This study reveals the complex nature of the connection between Eurasian snow and the following summer season＇s monsoon rainfall by using four different indicators of snow conditions and correlating each of them to s...This study reveals the complex nature of the connection between Eurasian snow and the following summer season＇s monsoon rainfall by using four different indicators of snow conditions and correlating each of them to summer monsoon rainfall. Using 46 years of historical records of mean winter snow depth, maximum snow depth, and snow starting dates, and 27 years of snow area coverage from remote sensing observations over Eurasia, the authors found diverse correlation patterns between snow conditions and the following warm season＇s rainfall over South and Southeast Asia. Some of the results contradict the well-known inverse relationships between snow and the summer monsoon. This study provides an easy comparison of results in that it shows the connections between Eurasian snow and monsoon rainfall by using different Eurasian snow indicators based on the best available historical records without discrimination of regional variations in snow conditions.展开更多
This study investigates the statistical linkage between summer rainfall in China and the preceding spring Eurasian snow water equivalent （SWE）, using the datasets of summer rainfall observations from 513 stations, s...This study investigates the statistical linkage between summer rainfall in China and the preceding spring Eurasian snow water equivalent （SWE）, using the datasets of summer rainfall observations from 513 stations, satellite-observed snow water equivalent, and atmospheric circulation variables in the NCEP/NCAR reanalysis during the period from 1979 to 2004. The first two coupled modes are identified by using the singular value decomposition （SVD） method. The leading SVD mode of the spring SWE variability shows a coherent negative anomaly in most of Eurasia with the opposite anomaly in some small areas of the Tibetan Plateau and East Asia. The mode displays strong interannual variability, superposed on an interdecadal variation that occurred in the late 1980s, with persistent negative phases in 1979-1987 and frequent positive phases afterwards. When the leading mode is in its positive phase, it corresponds to less SWE in spring throughout most of Eurasia. Meanwhile, excessive SWE in some small areas of the Tibetan Plateau and East Asia, summer rainfall in South and Southeast China tends to be increased, whereas it would be decreased in the up-reaches of the Yellow River. In recent two decades, the decreased spring SWE in Eurasia may be one of reasons for severe droughts in North and Northeast China and much more significant rainfall events in South and Southeast China. The second SVD mode of the spring SWE variability shows opposite spatial variations in western and eastern Eurasia, while most of the Tibetan Plateau and East Asia are in phase. This mode significantly correlates with the succeeding summer rainfall in North and Northeast China, that is, less spring SWE in western Eurasia and excessive SWE in eastern Eurasia and the Tibetan Plateau tend to be associated with decreased summer rainfall in North and Northeast China.展开更多
In this work,correlation analysis is applied to study the interannual relationships betWeen indian summer monsoon rainfall of different homogeneous regions and Eurasian Snow Cover(ESC) during winter and spring seasons...In this work,correlation analysis is applied to study the interannual relationships betWeen indian summer monsoon rainfall of different homogeneous regions and Eurasian Snow Cover(ESC) during winter and spring seasons for the time period from 1973 to 1992.The monsoon rainfall of the western and central regions of india,as well as the all-India monsoon rainfall,is significantly negatively correlated with the ESC averaged for the monthsDecember-March and with,especially,the ESC of February.This study may provide some useful information for the long-range prediction of the regional indian monsoon rainfall.展开更多
本文利用日本第二次全球大气再分析项目(JRA-55)提供的逐日积雪深度数据、欧洲中期天气预报中心(ECMWF)提供的全球再分析数据及Hadley海温数据分析了春季欧亚大陆积雪异常模态及其与北大西洋海温的遥相关关系,并通过模式模拟分析验证。...本文利用日本第二次全球大气再分析项目(JRA-55)提供的逐日积雪深度数据、欧洲中期天气预报中心(ECMWF)提供的全球再分析数据及Hadley海温数据分析了春季欧亚大陆积雪异常模态及其与北大西洋海温的遥相关关系,并通过模式模拟分析验证。结果表明:春季欧亚大陆雪深前两种模态差异显著,分别表现为东、西区域同向变化及反向变化两种非对称形态。其中,同期北大西洋"三极子型"海温模态与"马鞍型"海温模态分别与雪深第一、第二模态具有显著相关关系,这两种海温模态下对应的北半球中高纬波动作用通量分别呈丝绸之路(SRP)型和欧亚波列(EU)型两种传播特征,对中高纬西风气流的位置、强度产生了不同影响,进而对欧亚雪深分布产生遥相关作用。通过局地多尺度能量涡度分析法(Localized Multiscale Energy and Vorticity Analysis,简称MSE-VA)表明,北大西洋源区有自下向上的动能传输,另外,西风急流出口的平均动能转化增加,使得高层动能累积并向外辐散,从而对下游产生遥相关作用。通过CAM5.1模式模拟研究了北大西洋"三极子型"和"马鞍型"两种海温模态下的波作用通量传播特征,结果较好地验证了来自北大西洋的波动作用通量传播呈"SRP"型和"EU"型两种特征,对应的降雪分布表明两种模态下气候场要素的变化与对应雪深模态的分布特征一致。展开更多
This paper addresses the interannual variation of winter air temperature over Northeast China and its connection to preceding Eurasian snow cover. The results show that there is a significant negative correlation betw...This paper addresses the interannual variation of winter air temperature over Northeast China and its connection to preceding Eurasian snow cover. The results show that there is a significant negative correlation between October Eurasian snow cover and following-winter air temperature over Northeast China. The snow cover located in eastern Siberia and to the northeast of Lake Baikal plays an important role in the winter air temperature anomaly. More （less） eastern Siberia snow in October can cause an atmospheric circulation anomaly pattern in which the atmospheric pressure is higher （lower） than normal in the polar region and lower （higher） in the northern mid-high latitudes. Due to the persistence of the eastern Siberia snow from October to the following winter, the winter atmospheric anomaly is favorable （unfavorable） to the widespread movement of cold air masses from the polar region toward the northern mid-high latitudes and, hence, lower （higher） temperature over Northeast China. Simultaneously, when the October snow cover is more （less）, the SST in the northwestern Pacific is continuously lower （higher） as a whole; then, the Aleutian low and the East Asia trough are reinforced （weakened）, favoring the lower （higher） temperature over Northeast China.展开更多
文摘This study reveals the complex nature of the connection between Eurasian snow and the following summer season＇s monsoon rainfall by using four different indicators of snow conditions and correlating each of them to summer monsoon rainfall. Using 46 years of historical records of mean winter snow depth, maximum snow depth, and snow starting dates, and 27 years of snow area coverage from remote sensing observations over Eurasia, the authors found diverse correlation patterns between snow conditions and the following warm season＇s rainfall over South and Southeast Asia. Some of the results contradict the well-known inverse relationships between snow and the summer monsoon. This study provides an easy comparison of results in that it shows the connections between Eurasian snow and monsoon rainfall by using different Eurasian snow indicators based on the best available historical records without discrimination of regional variations in snow conditions.
基金supported by the National Basic Research Program of China (973 Pro-gram) (Grant No. 2007CB411505)the National Key Basic Research and Development Project of China (Grant No.2004CB418300)+1 种基金Coordinated Observation and Prediction of Earth System (COPES) project (GYHY200706005)the National Natural Science Foundation of China (GrantNo. 40875052)
文摘This study investigates the statistical linkage between summer rainfall in China and the preceding spring Eurasian snow water equivalent （SWE）, using the datasets of summer rainfall observations from 513 stations, satellite-observed snow water equivalent, and atmospheric circulation variables in the NCEP/NCAR reanalysis during the period from 1979 to 2004. The first two coupled modes are identified by using the singular value decomposition （SVD） method. The leading SVD mode of the spring SWE variability shows a coherent negative anomaly in most of Eurasia with the opposite anomaly in some small areas of the Tibetan Plateau and East Asia. The mode displays strong interannual variability, superposed on an interdecadal variation that occurred in the late 1980s, with persistent negative phases in 1979-1987 and frequent positive phases afterwards. When the leading mode is in its positive phase, it corresponds to less SWE in spring throughout most of Eurasia. Meanwhile, excessive SWE in some small areas of the Tibetan Plateau and East Asia, summer rainfall in South and Southeast China tends to be increased, whereas it would be decreased in the up-reaches of the Yellow River. In recent two decades, the decreased spring SWE in Eurasia may be one of reasons for severe droughts in North and Northeast China and much more significant rainfall events in South and Southeast China. The second SVD mode of the spring SWE variability shows opposite spatial variations in western and eastern Eurasia, while most of the Tibetan Plateau and East Asia are in phase. This mode significantly correlates with the succeeding summer rainfall in North and Northeast China, that is, less spring SWE in western Eurasia and excessive SWE in eastern Eurasia and the Tibetan Plateau tend to be associated with decreased summer rainfall in North and Northeast China.
文摘In this work,correlation analysis is applied to study the interannual relationships betWeen indian summer monsoon rainfall of different homogeneous regions and Eurasian Snow Cover(ESC) during winter and spring seasons for the time period from 1973 to 1992.The monsoon rainfall of the western and central regions of india,as well as the all-India monsoon rainfall,is significantly negatively correlated with the ESC averaged for the monthsDecember-March and with,especially,the ESC of February.This study may provide some useful information for the long-range prediction of the regional indian monsoon rainfall.
文摘本文利用日本第二次全球大气再分析项目(JRA-55)提供的逐日积雪深度数据、欧洲中期天气预报中心(ECMWF)提供的全球再分析数据及Hadley海温数据分析了春季欧亚大陆积雪异常模态及其与北大西洋海温的遥相关关系,并通过模式模拟分析验证。结果表明:春季欧亚大陆雪深前两种模态差异显著,分别表现为东、西区域同向变化及反向变化两种非对称形态。其中,同期北大西洋"三极子型"海温模态与"马鞍型"海温模态分别与雪深第一、第二模态具有显著相关关系,这两种海温模态下对应的北半球中高纬波动作用通量分别呈丝绸之路(SRP)型和欧亚波列(EU)型两种传播特征,对中高纬西风气流的位置、强度产生了不同影响,进而对欧亚雪深分布产生遥相关作用。通过局地多尺度能量涡度分析法(Localized Multiscale Energy and Vorticity Analysis,简称MSE-VA)表明,北大西洋源区有自下向上的动能传输,另外,西风急流出口的平均动能转化增加,使得高层动能累积并向外辐散,从而对下游产生遥相关作用。通过CAM5.1模式模拟研究了北大西洋"三极子型"和"马鞍型"两种海温模态下的波作用通量传播特征,结果较好地验证了来自北大西洋的波动作用通量传播呈"SRP"型和"EU"型两种特征,对应的降雪分布表明两种模态下气候场要素的变化与对应雪深模态的分布特征一致。
基金supported by the National Natural Science Foundation of China(Grant Nos.41130103 and 41210007)the National Basic Research Program of China(Grant No.2009CB421406)the CAS–CSIRO Cooperative Research Program(Grant No.GJHZ1223)
文摘This paper addresses the interannual variation of winter air temperature over Northeast China and its connection to preceding Eurasian snow cover. The results show that there is a significant negative correlation between October Eurasian snow cover and following-winter air temperature over Northeast China. The snow cover located in eastern Siberia and to the northeast of Lake Baikal plays an important role in the winter air temperature anomaly. More （less） eastern Siberia snow in October can cause an atmospheric circulation anomaly pattern in which the atmospheric pressure is higher （lower） than normal in the polar region and lower （higher） in the northern mid-high latitudes. Due to the persistence of the eastern Siberia snow from October to the following winter, the winter atmospheric anomaly is favorable （unfavorable） to the widespread movement of cold air masses from the polar region toward the northern mid-high latitudes and, hence, lower （higher） temperature over Northeast China. Simultaneously, when the October snow cover is more （less）, the SST in the northwestern Pacific is continuously lower （higher） as a whole; then, the Aleutian low and the East Asia trough are reinforced （weakened）, favoring the lower （higher） temperature over Northeast China.
