The surface energy budget on the debris-covered Koxkar Glacier in China

Energy fluxes were measured by using the eddy covariance system plus an automatic weather station at the debris-covered area on Koxkar Glacier from March to August, 2009. The coldest month of the glacier was January, and air temperature reached a maximum in July and August. Wind velocity at 2.0 m was higher in summer and lower in winter as a whole. Precipitation was concentrated from May to September and accounted for about 80 % of the total. Daily latent heat fluxes were higher than daily sensible heat fluxes during the observation period. The main reason for higher latent heat fluxes from March to April was snow cover. From June to August, latent heat fluxes during the daytime were limited by surface water content, and were lower than sensible heat fluxes, but latent heat fluxes were higher than sensible heat fluxes during summer nights because of air convection in the debris layer. Summer evaporation was higher than in the spring, and evaporation was 53.7 % of the precipitation from 19 June to 23 August. The Bowen ratio ranged from −2.0 to 2.0 at the site.