中国西北部乾燥地域(HEIFE領域)の様々な地表面における気象要素と熱収支特性

概要

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Surface meteorological and heat balance were analyzed based on various surface conditions over arid region in northwest China (HEIFE area). The different surface conditions were clearly observed in summer rather than in winter. Summer data were selected from the HEIFE database. Significant evening peaks of vapor pressure were also observed in Linze oasis as well as Zhangye oasis. And the peak was accompanied by air temperature dip and relative humidity peak in the lower layer. However, the peak cannot be observed in high wind condition as the mechanical mixing reduces the vertical gradients of air temperature and humidity. The oasis can be characterized by low wind speed due to wind sheltering by plants. In winter, plant activities are reduced and surface conditions are almost similar for desert and oasis, leading to no peak of vapor pressure. Surface heat balances were also analyzed based on 4-component radiation measurement and sensible and latent heat flux measurements by eddy covariance method. Net radiation in the oasis area is about 50% larger than desert area due to the smaller upwelling radiation in oasis. Heat distribution into sensible heat and latent heat was different between oasis and desert. This unbalance of heat can lead to local circulation between oasis and desert as "desart-oasis interaction".
2002-09-20