基于TRMM降水订正数据的祁连山地区最大降水高度带研究

采用TRMM卫星反演月降水数据和气象台站实测降水数据,通过误差评估等数理统计方法验证数据,并结合Kriging法对TRMM降水数据进行订正,以此研究了祁连山地区最大降水高度带的时空变化。结果表明:(1)TRMM降水数据在祁连山地区的整体适用性较好。其中TRMM降水数据与台站实测值的年均降水量相关系数达0.94;季节平均降水量的相关系数分别为春季(0.87)、夏季(0.89)、秋季(0.88)、冬季(0.70)。(2)祁连山地区27个气象台站实测值与TRMM降水数据的相关性较好,但在个别台站误差较大且存在低值高估、高值低估的现象。(3)祁连山地区年均降水量自东向西呈减少趋势。东、中、西三段最大降水高度带分别为4100 m、4500 m、4700 m,年均降水量的垂直变化率分别为16.6 mm/100 m、10.8 mm/100 m、9.8 mm/100 m。(4)1998-2016年祁连山地区东、中、西三段降水量均呈波动增加,最大降水高度带也呈波动上升趋势,祁连山地区年内各季节最大降水高度带按夏、春、秋、冬的次序降低。

Study on maximum precipitation height zone in Qilian Mountains area based on TRRM precipitation data

Atmospheric precipitation is the most important link in the process of global water vapor cycle and energy conversion, and it is the material basis for the global ecosystem to maintain stability. Therefore, it is increasingly important to monitor and forecast precipitation for regional climate analysis, water resources evaluation and hydrological process simulation. As an important ecological barrier, the Qilian Mountains plays a critical role in maintaining the natural environment and social development in Northwest China. Thus, it is of great significance to examine the distribution and variation of precipitation in the Qilian Mountains. However, there are relatively few studies on precipitation in mountainous areas due to some factors, such as insufficient measured data, complicated precipitation environment and so on, which limits the further study to some extent. In recent years, with the development of satellite inversion technology, the application of satellite to precipitation retrieval is becoming more and more mature, which provides data support for the study of precipitation in mountainous areas. Therefore, this paper uses the data of TRMM monthly precipitation and ground meteorological station precipitation, combined with the error evaluation and other mathematical statistics and Kriging interpolation method, to calibrate TRMM precipitation, so as to examine the spatiotemporal variations of the zone of the maximum precipitation in the study area. The results show that: (1) The overall performance of TRMM precipitation is good in the Qilian Mountains. The measured annual precipitation of 31 meteorological stations has a high correlation (0.94) with the TRMM data, and the correlation coefficients of the seasonal average precipitation are 0.87 (spring), 0.89 (summer), 0.88 (autumn) and 0.7 (winter). (2) The errors of some stations are large and the low values are overestimated and the high values are underestimated. (3) Annual average precipitation shows a decreasing trend from east to west in the region, and zones of the maximum precipitation in the eastern, central and western parts appear at 4100 m, 4500 m and 4700 m, respectively. The vertical variation rates of the average annual precipitation are 16.6 mm/100 m, 10.8 mm/100 m, 9.8 mm/100 m, respectively. (4) The precipitation fluctuated and increased in the eastern, central and western parts of the study area from 1998 to 2016. The zone of the maximum precipitation also shows a fluctuating upward trend. The maximum precipitation height in each season decreases in the order of summer, spring, autumn and winter.