摘要
利用NCEP／NCAR（1960-2006年）的全球再分析格点资料，研究了东亚地区水汽输送异常与重庆夏季旱涝的关系。结果表明：当重庆夏季（7～8月）降水偏多（涝）时，欧亚地区中高纬维持“两脊一槽”的“双阻”型：乌拉尔山和鄂霍茨克海地区分别存在阻高，贝加尔湖地区为一槽区。冷空气沿着贝加尔湖槽后偏北风和乌拉尔山阻塞高压的南支西风南下进入中国。热带太平洋地区为显著的高度距平正异常区。副热带地区是高度距平负异常区，西太平洋副热带高压脊线位置偏南、强度偏强。来自热带海洋地区的暖湿气流分别沿西太平洋副热带高压西南侧和经印度、盂加拉湾两条主要路径进入中国。当来自高、低纬地区的冷、暖空气在长江流域中上游相遇，就会造成重庆等长江中上游地区降水异常偏多，发生洪涝。反之，降水偏少（旱）年，在欧亚中高纬地区存在“一槽一脊”的环流形势：乌拉尔山附近为一深厚的槽区；鄂霍茨克海阻塞高压异常发展，一直延伸到贝加尔湖附近；西欧地区维持着深厚的高压脊。西太平洋副热带高压位置偏北、偏东，主体基本退出中国大陆地区。整个热带为高度距平负异常区。这样环流形势致使东亚地区中高纬地区受乌拉尔山大槽影响盛行偏南风，不利于冷空气南下。低纬地区的暖湿气流沿着西太平洋副热带高压南面的东南气流从华南进入中同。这样的环流配置易造成南下的冷空气偏弱，同时使来自热带地区的暖空气向北推进到中周华北和东北地区，致使冷、暖空气无法在长江中上游地区交汇，该区域降水显著减少，形成干旱。
Using the monthly mean reanalysis data（from 1960 to 2006） of the NCEP/NCAR, the relationship between water vapor transport over East Asia and drought and flood in summer of Chongqing is analyzed. The result shows that the distribution of water vapor over East Asia is obvious different in the abnormal years of Chongqing rainfall in summer （July, August）. When the rainfall is excessive in summer （July, August） of Chongqing, the circulation pattern of ＂two blocking＂ exists in the middle-high latitudes over Eurasian, which includes two blocking highs over Ural and Okhotsk area, respectively and a trough over Baikal. The positive departure of 500 hPa is over tropic of Pacific. The ridge line location of west Pacific subtropical high is south by south and the intensition is stronger. The middle latitudes area is low pressure area. The cool air enter into the middle latitude of China along the back of Baikal trough and south of Ural blocking, while the warm air enter into China along the southwest of west Pacific subtropical high and India and Bay of Bengal. The cool and warm air join near the basin of Yangtse Rive, which makes the flood over Chongqing city and upper-middle reaches of Yangtse Rive. When the rainfall is deficit, there is the circulation pattern of one trough one ridge. The ridge is over Ural, and the Okhotsk blocking high develops stronger to Baikal lake. There is a stronger high pressure ridge over West Europe. The position of west Pacific subtropical high is north by north and east by east. The main part of west Pacific subtropical high retreats from Chinese mainland. The whole of tropic is negative departure area. Ural makes the south wind controlling the middle-high latitudes of East Asia, which makes the cool air move to the south area difficultly. The warm air enters into China along the south of west Pacific subtropical high. This circulation pattern can＇t make the cool air and warm air joint over Yangtse Rive, then causes drought over Chongqing area.
出处
《高原气象》
CSCD
北大核心
2008年第6期1324-1332,共9页
Plateau Meteorology
基金
中国气象局气候业务建设项目"三峡库区气候监测
预警
评估业务运行和改进"
中国气象局气候变化专项项目(CCSF2007-24)
重庆市气象局气象科技课题"四川盆地夏季水汽输送异常及其与重庆旱涝的关系"共同资助
关键词
东亚地区
重庆
旱涝异常
水汽输送
西太平洋副热带高压
East Asia
Chongqing city
Anomaly of drought and flood years
Water vapor transport
West Pacific subtropical high
