新疆大气可降水量的气候特征及其变化

 利用1961—2000年NCEP/NCAR再分析逐日资料,分析了新疆地区不同季节大气可降水量（APW）的气候分布特征和变化趋势。结果表明:新疆夏季APW小于季风区界限25 mm,从该角度表明新疆为非季风区。APW空间分布呈塔里木盆地和准格尔盆地为高值区,海拔高的阿勒泰山、天山和昆仑山为低值区。APW夏季最大,但小于同纬度东部季风区,春、秋次之,冬季最少,春、秋和冬季APW与同纬度东部季风接近。APW的地理分布与实际降水量分布相反,其最大（最小）区域却为降水量最小（最大）区,受西风带影响,新疆APW模态主要表现全疆一致变化,分布稳定,与降水模态分布差异性大有显著不同,且近40 a来无显著变化趋势,表明决定新疆降水差异的根本原因不在于水汽的多少,而是由降水产生的动力条件、水汽辐合和其他因素差异决定的。

Climate Characteristics of Atmospheric Precipitable Water over Xinjiang and Its Variation

Using the daily NCEP/NCAR reanalysis data from 1961 to 2000, the features and variation trends of seasonal atmospheric precipitable water (APW) over Xinjiang region are analyzed. The results show that in summer the APW over Xinjiang is less than 25 mm—the APW limit of monsoon areas, indicating that Xinjiang is not in monsoon area. Over Tarim Basin and Junggar Basin there are the high APW,the low APW over high altitude Altay Mountains, Tianshan Mountains and Karakorum Mountains. The APW in summer is the maximum but less than the APW of eastern monsoon areas in the same latitude, that in spring and autumn is the second and that in winter is the minimum, and close to the APW of eastern monsoon areas in the same latitude. The APW distribution is opposite with the distribution of rainfall, the maximal(minimal) APW regions correspond to the minimal(maximal) rainfall regions. Influenced by westerly circulation the APW modes present accordant variations and steady distribution over whole Xinjiang area, showing prominent different from rainfall modes. The APW in Xinjiang had not obvious change trend in the last 40 years, indicating that the rainfall difference in Xinjiang is not mainly caused by the diversity of water vapor content, but by the diversity of dynamics condition, water vapor convergence and other factors.