To comprehensively investigate characteristics of summer droughts and floods in the Yangtze River valley, a meteorological and hydrological coupling index （MHCI） was developed using meteorological and hydro- logical...To comprehensively investigate characteristics of summer droughts and floods in the Yangtze River valley, a meteorological and hydrological coupling index （MHCI） was developed using meteorological and hydro- logical data. The results indicate that： （1） in representing drought/flood information for the Yangtze River valley, the MHCI can reflect composite features of precipitation and hydrological observations; （2） compre- hensive analysis of the interannual phase difference of the precipitation and hydrological indices is important to recognize and predict annual drought/flood events along the valley; the hydrological index contributes more strongly to nonlinear and continuity features that indicate transition from long-term drought to flood conditions; （3） time series of the MHCI from 1960-2009 are very effective and sensitive in reflecting annual drought/flood characteristics, i.e. there is more rainfall or typical flooding in the valley when the MHCI is positive, and vice versa; and （4） verification of the MHCI indicates that there is significant correlation between precipitation and hydrologic responses in the valley during summer; the correlation coefficient was found to reach 0.82, exceeding the 0.001 significance level.展开更多
The characteristic distributions of regional sand-dust storm （SDS） weather processes over Northeast Asia from 1980 to 2011 were investigated using the shared WMO surface station meteorological data, atmospheric soun...The characteristic distributions of regional sand-dust storm （SDS） weather processes over Northeast Asia from 1980 to 2011 were investigated using the shared WMO surface station meteorological data, atmospheric sounding data, China high density weather data, NCEP/NCAR reanalysis data, as well as the archived original weather maps of China. The concentration-weighted trajectory （CWT） method was used to calculate the SDS frequency from the discrete station data and to track the large-scale regional SDS weather processes in Northeast Asia. A spline trend analysis method was employed to investigate the variability of the SDS weather systems. The results show that during 1980-2011, the SDS weather processes exhibit both a historical persistence and abrupt transitions with an approximate 10-yr high-low occurrence oscillation. Through composite analysis of atmospheric circulation during high and low SDS years, it is found that the SDS occurrences are closely related to the anomalies of arctic vortex and midlatitude westerly, and the circulation patterns around the Lake Baikal. During the high frequency years, the meridianal flows in the upper and mid troposphere above the high SDS corridor in East Asia （from the Lake Balkhash along Northwest and North China, Korean Peninsula, meridianal flows during the low SDS frequency years, the midlatitude regions. and Japan Islands） are apparently stronger than the favoring the development and transport of SDSs in the midlatitude regions.展开更多
基金supported by project GYHY201106050the National"973"Program of China under Grant No.2011CB403404,and Project No.2009Y002
文摘To comprehensively investigate characteristics of summer droughts and floods in the Yangtze River valley, a meteorological and hydrological coupling index （MHCI） was developed using meteorological and hydro- logical data. The results indicate that： （1） in representing drought/flood information for the Yangtze River valley, the MHCI can reflect composite features of precipitation and hydrological observations; （2） compre- hensive analysis of the interannual phase difference of the precipitation and hydrological indices is important to recognize and predict annual drought/flood events along the valley; the hydrological index contributes more strongly to nonlinear and continuity features that indicate transition from long-term drought to flood conditions; （3） time series of the MHCI from 1960-2009 are very effective and sensitive in reflecting annual drought/flood characteristics, i.e. there is more rainfall or typical flooding in the valley when the MHCI is positive, and vice versa; and （4） verification of the MHCI indicates that there is significant correlation between precipitation and hydrologic responses in the valley during summer; the correlation coefficient was found to reach 0.82, exceeding the 0.001 significance level.
基金Supported by the Special Project on Public Welfare of Forestry(200804020)National Science and Technology Support Program of China(2008BAC40B02)+2 种基金National Natural Science Foundation of China(40875077)National Basic Research and Development(973)Program of China(2011CB403404 and 2011CB403401)Projects of the Chinese Academy of Meteorological Sciences(2010Z002,2009Z001,and 2009Y002)
文摘The characteristic distributions of regional sand-dust storm （SDS） weather processes over Northeast Asia from 1980 to 2011 were investigated using the shared WMO surface station meteorological data, atmospheric sounding data, China high density weather data, NCEP/NCAR reanalysis data, as well as the archived original weather maps of China. The concentration-weighted trajectory （CWT） method was used to calculate the SDS frequency from the discrete station data and to track the large-scale regional SDS weather processes in Northeast Asia. A spline trend analysis method was employed to investigate the variability of the SDS weather systems. The results show that during 1980-2011, the SDS weather processes exhibit both a historical persistence and abrupt transitions with an approximate 10-yr high-low occurrence oscillation. Through composite analysis of atmospheric circulation during high and low SDS years, it is found that the SDS occurrences are closely related to the anomalies of arctic vortex and midlatitude westerly, and the circulation patterns around the Lake Baikal. During the high frequency years, the meridianal flows in the upper and mid troposphere above the high SDS corridor in East Asia （from the Lake Balkhash along Northwest and North China, Korean Peninsula, meridianal flows during the low SDS frequency years, the midlatitude regions. and Japan Islands） are apparently stronger than the favoring the development and transport of SDSs in the midlatitude regions.
