The spatiotemporal variations of the site and regional droughts in China during 1960–2009 were analyzed by applying a daily composite-drought index （CDI） to 722 stations in China's Mainland. Droughts frequently...The spatiotemporal variations of the site and regional droughts in China during 1960–2009 were analyzed by applying a daily composite-drought index （CDI） to 722 stations in China's Mainland. Droughts frequently happened in a zone extended from Southwest China to the Yellow River, North China, and the southwestern part of Northeast China, with two centers of high frequency in North China and Southwest China. In Southwest and South China, droughts tend to happen during the winter. In North China and along the Yellow River, droughts mainly occur during the winter and during May–June. During the past 50 years, the geographical distribution of site drought events showed high frequencies （0.9–1.3 times per year） in the upper Yellow River basin and North China, comparing with moderate frequencies （0.6–0.9 times per year） in Southwest China and the southwestern part of Northeast China and with lower frequencies over the middle and lower Yangtze River basin. And the frequencies increased over China's Mainland except for the upper reaches of the Yangtze River. A regional drought （RD） event is a widespread and persistent event that covers at least five adjacent sites and lasts for at least 10 days. There were 252 RD events in the past 50 years—five times per year. Most RD events lasted for 100 days and covered 100 stations, but the longest and largest RD event lasted for 307 days from 6 September 1998 to 9 July 1999 and covered 327 stations from North to Southwest China.展开更多
Variation characteristics of persistent drought events in Guangdong province are analyzed using 45-year(1961-2005) and 86-station observational precipitation data of Guangdong,and the causes of drought events are disc...Variation characteristics of persistent drought events in Guangdong province are analyzed using 45-year(1961-2005) and 86-station observational precipitation data of Guangdong,and the causes of drought events are discussed from different angles(e.g.,atmospheric circulation,sea surface temperature) on the basis of global coverage datasets of sea surface temperature and atmospheric elements.It is found that the occurrence frequency of persistent drought events in Guangdong province is once every 26 months on average,and autumn-winter or winter-spring persistent drought events take up the majority.The persistent drought events possess large scale spatial characteristics.While the 1960s is the most frequent and strongest decade of drought events in the latter half of the 20th century,the occurrence is more frequent and the intensity is stronger in the first five years of the 21st century(2001-2005).This reflects the response of regional extreme climatic events in Guangdong to global climatic change.The atmospheric circulation,sea surface temperature,etc,appear to have different abnormal characteristics when drought events happen in different seasons.The results of this paper provide some good reference information for the drought forecast,especially for the dynamic interpretation of climatic model products.展开更多
Under the influence of global warming,the increasing intensity of compound hot drought events(CHDEs)presents a substantial threat to human society.However,the interdecadal variability and driving factors of CHDEs in N...Under the influence of global warming,the increasing intensity of compound hot drought events(CHDEs)presents a substantial threat to human society.However,the interdecadal variability and driving factors of CHDEs in Northern East Asia(NEA)remain insufficiently understood.Employing the multivariate copula method to characterize CHDEs,this study investigates the characteristics and mechanisms in this region during July.Our findings reveal two notable interdecadal shifts in the intensity and frequency of CHDEs during 1940-2022,occurring in the mid-1950s and the mid-1990s.These shifts correspond to periods of interdecadal weakening and intensification of CHDEs,respectively.The primary driver of this interdecadal variability has been identified as the Atlantic Multidecadal Oscillation(AMO).During the positive phase of the AMO,anomalously warm sea surface temperatures(SSTs)in the Atlantic Ocean influence wave trains that propagate along great circle routes,subsequently altering regional atmospheric circulation patterns in NEA.Concurrently,the upper-level subtropical westerly jet experiences a northward shift and intensification.These conditions foster the development of anomalously high pressure and downward vertical motion,leading to reduced precipitation and elevated temperatures,which in turn increase the intensity and frequency of CHDEs in NEA during this period.The Atlantic pacemaker simulations further corroborate these findings,highlighting the significant role of the AMO phase in driving interdecadal variations of CHDEs.This research provides essential insights for future interdecadal predictions of CHDEs in NEA,thereby contributing to the broader understanding of climate variability and its implications for societal resilience.展开更多
In the Mei-yu region,there has been noticeable increase in the occurrence of compound hot drought(CHD)events in recent years.However,the underlying causes of these occurrences remain poorly understood.To address this ...In the Mei-yu region,there has been noticeable increase in the occurrence of compound hot drought(CHD)events in recent years.However,the underlying causes of these occurrences remain poorly understood.To address this knowledge gap,we conducted a comprehensive study utilizing observational datasets,reanalysis datasets,and four numerical experiments to investigate the associated physical mechanisms.Our findings indicated that the prevalence of CHD events in the Mei-yu region is influenced strongly by two key factors:the decline in Barents Sea ice during February and the presence of a La Ni?alike pattern of sea surface temperature(SST)in April.The decline in Barents Sea ice generates an anomalous Rossby wave in the Arctic that propagates southeastward.The La Ni?a-like SST pattern regulates a Rossby wave over western America,propagating along the subtropical jet stream.These two Rossby waves induce northward movement and strengthened intensity of the subtropical westerly jet in East Asia.The local circulation patterns in the Mei-yu region are influenced by the position and intensity of the subtropical jet,leading to downward motion in accordance with the secondary circulation theory for high-altitude jet streams.Consequently,these local circulation patterns might contribute to occurrence of CHD events.Moreover,our analysis revealed that the impact of Barents Sea ice and the La Nina-like SST pattern can explain approximately two-thirds of the mild CHD events in the Mei-yu region,and that the influence of each is relatively independent.This research underscores influences of polartropical systems on climate extremes in eastern Asia.展开更多
An objective identifi cation technique for regional extreme events （OITREE） and the daily composite-drought index （CI） at 101 stations in Southwest China （including Sichuan, Yunnan, Guizhou, and Chongqing） are u...An objective identifi cation technique for regional extreme events （OITREE） and the daily composite-drought index （CI） at 101 stations in Southwest China （including Sichuan, Yunnan, Guizhou, and Chongqing） are used to detect regional meteorological drought events between 1960 and 2010. Values of the parameters of the OITREE method are determined. A total of 87 drought events are identifi ed, including 9 extreme events. The 2009-2010 drought is the most serious in Southwest China during the past 50 years. The regional meteorological drought events during 1960-2010 generally last for 10-80 days, with the longest being 231 days. Droughts are more common from November to next April, and less common in the remaining months. Droughts occur more often and with greater intensity in Yunnan and southern Sichuan than in other parts of Southwest China. Strong （extreme and severe） regional meteorological drought events can be divided into fi ve types. The southern type has occurred most frequently, and Yunnan is the area most frequently stricken by extreme and severe drought events. The regional meteorological drought events in Southwest China have increased in both frequency and intensity over the study period, and the main reason appears to be a signifi cant decrease in precipitation over this region, but a simultaneous increase in temperature also contributes.展开更多
Based on the Multi-Scale Standardized Precipitation Index （MSPI）, extreme severe drought events in China during 1961-2010 were identified, and the seasonal, annual, and interdecadal variations of the cluster- ing ex...Based on the Multi-Scale Standardized Precipitation Index （MSPI）, extreme severe drought events in China during 1961-2010 were identified, and the seasonal, annual, and interdecadal variations of the cluster- ing extreme drought events were investigated by using the spatial point process theory. It is found that severe droughts present a trend of gradual increase as a result of the significant increase and clustering tendency of severe droughts in autumn. The periodicity analysis of the clustering extreme droughts in different seasons suggests that there is a remarkable interdecadal change in the occurrence of clustering extreme droughts in winter. Meanwhile, it is revealed that the clustering extreme drought events exhibit greatly different annual mean spatial distributions during 1961 2010, with scattered and concentrated clustering zones alternating on the decadal timescale. Furthermore, it is found that the decadal-mean spatial distributions of extreme drought events in summer are correlated out of phase with those of the rainy bands over China in the past 50 years, and a good decadal persistence exists between the autumn and winter extreme droughts, implying a salient feature of consecutive autunm-winter droughts in this 50-yr period. Compared with other regions of China, Southwest China bears the most prominent characteristic of clustering extreme droughts.展开更多
For the area of Eurasia concentrated with developing countries(referred to here by the abbreviation DPEA),mainly located in Asia and Eastern Europe,this work presents datasets of gridded meteorological drought events ...For the area of Eurasia concentrated with developing countries(referred to here by the abbreviation DPEA),mainly located in Asia and Eastern Europe,this work presents datasets of gridded meteorological drought events and country-based drought risk by combining multiple drought indices and socio-economic data.A basic gridded dataset of the drought events during 1950-2015 is extracted from three drought indices:the self-calibrating Palmer Drought Severity Index,the Standardized Precipitation Index,and the Standardized Precipitation Evapotranspiration Index.The three drought indices generally show consistent characteristics of drought events in DPEA.A second-level dataset(a drought risk dataset)is then produced as the product of drought hazard,exposure and vulnerability during 2000-2015.For drought exposure,the indicators of population and livestock density,agricultural land and water stress are chosen,while drought vulnerability composites multiple social,economic and infrastructural factors.Drought hazard tends to concentrate at the southern rim of Eurasia.Relatively large differences in drought exposure exist between different countries,but for drought vulnerability the differences are small.After considering the socio-economic components in risk assessment,most countries in West,South-Central and South Asia have the highest drought risk in DPEA.The datasets of drought events and risks are available at http://www.dx.doi.org/10.11922/sciencedb.898.展开更多
Background Recent changes in climatic trends are resulting in an increased frequency and intensity of extreme events,with unknown effect on ecosystem dynamics in the near future.Extreme drought episodes are recognized...Background Recent changes in climatic trends are resulting in an increased frequency and intensity of extreme events,with unknown effect on ecosystem dynamics in the near future.Extreme drought episodes are recognized as disturbance factors capable of modifying forest dynamics and tree growth.Within this context,dioecious tree species may be impacted by climatic extremes,affecting male/female proportions and,consequently,reproductive processes and species persistence.Therefore,there is an urgent need for species-specific assessments of growth tolerance to extreme dry spells in dioecious tree species,to establish effective conservation strategies for these particular natural resources.Araucaria araucana(araucaria),an endangered dioecious Patagonian tree species,has recently undergone decay and mortality episodes in response to increasing dry climatic conditions.While sex-dependent tolerance to extreme drought episodes has been assessed in the species'humid distribution range,there is still a lack of information on the gender-based resilience of trees growing in the drier environments of the species'distribution.Methods We reconstructed,through dendrochronological methods,the sex-dependent response of 105 araucaria individuals(55 female and 50 male trees)to five regional extreme dry spells employing a set of different indices.Resistance,recovery period,and average growth reduction of standardized tree-ring growth were examined,analysing the effect of biotic(sex,pre-drought stem tree growth)and abiotic(local climatic conditions before,during,and after extreme climatic episodes)factors on tree resilience.Results Sex influences only the species resistance to climatic disturbance,with male individuals showing lower tolerance to extreme drought events.Pre-drought radial growth rates and local meteorological conditions preceding,during,and following extreme dry spells strongly modulated araucaria radial growth resilience regardless of tree sex,influencing the species resistance,recovery period,and average growth reduction.Conclusions We provide novel and crucial information for the species conservation and management in the current climate change scenario,and contribute to the debate regarding the role of tree sex as a factor influencing woody species growth under particularly adverse climatic conditions.In the face of climate change,an increase in extreme drought events is expected in the easternmost araucaria xeric end distribution area,which will likely decrease the species resilience.展开更多
Wheat(Triticum aestivum L.)is a highly valued cereal crop produced and consumed globally,particularly in arid or semi-arid regions(Zhou et al.,2020;Mao et al.,2023).However,its production is increasingly threatened by...Wheat(Triticum aestivum L.)is a highly valued cereal crop produced and consumed globally,particularly in arid or semi-arid regions(Zhou et al.,2020;Mao et al.,2023).However,its production is increasingly threatened by the rising incidence of drought events associated with climate change.Arid regions are especially susceptible to these droughts,which are intensifying in both severity and frequency(Eckardt et al.,2023;Mao et al.,2023;Yang and Qin,2023).As of a 2022 report,more than 92%of wheat-producing regions are estimated to experience one or more drought/heatwave events in each growing season.Furthermore,the duration and frequency of these combined stress events have increased by approximately 28%over the past four decades(He et al.,2022).To address this challenge,wheat breeding programs have allocated substantial and research efforts to developing elite,stress tolerant lines.This initiative is large part by rapid innovation in transgenic and genome editing strategies(Hu and Xiong,2014;Gao et al.,2021.展开更多
Droughts have caused tree growth decline and high tree mortality across temperate forests,however,how to manage planted forests to alleviate drought stress is still challenging.We used tree-ring and forest inventory d...Droughts have caused tree growth decline and high tree mortality across temperate forests,however,how to manage planted forests to alleviate drought stress is still challenging.We used tree-ring and forest inventory data from different density stands to investigate how competition,tree diameter at breast height(DBH),tree age,and their interactions influence drought sensitivity and resistance for three widely-distributed and planted conifer species(Larix principis-rupprechtii,Picea meyeri,and Pinus sylvestris var.mongolica).Our results showed that the drought sensitivity of the three species was influenced by competition,tree size,and their interactions.Large L.principis-rupprechtii trees were particularly sensitive to drought during the growing season in medium to high-density stands,while the growth of large P.sylvestris var.mongolica was most affected by precipitation at low to medium density stands.Drought resistance of L.principis-rupprechtii trees decreased as tree size increased.Large L.principis-rupprechtii trees had lower drought resistance than small trees in all stands.Drought resistance of large P.meyeri trees exhibited high resistance to drought only in high-density stands.However,drought resistance of P.sylvestris var.mongolica trees was affected by tree size,competition,and their interactions.These results indicated that targeted silvicultural interventions,such as thinning,can be implemented to enhance drought resistance specifically for large L.principis-rupprechtii trees and small P.sylvestris var.mongolica trees in medium and high competition stands,and small P.meyeri trees in high competition stands.Our results highlight that properly conducted thinning can in some cases enhance growth resistance to droughts,depending on stand density,tree size,and tree species.展开更多
The most famous deserts exist in subtropical regions which is the direct outcome of insufficient precipitation and high temperatures. The Middle East deserts are subjected often to dust, which reduces horizontal visib...The most famous deserts exist in subtropical regions which is the direct outcome of insufficient precipitation and high temperatures. The Middle East deserts are subjected often to dust, which reduces horizontal visibility to 5 km, and sometimes even to less than 100 m. The severe and prolong drought recently afflicting the west Asia region has been suggested to be instrumental in producing an increased output of dust into the atmosphere from the region. Regarding the increasing of dust events over the west of Iran with the external origin in the recent decade (from 2000 to present), so the main dust-source areas over Iraq and Syria have been detected using the dust-source map of the southwest of Asia, satellite images and soil type maps. We considered the relationship between the increasing of dust events in the western of Iran and drought expansion over the main dust-production areas during the recent decade. Dust frequency data series, and drought variables which include the VHI (vegetation health index), precipitation and temperature data series in long-term and monthly scales have been monitored and compared. And then we used the correlation analysis that indicated the significant proximity between the dust events and droughts/dryness in a yearly scale and also during the warm season (May to Aug). Meantime the derived results from the T-student test for the aforementioned data series confirm the fact that the droughts are parallel to the increasing of dust events from 1996 to 2011 (especially in the recent decade). We found that the recent droughts in the external dust source areas had the remarkable potential to increase the dust events in the west of Iran.展开更多
Ecological stability is a core issue in ecological research and holds significant implications forhumanity. The increased frequency and intensity of drought and wet climate events resulting from climatechange pose a m...Ecological stability is a core issue in ecological research and holds significant implications forhumanity. The increased frequency and intensity of drought and wet climate events resulting from climatechange pose a major threat to global ecological stability. Variations in stability among different ecosystemshave been confirmed, but it remains unclear whether there are differences in stability within the sameterrestrial vegetation ecosystem under the influence of climate events in different directions and intensities.China's grassland ecosystem includes most grassland types and is a good choice for studying this issue.This study used the Standardized Precipitation Evapotranspiration Index-12 (SPEI-12) to identify thedirections and intensities of different types of climate events, and based on Normalized DifferenceVegetation Index (NDVI), calculated the resistance and resilience of different grassland types for 30consecutive years from 1990 to 2019 (resistance and resilience are important indicators to measurestability). Based on a traditional regression model, standardized methods were integrated to analyze theimpacts of the intensity and duration of drought and wet events on vegetation stability. The resultsshowed that meadow steppe exhibited the highest stability, while alpine steppe and desert steppe had thelowest overall stability. The stability of typical steppe, alpine meadow, temperate meadow was at anintermediate level. Regarding the impact of the duration and intensity of climate events on vegetationecosystem stability for the same grassland type, the resilience of desert steppe during drought was mainlyaffected by the duration. In contrast, the impact of intensity was not significant. However, alpine steppewas mainly affected by intensity in wet environments, and duration had no significant impact. Ourconclusions can provide decision support for the future grassland ecosystem governance.展开更多
Increases in the frequency of extreme weather and climate events and the severity of their impacts on the natural environment and society have been observed across the globe in recent decades. In addition to natural c...Increases in the frequency of extreme weather and climate events and the severity of their impacts on the natural environment and society have been observed across the globe in recent decades. In addition to natural climate variability and greenhouse-induced climate change, extreme weather and climate events produce the most pronounced impacts. In this paper, the climate of three island countries in the Western Pacific: Fiji, Samoa and Tuvalu, has been analysed. Warming trends in annual average maximum and minimum temperatures since the 1950s have been identified, in line with the global warming trend. We present recent examples of extreme weather and climate events and their impacts on the island countries in the Western Pacific: the 2011 drought in Tuvalu, the 2012 floods in Fiji and a tropical cyclone, Evan, which devastated Samoa and Fiji in December 2012. We also relate occurrences of the extreme weather and climate events to phases of the El Niño-Southern Oscillation (ENSO) phenomenon. The impacts of such natural disasters on the countries are severe and the costs of damage are astronomical. In some cases, climate extremes affect countries to such an extent that governments declare a national state of emergency, as occurred in Tuvalu in 2011 due to the severe drought’s impact on water resources. The projected increase in the frequency of weather and climate extremes is one of the expected consequences of the observed increase in anthropogenic greenhouse gas concentration and will likely have even stronger negative impacts on the natural environment and society in the future. This should be taken into consideration by authorities of Pacific Island Countries and aid donors when developing strategies to adapt to the increasing risk of climate extremes. Here we demonstrate that the modern science of seasonal climate prediction is well developed, with current dynamical climate models being able to provide skilful predictions of regional rainfall two-three months in advance. The dynamic climate model-based forecast products are now disseminated to the National Meteorological Services of 15 island countries in the Western Pacific through a range of web-based information tools. We conclude with confidence that seasonal climate prediction is an effective solution at the regional level to provide governments and local communities of island nations in the Western Pacific with valuable assistance for informed decision making for adaptation to climate variability and change.展开更多
In the summer of 2024, following a strong El Ni?o event in the preceding winter, the tropical Indian Ocean and tropical North Atlantic recorded their highest SSTs since 1961, along with a significant westward shift an...In the summer of 2024, following a strong El Ni?o event in the preceding winter, the tropical Indian Ocean and tropical North Atlantic recorded their highest SSTs since 1961, along with a significant westward shift and intensification of the western Pacific subtropical high(WPSH). Under these conditions, China experienced its hottest summer since 1961,and was hit by a series of high-impact extreme weather and climate events. From 9 June to 2 July, southern China experienced an unprecedented extreme precipitation event that exceeded the well-known 1998 summer precipitation event in both duration and impact scope, resulting in devastating floods in the Yangtze River basin. Subsequently, in early to midJuly, the Huanghe-Huaihe Basin suffered from a severe drought–flood abrupt alternation event, heavily affecting Henan and Shandong. Meanwhile, southern China underwent a widespread heatwave event lasting 74 days, ranking as the second most intense since 1961. From late July to the end of August, northern China faced unusually frequent heavy precipitation events, with cumulative precipitation reaching the second highest for the same period since 1961, causing floods in many rivers of northern China. This study provides a timely summary and assessment of the characteristics and impacts of these extreme events. It serves as a reference for climate change research, including mechanism analysis, numerical simulation,and climate event attribution, and also offers valuable insights for improving meteorological disaster prevention and mitigation strategies.展开更多
随着全球变暖,复合型气候事件的发生特征逐渐成为近年来研究的热点。本研究采用第五代欧洲中期天气预报中心(The European Centre for Medium-Range Weather Forecasts,ECMWF)全球气候大气再分析(ECMWF Reanalysis v5,ERA5)数据中包含...随着全球变暖,复合型气候事件的发生特征逐渐成为近年来研究的热点。本研究采用第五代欧洲中期天气预报中心(The European Centre for Medium-Range Weather Forecasts,ECMWF)全球气候大气再分析(ECMWF Reanalysis v5,ERA5)数据中包含的日最高温和日降水数据分析了中国1982—2022年复合干热和湿热事件的发生特征,并引入了震级指数衡量复合事件的强度,结果显示复合事件的持续时间、频次和震级均显示不同程度的增长,其中复合湿热事件(CHTRE)的增长幅度均高于复合干热事件(CHTDE);极端型复合干热和湿热事件上升趋势最为明显(分别为0.24%和0.11%),高温主导了复合事件的变化趋势;6—8月是中国复合干热/复合湿热事件发生的主要月份,其中极端型复合事件多集中在7月。由于极端事件可能会随着全球持续变暖而增加,因此了解复合事件的发生特征对于增强中国抵御气候变化影响的能力至关重要。展开更多
基金supported jointly bythe National Natural Science Foundation of China (GrantNo. 40975039)the Key Technologies R&D Program(Grant No. 2009BAC51B04)+1 种基金the Chinese COPES Project (Grant No. GYHY201006018)The CDI data was provided by the Key Technologies R&D Program (GrantNo. 2007BAC29B06).
文摘The spatiotemporal variations of the site and regional droughts in China during 1960–2009 were analyzed by applying a daily composite-drought index （CDI） to 722 stations in China's Mainland. Droughts frequently happened in a zone extended from Southwest China to the Yellow River, North China, and the southwestern part of Northeast China, with two centers of high frequency in North China and Southwest China. In Southwest and South China, droughts tend to happen during the winter. In North China and along the Yellow River, droughts mainly occur during the winter and during May–June. During the past 50 years, the geographical distribution of site drought events showed high frequencies （0.9–1.3 times per year） in the upper Yellow River basin and North China, comparing with moderate frequencies （0.6–0.9 times per year） in Southwest China and the southwestern part of Northeast China and with lower frequencies over the middle and lower Yangtze River basin. And the frequencies increased over China's Mainland except for the upper reaches of the Yangtze River. A regional drought （RD） event is a widespread and persistent event that covers at least five adjacent sites and lasts for at least 10 days. There were 252 RD events in the past 50 years—five times per year. Most RD events lasted for 100 days and covered 100 stations, but the longest and largest RD event lasted for 307 days from 6 September 1998 to 9 July 1999 and covered 327 stations from North to Southwest China.
基金Project of Science Planning of Guangdong Province (2005B32601007)Natural Science Foundation of China (41075073,40675055)
文摘Variation characteristics of persistent drought events in Guangdong province are analyzed using 45-year(1961-2005) and 86-station observational precipitation data of Guangdong,and the causes of drought events are discussed from different angles(e.g.,atmospheric circulation,sea surface temperature) on the basis of global coverage datasets of sea surface temperature and atmospheric elements.It is found that the occurrence frequency of persistent drought events in Guangdong province is once every 26 months on average,and autumn-winter or winter-spring persistent drought events take up the majority.The persistent drought events possess large scale spatial characteristics.While the 1960s is the most frequent and strongest decade of drought events in the latter half of the 20th century,the occurrence is more frequent and the intensity is stronger in the first five years of the 21st century(2001-2005).This reflects the response of regional extreme climatic events in Guangdong to global climatic change.The atmospheric circulation,sea surface temperature,etc,appear to have different abnormal characteristics when drought events happen in different seasons.The results of this paper provide some good reference information for the drought forecast,especially for the dynamic interpretation of climatic model products.
基金supported by the National Natural Science Foundation of China(Grant No.42088101)supported by the Research Council of Norway funded project(MAPARC,Grant No.328943)。
文摘Under the influence of global warming,the increasing intensity of compound hot drought events(CHDEs)presents a substantial threat to human society.However,the interdecadal variability and driving factors of CHDEs in Northern East Asia(NEA)remain insufficiently understood.Employing the multivariate copula method to characterize CHDEs,this study investigates the characteristics and mechanisms in this region during July.Our findings reveal two notable interdecadal shifts in the intensity and frequency of CHDEs during 1940-2022,occurring in the mid-1950s and the mid-1990s.These shifts correspond to periods of interdecadal weakening and intensification of CHDEs,respectively.The primary driver of this interdecadal variability has been identified as the Atlantic Multidecadal Oscillation(AMO).During the positive phase of the AMO,anomalously warm sea surface temperatures(SSTs)in the Atlantic Ocean influence wave trains that propagate along great circle routes,subsequently altering regional atmospheric circulation patterns in NEA.Concurrently,the upper-level subtropical westerly jet experiences a northward shift and intensification.These conditions foster the development of anomalously high pressure and downward vertical motion,leading to reduced precipitation and elevated temperatures,which in turn increase the intensity and frequency of CHDEs in NEA during this period.The Atlantic pacemaker simulations further corroborate these findings,highlighting the significant role of the AMO phase in driving interdecadal variations of CHDEs.This research provides essential insights for future interdecadal predictions of CHDEs in NEA,thereby contributing to the broader understanding of climate variability and its implications for societal resilience.
基金supported by the National Natural Science Foundation of China(42088101)the National Key Research and Development Program of China(2022YFF0801704)the Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(316323005)。
文摘In the Mei-yu region,there has been noticeable increase in the occurrence of compound hot drought(CHD)events in recent years.However,the underlying causes of these occurrences remain poorly understood.To address this knowledge gap,we conducted a comprehensive study utilizing observational datasets,reanalysis datasets,and four numerical experiments to investigate the associated physical mechanisms.Our findings indicated that the prevalence of CHD events in the Mei-yu region is influenced strongly by two key factors:the decline in Barents Sea ice during February and the presence of a La Ni?alike pattern of sea surface temperature(SST)in April.The decline in Barents Sea ice generates an anomalous Rossby wave in the Arctic that propagates southeastward.The La Ni?a-like SST pattern regulates a Rossby wave over western America,propagating along the subtropical jet stream.These two Rossby waves induce northward movement and strengthened intensity of the subtropical westerly jet in East Asia.The local circulation patterns in the Mei-yu region are influenced by the position and intensity of the subtropical jet,leading to downward motion in accordance with the secondary circulation theory for high-altitude jet streams.Consequently,these local circulation patterns might contribute to occurrence of CHD events.Moreover,our analysis revealed that the impact of Barents Sea ice and the La Nina-like SST pattern can explain approximately two-thirds of the mild CHD events in the Mei-yu region,and that the influence of each is relatively independent.This research underscores influences of polartropical systems on climate extremes in eastern Asia.
基金Supported by the National Natural Science Foundation of China(41175075)Climate Change Special Fund of the China Meteorological Administration(CCSF201333)
文摘An objective identifi cation technique for regional extreme events （OITREE） and the daily composite-drought index （CI） at 101 stations in Southwest China （including Sichuan, Yunnan, Guizhou, and Chongqing） are used to detect regional meteorological drought events between 1960 and 2010. Values of the parameters of the OITREE method are determined. A total of 87 drought events are identifi ed, including 9 extreme events. The 2009-2010 drought is the most serious in Southwest China during the past 50 years. The regional meteorological drought events during 1960-2010 generally last for 10-80 days, with the longest being 231 days. Droughts are more common from November to next April, and less common in the remaining months. Droughts occur more often and with greater intensity in Yunnan and southern Sichuan than in other parts of Southwest China. Strong （extreme and severe） regional meteorological drought events can be divided into fi ve types. The southern type has occurred most frequently, and Yunnan is the area most frequently stricken by extreme and severe drought events. The regional meteorological drought events in Southwest China have increased in both frequency and intensity over the study period, and the main reason appears to be a signifi cant decrease in precipitation over this region, but a simultaneous increase in temperature also contributes.
基金Supported by the National Natural Science Foundation of China (41005043 and U1133603)National Basic Research and Development (973) Program of China (2012CB955901)
文摘Based on the Multi-Scale Standardized Precipitation Index （MSPI）, extreme severe drought events in China during 1961-2010 were identified, and the seasonal, annual, and interdecadal variations of the cluster- ing extreme drought events were investigated by using the spatial point process theory. It is found that severe droughts present a trend of gradual increase as a result of the significant increase and clustering tendency of severe droughts in autumn. The periodicity analysis of the clustering extreme droughts in different seasons suggests that there is a remarkable interdecadal change in the occurrence of clustering extreme droughts in winter. Meanwhile, it is revealed that the clustering extreme drought events exhibit greatly different annual mean spatial distributions during 1961 2010, with scattered and concentrated clustering zones alternating on the decadal timescale. Furthermore, it is found that the decadal-mean spatial distributions of extreme drought events in summer are correlated out of phase with those of the rainy bands over China in the past 50 years, and a good decadal persistence exists between the autumn and winter extreme droughts, implying a salient feature of consecutive autunm-winter droughts in this 50-yr period. Compared with other regions of China, Southwest China bears the most prominent characteristic of clustering extreme droughts.
基金This research was jointly supported by the Chinese Academy of Sciences Grant XDA19030402,XDA20020201,and 134111KYSB20160010.
文摘For the area of Eurasia concentrated with developing countries(referred to here by the abbreviation DPEA),mainly located in Asia and Eastern Europe,this work presents datasets of gridded meteorological drought events and country-based drought risk by combining multiple drought indices and socio-economic data.A basic gridded dataset of the drought events during 1950-2015 is extracted from three drought indices:the self-calibrating Palmer Drought Severity Index,the Standardized Precipitation Index,and the Standardized Precipitation Evapotranspiration Index.The three drought indices generally show consistent characteristics of drought events in DPEA.A second-level dataset(a drought risk dataset)is then produced as the product of drought hazard,exposure and vulnerability during 2000-2015.For drought exposure,the indicators of population and livestock density,agricultural land and water stress are chosen,while drought vulnerability composites multiple social,economic and infrastructural factors.Drought hazard tends to concentrate at the southern rim of Eurasia.Relatively large differences in drought exposure exist between different countries,but for drought vulnerability the differences are small.After considering the socio-economic components in risk assessment,most countries in West,South-Central and South Asia have the highest drought risk in DPEA.The datasets of drought events and risks are available at http://www.dx.doi.org/10.11922/sciencedb.898.
基金supported by the Agencia Nacional de Promoción Científica y Tecnológica of Argentina(PICT-2018-1056 to MAH)Cooperation International Project between CONICET and NSFC-2019 to MAHCooperation International Project between CONICET and Royal Society-2019 to FAR
文摘Background Recent changes in climatic trends are resulting in an increased frequency and intensity of extreme events,with unknown effect on ecosystem dynamics in the near future.Extreme drought episodes are recognized as disturbance factors capable of modifying forest dynamics and tree growth.Within this context,dioecious tree species may be impacted by climatic extremes,affecting male/female proportions and,consequently,reproductive processes and species persistence.Therefore,there is an urgent need for species-specific assessments of growth tolerance to extreme dry spells in dioecious tree species,to establish effective conservation strategies for these particular natural resources.Araucaria araucana(araucaria),an endangered dioecious Patagonian tree species,has recently undergone decay and mortality episodes in response to increasing dry climatic conditions.While sex-dependent tolerance to extreme drought episodes has been assessed in the species'humid distribution range,there is still a lack of information on the gender-based resilience of trees growing in the drier environments of the species'distribution.Methods We reconstructed,through dendrochronological methods,the sex-dependent response of 105 araucaria individuals(55 female and 50 male trees)to five regional extreme dry spells employing a set of different indices.Resistance,recovery period,and average growth reduction of standardized tree-ring growth were examined,analysing the effect of biotic(sex,pre-drought stem tree growth)and abiotic(local climatic conditions before,during,and after extreme climatic episodes)factors on tree resilience.Results Sex influences only the species resistance to climatic disturbance,with male individuals showing lower tolerance to extreme drought events.Pre-drought radial growth rates and local meteorological conditions preceding,during,and following extreme dry spells strongly modulated araucaria radial growth resilience regardless of tree sex,influencing the species resistance,recovery period,and average growth reduction.Conclusions We provide novel and crucial information for the species conservation and management in the current climate change scenario,and contribute to the debate regarding the role of tree sex as a factor influencing woody species growth under particularly adverse climatic conditions.In the face of climate change,an increase in extreme drought events is expected in the easternmost araucaria xeric end distribution area,which will likely decrease the species resilience.
基金supported by grants from the Major Project on Agricultural Bio-breeding of China(2023ZD04026)National Natural Science Foundation of China(31872866 and 32372124)+2 种基金China Postdoctoral Science Foundation(2022M721101)National Natural Science Foundation of Hunan(2023JJ40132)Natural Science Foundation of Chongqing(CSTB2023NSCQ-MSX0542).
文摘Wheat(Triticum aestivum L.)is a highly valued cereal crop produced and consumed globally,particularly in arid or semi-arid regions(Zhou et al.,2020;Mao et al.,2023).However,its production is increasingly threatened by the rising incidence of drought events associated with climate change.Arid regions are especially susceptible to these droughts,which are intensifying in both severity and frequency(Eckardt et al.,2023;Mao et al.,2023;Yang and Qin,2023).As of a 2022 report,more than 92%of wheat-producing regions are estimated to experience one or more drought/heatwave events in each growing season.Furthermore,the duration and frequency of these combined stress events have increased by approximately 28%over the past four decades(He et al.,2022).To address this challenge,wheat breeding programs have allocated substantial and research efforts to developing elite,stress tolerant lines.This initiative is large part by rapid innovation in transgenic and genome editing strategies(Hu and Xiong,2014;Gao et al.,2021.
基金funded by State Key Research and Development Program of China(No.2023YFD2200401)S&T Program of Hebei(Nos.226Z6801G,22326807D)Talent Introduction Program in Hebei Agricultural University(No.YJ201918).
文摘Droughts have caused tree growth decline and high tree mortality across temperate forests,however,how to manage planted forests to alleviate drought stress is still challenging.We used tree-ring and forest inventory data from different density stands to investigate how competition,tree diameter at breast height(DBH),tree age,and their interactions influence drought sensitivity and resistance for three widely-distributed and planted conifer species(Larix principis-rupprechtii,Picea meyeri,and Pinus sylvestris var.mongolica).Our results showed that the drought sensitivity of the three species was influenced by competition,tree size,and their interactions.Large L.principis-rupprechtii trees were particularly sensitive to drought during the growing season in medium to high-density stands,while the growth of large P.sylvestris var.mongolica was most affected by precipitation at low to medium density stands.Drought resistance of L.principis-rupprechtii trees decreased as tree size increased.Large L.principis-rupprechtii trees had lower drought resistance than small trees in all stands.Drought resistance of large P.meyeri trees exhibited high resistance to drought only in high-density stands.However,drought resistance of P.sylvestris var.mongolica trees was affected by tree size,competition,and their interactions.These results indicated that targeted silvicultural interventions,such as thinning,can be implemented to enhance drought resistance specifically for large L.principis-rupprechtii trees and small P.sylvestris var.mongolica trees in medium and high competition stands,and small P.meyeri trees in high competition stands.Our results highlight that properly conducted thinning can in some cases enhance growth resistance to droughts,depending on stand density,tree size,and tree species.
文摘The most famous deserts exist in subtropical regions which is the direct outcome of insufficient precipitation and high temperatures. The Middle East deserts are subjected often to dust, which reduces horizontal visibility to 5 km, and sometimes even to less than 100 m. The severe and prolong drought recently afflicting the west Asia region has been suggested to be instrumental in producing an increased output of dust into the atmosphere from the region. Regarding the increasing of dust events over the west of Iran with the external origin in the recent decade (from 2000 to present), so the main dust-source areas over Iraq and Syria have been detected using the dust-source map of the southwest of Asia, satellite images and soil type maps. We considered the relationship between the increasing of dust events in the western of Iran and drought expansion over the main dust-production areas during the recent decade. Dust frequency data series, and drought variables which include the VHI (vegetation health index), precipitation and temperature data series in long-term and monthly scales have been monitored and compared. And then we used the correlation analysis that indicated the significant proximity between the dust events and droughts/dryness in a yearly scale and also during the warm season (May to Aug). Meantime the derived results from the T-student test for the aforementioned data series confirm the fact that the droughts are parallel to the increasing of dust events from 1996 to 2011 (especially in the recent decade). We found that the recent droughts in the external dust source areas had the remarkable potential to increase the dust events in the west of Iran.
基金the National Natural Science Foundation of China(42271289).
文摘Ecological stability is a core issue in ecological research and holds significant implications forhumanity. The increased frequency and intensity of drought and wet climate events resulting from climatechange pose a major threat to global ecological stability. Variations in stability among different ecosystemshave been confirmed, but it remains unclear whether there are differences in stability within the sameterrestrial vegetation ecosystem under the influence of climate events in different directions and intensities.China's grassland ecosystem includes most grassland types and is a good choice for studying this issue.This study used the Standardized Precipitation Evapotranspiration Index-12 (SPEI-12) to identify thedirections and intensities of different types of climate events, and based on Normalized DifferenceVegetation Index (NDVI), calculated the resistance and resilience of different grassland types for 30consecutive years from 1990 to 2019 (resistance and resilience are important indicators to measurestability). Based on a traditional regression model, standardized methods were integrated to analyze theimpacts of the intensity and duration of drought and wet events on vegetation stability. The resultsshowed that meadow steppe exhibited the highest stability, while alpine steppe and desert steppe had thelowest overall stability. The stability of typical steppe, alpine meadow, temperate meadow was at anintermediate level. Regarding the impact of the duration and intensity of climate events on vegetationecosystem stability for the same grassland type, the resilience of desert steppe during drought was mainlyaffected by the duration. In contrast, the impact of intensity was not significant. However, alpine steppewas mainly affected by intensity in wet environments, and duration had no significant impact. Ourconclusions can provide decision support for the future grassland ecosystem governance.
文摘Increases in the frequency of extreme weather and climate events and the severity of their impacts on the natural environment and society have been observed across the globe in recent decades. In addition to natural climate variability and greenhouse-induced climate change, extreme weather and climate events produce the most pronounced impacts. In this paper, the climate of three island countries in the Western Pacific: Fiji, Samoa and Tuvalu, has been analysed. Warming trends in annual average maximum and minimum temperatures since the 1950s have been identified, in line with the global warming trend. We present recent examples of extreme weather and climate events and their impacts on the island countries in the Western Pacific: the 2011 drought in Tuvalu, the 2012 floods in Fiji and a tropical cyclone, Evan, which devastated Samoa and Fiji in December 2012. We also relate occurrences of the extreme weather and climate events to phases of the El Niño-Southern Oscillation (ENSO) phenomenon. The impacts of such natural disasters on the countries are severe and the costs of damage are astronomical. In some cases, climate extremes affect countries to such an extent that governments declare a national state of emergency, as occurred in Tuvalu in 2011 due to the severe drought’s impact on water resources. The projected increase in the frequency of weather and climate extremes is one of the expected consequences of the observed increase in anthropogenic greenhouse gas concentration and will likely have even stronger negative impacts on the natural environment and society in the future. This should be taken into consideration by authorities of Pacific Island Countries and aid donors when developing strategies to adapt to the increasing risk of climate extremes. Here we demonstrate that the modern science of seasonal climate prediction is well developed, with current dynamical climate models being able to provide skilful predictions of regional rainfall two-three months in advance. The dynamic climate model-based forecast products are now disseminated to the National Meteorological Services of 15 island countries in the Western Pacific through a range of web-based information tools. We conclude with confidence that seasonal climate prediction is an effective solution at the regional level to provide governments and local communities of island nations in the Western Pacific with valuable assistance for informed decision making for adaptation to climate variability and change.
基金supported by the National Natural Science Foundation of China (Grant Nos.42005029 and 41701103)the China Meteorological Administration Special Foundation for Innovation and Development (Grant No.CXFZ2024Q007)。
文摘In the summer of 2024, following a strong El Ni?o event in the preceding winter, the tropical Indian Ocean and tropical North Atlantic recorded their highest SSTs since 1961, along with a significant westward shift and intensification of the western Pacific subtropical high(WPSH). Under these conditions, China experienced its hottest summer since 1961,and was hit by a series of high-impact extreme weather and climate events. From 9 June to 2 July, southern China experienced an unprecedented extreme precipitation event that exceeded the well-known 1998 summer precipitation event in both duration and impact scope, resulting in devastating floods in the Yangtze River basin. Subsequently, in early to midJuly, the Huanghe-Huaihe Basin suffered from a severe drought–flood abrupt alternation event, heavily affecting Henan and Shandong. Meanwhile, southern China underwent a widespread heatwave event lasting 74 days, ranking as the second most intense since 1961. From late July to the end of August, northern China faced unusually frequent heavy precipitation events, with cumulative precipitation reaching the second highest for the same period since 1961, causing floods in many rivers of northern China. This study provides a timely summary and assessment of the characteristics and impacts of these extreme events. It serves as a reference for climate change research, including mechanism analysis, numerical simulation,and climate event attribution, and also offers valuable insights for improving meteorological disaster prevention and mitigation strategies.
文摘随着全球变暖,复合型气候事件的发生特征逐渐成为近年来研究的热点。本研究采用第五代欧洲中期天气预报中心(The European Centre for Medium-Range Weather Forecasts,ECMWF)全球气候大气再分析(ECMWF Reanalysis v5,ERA5)数据中包含的日最高温和日降水数据分析了中国1982—2022年复合干热和湿热事件的发生特征,并引入了震级指数衡量复合事件的强度,结果显示复合事件的持续时间、频次和震级均显示不同程度的增长,其中复合湿热事件(CHTRE)的增长幅度均高于复合干热事件(CHTDE);极端型复合干热和湿热事件上升趋势最为明显(分别为0.24%和0.11%),高温主导了复合事件的变化趋势;6—8月是中国复合干热/复合湿热事件发生的主要月份,其中极端型复合事件多集中在7月。由于极端事件可能会随着全球持续变暖而增加,因此了解复合事件的发生特征对于增强中国抵御气候变化影响的能力至关重要。
