湖-冰接触型冰湖水温影响入湖冰川融水量和冰碛坝温度，对研究冰川消融和冰碛坝稳定性具有重要意义。本文基于2012—2021年对龙巴萨巴湖现场水温观测等数据，探讨冰前湖水温变化特征及影响因素。研究发现，在观测的10~200 cm深度，冰前湖水温与气温密切相关，但冰川融水的汇入影响显著。夏季受大量冰川融水汇入的影响，夏季水温均值在4 ℃左右，湖水无明显分层现象；在日水温>4 ℃时，冰湖水温主要受太阳辐射强度和日间天气条件影响，形成日间热分层现象。冬季则具有明显温度分层。龙巴萨巴湖年结冰期主要受夏季水温和冰川补给量影响，大约从10月下旬至次年5月下旬，年结冰期约200天；湖冰厚度变化显著，2月份湖冰最厚，一般在100~200 cm之间。冰湖水温的变化，通过湖水-坝体热交换对坝体内部温度场产生影响，进而影响坝体冻融状态及稳定性。

The water temperature of glacial lakes is the basis for studying the physical， chemical， biological and hydrodynamic processes of glacial lakes， as well as the material and energy exchange among glaciers， glacial lakes and moraine dams. In addition to the influence of solar radiation on the water temperature of the glacial lake， the melt water impounded by the glacial lake aggravates the complexity of the temporal and spatial variation of the water temperature of the glacial lake. Moreover， the change of the lake water temperature affects the temperature field and water field of the moraine dam through the heat exchange interaction between the lake water and the dam body， and therefor affects the stability of the dam body. Thus， it is of great significance to study the ablation of lake-terminal glaciers and the stability of moraine dams by establishing long-term field monitoring of lake water temperature and deeply analyzing the characteristics of water temperature changes in glacial lakes. Based on the data of preglacial lake temperature， solar radiation and water temperature at 10~200 cm depth obtained by the automatic observation station of Longba Saba Lake （27°57′17″ N， 88°04′55″ E， 5 499 m a.s.l.） from 2012 to 2021， this paper discussed the characteristics and influencing factors of water temperature change in preglacial lake. The results show that the changes of water temperature and annual freezing period of Longbasaba Lake is the result of many factors， such as air temperature， solar radiation intensity and glacier meltwater， among which the inflow of glacier meltwater has the most significant influence on the variation of water temperature of glacial lakes. In summer， due to the influence of a large amount of glacier meltwater， the water temperatures at different depths are not much different， and the average temperature is about 4 ℃. The water temperature of the observed 10~200 cm water depth varied little （the temperature difference is less than 0.2 ℃）， and there is no obvious stratification in the mixed state. The maximum water temperature appeared in August or September， and the temperature peak had a lag of 1-2 months to the peak of air temperature. In general， the solar radiation is reduced and the water temperature decreases at night. However， due to the influence of hydrodynamic mixing caused by glacier meltwater or floating ice on lake， it is found that at about 12 p.m.， the observed temperature rises at 10~200 cm depth （about 1~2 ℃） or hinders the cooling process of the lake water， forming the phenomenon of inverse stratification at night. Moreover， the frequency of this reverse stratification phenomenon at night also increases with the increase of water temperature. When the water temperature is > 4 ℃ throughout the day， the water temperature of the glacial lake is mainly affected by the solar radiation intensity and weather conditions of daytime， so that the surface water is stratified in days （the temperature difference between the lake water at a depth of 10 cm and 100 cm is greater than 1 ℃）， generally lasting for 2~6 h. In winter， the temperature of lake water at different depths varies greatly， and the temperature difference between 10 cm and 100 cm depths is about 1~7 ℃， and the lake water temperature shows obvious stratification feature. The annual freezing period of Longbasaba Lake is mainly affected by summer water temperature and glacier meltwater recharge. It is about 200 days from late October to late May of the next year. The thickness of lake ice changes significantly， and the thickness of lake ice is the thickest in February， generally between 100 cm and 200 cm. The inflow of glacier meltwater in summer inhibits the rise of lake water temperature to a certain extent， reducing the daily temperature difference of lake water temperature， and affecting the internal temperature field of dam body through the heat exchange between lake water and dam body， consequently affecting the melting process of buried ice and frozen soil in dam body.