关中平原降水、蒸发和降水蒸发差时空变化特征

Temporal and Spatial Variation Characteristics of Precipitation, Evaporation and Precipitation-Evaporation Difference in Guanzhong Plain

利用1970~2020年35个国家自动气象站降水、气温、相对湿度等资料,对关中平原降水、蒸发、降水蒸发差时空变化特征及影响因子进行分析。结果表明:1) 关中平原东北部降水、蒸发及降水蒸发差偏小,西南部偏大,西北部降水较大但蒸发较小,降水蒸发差较大;除秦岭北麓附近低海拔区域外关中平原降水蒸发差均呈下降趋势;2) 近51a关中平原春、夏、秋季降水、蒸发及降水蒸发差呈下降趋势,春季下降最明显,20世纪90年代末4个季节降水蒸发差最小,7~10月降水、蒸发及降水蒸发差大,5~6月降水量较大,蒸发旺盛,降水蒸发差偏小,其余月份降水、蒸发及降水蒸发差小;3) 关中平原降水、蒸发变化的主周期分别为16~34a和27~28a;在4~8a尺度上存在相对较强的降水蒸发差变化;4) 气温和相对湿度是影响关中平原降水、蒸发、降水蒸发差的主要气象因子,降水蒸发差与气温、相对湿度呈显著正相关。

By using the precipitation, temperature, relative humidity and other data of 35 national automatic weather stations during the period of 1970 to 2020, the temporal and spatial variation characteristics and its influencing factors of precipitation, evaporation and precipitation-evaporation difference in Guanzhong Plain are analyzed. The results show that: 1) The precipitation, evaporation and precipitation-evaporation difference in the northeastern of Guanzhong Plain are relatively little, while they are large in the southwest. In the northwest of Guanzhong Plain, precipita-tion-evaporation difference is large due to the relatively large precipitation and little evaporation. The precipitation-evaporation difference in Guanzhong Plain shows a downward trend except for low-altitude areas near the northern foot of Qinling Mountain. 2) In the past 51 years, precipitation, evaporation and precipitation-evaporation difference in Guanzhong Plain shows a downward trend in spring, summer, autumn, and an insignificant upward trend in winter, among them the most obvious decline are in spring, and the precipitation-evaporation difference is the smallest in all seasons in the late 1990s. Precipitation, evaporation and precipitation-evaporation difference are all large from July to October in Guanzhong Plain, and precipitation-evaporation difference is relatively small from May to June owing to large precipitation and strong evaporation. In the rest of the month, the three variables are all small. 3) The main period of precipitation and evaporation change in Guanzhong Plain is 16~34, 27~28 years respectively, and precipitation-evaporation dif-ference change is relatively strong on the scale of 4~8 years. 4) Temperature and relative humidity are the main meteorological factors which affecting the precipitation, evaporation, and precipitation-evaporation difference in Guanzhong Plain. Precipitation-evaporation difference has a signifi-cant positive correlation with air temperature and relative humidity.