2001及2003年夏季青藏高原及附近大气热源(汇)的变化特征

Atmospheric Heat Source/Sink Change Characteristics Over Qinghai-Xizang Plateau and Its Vicinity Region in Summer of 2001 and 2003

利用NCEP/NCAR再分析资料,计算了2001及2003年青藏高原及其附近地区的大气热源(汇),再用CEOF方法分析了它俩的异同。结果表明:(1)该两年冬夏季节转换前的4月份,热源(汇)分布相似,强度不同;季节转换后的6月份,热源(汇)分布明显不同,强度也有很大差异;(2)该两年分别在青藏高原南侧到孟加拉湾北部和阿拉伯海东部到印度半岛西侧各有一个高值中心,但强度明显不同:表现为2001年夏季孟加拉湾地区的热源强度明显比阿拉伯海地区强,2003年夏季则相反;(3)两年季节转换期间的5月到6月下旬期间,高原及其南侧的热源变化趋势也是不同的。2003年6月下旬达最强值;2001年则是5月中下旬到6月初已达到较强,到6月下旬又突然减弱;(4)该两年<Q1>第一特征向量的空间位相上也是不同的。在2001年,印度半岛中部是晚位相中心,其四周的位相都相对较早,位相差近180°,因此印度半岛大部与其周围的大气热源(汇)有近似相反的变化趋势;而在2003年情况则有所不同,印度半岛与其两侧的阿拉伯海和孟加拉湾北部仅是一个相对高晚位相区,其西北部和南端是晚位相中心,高原南部和赤道附近的洋面上是早位相区。因此,在2003年的大气热源(汇)变化趋势与2001年有明显的不同。2001及2003年夏季青藏高原及其附近地区大气热源(汇)的这些差异可能正是影响我国江淮地区严重干旱/洪涝的原因之一。

Using the NCEP/ NCAR data, the atmospheric heat source and convergence （Q~） of the Qinghai-Xizang Plateau and its vicinity region in 2001 and 2003 were computed. Through the method of CEOF, the differences of Q1 between 2001 and 2003 were analyzed. The results show that： （1） In April, the initial time of season change, the distribution of Q1 in 2001 and 2003 is similar, but intensity is different. In June, the time after season change, the distribution of Q1 is obvious different and the intensity is different too. （2） There is high value center on the south side of Qinghai-Xizang Plateau to the north Bengalese gulf and the Arabian sea eastern regions to the peninsula west side of India in 2001 and 2003, respectively, but intensity is obvious different： The change of heat source of Bengalese gulf region in summer of 2001 is stronger than the Arabian sea region but summer of 2003 is contrary. （3） During the period of season change from May to the end of June, the change trend of Q1 of the Plateau and its south side is different too. the maximum value appears the end of June in 2003, the amplitude has already reach a strong level in the middle of May to beginning of June in 2001, and suddenly down in the last ten days of June. （4） the space of the first characteristic vector 〈Q1〉 in 2001 and 2002 is also different. In 2001, there are two main paths： one is from the south of India peninsula to the southwest of Bengalese gulf, and another face to west from the north of Arabian Sea. In 2003, the main path face to north from the south of India peninsula. These differences of heat source （convergence） of atmosphere in 2001 and 2003 may be exactly the reason for difference of our country weather and atmospheric circulation.