青藏高原东坡高原草甸近地层气象要素与能量输送季节变化分析

Seasonal Characteristics of Turbulent Flux and Meteorology Elements in the Atmosphere Surface Layer over the Alpine Meadow on Eastern Slop of Tibetan Plateau

  • 摘要: 本文简要介绍了青藏高原东坡理塘大气综合观测站的情况。利用该站20072008年观测资料, 分析比较了青藏高原东坡地区高原草甸下垫面情况下近地层气象要素及能量输送的季节变化特征。结果表明:理塘地区近地层气象要素及能量输送的季节变化显著, 具有明显的水热同期特点。各个季节近地层气象要素和湍流通量, 如风、气温、感热通量、潜热通量等, 日变化显著。风速、动量通量、摩擦速度等要素的平均日最大值和最小值分别出现在下午和日出前。比湿的峰值出现在日出前。辐射和热平衡分量的日均最大值与最小值分别出现在正午及日出前。地表热源强度分析表明, 理塘白天为热源, 在春夏秋三季夜间为弱的热源与冷源交替出现。在雨季, 潜热输送在陆气间热量交换过程中占主导作用, 感热输送是次要的;干季的结果与雨季相反, 感热是首要的。

     

    Abstract: In this paper, a comprehensive observatory of atmospheric boundary layer over the alpine meadow surface at Litang on eastern slope of the Tibetan Plateau by IPM, CMA (Institute of Plateau Meteorology, China Meteorological Administration) is briefly introduced.Based on the data acquired from 2007 to 2008 at Litang site, the characteristics of micrometeorology elements and turbulence flux densities in different season are preliminarily analyzed and compared.Resultsshow that: in every season the diurnal cycle of micrometeorology elements and turbulence fluxes, such as wind, temperature, sensible heat flux, latent heat flux etc., are evident.The maximum and minimum value of diurnal averaged variations of wind speed, momentum flux, fraction velocity etc.were observed in the afternoon and at sunrise respectively.The peak value of specific humidity emerges before sunrise.The maximum and minimum values of diurnal averaged variations of radiation and the components of heat energy balance were observed at the noon and sunrise.Intensity of surface heat is analyzed to be a heat source in daytime, while it's analyzed to be both a weak heat source and heat sink at night in spring、summer and autumn.In rainy season the latent heat transfer plays a dominant role in the heat transfer between the atmosphere and the land surface, while the sensible heat transfer is secondary.The result in dry season is just the reverse of rainy season, the sensible heat transfer takes the lead.

     

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