夏季金塔绿洲与沙漠次级环流近地层风场的初步分析

利用2004年6～8月在甘肃省酒泉金塔地区进行的“绿洲-沙漠能量和水分循环的野外观测试验”的风场资料，分析了该地区两种不同的绿洲沙漠低层风场结构。结果表明：绿洲沙漠的温差效应可以激发绿洲和沙漠间的次级环流，在白天绿洲沙漠边缘低层是辐散气流，夜间表现为辐合气流；在大背景风场较强的情况下，在背景风场风向方向上局地环流被掩盖，而其它方向上局地环流占主导地位；大背景风场处于转换期，如西风转东风时，当西风削弱。而东风还没有产生时，绿洲地区背景风场很小，绿洲沙漠环流较为明显。

Preliminary Analyses on Ground Level Wind Field of Second Circulation in Jinta Oasis and Desert in Summer

The experiment for energy and moisture transferringbetween oasis and desert was going from June to August 2004. Two different kinds of wind systems in Jinta oasis of Gansu province were analyzed using the observed wind data. The results showed that the second circulation was incited because of differenttemperature between the oasis and the desert. Winds blew away from the oasis in the day and converged around the desert from at nigh. The second circulation was not obvious when the background wind was strong and controlledthe parallel direction of it. The second circulation controlledthe vertical direction of the background wind. The west wind became weak and east wind didnt appear when the background wind changed. During that time, the second circulation appeared in the circle of the oasis.