In a warming world,climate extremes tend to be more frequent and intense.The exceptional response of ecosystems triggered by extreme climate events under a warmer and wetter climate in northwest China(NWC)has aroused ...In a warming world,climate extremes tend to be more frequent and intense.The exceptional response of ecosystems triggered by extreme climate events under a warmer and wetter climate in northwest China(NWC)has aroused growing concern.However,understanding the responses of vegetation to climate extremes from the compound events perspective remains challenging.In this study,we identify the climate dynamics in NWC during 1971–2020 based on daily meteorological observations,focusing on the changes in compound hot-dry events(CHDEs)during the warmer and wetter period.We further explore the effects of CHDEs on vegetation by examining vegetation anomalies and recovery time using daily gross primary productivity(GPP)data.The results show a clear warmer and wetter period in NWC during 2000–2020.No signs of a hiatus in CHDEs increase are observed during this period,and even the duration of CHDEs in western NWC keeps showing an increasing tendency.Vegetation in eastern NWC,with a lower probability of GPP anomalies,exhibits stronger resistance of ecosystems to CHDEs than in western NWC.In NWC,vegetation typically returns to its normal state in 5.50 days on average,but exhibits greater resilience in the western region,where it takes less recovery time(4.82 days).Vegetation in the central region shows the lowest probability of GPP anomalies and relatively longer recovery time,likely due to its higher altitudes.Our research underscores the imperative to address the considerable impacts of CHDEs on vegetation growth even as the regional climate becomes increasingly warmer and wetter.展开更多
Against the backdrop of global warming,China has been facing increasingly frequent and severe extreme weather and climate events,with a prominent risk of compound extreme events induced by interactions among multiple ...Against the backdrop of global warming,China has been facing increasingly frequent and severe extreme weather and climate events,with a prominent risk of compound extreme events induced by interactions among multiple climate drivers and/or hazards.The present study first reviews the definition and classification of compound extreme events in China.Then,it summarizes research progress on the evolutionary characteristics,formation mechanisms,and future projections of different types of compound extreme events.The potential risks and possible impact pathways of three specific event types—namely,continuous day–night hot extremes,temperature–humidity compound events,and high-temperature–ozone compound events—on the health of the Chinese population are then explored.Finally,a framework for assessing the hazard risk of compound extreme events is constructed,accompanied by response strategies based on carbon neutrality targets.Building on existing research achievements,five future research directions are proposed:(1)identifying the risk chains of compound events;(2)addressing the constraints of observational records and coupled model performances;(3)attributing and understanding the drivers of compound extreme events;(4)finding optimal pathways for carbon reduction and air quality improvement;and(5)promoting inter-disciplinary,multi-regional,and cross-sectoral collaboration.Strengthening research in these directions will deepen our understanding of compound extreme events and provide technological support for climate change adaptation and health risk responses in China.展开更多
The increasing frequency of compound extreme events under ongoing climate change threatens global food security.Compared to individual extreme events,the simultaneous occurrence of multiple extreme events can exacerba...The increasing frequency of compound extreme events under ongoing climate change threatens global food security.Compared to individual extreme events,the simultaneous occurrence of multiple extreme events can exacerbate crop yield reductions,yet comprehensive assessments of these compound effects remain limited.To bridge this gap,we applied a linear mixed-effects model to quantify the impacts of individual extreme events(cold days(CD)and killing degree days(KDD))and triple compound extreme events(heatwave and low precipitation(HWLP)and hot-dry-windy(HDW))on the global yields of winter wheat,soybeans,and maize from 1982 to 2016.Our analysis indicated that regions severely impacted by extreme events(exceeding the 95%threshold)experienced total crop yield losses of more than 9.16,24.89,26.69,and 7.12%due to CD,KDD,HWLP,and HDW,respectively.The adverse effects of compound events were particularly pronounced during critical growth stages.HWLP results in yield losses of 9.4%for winter wheat and 6.8%for maize per 10 hours of exposure during the heading to harvesting stages,while soybean yields declined by 8.8%per 10 hours during the planting to three-true-leaf stage.Similarly,KDD caused a 7.4%yield reduction in winter wheat per 10°C day during the heading to harvesting stages,a 9.5%reduction in maize per 10°C day during the planting to jointing stages,and a 3.8%reduction in soybean per 10°C day during the planting to three-true-leaf stages.These findings underscore the substantial contribution of compound extreme events,which are often overlooked in existing risk assessments,in determining the global yields of major staple crops.展开更多
This study investigates the extreme compound cold-wet event in southern China during January–February 2024,which was the second most extreme event recorded since 1960.Two cold-wet processes occurred during this perio...This study investigates the extreme compound cold-wet event in southern China during January–February 2024,which was the second most extreme event recorded since 1960.Two cold-wet processes occurred during this period.The first process,from 22 January to 23 January,exhibited a more intense cold surge,while the second,from 1 February to 7 February,featured more extreme precipitation and longer duration.This extreme cold-wet event was attributed to the combined effects of El Niño and positive North Atlantic Oscillation(NAO)in winter,coupled with intense convection in the western tropical Indian Ocean associated with a positive Indian Ocean Dipole(IOD)from the preceding autumn.El Niño and the Indian Ocean Basin mode in winter are conductive to enhanced anticyclone over the western North Pacific.Over the western tropical Indian Ocean,the enhanced convection associated with the warm sea surface temperature in winter and the positive IOD in preceding autumn can trigger an anomalous upper-level anticyclone over the Arabian Sea,enhancing the subtropical jet and deepening the India-Myanmar trough.The deepened India-Myanmar trough and the strengthened subtropical anticyclone over the western North Pacific enhance water vapor transport and subsequent extreme precipitation in southern China.Moreover,positive NAO and strengthened westerly jet stream induce widespread cooling in subtropical Eurasia,including southern China.Analysis from the backward trajectories using the HYSPLIT model confirms that moisture from the west and cold air from northern China at the near surface favored the compound cold-wet event in southern China.The extreme conditions of ENSO and NAO in winter and IOD in autumn jointly contributed to this extreme compound event.展开更多
Compound extreme climate events may profoundly affect human activity in the Yangtze River Basin.This study analyzed the long-term spatiotemporal distribution characteristics of compound heatwave-drought and heatwave-w...Compound extreme climate events may profoundly affect human activity in the Yangtze River Basin.This study analyzed the long-term spatiotemporal distribution characteristics of compound heatwave-drought and heatwave-waterlogging events in the Yangtze River Basin using multi-period historical observation data and future scenario climate model data.It also examined the changes in population exposure to compound extreme climate events in the basin and their driving factors by combining population statistics and forecast data.The results show that the occurrence days of compound heatwave-drought and heatwave-waterlogging events in the Yangtze River Basin have shown a significant upward trend both in historical periods and future scenarios,accompanied by a marked expansion in the affected areas.Compared to historical periods,population exposure in the Yangtze River Basin under future scenarios is expected to increase by 1.5–2 times,primarily concentrated in the key urban areas of the basin.The main factors driving the changes in population exposure are the increased frequency of extreme climate events and population decline in future scenarios.These findings provide scientific evidence for early mitigation of meteorological disasters in the Yangtze River Basin.展开更多
Exposure assessment is critical for hazard risk management.It is important to investigate the cropland exposure to compound drought and heatwave(CDHW)events because of their severe impacts on agriculture.We quantified...Exposure assessment is critical for hazard risk management.It is important to investigate the cropland exposure to compound drought and heatwave(CDHW)events because of their severe impacts on agriculture.We quantified the variations in CDHW characteristics(i.e.,frequency,duration,and magnitude)and the cropland exposure to CDHW events in Northeast China using 20 CMIP6 climate projections for each of the four Shared Socioeconomic Pathways(i.e.,SSP126,SSP245,SSP370,and SSP585).The results indicate that the intensification of CDHW events leading to an anticipated increase in cropland exposure ranges from 1.6-fold to 5.8-fold(the range describes the differences among SSPs),with the west and northeast of the region poised to experience more pronounced increases.Notably,adherence to the SSP126 pathway can reduce both the increase rate of CDHW magnitude and cropland exposure compared to other SSPs.Path analysis demonstrates that cropland exposure is primarily driven by maximum temperature(Tmax).Although precipitation(Pre)increases(0.36-0.75 mm year^(-1)),the rise in potential evapotranspiration(PET)due to global warming is higher than that of Pre(0.26-1.07 mm year^(-1))except for SSP126,resulting in more drought events.Futhermore,elevated Tmax increases the frequency of extreme temperature events.Therefore,increases in Tmax and agricultural land area collectively contribute to exposure rise,with Tmax being the dominant factor in this process.Our findings emphasize the pivotal role of regulating the development pathway into SSP126 for sustainable agriculture,and optimizing crop patterns and planting heat-tolerant crop varieties are recommended for CDHW adaption.展开更多
Taklamakan Desert(TD)has been characterized by numerous heatwaves and dust storms,leading to negative effects on societies and ecosystems at regional and global scales.However,the association between heatwaves and dus...Taklamakan Desert(TD)has been characterized by numerous heatwaves and dust storms,leading to negative effects on societies and ecosystems at regional and global scales.However,the association between heatwaves and dust storms is poorly known.In this study,we describe the association between heatwaves and dust events and propose a mechanism for such compound events in the TD.The results show that,from 1993 to 2022,the frequency and intensity of heatwaves in the TD have increased at a rate of 0.21 days year^(-1)and 0.02℃ year^(-1),respectively.More than 40% of heatwaves existed with dust events,which significantly lagged behind heatwaves.Mechanically,the higher the air temperature,the hotter and drier the soil,leading to more dust emissions in the TD.In high-occurrence heatwave years,a large-scale wave train of“cyclone-anticyclone-cyclone”in the northwest-southeast direction was found,with the anticyclone of which hovered over the TD region.The anomalous anticyclones favored the formation and maintenance of heatwaves,and subsequent anomalous cyclones in the wave train triggered strong dust events followed by heatwaves.With climate warming,the compound events of heatwave and dust storm are becoming bigger hazards threatening the socioeconomic and ecological security in the TD,the profound study of which is critical to understanding regional extreme responses.展开更多
Compound extreme climate events involving multiple meteorological elements usually have a more severe impact on the environment and human health than single-element extreme events.However,the current definition of mul...Compound extreme climate events involving multiple meteorological elements usually have a more severe impact on the environment and human health than single-element extreme events.However,the current definition of multi-element compound extreme events is proposed from meteorological and statistical perspectives,without integrating health data,making the conclusions less practical for guiding health risk prevention.This study identified the threshold for hot–dry compound extreme events with high mortality risks(HMHDs)in China,using daily mortality data and temperature–humidity data from 278 districts or counties,and explored the interdecadal change and driving mechanisms of HMHD frequency in China from 1979 to 2021.The results show a significant increase in annual HMHD frequency in China after 2000,mainly occurring in summer(June,July,August).The northwestern to western regions of China(Xinjiang,Inner Mongolia,Gansu),and from the southwestern to the areas south of the Yangtze River(Sichuan,Hubei,Hunan,Jiangxi,Fujian,Guizhou,Yunnan),experience an increase of>10 days.The authors find that the interdecadal abrupt change in HMHD frequency can be attributed to the shift of the Atlantic Multidecadal Oscillation from a negative to a positive phase by affecting the Silk Road teleconnection.展开更多
BACKGROUND： Previous studies of attentional control have focused primarily on pre-cue control of attentional cue and direction. OBJECTIVE： To measure the differences in electrical activity of brain cells while proce...BACKGROUND： Previous studies of attentional control have focused primarily on pre-cue control of attentional cue and direction. OBJECTIVE： To measure the differences in electrical activity of brain cells while processing pre-cue and post-cue compound stimuli, and to explore brain electrical activity during global and local processing of compound stimuli according to electroencephalogram （EEG） recordings. DESIGN, TIME AND SETTING： A within-subject design study was performed at the School of Psychology, State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, China from March to May 2006. PARTICIPANTS： A total of 30 healthy, undergraduate students, aged 17-24 years, comprising 12 males and 18 females, were voluntarily enrolled from Beijing Normal University. Subjects exhibited normal or corrected-to-normal visual acuity. No significant non signal wave drift was detected during testing. METHODS： A total of 30 subjects were subjected to pre-cue and post-cue compound stimulus processing using event-related potential and EEG recordings. MAIN OUTCOME MEASURES： Evoked potential was recorded in different brain regions utilizing event-related potential to observe hemispheric symmetry, cue consistency and global-local features. RESULTS： Pre-cue compound stimuli resulted in hemispheric asymmetry for early wave （N1） and late wave （P3） in anterior brain regions. Early- and late-wave induced hemispheric asymmetry for electrode points （O1, 02, P3, P4, Pz, F3, F4, F7, F8, Fz, FP1, FP2, T7, TS, C3, C4, and Cz） during processing of pre-cue compound stimuli （P 〈 0.05）. Post-cue compound stimuli did not induce hemispheric asymmetry of brain waves induced by the above-described electrode points. No significant differences in global and local responses were determined during processing of post-cue compound stimuli. Under pre-cue conditions, significant differences were observed in N1 and P3 in the above-mentioned electrode points （P 〈 0.05）. However, under post-cue conditions, no significant differences were observed in N1 and P3 using the above-mentioned electrode points. Significant differences in early waves （N1 and P1） using the above-mentioned electrode points were detected between anterior and posterior brain regions, regardless of consistent or inconsistent, large or small letters （P 〈 0.05）. CONCLUSION： Cue location effected mechanisms underlying global and local processing of compound stimuli. Pre- or post-cue conditions resulted in differences in hemispheric symmetry, cue consistency, and global and local features. Under pre-cue conditions, hemispheric dominance was detected in global and local processing following compound stimuli. Under post-cue conditions, hemispheric dominance was not determined.展开更多
The escalation of compound extreme events has resulted in noteworthy economic and property losses.Recognizing the intricate interconnections among these events has become imperative.To tackle this challenge,we have fo...The escalation of compound extreme events has resulted in noteworthy economic and property losses.Recognizing the intricate interconnections among these events has become imperative.To tackle this challenge,we have formulated a comprehensive framework for the systematic analysis of their dependencies.This framework consists of three steps.(1)Define extreme events using Mahalanobis distance thresholds.(2)Represent dependencies among multiple extreme events through a point process-based method.(3)Verify dependencies with residual tail coefficients,determining thefinal dependency structure.Applying this framework to assess the extreme dependence of precipitation on wind speed and temperature in China,revealed four distinct dependency structures.In northern,Jianghuai,and southern China,precipitation heavily relies on wind speed,while tempera-tures maintain relative independence.In northeastern and northwestern China,precipitation exhibits relative independence,yet a notable dependence exists between temperatures and wind speed.In southwestern China,precipitation strongly depends on temperature,while wind speed remains relatively indepen-dent.The Qinghai–Tibet Plateau region displays a significant dependence relationship among precipitation,wind speed,and temperature,with weaker dependence between extreme wind speed and temperature.This framework is instrumental for analyzing dependencies among extreme values in compound events.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
为探究高温干旱复合事件(Compound drought and hot events,CH)对朔州饲用燕麦(Avena sativa L.)生产力及物候期的影响,并探讨为应对该类事件饲用燕麦的生育期积温需求应如何改变。为此,本研究基于验证的APSIM(Agricultural Production ...为探究高温干旱复合事件(Compound drought and hot events,CH)对朔州饲用燕麦(Avena sativa L.)生产力及物候期的影响,并探讨为应对该类事件饲用燕麦的生育期积温需求应如何改变。为此,本研究基于验证的APSIM(Agricultural Production System sIMulator)模型,结合气候模型对历史及未来情景下朔州市6个站点进行模拟分析。基于APSIM模型验证及情景模拟,2023年地上生物量归一化均方根误差(Normalized root mean square erro,NRMSE)9.19%,2022-2023年土壤水分NRMSE 25.69%,结果表明:未来晋北地区气候危害加剧,2070s的CH频率、持续时间和强度总体升高且自东向西递减,导致发生CH年份的饲用燕麦产草量较多年平均低2046.2 kg·hm^(-2),出苗至初花期和初花至盛花期分别延长0.97和0.26 d;但通过站点气候优化选育改良品种可提升产草量1.95%~23.65%。研究结果可为饲用燕麦应对CH提供理论基础,并为未来饲用燕麦的育种方向和生产管理提供一定的指导。展开更多
东南亚及中国海南岛植胶区面临日益频发的复合干热事件(Compound Drought and Hot Events,CDHEs)威胁。为克服传统气象指标对生态胁迫的指征偏差,文章提出基于总初级生产力(Gross Primary Productivity, GPP)最优生长阈值的环境胁迫量...东南亚及中国海南岛植胶区面临日益频发的复合干热事件(Compound Drought and Hot Events,CDHEs)威胁。为克服传统气象指标对生态胁迫的指征偏差,文章提出基于总初级生产力(Gross Primary Productivity, GPP)最优生长阈值的环境胁迫量化方法,通过构建土壤、大气和生态3种干旱与高温复合的CDHEs识别模式,以环境条件偏离最优阈值的程度量化CDHEs对橡胶林GPP的影响。结果表明:1)橡胶林最优生长阈值具有显著的纬度地带性和季节性,赤道区域土壤湿度阈值较高且全年平稳,而高纬度地区阈值的季节变化波动较大;2)1982—2018年,CDHEs频率和强度均呈上升趋势,其中大气干旱-高温复合事件数量增幅最大(0.021 6次/a),主要集中于中南半岛内陆;3)不同CDHEs识别模式存在空间适用性差异,大气干旱-高温模式全区适用,土壤干旱-高温和生态干旱-高温模式主要适用于低纬度,在10°N以北则识别能力受限;4)CDHEs造成的橡胶林GPP损失显著高于单一胁迫(P<0.001),受损像元比例达70.64%,具有协同放大效应;5)GPP损失的时空分异明显,10°N—24°N损失峰值在3—5月,月均损失达45.539 g·C/m^(2),而南、北纬10°以内,损失峰值则出现在8月,月损失分别为48.763和55.862 g·C/m^(2)。展开更多
基金supported by the National Natural Science Foundation of China(Grant No.42371423)the Fundamental Research Funds for the Central Universities(Grant No.2042023kfyq04)+1 种基金the China Postdoctoral Science Foundation(Grant No.2023M742682)the Postdoctoral Fellowship Program of CPSF(Grant No.GZB20230539).
文摘In a warming world,climate extremes tend to be more frequent and intense.The exceptional response of ecosystems triggered by extreme climate events under a warmer and wetter climate in northwest China(NWC)has aroused growing concern.However,understanding the responses of vegetation to climate extremes from the compound events perspective remains challenging.In this study,we identify the climate dynamics in NWC during 1971–2020 based on daily meteorological observations,focusing on the changes in compound hot-dry events(CHDEs)during the warmer and wetter period.We further explore the effects of CHDEs on vegetation by examining vegetation anomalies and recovery time using daily gross primary productivity(GPP)data.The results show a clear warmer and wetter period in NWC during 2000–2020.No signs of a hiatus in CHDEs increase are observed during this period,and even the duration of CHDEs in western NWC keeps showing an increasing tendency.Vegetation in eastern NWC,with a lower probability of GPP anomalies,exhibits stronger resistance of ecosystems to CHDEs than in western NWC.In NWC,vegetation typically returns to its normal state in 5.50 days on average,but exhibits greater resilience in the western region,where it takes less recovery time(4.82 days).Vegetation in the central region shows the lowest probability of GPP anomalies and relatively longer recovery time,likely due to its higher altitudes.Our research underscores the imperative to address the considerable impacts of CHDEs on vegetation growth even as the regional climate becomes increasingly warmer and wetter.
基金the National Natural Science Foundation of China[grant numbers 42141019 and 42261144687]An Investigation Research Program between Ecological Environment and Human Health in Wuyi Mountain[grant number 20242120035]Natural Science Foundation of Hubei Province,China[grant number 2024AF-B115]。
文摘Against the backdrop of global warming,China has been facing increasingly frequent and severe extreme weather and climate events,with a prominent risk of compound extreme events induced by interactions among multiple climate drivers and/or hazards.The present study first reviews the definition and classification of compound extreme events in China.Then,it summarizes research progress on the evolutionary characteristics,formation mechanisms,and future projections of different types of compound extreme events.The potential risks and possible impact pathways of three specific event types—namely,continuous day–night hot extremes,temperature–humidity compound events,and high-temperature–ozone compound events—on the health of the Chinese population are then explored.Finally,a framework for assessing the hazard risk of compound extreme events is constructed,accompanied by response strategies based on carbon neutrality targets.Building on existing research achievements,five future research directions are proposed:(1)identifying the risk chains of compound events;(2)addressing the constraints of observational records and coupled model performances;(3)attributing and understanding the drivers of compound extreme events;(4)finding optimal pathways for carbon reduction and air quality improvement;and(5)promoting inter-disciplinary,multi-regional,and cross-sectoral collaboration.Strengthening research in these directions will deepen our understanding of compound extreme events and provide technological support for climate change adaptation and health risk responses in China.
基金supported by the National Natural Science Foundation of China(42371483,and 42401573)the Guangdong Basic and Applied Basic Research Foundation,China(2022B1515130001)+2 种基金the Natural Science Foundation of Guangdong Province,China(2024A1515012081 and 2025A1515010770)the Guangzhou Basic and Applied Basic Research Project,China(202201011666)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(GZB20240880).
文摘The increasing frequency of compound extreme events under ongoing climate change threatens global food security.Compared to individual extreme events,the simultaneous occurrence of multiple extreme events can exacerbate crop yield reductions,yet comprehensive assessments of these compound effects remain limited.To bridge this gap,we applied a linear mixed-effects model to quantify the impacts of individual extreme events(cold days(CD)and killing degree days(KDD))and triple compound extreme events(heatwave and low precipitation(HWLP)and hot-dry-windy(HDW))on the global yields of winter wheat,soybeans,and maize from 1982 to 2016.Our analysis indicated that regions severely impacted by extreme events(exceeding the 95%threshold)experienced total crop yield losses of more than 9.16,24.89,26.69,and 7.12%due to CD,KDD,HWLP,and HDW,respectively.The adverse effects of compound events were particularly pronounced during critical growth stages.HWLP results in yield losses of 9.4%for winter wheat and 6.8%for maize per 10 hours of exposure during the heading to harvesting stages,while soybean yields declined by 8.8%per 10 hours during the planting to three-true-leaf stage.Similarly,KDD caused a 7.4%yield reduction in winter wheat per 10°C day during the heading to harvesting stages,a 9.5%reduction in maize per 10°C day during the planting to jointing stages,and a 3.8%reduction in soybean per 10°C day during the planting to three-true-leaf stages.These findings underscore the substantial contribution of compound extreme events,which are often overlooked in existing risk assessments,in determining the global yields of major staple crops.
基金Guangdong Major Project of Basic and Applied Basic Research Foundation(2020B0301030004)National Natural Science Foundation of China(42375029)+2 种基金Guangdong Basic and Applied Basic Research Foundation(2023A1515010908)Science and Technology Planning Project of Guangdong Province(2023B1212060019)Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(SML2024SP012)。
文摘This study investigates the extreme compound cold-wet event in southern China during January–February 2024,which was the second most extreme event recorded since 1960.Two cold-wet processes occurred during this period.The first process,from 22 January to 23 January,exhibited a more intense cold surge,while the second,from 1 February to 7 February,featured more extreme precipitation and longer duration.This extreme cold-wet event was attributed to the combined effects of El Niño and positive North Atlantic Oscillation(NAO)in winter,coupled with intense convection in the western tropical Indian Ocean associated with a positive Indian Ocean Dipole(IOD)from the preceding autumn.El Niño and the Indian Ocean Basin mode in winter are conductive to enhanced anticyclone over the western North Pacific.Over the western tropical Indian Ocean,the enhanced convection associated with the warm sea surface temperature in winter and the positive IOD in preceding autumn can trigger an anomalous upper-level anticyclone over the Arabian Sea,enhancing the subtropical jet and deepening the India-Myanmar trough.The deepened India-Myanmar trough and the strengthened subtropical anticyclone over the western North Pacific enhance water vapor transport and subsequent extreme precipitation in southern China.Moreover,positive NAO and strengthened westerly jet stream induce widespread cooling in subtropical Eurasia,including southern China.Analysis from the backward trajectories using the HYSPLIT model confirms that moisture from the west and cold air from northern China at the near surface favored the compound cold-wet event in southern China.The extreme conditions of ENSO and NAO in winter and IOD in autumn jointly contributed to this extreme compound event.
基金supported by the National Natural Science Foundation of China(Nos.42301029,42371354)the Scientific Research Start-up Fund for New Young Faculty,China University of Geosciences,Wuhan(No.CUGXQN2307)China Meteorological Administration Innovation and Development Project(No.CXFZ2023J051).
文摘Compound extreme climate events may profoundly affect human activity in the Yangtze River Basin.This study analyzed the long-term spatiotemporal distribution characteristics of compound heatwave-drought and heatwave-waterlogging events in the Yangtze River Basin using multi-period historical observation data and future scenario climate model data.It also examined the changes in population exposure to compound extreme climate events in the basin and their driving factors by combining population statistics and forecast data.The results show that the occurrence days of compound heatwave-drought and heatwave-waterlogging events in the Yangtze River Basin have shown a significant upward trend both in historical periods and future scenarios,accompanied by a marked expansion in the affected areas.Compared to historical periods,population exposure in the Yangtze River Basin under future scenarios is expected to increase by 1.5–2 times,primarily concentrated in the key urban areas of the basin.The main factors driving the changes in population exposure are the increased frequency of extreme climate events and population decline in future scenarios.These findings provide scientific evidence for early mitigation of meteorological disasters in the Yangtze River Basin.
基金financially supported by the National Key Research and Development Program of China(Grant No.2023YFF0805704)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA28020503)。
文摘Exposure assessment is critical for hazard risk management.It is important to investigate the cropland exposure to compound drought and heatwave(CDHW)events because of their severe impacts on agriculture.We quantified the variations in CDHW characteristics(i.e.,frequency,duration,and magnitude)and the cropland exposure to CDHW events in Northeast China using 20 CMIP6 climate projections for each of the four Shared Socioeconomic Pathways(i.e.,SSP126,SSP245,SSP370,and SSP585).The results indicate that the intensification of CDHW events leading to an anticipated increase in cropland exposure ranges from 1.6-fold to 5.8-fold(the range describes the differences among SSPs),with the west and northeast of the region poised to experience more pronounced increases.Notably,adherence to the SSP126 pathway can reduce both the increase rate of CDHW magnitude and cropland exposure compared to other SSPs.Path analysis demonstrates that cropland exposure is primarily driven by maximum temperature(Tmax).Although precipitation(Pre)increases(0.36-0.75 mm year^(-1)),the rise in potential evapotranspiration(PET)due to global warming is higher than that of Pre(0.26-1.07 mm year^(-1))except for SSP126,resulting in more drought events.Futhermore,elevated Tmax increases the frequency of extreme temperature events.Therefore,increases in Tmax and agricultural land area collectively contribute to exposure rise,with Tmax being the dominant factor in this process.Our findings emphasize the pivotal role of regulating the development pathway into SSP126 for sustainable agriculture,and optimizing crop patterns and planting heat-tolerant crop varieties are recommended for CDHW adaption.
基金supported by the National Natural Science Foundation of China(Grant Nos.41991231 and 91937302)the Fundamental Research Funds for the Central Universities(Grant No.lzujbky-2022-kb11)。
文摘Taklamakan Desert(TD)has been characterized by numerous heatwaves and dust storms,leading to negative effects on societies and ecosystems at regional and global scales.However,the association between heatwaves and dust storms is poorly known.In this study,we describe the association between heatwaves and dust events and propose a mechanism for such compound events in the TD.The results show that,from 1993 to 2022,the frequency and intensity of heatwaves in the TD have increased at a rate of 0.21 days year^(-1)and 0.02℃ year^(-1),respectively.More than 40% of heatwaves existed with dust events,which significantly lagged behind heatwaves.Mechanically,the higher the air temperature,the hotter and drier the soil,leading to more dust emissions in the TD.In high-occurrence heatwave years,a large-scale wave train of“cyclone-anticyclone-cyclone”in the northwest-southeast direction was found,with the anticyclone of which hovered over the TD region.The anomalous anticyclones favored the formation and maintenance of heatwaves,and subsequent anomalous cyclones in the wave train triggered strong dust events followed by heatwaves.With climate warming,the compound events of heatwave and dust storm are becoming bigger hazards threatening the socioeconomic and ecological security in the TD,the profound study of which is critical to understanding regional extreme responses.
基金funded by the National Natural Science Foundation of China[grant number U2442202]the National Key Research and Development Program of China[grant number 2018YFA0606200]+1 种基金the Guangdong Major Project of Basic and Applied Basic Research[grant number 2020B0301030004]the Science and Technology Project of the Tibet Autonomous Region[grant number XZ202402ZD0006-06]。
文摘Compound extreme climate events involving multiple meteorological elements usually have a more severe impact on the environment and human health than single-element extreme events.However,the current definition of multi-element compound extreme events is proposed from meteorological and statistical perspectives,without integrating health data,making the conclusions less practical for guiding health risk prevention.This study identified the threshold for hot–dry compound extreme events with high mortality risks(HMHDs)in China,using daily mortality data and temperature–humidity data from 278 districts or counties,and explored the interdecadal change and driving mechanisms of HMHD frequency in China from 1979 to 2021.The results show a significant increase in annual HMHD frequency in China after 2000,mainly occurring in summer(June,July,August).The northwestern to western regions of China(Xinjiang,Inner Mongolia,Gansu),and from the southwestern to the areas south of the Yangtze River(Sichuan,Hubei,Hunan,Jiangxi,Fujian,Guizhou,Yunnan),experience an increase of>10 days.The authors find that the interdecadal abrupt change in HMHD frequency can be attributed to the shift of the Atlantic Multidecadal Oscillation from a negative to a positive phase by affecting the Silk Road teleconnection.
基金the Planning Program Foundation of Application and Experimental Psychology of Beijing Key Laboratory from 2008 to 2009.No.JD100270541
文摘BACKGROUND： Previous studies of attentional control have focused primarily on pre-cue control of attentional cue and direction. OBJECTIVE： To measure the differences in electrical activity of brain cells while processing pre-cue and post-cue compound stimuli, and to explore brain electrical activity during global and local processing of compound stimuli according to electroencephalogram （EEG） recordings. DESIGN, TIME AND SETTING： A within-subject design study was performed at the School of Psychology, State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, China from March to May 2006. PARTICIPANTS： A total of 30 healthy, undergraduate students, aged 17-24 years, comprising 12 males and 18 females, were voluntarily enrolled from Beijing Normal University. Subjects exhibited normal or corrected-to-normal visual acuity. No significant non signal wave drift was detected during testing. METHODS： A total of 30 subjects were subjected to pre-cue and post-cue compound stimulus processing using event-related potential and EEG recordings. MAIN OUTCOME MEASURES： Evoked potential was recorded in different brain regions utilizing event-related potential to observe hemispheric symmetry, cue consistency and global-local features. RESULTS： Pre-cue compound stimuli resulted in hemispheric asymmetry for early wave （N1） and late wave （P3） in anterior brain regions. Early- and late-wave induced hemispheric asymmetry for electrode points （O1, 02, P3, P4, Pz, F3, F4, F7, F8, Fz, FP1, FP2, T7, TS, C3, C4, and Cz） during processing of pre-cue compound stimuli （P 〈 0.05）. Post-cue compound stimuli did not induce hemispheric asymmetry of brain waves induced by the above-described electrode points. No significant differences in global and local responses were determined during processing of post-cue compound stimuli. Under pre-cue conditions, significant differences were observed in N1 and P3 in the above-mentioned electrode points （P 〈 0.05）. However, under post-cue conditions, no significant differences were observed in N1 and P3 using the above-mentioned electrode points. Significant differences in early waves （N1 and P1） using the above-mentioned electrode points were detected between anterior and posterior brain regions, regardless of consistent or inconsistent, large or small letters （P 〈 0.05）. CONCLUSION： Cue location effected mechanisms underlying global and local processing of compound stimuli. Pre- or post-cue conditions resulted in differences in hemispheric symmetry, cue consistency, and global and local features. Under pre-cue conditions, hemispheric dominance was detected in global and local processing following compound stimuli. Under post-cue conditions, hemispheric dominance was not determined.
基金National Key R&D Program of China,Grant/Award Number:2022YFC3002705National Natural Science Foundation of China,Grant/Award Number:5220904China Institute of Water Resources and Hydropower Research,Grant/Award Number:SKL2022TS11。
文摘The escalation of compound extreme events has resulted in noteworthy economic and property losses.Recognizing the intricate interconnections among these events has become imperative.To tackle this challenge,we have formulated a comprehensive framework for the systematic analysis of their dependencies.This framework consists of three steps.(1)Define extreme events using Mahalanobis distance thresholds.(2)Represent dependencies among multiple extreme events through a point process-based method.(3)Verify dependencies with residual tail coefficients,determining thefinal dependency structure.Applying this framework to assess the extreme dependence of precipitation on wind speed and temperature in China,revealed four distinct dependency structures.In northern,Jianghuai,and southern China,precipitation heavily relies on wind speed,while tempera-tures maintain relative independence.In northeastern and northwestern China,precipitation exhibits relative independence,yet a notable dependence exists between temperatures and wind speed.In southwestern China,precipitation strongly depends on temperature,while wind speed remains relatively indepen-dent.The Qinghai–Tibet Plateau region displays a significant dependence relationship among precipitation,wind speed,and temperature,with weaker dependence between extreme wind speed and temperature.This framework is instrumental for analyzing dependencies among extreme values in compound events.
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。
文摘为探究高温干旱复合事件(Compound drought and hot events,CH)对朔州饲用燕麦(Avena sativa L.)生产力及物候期的影响,并探讨为应对该类事件饲用燕麦的生育期积温需求应如何改变。为此,本研究基于验证的APSIM(Agricultural Production System sIMulator)模型,结合气候模型对历史及未来情景下朔州市6个站点进行模拟分析。基于APSIM模型验证及情景模拟,2023年地上生物量归一化均方根误差(Normalized root mean square erro,NRMSE)9.19%,2022-2023年土壤水分NRMSE 25.69%,结果表明:未来晋北地区气候危害加剧,2070s的CH频率、持续时间和强度总体升高且自东向西递减,导致发生CH年份的饲用燕麦产草量较多年平均低2046.2 kg·hm^(-2),出苗至初花期和初花至盛花期分别延长0.97和0.26 d;但通过站点气候优化选育改良品种可提升产草量1.95%~23.65%。研究结果可为饲用燕麦应对CH提供理论基础,并为未来饲用燕麦的育种方向和生产管理提供一定的指导。
