Compound heat–humidity extremes(CTHEs)pose escalating threats to human health,particularly for vulnerable populations(children and elderly)with limited physiological adaptability.This study reveals the expansion of C...Compound heat–humidity extremes(CTHEs)pose escalating threats to human health,particularly for vulnerable populations(children and elderly)with limited physiological adaptability.This study reveals the expansion of CTHE-active seasons across eastern China from 1961 to 2022.Southern China(SC)and the Yangtze–Huaihe region(YH)exhibit earlier onsets and delayed terminations,prolonging hazardous CTHE seasons by one month post-2015 in SC.The prolonged CTHE-active seasons,coupled with population growth,have driven sharp increases in exposure across eastern China,with annual CTHE and hazardous CTHE exposure increasing by 106 million and 78 million person-days since the 2000s.Vulnerable groups constitute 39%of total exposure,with 11%(CTHEs)and 34%(hazardous CTHEs)attributable to season prolongation.Mechanistically,an intensified and westward-extended western North Pacific subtropical high enhances diabatic heating and moisture advection,driving prolonged CTHE-active seasons in SC and YH.These findings quantify climate–demographic synergies in heat–health risks,providing a scientific basis for climate-resilient health strategies targeting age-sensitive populations in eastern China’s warming and humidifying hotspots.展开更多
Determining net radiation is crucial for understanding soil–atmosphere interactions and plays a key role in defining thermal boundary conditions for thermo-hydro-mechanical models of slopes.Current methods for estima...Determining net radiation is crucial for understanding soil–atmosphere interactions and plays a key role in defining thermal boundary conditions for thermo-hydro-mechanical models of slopes.Current methods for estimating net radiation at soil surfaces typically overlook the influence of slope angle.For this purpose,this study aims to propose two refined methods for calculating net radiation on slope surfaces,which were developed from two widely acknowledged mathematical methods for horizontal surfaces.To evaluate the refined methods,we focused on net radiations that were calculated from monitored meteorological data.The calculated net radiation was then input into a coupled hydro-thermal model to compute the slope temperature distributions,which were subsequently compared to the measured temperatures.Satisfactory agreement was observed,demonstrating the feasibility of both methods.Afterwards,we examined the influence of slope angle on solar and net radiation results,then used a coupled hydro-thermal model to quantify differences in numerical temperature results when slope angle is either considered or neglected.Results indicate that the solar radiation received on slope surface is additionally affected by slope angle.In our simulation scenarios,the slope angle causes a maximum net radiation difference of 347.83 W/m²,and a maximum temperature difference of 6.5℃.展开更多
涡动相关法的不足是导致地表能量不平衡的重要原因。本文对文献中提出的能显著提升涡动相关法计算精度,并能使地表能量实现平衡的大涡平均法与Durand法展开研究,在白天通过5组试验对比研究了两者的异同、综合效应与改进方法。结果发现:...涡动相关法的不足是导致地表能量不平衡的重要原因。本文对文献中提出的能显著提升涡动相关法计算精度,并能使地表能量实现平衡的大涡平均法与Durand法展开研究,在白天通过5组试验对比研究了两者的异同、综合效应与改进方法。结果发现:(1)白天地表能量闭合水平与序列长度有一定关系,序列长度过长,闭合水平变差;过短,闭合水平则不一致,两者之间存在一个转折点。在此转折点长度上,闭合水平可达最优。(2)原始的能量闭合率(Energy balance ratio,简称EBR)为0.80,能量残差(Residual,简称Res)为64.9 W m-2,占可用能量的23.8%,远未平衡。(3)考虑大涡平均法后,EBR提高了0.18,达到0.98,Res降低到可用能量的5.3%(14.5 W m-2),达到平衡。(4)考虑Durand法后,EBR提高了0.15,达到0.95,Res降低到25.1 W m-2,占可用能量的9.2%,效果逊于大涡平均法。(5)既考虑大涡平均法、又考虑Durand法后,EBR提高到1.17,Res降低到-35.1 W m-2,严重过闭合。分析发现,严重过闭合的原因是Durand法的感热附加项在白天过度累加了气体膨胀做功项所致。(6)去除Durand法的感热附加项这一累加部分,只考虑其潜热附加项,并同时考虑大涡平均法,结果可使EBR达到1.0,Res降低到只占可用能量3.2%(8.7 W m-2)的理想闭合状况。分析发现,大涡平均法是实现地表能量闭合的主导因素。展开更多
研究三峡库区地表能量收支的细节特征可以为定量评估水库气候效应提供科学依据。基于再分析资料CRA-40驱动WRF(Weather Research and Forcasting Model)区域气候模式,对2013—2022年三峡库区夏季气候进行高精度模拟,利用站点观测数据和E...研究三峡库区地表能量收支的细节特征可以为定量评估水库气候效应提供科学依据。基于再分析资料CRA-40驱动WRF(Weather Research and Forcasting Model)区域气候模式,对2013—2022年三峡库区夏季气候进行高精度模拟,利用站点观测数据和ERA5再分析数据验证模式的可靠性,在此基础上分析地表能量收支与辐射平衡的时空变化特征。结果表明:WRF模式能较好地再现三峡库区气温和辐射的时空分布,模拟结果显示云层是调控地表能量分配的关键因子,全天空条件下的地表向下短波辐射和净短波辐射较晴空条件平均分别减少70~130 W·m-2和50~100 W·m-2。地表能量收支由潜热通量主导,其与净辐射的时间变化高度同步,且均表现出显著的季节内变化和昼夜变化特征,峰值分别出现在7月末至8月初和白天午后。库区水体具有显著的储热效应,晴空午间的储热通量可超过650 W·m-2,主导了净辐射的能量分配去向。研究结果可为深入理解三峡工程的气候与环境效应提供有价值的数据参考。展开更多
Surface-latent heat(LE)and sensible heat(SH)fluxes play a pivotal role in governing hydrological,biological,geochemical,and ecological processes on the land surface in the Tibetan Plateau.However,to accurately assess ...Surface-latent heat(LE)and sensible heat(SH)fluxes play a pivotal role in governing hydrological,biological,geochemical,and ecological processes on the land surface in the Tibetan Plateau.However,to accurately assess and understand the spatial distribution of LE and SH fluxes across different underlying surfaces,it is crucial to verify the validity and reliability of ERA-5,GLDAS,and MODIS data against ground measurements obtained from the Flux Net micrometeorological tower network.This study analyzed the spatial patterns of LE and SH over the Tibetan Plateau using data from ERA-5,GLDAS,and MODIS.The results were compared with ground measurements from Flux Net tower observations on different underlying surfaces,and five statistical parameters(Pearson's r,LR slope,RMSE,MBE,and MAE)were used to validate the data.The results showed that:(1)MODIS LE data and ERA-5 SH data exhibited the closest agreement with ground observations,as indicated by their lowest root mean square error and mean bias area values.(2)The accuracy of ERA-5 SH was the highest in meadows and steppes,while GLDAS SH performed optimally in shrublands.Notably,MODIS LE consistently outperformed the other datasets across all vegetation types.(3)The spatial distribution of LE and SH displayed considerable heterogeneity,contingent upon the specific data sources and underlying surfaces.Notably,there was a contrasting trend between GLDAS and ERA-5,as well as MODIS,in terms of SH distribution in the shrubland.In shrublands and meadows,MODIS SH and LE exhibited more pronounced changes than ERA-5 and GLDAS.Additionally,ERA-5 SH demonstrated the opposite variation in meadow and steppe regions compared to GLDAS and MODIS.展开更多
利用上海郊区奉贤夏季地表能量平衡观测资料,检验了城市陆面模式(Surface Urban Energy and Water Balance Scheme,SUEWS)的适用性及对地表覆盖变化和人类活动的敏感性。结果表明:SUEWS模式能较好再现辐射通量的日变化趋势,且能较好模...利用上海郊区奉贤夏季地表能量平衡观测资料,检验了城市陆面模式(Surface Urban Energy and Water Balance Scheme,SUEWS)的适用性及对地表覆盖变化和人类活动的敏感性。结果表明:SUEWS模式能较好再现辐射通量的日变化趋势,且能较好模拟感热通量和潜热通量日变化及量级。通过对比夏季较干燥和较潮湿月份平均波文比发现较干燥月份波文比(0.74)接近较潮湿月份(0.40)的2倍,表明空气湿度对湍流热通量有显著影响。通过多组下垫面覆盖敏感性试验发现,相对于树林而言,SUEWS模拟的感热通量和潜热通量对草地面积更为敏感,当自然地表覆盖率一定时,草地面积增大,表现为波文比的明显减小。当人口密度增大时,模拟的人为热通量明显增加,导致模拟的感热通量和波文比的明显增大。展开更多
Surface albedo,as one of the important properties of the underlying surface,has a significant impact on the surface energy balance in cold regions.However,due to the complexity of the factors affecting surface albedo,...Surface albedo,as one of the important properties of the underlying surface,has a significant impact on the surface energy balance in cold regions.However,due to the complexity of the factors affecting surface albedo,existing calculations still contain inaccuracies.Therefore,this study conducted surface albedo experiments on loess with different water contents and temperatures.By analyzing the surface albedo measurements of samples with varying temperature and water content levels,as well as the soil freezing characteristic curve(SFCC)and soil-water characteristic curve(SWCC)of loess,the study explores the influence of soil temperature and water content on the surface albedo of loess.The results indicate that both the temperature and water content of loess jointly affect surface albedo.During the process of albedo change,there exists a water content threshold that alters the trend of surface albedo.Soil temperature influences surface albedo by affecting the content of pore ice and liquid water within the soil.When the water content of loess is relatively low,the surface albedo decreases as the unfrozen water content decreases.However,this trend changes as the water content of loess increases.Additionally,a decrease in soil temperature lowers the moisture content threshold during the changes in surface albedo.This study provides a reference for exploring and determining the surface energy balance in cold regions under the background of warm and humid climates,as well as for establishing thermal calculation boundaries.展开更多
基金supported by the National Natural Science Foundation of China [grant number U2342208]。
摘要Compound heat–humidity extremes(CTHEs)pose escalating threats to human health,particularly for vulnerable populations(children and elderly)with limited physiological adaptability.This study reveals the expansion of CTHE-active seasons across eastern China from 1961 to 2022.Southern China(SC)and the Yangtze–Huaihe region(YH)exhibit earlier onsets and delayed terminations,prolonging hazardous CTHE seasons by one month post-2015 in SC.The prolonged CTHE-active seasons,coupled with population growth,have driven sharp increases in exposure across eastern China,with annual CTHE and hazardous CTHE exposure increasing by 106 million and 78 million person-days since the 2000s.Vulnerable groups constitute 39%of total exposure,with 11%(CTHEs)and 34%(hazardous CTHEs)attributable to season prolongation.Mechanistically,an intensified and westward-extended western North Pacific subtropical high enhances diabatic heating and moisture advection,driving prolonged CTHE-active seasons in SC and YH.These findings quantify climate–demographic synergies in heat–health risks,providing a scientific basis for climate-resilient health strategies targeting age-sensitive populations in eastern China’s warming and humidifying hotspots.
基金supported by the National Natural Science Foundation of China(Grant Nos.42525201 and 42230710).
摘要Determining net radiation is crucial for understanding soil–atmosphere interactions and plays a key role in defining thermal boundary conditions for thermo-hydro-mechanical models of slopes.Current methods for estimating net radiation at soil surfaces typically overlook the influence of slope angle.For this purpose,this study aims to propose two refined methods for calculating net radiation on slope surfaces,which were developed from two widely acknowledged mathematical methods for horizontal surfaces.To evaluate the refined methods,we focused on net radiations that were calculated from monitored meteorological data.The calculated net radiation was then input into a coupled hydro-thermal model to compute the slope temperature distributions,which were subsequently compared to the measured temperatures.Satisfactory agreement was observed,demonstrating the feasibility of both methods.Afterwards,we examined the influence of slope angle on solar and net radiation results,then used a coupled hydro-thermal model to quantify differences in numerical temperature results when slope angle is either considered or neglected.Results indicate that the solar radiation received on slope surface is additionally affected by slope angle.In our simulation scenarios,the slope angle causes a maximum net radiation difference of 347.83 W/m²,and a maximum temperature difference of 6.5℃.
摘要涡动相关法的不足是导致地表能量不平衡的重要原因。本文对文献中提出的能显著提升涡动相关法计算精度,并能使地表能量实现平衡的大涡平均法与Durand法展开研究,在白天通过5组试验对比研究了两者的异同、综合效应与改进方法。结果发现:(1)白天地表能量闭合水平与序列长度有一定关系,序列长度过长,闭合水平变差;过短,闭合水平则不一致,两者之间存在一个转折点。在此转折点长度上,闭合水平可达最优。(2)原始的能量闭合率(Energy balance ratio,简称EBR)为0.80,能量残差(Residual,简称Res)为64.9 W m-2,占可用能量的23.8%,远未平衡。(3)考虑大涡平均法后,EBR提高了0.18,达到0.98,Res降低到可用能量的5.3%(14.5 W m-2),达到平衡。(4)考虑Durand法后,EBR提高了0.15,达到0.95,Res降低到25.1 W m-2,占可用能量的9.2%,效果逊于大涡平均法。(5)既考虑大涡平均法、又考虑Durand法后,EBR提高到1.17,Res降低到-35.1 W m-2,严重过闭合。分析发现,严重过闭合的原因是Durand法的感热附加项在白天过度累加了气体膨胀做功项所致。(6)去除Durand法的感热附加项这一累加部分,只考虑其潜热附加项,并同时考虑大涡平均法,结果可使EBR达到1.0,Res降低到只占可用能量3.2%(8.7 W m-2)的理想闭合状况。分析发现,大涡平均法是实现地表能量闭合的主导因素。
摘要研究三峡库区地表能量收支的细节特征可以为定量评估水库气候效应提供科学依据。基于再分析资料CRA-40驱动WRF(Weather Research and Forcasting Model)区域气候模式,对2013—2022年三峡库区夏季气候进行高精度模拟,利用站点观测数据和ERA5再分析数据验证模式的可靠性,在此基础上分析地表能量收支与辐射平衡的时空变化特征。结果表明:WRF模式能较好地再现三峡库区气温和辐射的时空分布,模拟结果显示云层是调控地表能量分配的关键因子,全天空条件下的地表向下短波辐射和净短波辐射较晴空条件平均分别减少70~130 W·m-2和50~100 W·m-2。地表能量收支由潜热通量主导,其与净辐射的时间变化高度同步,且均表现出显著的季节内变化和昼夜变化特征,峰值分别出现在7月末至8月初和白天午后。库区水体具有显著的储热效应,晴空午间的储热通量可超过650 W·m-2,主导了净辐射的能量分配去向。研究结果可为深入理解三峡工程的气候与环境效应提供有价值的数据参考。
基金funded by the West Light Scholar of the Chinese Academy of Sciences(xbzg-zdsys-202202)the Natural Science Foundation of Henan(Grant No.232300420165)Integrated Scientific Investigation of the North-South Transitional Zone of China(2017FY100900)。
摘要Surface-latent heat(LE)and sensible heat(SH)fluxes play a pivotal role in governing hydrological,biological,geochemical,and ecological processes on the land surface in the Tibetan Plateau.However,to accurately assess and understand the spatial distribution of LE and SH fluxes across different underlying surfaces,it is crucial to verify the validity and reliability of ERA-5,GLDAS,and MODIS data against ground measurements obtained from the Flux Net micrometeorological tower network.This study analyzed the spatial patterns of LE and SH over the Tibetan Plateau using data from ERA-5,GLDAS,and MODIS.The results were compared with ground measurements from Flux Net tower observations on different underlying surfaces,and five statistical parameters(Pearson's r,LR slope,RMSE,MBE,and MAE)were used to validate the data.The results showed that:(1)MODIS LE data and ERA-5 SH data exhibited the closest agreement with ground observations,as indicated by their lowest root mean square error and mean bias area values.(2)The accuracy of ERA-5 SH was the highest in meadows and steppes,while GLDAS SH performed optimally in shrublands.Notably,MODIS LE consistently outperformed the other datasets across all vegetation types.(3)The spatial distribution of LE and SH displayed considerable heterogeneity,contingent upon the specific data sources and underlying surfaces.Notably,there was a contrasting trend between GLDAS and ERA-5,as well as MODIS,in terms of SH distribution in the shrubland.In shrublands and meadows,MODIS SH and LE exhibited more pronounced changes than ERA-5 and GLDAS.Additionally,ERA-5 SH demonstrated the opposite variation in meadow and steppe regions compared to GLDAS and MODIS.
摘要利用上海郊区奉贤夏季地表能量平衡观测资料,检验了城市陆面模式(Surface Urban Energy and Water Balance Scheme,SUEWS)的适用性及对地表覆盖变化和人类活动的敏感性。结果表明:SUEWS模式能较好再现辐射通量的日变化趋势,且能较好模拟感热通量和潜热通量日变化及量级。通过对比夏季较干燥和较潮湿月份平均波文比发现较干燥月份波文比(0.74)接近较潮湿月份(0.40)的2倍,表明空气湿度对湍流热通量有显著影响。通过多组下垫面覆盖敏感性试验发现,相对于树林而言,SUEWS模拟的感热通量和潜热通量对草地面积更为敏感,当自然地表覆盖率一定时,草地面积增大,表现为波文比的明显减小。当人口密度增大时,模拟的人为热通量明显增加,导致模拟的感热通量和波文比的明显增大。
基金supported by the National Natural Science Foundation of China(42261028)the Chinese Academy of Sciences“Light of West China”Program for Western Young Scholars(23JR6KA027)+3 种基金the Science Foundation for Distinguished Young Scholars of Gansu Province(24JRRA167)the Key Research and Development Program on Ecological Civilization Construction of Gansu Province(25YFFA012)Gansu Provincial Science and Technology Plan Fund Project(24CXGA063)Scientific Research Projects on Ecological and Environmental Protection in Heilongjiang Province in 2023(Grant No.:HST2023ZR005)。
摘要Surface albedo,as one of the important properties of the underlying surface,has a significant impact on the surface energy balance in cold regions.However,due to the complexity of the factors affecting surface albedo,existing calculations still contain inaccuracies.Therefore,this study conducted surface albedo experiments on loess with different water contents and temperatures.By analyzing the surface albedo measurements of samples with varying temperature and water content levels,as well as the soil freezing characteristic curve(SFCC)and soil-water characteristic curve(SWCC)of loess,the study explores the influence of soil temperature and water content on the surface albedo of loess.The results indicate that both the temperature and water content of loess jointly affect surface albedo.During the process of albedo change,there exists a water content threshold that alters the trend of surface albedo.Soil temperature influences surface albedo by affecting the content of pore ice and liquid water within the soil.When the water content of loess is relatively low,the surface albedo decreases as the unfrozen water content decreases.However,this trend changes as the water content of loess increases.Additionally,a decrease in soil temperature lowers the moisture content threshold during the changes in surface albedo.This study provides a reference for exploring and determining the surface energy balance in cold regions under the background of warm and humid climates,as well as for establishing thermal calculation boundaries.