青藏高原东南缘近地层微气象学特征对比分析
Comparative Analysis of Surface- layer Micrometeorological Characteristics in the Surrounding Area on the Southeast Edge of Tibetan Plateau
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摘要: 本文利用位于青藏高原东南缘的温江和大理大气边界层野外观测资料,对比分析了两站包括风温湿、辐射、湍流通量等在内的近地层微气象学特征,主要结果如下:(1)两站风速值均随着高度的增加而增大,但温江站冬季4~10 m风速在白天出现随高度减小的现象。温江站冬季以东北风为主,夏季以西北风和南风为主;大理站冬季以东南风为主,其次为西南风,夏季则以东风和东南风为主。两站近地层逆温和逆湿现象都非常显著。(2)同一季节温江站大气逆辐射和地表长波辐射大于大理站,向下短波辐射小于大理站。温江站地表长波辐射总是大于大气逆辐射,而大理站白天地表长波辐射大于大气逆辐射,晚上则相反。(3)温江站感热通量冬季大于大理站,夏季小于大理站,而潜热通量无论冬夏都要小于大理站。两站潜热通量均大于感热通量,并且大理站潜热通量月平均日变化值全天始终大于零。无论冬夏,温江站土壤热通量都要小于大理站,随着深度的增加两站土壤热通量均有位相上的延迟。Abstract: By using the field observational data in Wenjiang and Dali site on the southeast edge of Tibetan Plateau in January and July of 2008 which represent winter and summer season respectively, some micrometeorological characteristics are preliminarily analyzed and compared. The main results are as follows: (1) Wind speed both in two sites rises up as height increasing, but in the layer of 4- 10 m it decreases with height increasing in the daytime in Wenjiang site. As to frequency distribution of wind direction, northeast wind is dominant in winter and northwest / south wind in summer in Wenjiang site; the main direction in Dali site is southeast / southwest wind in winter and east / southeast wind in summer. Temperature inversion and humidity inversion phenomena in the surface layer are remarkable both in two sites. (2) In the same season, atmospheric counter radiation and surface longwave radiation in Wenjiang site are bigger than those in Dali site, but solar radiation is smaller. Surface longwave radiation is bigger than atmospheric counter radiation in Wenjiang site in the whole day, while in Dali site, it shows the same trend in the daytime and the opposite trend in the nighttime. (3) Sensible heat flux in Wenjiang site is bigger than that in Dali site in winter and smaller in summer, but latent heat flux is smaller than that in Dali site both in winter and summer. Latent heat flux is higher than sensible heat flux both in two sites and diurnal average of latent heat flux is above zero all the day in Dali site. Soil heat flux in Wenjiang site is smaller than that in Dali site and has phase delay with depth increasing.