2008-2013年库姆塔格沙漠及阿尔金山降水特征

库姆塔格沙漠极端干旱,而其南部阿尔金山比较湿润.研究库姆塔格沙漠及南部阿尔金山的降水特征,对揭示库姆塔格沙漠水源补给机制和地貌形成原因具有重要作用.本文利用中国自动气象站与CMORPH融合逐时降水量0.1°网格数据集,分析了库姆塔格沙漠及阿尔金山的降水特征.结果表明:(1)库姆塔格沙漠降水主要集中在夏季,其他季节降水较少;而阿尔金山降水主要集中在春、秋两季,并存在一条降水量大值带,3月范围最大而夏季消失;(2)阿尔金山对库姆塔格沙漠的水源补给作用主要体现在春、秋两季,夏季降水基本与库姆塔格沙漠持平,春季降水超出库姆塔格沙漠最多;(3)阿尔金山各月平均逐小时降水量演变特征有很大不同,冬季12、1月及夏季6、7月每月逐时降水演变特征以"凌晨型"为主,可能与凌晨云顶辐射冷却引起的大气层结不稳定有关;春、秋两季每月逐时降水演变特征以"午后-黄昏型"为主, 可能与午后太阳辐射地面加热引起的大气层结不稳定有关;2、8月是两种类型的过渡时期.本文研究结果可为探索库姆塔格沙漠水源补给机制以及"羽毛状沙丘"独特的沙漠景观形成原因提供一定的参考依据.

Precipition during 2008-2013 in the Kumtagh Desert and Altun Mountains

The Kumtagh Desert is an extremely arid desert, while the Altun Mountains, southward of the Kumtagh Desert, is quite moist. Thus, We expect that a comparison of the precipitation in these two regions could provide some insight about the water supply mechanism and topography formation of the Kumtagh Desert. To this end, we analyzed China automatic observation stations-CMORPH combined 0.1° grid hourly precipitation dataset. We first found that precipitation in the Kumtagh Desert mainly concentrated in summer while concentrated in spring and autumn in the Altun Mountains, and that there existed a large precipitation belt in the Altun Mountains, which was most extensive during March but almost disappeared in summer. Therefore, the Altun Mountains mainly provided water supplement to the Kumtagh Desert during spring and autumn and precipitation of these two regions was most different in spring while almost comparable in summer. Also we found that the monthly mean hourly precipitation in the Alutn Mountains varied significantly with season: "the early morning" type dominated in December and January of winter and in June and July of summer, which may be related with instability resulted from cloud top radiation cooling; "the afternoon-twilight" type dominated in spring and autumn, which may be related with the instability resulted from surface heating by solar radiation in afternoon; February and August are the transition periods. Our findings could provide a basis for further exploration of the water supply mechanisms and the unique "feathery dunes" landscape in the Kumtagh Desert.