Page 18 - 《高原气象》2025年第6期

高 原 气 象 44 卷
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zang Plateau （QXP） and its downstream areas through the snow albedo feedback mechanism. Given that snow
cover on the QXP is relatively thin and characterized by repeated accumulation and ablation， this paper aims to
conduct an in-depth study on the variation characteristics of soil hydrothermal processes and surface energy flux‐
es on the QXP under snow-covered and snow-free conditions. Based on daily-scale data， this study explores the
impact of snow cover on surface micrometeorological characteristics under different underlying surface types by
setting a criterion that albedo is greater than 0. 5. The research results show that the multi-year average surface al‐
bedo of the QXP is 0. 22， exhibiting a spatial distribution characteristic of "high in the northwest and low in the
southeast" and a seasonal variation pattern of "high in winter and spring， low in summer and autumn". The sur‐
face albedo of the QXP is affected by snow cover， with significant regional and seasonal differences. The area of
perennial snow cover is small， accounting for only 0. 55% of the total area. This paper selects Naqu Station，
Namors Station， and Yakou Station located in different climate zones to analyze the soil hydrothermal character‐
istics and surface energy flux characteristics under snow-covered and snow-free conditions. The main conclusions
are as follows： （1） When snow cover exists， the surface albedo at noon usually exceeds 0. 6， while under snow-
free conditions， the albedo at noon is usually lower than 0. 3； （2） When snow cover exists， the soil hydrother‐
mal synergistic effect is relatively stable. Specifically， at Naqu Station， although the snow cover state is unstable
and the heat preservation effect is weak， the presence of snow cover can reduce the fluctuation of soil tempera‐
ture. The snow cover states at Namors Station and Yakou Station are stable， and the heat preservation effect is
more obvious. Compared with the snow-free conditions， the soil temperature and soil water content are higher，
the variation range is smaller， and the soil freezing depth is shallower； （3） Under snow-covered conditions， the
closure rate of surface energy is low， and the correlation between turbulent flux and effective energy is strong.
Due to the different snow cover conditions at Naqu Station and Yakou Station， there are obvious differences in
surface energy distribution between the two stations. Regardless of snow cover， the net radiation at Naqu Station
is mainly allocated to sensible heat flux， but shallow snow cover increases the proportion of latent heat flux； at
Yakou Station， snow cover is continuous. When there is snow cover， net radiation is mainly allocated to latent heat
flux， and when there is no snow cover， net radiation is mainly allocated to sensible heat flux； when there is snow
cover， the underlying surface is wet， and the Bowen ratio is mostly below 1. 0， while when there is no snow cov‐
er， the Bowen ratio is larger； （4） In winter， when there is snow cover， the heat preservation effect of snow cover
makes the soil temperature higher than the atmospheric temperature， and the soil heat flux is mainly transmitted to
the atmosphere. As the snow gradually melts， the energy received by the surface gradually increases.
Key words： Qinghai-Xizang Plateau； snow cover； albedo； surface energy； soil moisture-thermal