摘要
为了更好地理解华北及西北地区的夏季降水气候 ,我们利用NCEP的再分析格点资料等 ,对华北和西北两区干、湿年 (月 )的水汽场及夏季风状况作了对比分析。主要结论是 :(1)近 5 0年来华北和西北区东部明显干旱化 ,这可能与同期内东亚夏季风强度趋弱 ,大气可降水量逐渐减少有关 ;(2 )两地区干、湿年 (月 )间气柱可降水量差别明显 ;(3)两地区干、湿年 (月 )的夏季风、水汽输送通道的位置及强度 ,以及水汽通量的辐散辐合情况均不同 ;(4 )高原与太平洋间的海陆温差指数及东亚夏季风指数(SMI)对表征东亚夏季风的季节变化及夏季风强度的年际变化有一定的能力。冬春季高原与太平洋间的海陆温差对其后东亚夏季风的强弱及西北和华北区的干湿状况有部分指示意义 ;作西北区夏季降水预报时要注意四川盆地的水汽场及广元—汉中一带 ,以及闽、台和两广的水汽输送状况。
In order to better understand the precipitation climate over North China (hereafter NC) and Northwest China (NWC) in summer months (JJA), in this paper, the linkages between the water vapor fields and moving northward of East Asia Summer Monsoon (EASM) during five dry and wet years (months) over NC and NWC regions have been investigated by utilizing the NCEP reanalysis gridded data. The main results are as follows: (1) The precipitable water in NC and the east part of NWC was obviously decreasing since 1950' s, it may relate to the getting weak EASM in the same period. (2) There are considerable differences in the summer column precipitable water over NC and NWC in dry and wet years (months). (3) The EASM circulation, the position and strength of water vapor transport channels, along with the convergence and divergence of water vapor flux are quite different from each other during the dry and wet years (months) over NC and NWC. (4) It seems that the different land|sea thermal contrasts cause firstly the different conditions of moving northward of the EASM, then cause again the different dry and wet years (months) over NC and NWC. And also the upper air temperature difference index between Qinghai-Xizang Plateau and West Pacific Ocean and the surface EASM index have certainly ability to explain the abrupt seasonal change and the interannual variation of EASM.
出处
《高原气象》
CSCD
北大核心
2003年第1期14-23,共10页
Plateau Meteorology
基金
中国科学院知识创新工程重要方向项目(ZKCX2 SW -2 10 )
国家自然科学基金项目 ( 4 0 175 0 2 2 )
973项目 (G19980 40 90 8)的共同资助
关键词
水汽场
可降水量
水汽输送通量
海陆对比
夏季风指数
华北地区
东亚地区
湿年
干年
降水
西北地区
Contrast analyses of dry and wet years (months) in NC and NWC
Precipitable water
Water vapor transport flux
Land-sea thermal contrast
Summer monsoon index
