华北地区大气水汽含量特征及其变化趋势

使用美国国家环境保护委员会/国家大气研究中心(NCEP/NCAR)1948-2003年再分析格点资料,研究了华北地区大气中水汽含量的时空分布特征、沿375°N不同经度和沿115°E不同纬度大气中水汽含量的年变化、大气中水汽含量的变化趋势。分析结果表明:①华北地区大气中水汽含量主要集中在东部和南部,西部和北部水汽含量较少;②华北地区大气中水汽含量夏季最多,冬季最少;③华北地区大气中水汽含量自20世纪50年代末至80年代中期呈持续下降趋势。大气水汽含量高值期出现在20世纪40年代末至70年代中期。70年代中期至21世纪初期,大气水汽含量距平基本处于0线以下,为低值期;④华北地区大气水汽含量的年际波动变化与厄尔尼诺(ElNino)与南方涛动(ENSO)事件有很好的相关性。

Water vapor content in the atmosphere and its variation trend over North China

Based on the NCEP/NCAR global re-analysis grid data(2.5°×2.5° Lat/Lon) for 56 years (1948-2003), the water vapor contents in the atmosphere are calculated over North China.We analyze the geographic distribution of water vapor content in the whole atmospheric layer, annual variations of water vapor content along 37.5°N, annual variat ions of water vapor content along 115°E and the inter-annual variations of water vapor content from 1948-2003 over North China.The result shows that (1) the water vapor content in the atmosphere over Huabei areas mainly concentrates in the east and the south, but there is very little in the west and the north; (2) the water vapor content in the atmosphere over Huabei areas reaches the maximum in summer, and the minimum in winter; (3) the tendency of water vapor content in the atmosphere over Huabei areas is continually decreasing from the end of fifties to the middle of eight ies of the 20th contury.From the end of forties to the middle of sevent ies of the 20th contury, there exists higher water vapor content in the atmosphere; from the middle of seventies to the beginning of 21th century, the anomaly of water vapor content in the atmosphere is basically below zero, namely, the period of low value; and (4) there are obviously correlations between the inter-annual vacillation of water vapor content and the ENSO events.