decade (-0.2°C/decade) and relative humidity of +1.2%/decade (-3%/decade) at the low and middle (high) troposphere. There is a visible rising trend in most of the evaluated instability indices over the last few decades. The increasing trends of some extreme precipitation indices are probably allied to the precipitable water increasing trend of +1.2 mm/decade.
基金Supported by the China Meteorological Administration Special Public Welfare Research Fund Province(GYHY201406024)National Natural Science Foundation of China(41330425)+1 种基金Creative Program of Science&Technology of Jiangsu(KYZZ-0239and CXZZ12_0485)Creative Program of the State Key Laboratory of Severe Weather(2015LASW-A03)
文摘Based on the daily rainfall data from China Meteorological Administration,the tropical cyclone(TC) best track data from Japan Meteorological Agency,and the NCEP-NCAR reanalysis data from NOAA,regional mean daily precipitation extreme(RDPE) events over southeastern China(specifically,the Fujian-Jiangxi region(FJR)) and the associated circulation anomalies are investigated.For the summers of 1979-2011,a total of 105 RDPE events are identified,among which 35 are TC-infiuenced(TCIn-RDPE) and 70 are TCfree events(TCFr-RDPE).Distinct differences between these two types of RDPEs are found in both their statistical features and the related circulation patterns.TCFr-RDPEs usually occur in June,while TCInRDPEs mainly take place during July-August.When TCFr-RDPEs happen,a center of the anomalous cyclonic circulation is observed over the FJR,with an anomalous anticyclonic circulation to the south of this region.The warm/moist air flows from the South China Sea(SCS) and western Pacific meet with colder air from the north,forming a narrow convergent belt of water vapor over the FJR.Simultaneously,positive diabatic forcing anomalies are observed over the FJR,whereas negative anomalies appear over both its south and north sides,facilitating the formation and maintenance of the cyclonic circulation anomaly,as well as the upward motion of the atmosphere,over the FJR.When TCIn-RDPEs occur,southeastern China is dominated by a TC-related stronger anomalous cyclonic circulation.An anomalous anticyclonic circulation in the mid and high latitudes north of the FJR exists in the mid and upper troposphere,opposite to the situation during TCFr-RDPE events.Abundant warm/wet air is carried into the FJR from both the Indian Ocean and the SCS,leading to a large amount of latent heat release over the FJR and inducing strong ascending motion there.Furthermore,large differences are also found in the manifestation of Rossby wave energy propagation between these two types of RDPE events.The results of this study are helpful to deepen our understanding of the mechanisms behind these two types of RDPE events.
基金Supported by the National Natural Science Foundation of China(41330425)China Meteorological Administration Special Public Welfare Research Fund(GYHY201406024)
文摘The variations of regional mean daily precipitation extreme (RMDPE) events in central China and associated circulation anomalies during June, July, and August (JJA) of 1961-2010 are investigated by using daily in-situ precipitation observations and the NCEP/NCAR reanalysis data. The precipitation data were collected at 239 state-level stations distributed throughout the provinces of Henan, Hubei, and Hunan. During 1961-2010, the 99th percentile threshold for RMDPE is 23.585 mm day-1. The number of RMDPE events varies on both interannual and interdecadal timescales, and increases significantly after the mid 1980s. The RMDPE events happen most frequently between late June and mid July, and are generally associated with anomalous baroclinic tropospheric circulations. The supply of moisture to the southern part of central China comes in a stepping way from the outer-region of an abnormal anticyclone over the Bay of Bengal and the South China Sea. Fluxes of wave activity generated over the northeastern Tibetan Plateau converge over central China, which favors the genesis and maintenance of wave disturbances over the region. RMDPE events typically occur in tandem with a strong heating gradient formed by net heating in central China and the large-scale net cooling in the surrounding area. The occurrence of RMDPE events over central China is tied to anomalous local cyclonic circulations, topographic forcing over the northeast Tibetan Plateau, and anomalous gradients of diabatic heating between central China and the surrounding areas.
基金the National Key Research and Development Program of China(2017YFA0603701)National Natural Science Foundation of China(41671211 and 41907398)。
文摘The floods caused by the extreme precipitation in the Yangtze River basin(YRB)and Murray–Darling River basin(MDRB),the largest basins in China and Australia,have significant impacts on the society and regional economies.Based on the spatial–temporal analysis of the daily precipitation extremes(DPEs)during 1982–2016,we found that for both basins,the whole-basin-type DPEs have the highest proportion and a synchronous DPE interannual variation characteristic exists in the two basins,with the 3-yr running correlation coefficient of the annual DPE days(DPEDs)reaching almost 0.7(significant at the 0.01 level).The El Ni?o–Southern Oscillation(ENSO),which is one of the most significant climate disturbance factors in the world,plays an important role in modulating the variability of the DPEs in the two basins.Singular value decomposition(SVD)analysis revealed that both the YRB and the MDRB’s whole-basin-type DPEs are closely coupled with the procedure that the preceding winter eastern Pacific(EP)-type El Ni?o faded to a central Pacific(CP)-type La Nina.This means that the DPEs in the YRB and MDRB may synchronously occur more frequently when the above process occurs.Owing to the atmosphere–ocean interaction from the east–west dipole sea surface temperature(SST)anomaly pattern,the atmospheric circulation disturbance exhibits a pattern in which the equatorial eastern Pacific region is a mass source anomaly with a higher pressure,drier air,and weaker convection,while the equatorial western Pacific region is a mass sink anomaly with a lower pressure,wetter air,and stronger convection.Moreover,two wave trains that originated from the tropical western Pacific were found to extend to the YRB and MDRB.The interaction between the wave train’s interphase dynamics and water vapor transport disturbance results in the ascent conditions and enhanced water vapor transport,which leads to the synchronous occurrence of DPEs in the YRB and MDRB on an interannual scale.
基金supported by the Science and Technology Incubator Youth Program,managed by the Center for Science and Technology Development,Ho Chi Minh Communist Youth Union(Contract Number 17/2018/HD-KHCN-VƯ)partly funded by Ho Chi Minh City’s Department of Science and Technology(HCMC-DOST)Institute for Computational Science and Technology(ICST)(Grant Number 05/2019/HD-KHCNTT)
文摘In this study,the spatiotemporal variability of trends in extreme precipitation events in Ho Chi Minh City during the period 1980–2017 was analyzed based on several core extreme precipitation indices(Rx1 day,Rx5 day,CDD,CWD,R20 mm,R25 mm,R95 p,and SDII).The nonparametric Mann–Kendall and Sen’s slope methods were used to compute the statistical strength,stability,and magnitude of trends in annual rainfall,as well as the extreme precipitation indices.We found that 64%of the stations had statistically significant upward trends in yearly rainfall,with high magnitudes frequently observed in the northern and southern regions of the city.For the extreme precipitation indices,only SDII and R25 mm showed dominantly significant trends.Additionally,there were increasing trends in the frequency and duration at the southern and central regions of the city during the study period.Furthermore,El Ni?o-Southern Oscillation and Pacific Decadal Oscillation positively correlated with the duration and negatively correlated with the intensity and frequency of extreme precipitation.Thus,water management plans should be adjusted appropriately to reduce the severe impacts of precipitation extremes on communities and ecosystems.