资源环境科技发展态势分析平台

Snow cover on the Tibetan Plateau (TP) affects the surface heating in spring and then modulates the Asian summer monsoon. The snow of the TP is known for the thin thickness and rapid change, different from that in high-latitude areas. However, many reanalysis data and model products cannot well capture the variation of the TP snow, partly related to poorly understanding of water and heat transfer through the snowpack. Using the observation data, this study documents the characteristics of water-heat transfer and effective thermal conductivity of a snowpack that lasted more than five months in the eastern TP. The main results are as follows: The negative sensible heat flux (H) prevailed during the snow cover period and nearly half energy of latent heat flux (LE) was derived from H. With the melting of snow, H and LE increased rapidly, and strong LE persisted for more than a month. Diurnal snow albedo presented an asymmetric U-shaped pattern, with the minimum value at 13:00–16:00. The snow albedo around noon mostly ranged from 0.6 to 0.8 and can reach 0.95 for the fresh snow. Frequency of strong temperature gradients was significantly higher in the upper and bottom snowpack than in the middle, in which the largest gradient (151.8 °C m⁻¹) appeared in November. The proportion of weak gradients was much less than that in other areas. Duration of isothermal snowpack is transient during the snow melting period. The soil heat flux at −0.05 m increased almost linearly throughout the snow cover period, and the turning point from negative to positive appeared in late March. Around noon in late March, the upper snow layer was warmer than the bottom layer, and the snow temperature increased gradually from bottom to top in afternoon, opposite to the previous pattern. The effective thermal conductivity of snow slowly increased from November to mid-February and increased dramatically in late March, whose average values were 0.075 ± 0.02 W m⁻¹ K⁻¹ for the bottom snow (0.01–0.08 m) and 0.04 ± 0.013 W m⁻¹ K⁻¹ for 0.01–0.15 m. This study will bring to light the verification and simulation of the TP snow.