Characteristics of energy transfer and micrometeorology in the atmosphere surface layer over the alpine meadow at Litang on eastern slop of the Tibetan Plateau

In this paper, a comprehensive observatory of atmospheric boundary layer over the alpine meadow surface at Litang on eastern slop 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 2009 at Litang site, the characteristics of micrometeorology elements and turbulence flux densitiec in different season are preliminarily analyzed and compared. Results show 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 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 resvers of rainy season,the sensible heat transfer takes the lead.