Preliminary analysis of heat budget over the arctic tundra

摘要

Using the micrometeorological data (Harazono et al., 1995) obtained at the Arctic Tundra at Barrow, Alaska in the summer of 1993, preliminary analysis was made and the daily and seasonal variations of evapotranspiration, radiation, ground heat flux, and surface temperature were estimated. On fine days, the value of sensible and latent heat fluxes increased to maximums of approximately 200 to 300 Wm~(-2) during the midday, then decreased to about zero (sensible heat flux) and -30 to -80 Wm~(-2) (latent heat flux) around the time of the sun's northing. It is found that the surface evaporation efficiency #beta#, having a mean value of 0.3, decreases with increasing wind speed. Using a model calculation, it is obtained that the mean value of evapotranspiration at the IBP site for 71 days, from 16 July to 25 August, is 0.89 mmd~(-1) which is 40 percent of the potential evaporation (defined by Kondo and Xu, 1997a).