The likelihood of extreme heat occurrence is continuously increasing with global warming.Under high temperatures,humidity may exacerbate the heat impact on humanity.As atmospheric humidity depends on moisture availabi...The likelihood of extreme heat occurrence is continuously increasing with global warming.Under high temperatures,humidity may exacerbate the heat impact on humanity.As atmospheric humidity depends on moisture availability and is constrained by air temperature,it is important to project the changes in the distribution of atmospheric humidity conditional on air temperature as the climate continuously warms.Here,a non-crossing quantile smoothing spline is employed to build quantile regression models emulating conditional distributions of dew point(a measure of humidity)on local temperature evolving with escalating global mean surface temperature.By applying these models to 297 weather stations in seven regions in China,the study analyzes historical trends of humid-heat and dry-hot days,and projects their changes under global warming of 2.0℃ and 4.5℃.In response to global warming,rising trends of humid-heat extremes,while weakening trends of dry-hot extremes,are observed at most stations in Northeast China.Additionally,results indicate an increasing trend in dry-hot extremes at numerous stations across central China,but a rise in humid-heat extremes over Northwest China and coastal regions.These trends found in the current climate state are projected to intensify under 2.0℃ and 4.5℃ warming,possibly influenced by the heterogeneous variations in precipitation,soil moisture,and water vapor fluxes.Requiring much lower computational resources than coupled climate models,these quantile regression models can further project compound humidity and temperature extremes in response to different levels of global warming,potentially informing the risk management of compound humid-heat extremes on a local scale.展开更多
Compound extremes,whose socioeconomic and ecological impacts are severer than that caused by each event occurring in isolation,have evolved into a hot topic in Earth Science in the past decade.In the context of climat...Compound extremes,whose socioeconomic and ecological impacts are severer than that caused by each event occurring in isolation,have evolved into a hot topic in Earth Science in the past decade.In the context of climate change,many compound extremes have exhibited increasing frequency and intensity,and shown novel fashions of combinations,posing more pressing demands and tougher challenges to scientific research and disaster prevention and response.This article,via a perspective of multi-sphere interactions within the Earth System,systematically reviews the status quo,new scientific understanding,and deficiencies regarding the definition,mechanism,change,attribution,and projection of compound extremes.This study also sorts out existing challenges and outlines a potential roadmap in advancing the study on compound extremes with respect to data requirement,mechanistic diagnosis,numerical modeling,attribution and projection,risk assessment,and adaptive response.Further directions of compound extremes studies and key research topics that warrant multi-disciplinary and multisectoral coordinated efforts are also proposed.Given that climate change has reshaped the type of extremes,a transformation from the traditional single-event perspective to a compound-event perspective is needed for scientific research,disaster prevention and mitigation,and climate change adaptation,calling for bottom-up innovation in research objects,ideas,and methods.This article will add value to promoting the research on compound extremes and interdisciplinary cooperations.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
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
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
Urban agglomerations are increasingly emerging as the primary form of new urbanization and a crucial vehicle for modernization.The climatic effects induced by urbanization have become a research frontier with signific...Urban agglomerations are increasingly emerging as the primary form of new urbanization and a crucial vehicle for modernization.The climatic effects induced by urbanization have become a research frontier with significant scientific and practical relevance.As a direct energy source for the atmosphere,the surface heat source undergoes changes profoundly influenced by alterations in land surface characteristics and human activities during urbanization.This is particularly critical in urban agglomerations,where compound high-temperature events frequently occur,exerting substantial impacts on urban habitability and societal functioning.However,a systematic understanding of the relationship between surface heat sources and these compound events is still lacking.Based on high-resolution CMA and ERA5 reanalysis data,this study analyzes the spatiotemporal distribution and evolution characteristics of surface heat sources in four major Chinese urban agglomerations:the Pearl River Delta,Yangtze River Delta,Chengdu-Chongqing region,and Beijing-Tianjin-Hebei region.It compares their regional differences and explores the mechanisms linking them to compound high-temperature events.The results indicate that the surface heat sources in these four urban agglomerations generally exhibit a seasonal pattern of“strong in summer and weak in winter.”In some seasons,the urban surface shifts from being a heat source to a heat sink,with densely urbanized areas prone to forming extreme value centers for heat source/sink.Changes in surface heat sources significantly affect the frequency of compound high-temperature events,while their influence on intensity is relatively limited.Furthermore,the identification of compound high-temperature events is highly sensitive to the choice of the baseline period;differences in the climatic background reflected by the baseline period are key to inconsistent trend judgments.This study provides new insights for addressing the environmental challenges posed by urbanization,enhancing urban climate resilience,and improving residents'quality of life.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
Recently,extreme meteorological droughts have affected China,causing terrible socioeconomic impacts.Despite previous research on the spatiotemporal characteristics and mechanisms of drought,two crucial issues remain s...Recently,extreme meteorological droughts have affected China,causing terrible socioeconomic impacts.Despite previous research on the spatiotemporal characteristics and mechanisms of drought,two crucial issues remain seldom explored.First,an event-oriented drought chronology with detailed spatiotemporal evolutions is urgently required.Second,the complex migration patterns and diversity of synchronous temperature extremes need to be quantitatively investigated.Accordingly,the main achievements of our investigation are as follows.We produced an event-oriented set of extreme meteorological droughts over China through the application of a newly developed 3D DBSCAN-based detection method(deposited on https://doi.org/10.25452/figshare.plus.25512334),which was verified with a historical atlas and monographs on a case-by-case basis.In addition,distinctive migration patterns(i.e.,stationary/propagation types)are identified and ranked,considering the differences in latitudinal zones and coastal/inland locations.We also analyze the diversity of synchronous temperature extremes(e.g.,hotness and coldness).Notably,an increasing trend in hot droughts occurred over China since the late 1990s,predominantly appearing to the south of 30°N and north of 40°N.All drought events and synchronous temperature extremes are ranked using a comprehensive magnitude index,with the 2022 summer-autumn Yangtze River hot drought being the hottest.Furthermore,Liang-Kleeman information flow-based causality analysis emphasizes key areas where the PDO and AMO influenced decadal variations in coverages of droughts and temperature extremes.We believe that the achievements in this study may offer new insights into sequential mechanism exploration and prediction-related issues.展开更多
This paper puts forward a Poisson-generalized Pareto (Poisson-GP) distribution. This new form of compound extreme value distribution expands the existing application of compound extreme value distribution, and can be ...This paper puts forward a Poisson-generalized Pareto (Poisson-GP) distribution. This new form of compound extreme value distribution expands the existing application of compound extreme value distribution, and can be applied to predicting financial risk, large insurance settlement and high-grade earthquake, etc. Compared with the maximum likelihood estimation (MLE) and compound moment estimation (CME), probability-weighted moment estimation (PWME) is used to estimate the parameters of the distribution function. The specific formulas are presented. Through Monte Carlo simulation with sample sizes 10, 20, 50, 100, 1 000, it is concluded that PWME is an efficient method and it behaves steadily. The mean square errors (MSE) of estimators by PWME are much smaller than those of estimators by CME, and there is no significant difference between PWME and MLE. Finally, an example of foreign exchange rate is given. For Dollar/Pound exchange rates from 1990-01-02 to 2006-12-29, this paper formulates the distribution function of the largest loss among the investment losses exceeding a certain threshold by Poisson-GP compound extreme value distribution, and obtains predictive values at different confidence levels.展开更多
We report an optical spectroscopy study on LaSb, a compound recently identified to exhibit extremely large magnetoresistance. Our optieal measurement indicates that the material has a low carrier density. More inter- ...We report an optical spectroscopy study on LaSb, a compound recently identified to exhibit extremely large magnetoresistance. Our optieal measurement indicates that the material has a low carrier density. More inter- estingly, the study reveals that the plasma frequency increases with decreasing temperature. This phenomenon suggests either an increase of the conducting carrier density or/and a decrease of the effective mass of carriers with decreasing temperature. We attribute it primarily to the latter effect. Two possible scenarios on its physical origin are examined and discussed. The study offers new insight into the electronic structure of this compound.展开更多
The accurate prediction of the typhoon （hurricane） induced extreme sea environments is very important for the coastal structure design in areas influenced by typhoon （hurricane）. In 2005 Hurricane Katrina brought ...The accurate prediction of the typhoon （hurricane） induced extreme sea environments is very important for the coastal structure design in areas influenced by typhoon （hurricane）. In 2005 Hurricane Katrina brought a severe catastrophe in New Orleans by combined effects of hurricane induced extreme sea environments and upper flood of the Mississippi River. Like the New Orleans City, Shanghai is located at the estuarine area of the Changjiang River and the combined effect of typhoon induced extreme sea en- vironments, flood peak runoff from the Changjiang River coupled with the spring tide is the dominate factor for disaster prevention design criteria. The Poisson-nested logistic trivariate compound extreme value distribution （PNLTCEYD） is a new type of joint probability model which is proposed by compounding a discrete distribution （typhoon occurring frequency） into a continuous multivariate joint distribution （ typhoon induced extreme events）. The new model gives more reasonable predicted results for New Orleans and Shanghai disaster prevention design criteria.展开更多
The hazard produced by natural phenomena on infrastructure and urban populations has been widely studied in the last 50 years. Researchers have recognised that the real danger posed by these phenomena depends on their...The hazard produced by natural phenomena on infrastructure and urban populations has been widely studied in the last 50 years. Researchers have recognised that the real danger posed by these phenomena depends on their extreme values. Most researchers focus on the extremes of natural phenomena considered in isolation, one variable at a time. However, what is relevant in hazard studies is coincident extremes of several climatic variables, i.e., the presence of compound extremes. The peak value of these extremes seldom coincides, but off-peak values located in the tail of the distributions are often concurrent and can lead to catastrophic events. What is essential in hazard studies is to calculate the probabilistic distribution of the extremes of coincident climatic variables. The presence of correlations between these variables complicates the problem. This paper presents a computationally efficient and robust mathematical methodology to solve the problem. The procedure is based on the convolution of the distributions of the climatic variables. Once the probabilistic distribution of the compound variables is found, it is possible to calculate the curves of the return period, which is the indicator of importance in hazard and risk studies. This compound Return Period is computed using the Statistics of Extreme Values. To illustrate the problem, the case of a cyclone landing close to a low-gradient coastal city is discussed, and its probability of flooding and recurrence period is calculated. We show that the failure to correctly model the correlation between variables can result in overestimating the Return Period curve, consequently increasing mitigation costs.展开更多
In using the PGCEVD （Poisson-Gumbel Compound Extreme Value Distribution） model to calculate return values of typhoon wave height, the quantitative selection of the threshold has blocked its application. By analyzing...In using the PGCEVD （Poisson-Gumbel Compound Extreme Value Distribution） model to calculate return values of typhoon wave height, the quantitative selection of the threshold has blocked its application. By analyzing the principle of the threshold selection of PGCEVD model and in combination of the change point statistical methods, this paper proposes a new method for quantitative calculation of the threshold in PGCEVD model. Eleven samples from five engineering points in several coastal waters of Guangdong and Hainan, China, are calculated and analyzed by using PGCEVD model and the traditional Pearson type III distribution （P-III） model, respectively. By comparing the results of the two models, it is shown that the new method of selecting the optimal threshold is feasible. PGCEVD model has more stable results than that of P-III model and can be used for the return wave height in every direction.展开更多
Hurricanes Katrina and Rita resulted in the largest number of platforms destroyed and damaged in the history of Gulf of Mexico operations. With the trend of global warming, sea level rising and the frequency and inten...Hurricanes Katrina and Rita resulted in the largest number of platforms destroyed and damaged in the history of Gulf of Mexico operations. With the trend of global warming, sea level rising and the frequency and intensity of typhoon increase. How to determine a reasonable deck elevation against the largest hurricane waves has become a key issue in offshore platforms design and construction for the unification of economy and safety. In this paper, the multivariate compound extreme value distribution （MCEVD） model is used to predict the deck elevation with different combination of tide, surge height, and crest height. Compared with practice recommended by American Petroleum Institute （API）, the prediction by MCEVD has probabilistic meaning and universality.展开更多
A typhoon leading is an important natural disaster to many disasters to China. A giant wave caused by it has brought large threat for an offshore project. Based on the maximum entropy principle,one new model which has...A typhoon leading is an important natural disaster to many disasters to China. A giant wave caused by it has brought large threat for an offshore project. Based on the maximum entropy principle,one new model which has 4 undetermined parameters is constructed,which is called the discrete maximum entropy probabilistic model. In practical applications,the design wave height is considered as soon as possible in a typhoon affected sea areas,the result fits the observed data well. Further more this model does not have the priority compared with other distributions as Poisson distribution. The model provides a theoretical basis for the engineering design more reasonable when considering typhoon factors comprehensively.展开更多
Extreme value analysis is an indispensable method to predict the probability of marine disasters and calculate the design conditions of marine engineering.The rationality of extreme value analysis can be easily affect...Extreme value analysis is an indispensable method to predict the probability of marine disasters and calculate the design conditions of marine engineering.The rationality of extreme value analysis can be easily affected by the lack of sample data.The peaks over threshold(POT)method and compound extreme value distribution(CEVD)theory are effective methods to expand samples,but they still rely on long-term sea state data.To construct a probabilistic model using shortterm sea state data instead of the traditional annual maximum series(AMS),the binomial-bivariate log-normal CEVD(BBLCED)model is established in this thesis.The model not only considers the frequency of the extreme sea state,but it also reflects the correlation between different sea state elements(wave height and wave period)and reduces the requirement for the length of the data series.The model is applied to the calculation of design wave elements in a certain area of the Yellow Sea.The results indicate that the BBLCED model has good stability and fitting effect,which is close to the probability prediction results obtained from the long-term data,and reasonably reflects the probability distribution characteristics of the extreme sea state.The model can provide a reliable basis for coastal engineering design under the condition of a lack of marine data.Hence,it is suitable for extreme value prediction and calculation in the field of disaster prevention and reduction.展开更多
Due to global climate anomalies,the intensity and spatial extent of weather and climate extremes have increased notably.Therefore,extreme events must be studied to ensure agricultural production.In this study,the grow...Due to global climate anomalies,the intensity and spatial extent of weather and climate extremes have increased notably.Therefore,extreme events must be studied to ensure agricultural production.In this study,the growing season accumulated temperature above 10°C(GSAT 10)was used as the climate regionalization index for maize in the Songliao Plain region,and the study area was divided into three climate zones.The standardized precipitation requirement index(SPRI)and standardized temperature index(STI)were introduced to analyze the spatial and temporal patterns of drought,waterlogging,and heat during the maize growing season from May to September using meteorological station data from the Songliao Plain between 1991 and 2020.The compound event magnitude indices were constructed by modeling the marginal distribution to detect the patterns of compound drought and heat events(CDHEs)and compound waterlogging and heat events(CWHEs),and to assess their potential impacts on maize production.The results show that:(1)The major meteorological disasters in the Songliao Plain region were drought and heat.The areas with prolonged high temperatures were similar to the areas with higher severity of temperature extremes,and were mainly concentrated in the central and southern parts of the study area(Zone 3).(2)The CWHEs mainly occurred in the northern part of the study area(Zones 1 and 2),and the CDHEs predominantly occurred in the central and southern parts of the study area.(3)For most sites on the Songliao Plain,the duration,severity,and intensity of compound extreme events were positively correlated with relative meteorological yield(Y_(w)).Maize yield reduction was signifi cantly affected by the CDHEs.展开更多
Growing evidence indicates that extreme heat and rain may occur in succession within short time periods and cause greater impacts than individual events separated in time and space.Therefore,many studies have examined...Growing evidence indicates that extreme heat and rain may occur in succession within short time periods and cause greater impacts than individual events separated in time and space.Therefore,many studies have examined the impacts of compound hazard events on the social-ecological system at various scales.The definition of compound events is fundamental for such research.However,there are no existing studies that support the determination of time interval between individual events of a compound rainstorm and heatwave(CRH)event,which consists of two or more potentially qualifying component heatwave and rainstorm events.To address the deficiency in defining what individual events can constitute a CRH event,this study proposed a novel method to determine the maximum time interval for CRH events through the change in CRH event frequency with increasing time interval between individual events,using southern China as a case study.The results show that the threshold identified by the proposed method is reasonable.For more than 90%of the meteorological stations,the frequency of CRH events has reached a maximum when the time interval is less than or equal to the threshold.This study can aid in time interval selection,which is an important step for subsequent study of CRH events.展开更多
Concurrent compound dry and hot events(CDHEs)amplified more damange on the ecosystems and human society than individual extremes.Under climate change,compound dry and hot events become more frequent on a global scale....Concurrent compound dry and hot events(CDHEs)amplified more damange on the ecosystems and human society than individual extremes.Under climate change,compound dry and hot events become more frequent on a global scale.This paper proposes a mathematical method to quantitatively attribute changes of CDHEs to changes of precipitation,change in temperature and change in the dependence between precipitation and temperature.The attribution is achieved by formulating the total differential equation of the return period of CDHEs among Meta-gaussian model.A case study of China is devised based on monthly precipitation and temperature data during the period from 1921 to 2020 for 80 major river basins.It is found that temperature is the main driving factor of increases in CDHEs for 49 major river basins in China,except for the upper and middle reaches of the Yangtze River.In West China,precipitation changes drove the increase in CDHEs in 18 river basins(23%),particularly in parts of North Xinjiang,Qinghai and Gansu.On the other hand,dependence between precipitation and temperature dominated changes of CDHEs in 13 river basins(16%)of China with other factors,including parts of South China,East China and Northwestern China.Furthermore,changes in both the mean and spread of precipitation and temperature can also contribute to changes in CDHEs.展开更多
基金supported by the National Natural Science Foundation of China[grant number 42175066]the Shanghai International Science and Technology Partnership Project[grant number 21230780200].
文摘The likelihood of extreme heat occurrence is continuously increasing with global warming.Under high temperatures,humidity may exacerbate the heat impact on humanity.As atmospheric humidity depends on moisture availability and is constrained by air temperature,it is important to project the changes in the distribution of atmospheric humidity conditional on air temperature as the climate continuously warms.Here,a non-crossing quantile smoothing spline is employed to build quantile regression models emulating conditional distributions of dew point(a measure of humidity)on local temperature evolving with escalating global mean surface temperature.By applying these models to 297 weather stations in seven regions in China,the study analyzes historical trends of humid-heat and dry-hot days,and projects their changes under global warming of 2.0℃ and 4.5℃.In response to global warming,rising trends of humid-heat extremes,while weakening trends of dry-hot extremes,are observed at most stations in Northeast China.Additionally,results indicate an increasing trend in dry-hot extremes at numerous stations across central China,but a rise in humid-heat extremes over Northwest China and coastal regions.These trends found in the current climate state are projected to intensify under 2.0℃ and 4.5℃ warming,possibly influenced by the heterogeneous variations in precipitation,soil moisture,and water vapor fluxes.Requiring much lower computational resources than coupled climate models,these quantile regression models can further project compound humidity and temperature extremes in response to different levels of global warming,potentially informing the risk management of compound humid-heat extremes on a local scale.
基金supported by the National Natural Science Foundation of China(Grant No.42271024)the Science&Technology Development Funding of Chinese Academy of Meteorological Sciences(Grant No.2023KJ015)。
文摘Compound extremes,whose socioeconomic and ecological impacts are severer than that caused by each event occurring in isolation,have evolved into a hot topic in Earth Science in the past decade.In the context of climate change,many compound extremes have exhibited increasing frequency and intensity,and shown novel fashions of combinations,posing more pressing demands and tougher challenges to scientific research and disaster prevention and response.This article,via a perspective of multi-sphere interactions within the Earth System,systematically reviews the status quo,new scientific understanding,and deficiencies regarding the definition,mechanism,change,attribution,and projection of compound extremes.This study also sorts out existing challenges and outlines a potential roadmap in advancing the study on compound extremes with respect to data requirement,mechanistic diagnosis,numerical modeling,attribution and projection,risk assessment,and adaptive response.Further directions of compound extremes studies and key research topics that warrant multi-disciplinary and multisectoral coordinated efforts are also proposed.Given that climate change has reshaped the type of extremes,a transformation from the traditional single-event perspective to a compound-event perspective is needed for scientific research,disaster prevention and mitigation,and climate change adaptation,calling for bottom-up innovation in research objects,ideas,and methods.This article will add value to promoting the research on compound extremes and interdisciplinary cooperations.
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(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 Key Program of the National Natural Science Foundation of China(Grant No.42330601)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP,Grant No.2019QZKK010303)。
文摘Urban agglomerations are increasingly emerging as the primary form of new urbanization and a crucial vehicle for modernization.The climatic effects induced by urbanization have become a research frontier with significant scientific and practical relevance.As a direct energy source for the atmosphere,the surface heat source undergoes changes profoundly influenced by alterations in land surface characteristics and human activities during urbanization.This is particularly critical in urban agglomerations,where compound high-temperature events frequently occur,exerting substantial impacts on urban habitability and societal functioning.However,a systematic understanding of the relationship between surface heat sources and these compound events is still lacking.Based on high-resolution CMA and ERA5 reanalysis data,this study analyzes the spatiotemporal distribution and evolution characteristics of surface heat sources in four major Chinese urban agglomerations:the Pearl River Delta,Yangtze River Delta,Chengdu-Chongqing region,and Beijing-Tianjin-Hebei region.It compares their regional differences and explores the mechanisms linking them to compound high-temperature events.The results indicate that the surface heat sources in these four urban agglomerations generally exhibit a seasonal pattern of“strong in summer and weak in winter.”In some seasons,the urban surface shifts from being a heat source to a heat sink,with densely urbanized areas prone to forming extreme value centers for heat source/sink.Changes in surface heat sources significantly affect the frequency of compound high-temperature events,while their influence on intensity is relatively limited.Furthermore,the identification of compound high-temperature events is highly sensitive to the choice of the baseline period;differences in the climatic background reflected by the baseline period are key to inconsistent trend judgments.This study provides new insights for addressing the environmental challenges posed by urbanization,enhancing urban climate resilience,and improving residents'quality of life.
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.
基金jointly supported by the National Key R&D Program of China(Grant No.2022YFC3002801)the National Natural Science Foundation of China Grants(Grant Nos.42192563,42120104001)+1 种基金the National Natural Science Foundation of China for Youth(Grant No.42205191)the National Key Scientific and Technological Infrastructure project“Earth System Numerical Simulation Facility”(EarthLab).
文摘Recently,extreme meteorological droughts have affected China,causing terrible socioeconomic impacts.Despite previous research on the spatiotemporal characteristics and mechanisms of drought,two crucial issues remain seldom explored.First,an event-oriented drought chronology with detailed spatiotemporal evolutions is urgently required.Second,the complex migration patterns and diversity of synchronous temperature extremes need to be quantitatively investigated.Accordingly,the main achievements of our investigation are as follows.We produced an event-oriented set of extreme meteorological droughts over China through the application of a newly developed 3D DBSCAN-based detection method(deposited on https://doi.org/10.25452/figshare.plus.25512334),which was verified with a historical atlas and monographs on a case-by-case basis.In addition,distinctive migration patterns(i.e.,stationary/propagation types)are identified and ranked,considering the differences in latitudinal zones and coastal/inland locations.We also analyze the diversity of synchronous temperature extremes(e.g.,hotness and coldness).Notably,an increasing trend in hot droughts occurred over China since the late 1990s,predominantly appearing to the south of 30°N and north of 40°N.All drought events and synchronous temperature extremes are ranked using a comprehensive magnitude index,with the 2022 summer-autumn Yangtze River hot drought being the hottest.Furthermore,Liang-Kleeman information flow-based causality analysis emphasizes key areas where the PDO and AMO influenced decadal variations in coverages of droughts and temperature extremes.We believe that the achievements in this study may offer new insights into sequential mechanism exploration and prediction-related issues.
基金National Natural Science Foundation of China (No.70573077)
文摘This paper puts forward a Poisson-generalized Pareto (Poisson-GP) distribution. This new form of compound extreme value distribution expands the existing application of compound extreme value distribution, and can be applied to predicting financial risk, large insurance settlement and high-grade earthquake, etc. Compared with the maximum likelihood estimation (MLE) and compound moment estimation (CME), probability-weighted moment estimation (PWME) is used to estimate the parameters of the distribution function. The specific formulas are presented. Through Monte Carlo simulation with sample sizes 10, 20, 50, 100, 1 000, it is concluded that PWME is an efficient method and it behaves steadily. The mean square errors (MSE) of estimators by PWME are much smaller than those of estimators by CME, and there is no significant difference between PWME and MLE. Finally, an example of foreign exchange rate is given. For Dollar/Pound exchange rates from 1990-01-02 to 2006-12-29, this paper formulates the distribution function of the largest loss among the investment losses exceeding a certain threshold by Poisson-GP compound extreme value distribution, and obtains predictive values at different confidence levels.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11327806 and GZ1123the National Key Research and Development Program of China under Grant No 2016YFA0300902
文摘We report an optical spectroscopy study on LaSb, a compound recently identified to exhibit extremely large magnetoresistance. Our optieal measurement indicates that the material has a low carrier density. More inter- estingly, the study reveals that the plasma frequency increases with decreasing temperature. This phenomenon suggests either an increase of the conducting carrier density or/and a decrease of the effective mass of carriers with decreasing temperature. We attribute it primarily to the latter effect. Two possible scenarios on its physical origin are examined and discussed. The study offers new insight into the electronic structure of this compound.
基金supported by the National Natural Science Foundation of China under contract No.50379051.
文摘The accurate prediction of the typhoon （hurricane） induced extreme sea environments is very important for the coastal structure design in areas influenced by typhoon （hurricane）. In 2005 Hurricane Katrina brought a severe catastrophe in New Orleans by combined effects of hurricane induced extreme sea environments and upper flood of the Mississippi River. Like the New Orleans City, Shanghai is located at the estuarine area of the Changjiang River and the combined effect of typhoon induced extreme sea en- vironments, flood peak runoff from the Changjiang River coupled with the spring tide is the dominate factor for disaster prevention design criteria. The Poisson-nested logistic trivariate compound extreme value distribution （PNLTCEYD） is a new type of joint probability model which is proposed by compounding a discrete distribution （typhoon occurring frequency） into a continuous multivariate joint distribution （ typhoon induced extreme events）. The new model gives more reasonable predicted results for New Orleans and Shanghai disaster prevention design criteria.
文摘The hazard produced by natural phenomena on infrastructure and urban populations has been widely studied in the last 50 years. Researchers have recognised that the real danger posed by these phenomena depends on their extreme values. Most researchers focus on the extremes of natural phenomena considered in isolation, one variable at a time. However, what is relevant in hazard studies is coincident extremes of several climatic variables, i.e., the presence of compound extremes. The peak value of these extremes seldom coincides, but off-peak values located in the tail of the distributions are often concurrent and can lead to catastrophic events. What is essential in hazard studies is to calculate the probabilistic distribution of the extremes of coincident climatic variables. The presence of correlations between these variables complicates the problem. This paper presents a computationally efficient and robust mathematical methodology to solve the problem. The procedure is based on the convolution of the distributions of the climatic variables. Once the probabilistic distribution of the compound variables is found, it is possible to calculate the curves of the return period, which is the indicator of importance in hazard and risk studies. This compound Return Period is computed using the Statistics of Extreme Values. To illustrate the problem, the case of a cyclone landing close to a low-gradient coastal city is discussed, and its probability of flooding and recurrence period is calculated. We show that the failure to correctly model the correlation between variables can result in overestimating the Return Period curve, consequently increasing mitigation costs.
基金supported by the National Natural Science Foundation of China(Grant No.10902039)the Major Project Research of the Ministry of Railways of the People's Republic of China(Grant No.2010-201)
文摘In using the PGCEVD （Poisson-Gumbel Compound Extreme Value Distribution） model to calculate return values of typhoon wave height, the quantitative selection of the threshold has blocked its application. By analyzing the principle of the threshold selection of PGCEVD model and in combination of the change point statistical methods, this paper proposes a new method for quantitative calculation of the threshold in PGCEVD model. Eleven samples from five engineering points in several coastal waters of Guangdong and Hainan, China, are calculated and analyzed by using PGCEVD model and the traditional Pearson type III distribution （P-III） model, respectively. By comparing the results of the two models, it is shown that the new method of selecting the optimal threshold is feasible. PGCEVD model has more stable results than that of P-III model and can be used for the return wave height in every direction.
基金supported bythe National Natural Science Foundation of China (Grant No.51010009)
文摘Hurricanes Katrina and Rita resulted in the largest number of platforms destroyed and damaged in the history of Gulf of Mexico operations. With the trend of global warming, sea level rising and the frequency and intensity of typhoon increase. How to determine a reasonable deck elevation against the largest hurricane waves has become a key issue in offshore platforms design and construction for the unification of economy and safety. In this paper, the multivariate compound extreme value distribution （MCEVD） model is used to predict the deck elevation with different combination of tide, surge height, and crest height. Compared with practice recommended by American Petroleum Institute （API）, the prediction by MCEVD has probabilistic meaning and universality.
基金Open Fund of the Key Laboratory of Research on Marine Hazards Forecasting under contract No. LOMF1101the National Natural Science Foundation of China under contract No. 40776006Shanghai Typhoon Research Fund under contract No. 2009ST05
文摘A typhoon leading is an important natural disaster to many disasters to China. A giant wave caused by it has brought large threat for an offshore project. Based on the maximum entropy principle,one new model which has 4 undetermined parameters is constructed,which is called the discrete maximum entropy probabilistic model. In practical applications,the design wave height is considered as soon as possible in a typhoon affected sea areas,the result fits the observed data well. Further more this model does not have the priority compared with other distributions as Poisson distribution. The model provides a theoretical basis for the engineering design more reasonable when considering typhoon factors comprehensively.
文摘Extreme value analysis is an indispensable method to predict the probability of marine disasters and calculate the design conditions of marine engineering.The rationality of extreme value analysis can be easily affected by the lack of sample data.The peaks over threshold(POT)method and compound extreme value distribution(CEVD)theory are effective methods to expand samples,but they still rely on long-term sea state data.To construct a probabilistic model using shortterm sea state data instead of the traditional annual maximum series(AMS),the binomial-bivariate log-normal CEVD(BBLCED)model is established in this thesis.The model not only considers the frequency of the extreme sea state,but it also reflects the correlation between different sea state elements(wave height and wave period)and reduces the requirement for the length of the data series.The model is applied to the calculation of design wave elements in a certain area of the Yellow Sea.The results indicate that the BBLCED model has good stability and fitting effect,which is close to the probability prediction results obtained from the long-term data,and reasonably reflects the probability distribution characteristics of the extreme sea state.The model can provide a reliable basis for coastal engineering design under the condition of a lack of marine data.Hence,it is suitable for extreme value prediction and calculation in the field of disaster prevention and reduction.
基金supported by the National K&D Program of China(2022YFD2300201)the National Natural Science Foundation of China(U21A2040)+3 种基金the National Natural Science Foundation of China(42077443)the Science and Technology Development Planning of Jilin Province(20210203153SF)the Key Scientific and Technology Research and Development Program of Jilin Province(20200403065SF)the Construction Project of the Science and Technology Innovation Center(20210502008ZP)。
文摘Due to global climate anomalies,the intensity and spatial extent of weather and climate extremes have increased notably.Therefore,extreme events must be studied to ensure agricultural production.In this study,the growing season accumulated temperature above 10°C(GSAT 10)was used as the climate regionalization index for maize in the Songliao Plain region,and the study area was divided into three climate zones.The standardized precipitation requirement index(SPRI)and standardized temperature index(STI)were introduced to analyze the spatial and temporal patterns of drought,waterlogging,and heat during the maize growing season from May to September using meteorological station data from the Songliao Plain between 1991 and 2020.The compound event magnitude indices were constructed by modeling the marginal distribution to detect the patterns of compound drought and heat events(CDHEs)and compound waterlogging and heat events(CWHEs),and to assess their potential impacts on maize production.The results show that:(1)The major meteorological disasters in the Songliao Plain region were drought and heat.The areas with prolonged high temperatures were similar to the areas with higher severity of temperature extremes,and were mainly concentrated in the central and southern parts of the study area(Zone 3).(2)The CWHEs mainly occurred in the northern part of the study area(Zones 1 and 2),and the CDHEs predominantly occurred in the central and southern parts of the study area.(3)For most sites on the Songliao Plain,the duration,severity,and intensity of compound extreme events were positively correlated with relative meteorological yield(Y_(w)).Maize yield reduction was signifi cantly affected by the CDHEs.
基金funded by the Joint Funds of the National Natural Science Foundation of China(Grant No.U22B2011)the Ministry of Education and State Administration of Foreign Experts Aff airs,China(Grant No.BP0820003)the Key Laboratory of Environmental Change and Natural Disaster of Ministry of Education(2023-KF-13)。
文摘Growing evidence indicates that extreme heat and rain may occur in succession within short time periods and cause greater impacts than individual events separated in time and space.Therefore,many studies have examined the impacts of compound hazard events on the social-ecological system at various scales.The definition of compound events is fundamental for such research.However,there are no existing studies that support the determination of time interval between individual events of a compound rainstorm and heatwave(CRH)event,which consists of two or more potentially qualifying component heatwave and rainstorm events.To address the deficiency in defining what individual events can constitute a CRH event,this study proposed a novel method to determine the maximum time interval for CRH events through the change in CRH event frequency with increasing time interval between individual events,using southern China as a case study.The results show that the threshold identified by the proposed method is reasonable.For more than 90%of the meteorological stations,the frequency of CRH events has reached a maximum when the time interval is less than or equal to the threshold.This study can aid in time interval selection,which is an important step for subsequent study of CRH events.
基金This work was supported by the National Key Research and Development Program of China(Grant No.2021YFC3001000)the National Natural Science Foundation of China(Grant No.51979295)the Guangdong Provincial Department of Science and Technology(Grant No.2019ZT08G090).
文摘Concurrent compound dry and hot events(CDHEs)amplified more damange on the ecosystems and human society than individual extremes.Under climate change,compound dry and hot events become more frequent on a global scale.This paper proposes a mathematical method to quantitatively attribute changes of CDHEs to changes of precipitation,change in temperature and change in the dependence between precipitation and temperature.The attribution is achieved by formulating the total differential equation of the return period of CDHEs among Meta-gaussian model.A case study of China is devised based on monthly precipitation and temperature data during the period from 1921 to 2020 for 80 major river basins.It is found that temperature is the main driving factor of increases in CDHEs for 49 major river basins in China,except for the upper and middle reaches of the Yangtze River.In West China,precipitation changes drove the increase in CDHEs in 18 river basins(23%),particularly in parts of North Xinjiang,Qinghai and Gansu.On the other hand,dependence between precipitation and temperature dominated changes of CDHEs in 13 river basins(16%)of China with other factors,including parts of South China,East China and Northwestern China.Furthermore,changes in both the mean and spread of precipitation and temperature can also contribute to changes in CDHEs.
