利用2001年青藏高原及周边地区的地基GPS观测资料、M O DIS卫星遥感资料和N CEP格点再分析资料分析了青藏高原及周边地区大气水汽分布及其变化特征。研究结果表明,青藏高原东南部地区大气总水汽量的年变化在0.3～3.0cm之间,高原其它地...利用2001年青藏高原及周边地区的地基GPS观测资料、M O DIS卫星遥感资料和N CEP格点再分析资料分析了青藏高原及周边地区大气水汽分布及其变化特征。研究结果表明,青藏高原东南部地区大气总水汽量的年变化在0.3～3.0cm之间,高原其它地区大气总水汽量的年变化在0.2～2.0cm之间;青藏高原东南部河谷的导流作用非常显著,是暖湿气流进入青藏高原内部地区的重要途径;地理纬度和海拔高度决定了青藏高原地区南湿北干的大气水汽分布特征,而大气环流变化则是造成青藏高原及周边地区大气水汽分布季节变化的主要原因。展开更多
Fisher discriminant analysis can comprehensively take multiple factors into consideration and effectively conduct separations between two classes.If it can be used to detect the occurrences of drought,drought can be d...Fisher discriminant analysis can comprehensively take multiple factors into consideration and effectively conduct separations between two classes.If it can be used to detect the occurrences of drought,drought can be detected more effectively and accurately.Based on 9-year carbon flux and corresponding meteorological data,soil water content(SWC)and vapor pressure deficit(VPD)were selected as the discriminant factors.Drought occurrences were detected by applying the Fisher discriminant analysis method in an alpine ecosystem in Tibet.Fisher discriminant analysis was successfully applied to detect drought occurrence in an alpine meadow ecosystem.The soil water deficit and atmospheric water deficit were comprehensively taken into consideration.Consequently,this method could detect the onset and end date of droughts more accurately and reasonably.Based on the characteristics of drought and non-drought samples,the discriminant equation was constructed as y=24.46SWC-4.60vPD.When y>1,the days were distributed above the critical line.In addition,when y was greater than one for more than 10 days,it was labeled as one drought event.If the interval between two drought processes was less than 2 days,it was considered one drought event.With increasing the study period and continued accumulation of observation data,the discriminant equation could be further optimized in the future,resulting in more accurate drought detection.展开更多
文摘利用2001年青藏高原及周边地区的地基GPS观测资料、M O DIS卫星遥感资料和N CEP格点再分析资料分析了青藏高原及周边地区大气水汽分布及其变化特征。研究结果表明,青藏高原东南部地区大气总水汽量的年变化在0.3～3.0cm之间,高原其它地区大气总水汽量的年变化在0.2～2.0cm之间;青藏高原东南部河谷的导流作用非常显著,是暖湿气流进入青藏高原内部地区的重要途径;地理纬度和海拔高度决定了青藏高原地区南湿北干的大气水汽分布特征,而大气环流变化则是造成青藏高原及周边地区大气水汽分布季节变化的主要原因。
基金the National Natural Science Foundation of China(41725003,31600362 and 32061143037)the National Key Research and Development Program of China(2017YFA0604801)the China Postdoctoral Science Foundation funded project(2018M631819 and 2021M692230)。
文摘Fisher discriminant analysis can comprehensively take multiple factors into consideration and effectively conduct separations between two classes.If it can be used to detect the occurrences of drought,drought can be detected more effectively and accurately.Based on 9-year carbon flux and corresponding meteorological data,soil water content(SWC)and vapor pressure deficit(VPD)were selected as the discriminant factors.Drought occurrences were detected by applying the Fisher discriminant analysis method in an alpine ecosystem in Tibet.Fisher discriminant analysis was successfully applied to detect drought occurrence in an alpine meadow ecosystem.The soil water deficit and atmospheric water deficit were comprehensively taken into consideration.Consequently,this method could detect the onset and end date of droughts more accurately and reasonably.Based on the characteristics of drought and non-drought samples,the discriminant equation was constructed as y=24.46SWC-4.60vPD.When y>1,the days were distributed above the critical line.In addition,when y was greater than one for more than 10 days,it was labeled as one drought event.If the interval between two drought processes was less than 2 days,it was considered one drought event.With increasing the study period and continued accumulation of observation data,the discriminant equation could be further optimized in the future,resulting in more accurate drought detection.
