Characteristics and influencing factors of lake ice growth and decay in a shallow lake from a cold region<sup>*</sup>

基于2019-2020期间在盘锦市含章湖利用浮式观测平台开展湖冰原型观测试验，分析不同因素对湖冰变化造成的影响.结果表明：99 d冰期内湖冰的生消过程可概述为：湖泊封冻（3 d）-稳定生长（62 d）-冰厚稳定（7 d）-加速消融（24 d）-破碎分解（3 d）.生长期冰厚的平均增长速率为0.4 cm/d，最大冰厚为30.7 cm；不同深度（5~17 cm）冰温对气温变化的响应存在滞后性，滞后时间为70~158 min，冰温与气温的最大相关系数为0.52~0.89；降雨过程造成冰面反照率由0.22降至0.09，影响了冰内温度以及冰下40 cm以内的浅层水温，但14 mm的降雨量并未引起表面冰厚增加；降雪过程造成冰面反照率由0.25升至0.90，同时阻碍了5 cm以内的浅层冰温对气温变化的响应，但风速长时间大于8 m/s时会导致冰面积雪被吹散，冰面重新裸露；消融期冰厚的衰减过程呈抛物线趋势，存在显著的加速过程，融化速率由0.3 cm/d逐渐增加到2.7 cm/d；湖冰生长期的冰底热通量均值为4.8 W/m²；到消融期增加至8.1 W/m²，为生长期的1.7倍；太阳辐射与湖冰边界侧向融化是导致湖冰加速融化的关键因素.本研究填补了国内湖冰冻融全过程实测资料的空缺，为湖冰热力学模型的改进提供了科学支撑.;Based on the prototype observation experiment of lake ice used a floating observation platform in Lake Hanzhang, Panjin City during 2019-2020, the impact of different factors on the evolution of lake ice was analyzed. The results showed that: the growth and decay processes of lake ice in 99 days can be summarized as follows: freeze up (3 d)-stable growth (62 d)-ice thickness stability (7 d)-accelerated decay (24 d)-break up (3 d). The average growth rate of ice cover during the growth period was 0.4 cm/d, and the maximum ice thickness was 30.7 cm. The ice temperature at different depths (5-17 cm) had a lag in response to air temperature changes, the lag time was 70-158 min, and the maximum correlation coefficient between ice temperature and the air temperature was 0.52-0.89. The rainfall reduced the albedo from 0.22 to 0.09, which affected the ice temperature and the shallow water temperature within 40 cm below the ice, but the rainfall of 14 mm did not increase the ice thickness on the upper surface. The snowfall increased the albedo from 0.25 to 0.90, and at the same time prevented the shallow ice temperature within 5 cm from responding to temperature changes, but the wind speed greatly controlled the duration of this effect. However, when the wind speed was greater than 8 m/s for a long time, the snow on the surface of the ice cover will be blown away, causing the ice surface to be exposed again. The attenuation processes of ice thickness during the melting period showed a parabolic trend, and there were significant acceleration processes. The melting rate gradually increased from 0.3 cm/d to 2.7 cm/d. The average water-to-ice heat flux of the lake ice during the growth period was 4.8 W/m². It increased to 8.1 W/m² during the decay period, which was 1.7 times that of the growth period. Solar radiation and the lateral melting behaviour of the lake ice boundary were the key factors leading to the accelerated melting of lake ice. This study fills the gap of the measured data of the whole processes of lake freezing and melting in China, and provides scientific support for the improvement of the thermodynamic model of lake ice.