宁夏水汽输送气候特征

利用NCEP／NCAR和欧洲中心提供的逐日、逐月再分析资料（包括风场、湿度场资料，分别为17层等压面和23层等压面）和地面气压场资料，计算了宁夏区域的水汽汇和水汽通量。结果表明：宁夏区域水汽汇空间分布在春季为南北正东西负型，夏季为中间正、东西侧负型，秋季为南正北负型，冬季为东正西负型。夏季整个区域的水汽汇为正值。各季的多年时间变化具有相似的特点，为线性减少趋势，3次曲线拟合为先增后减再增的趋势。宁夏地区的水汽来自3个方向：西向、西南向和东南向，其中西南向的值较大，是宁夏的主要水汽通道。多年水汽汇的19a周期通过了0．1信度的红噪声检验，多年水汽汇序列变化较为剧烈，发生了多次突变。

Analysis on Characteristic of Vapor Transportation in Ningxia

Based on the reanalysis data of the global daily and monthly mean wind and humidity fields provided by NCEP/NCAR and ECMWF as well as surface pressure fields, the moisture sink and vapor transport flux in Ningxia were eaculated. The results show that in spring there was positive moisture sink in north and south region, and negative in east and west region of Ningxia, in summer it was positive in the middle region and negative in east and west sides, and in autumn it was positive in south and negative in north, in winter it was positive in east and negative in west. In summer, the moisture sink in the whole region was positive. The temporal changes of moisture sink were similar in four seasons and presented decline trend, the cubic curve fitting showed increase - decrease - increase trend. The vapor over Ningxia came from west, southwest and southeast direction, but the vapor mainly from southwest. The 19 -year period of moisture sinks was through the red noise test at 0.1 confidence level, and the moisture sink sequence changed sharply these years.