To gain more understanding of lake ice melting process, field research was carried out in an arctic tundra lake, Kilpisjärvi (surface area 37.1 km2, maximum depth 57 m) in the melting periods of 2013 and 2014. The heat budget of the ice cover was dominated by the radiation balance; turbulent heat fluxes were large in 2013 due to warm air advection but small in 2014. Transmittance of solar radiation through ice was 0.25 in 2013 and 0.10 in 2014, snow-ice was absent in 2013 but in 2014 accounted for 50% of the ice cover. The melting rate was 4.4 cm d-1 in 2013, 1.9 cm d-1 in 2014. The portions of surface, bottom and internal melting were, respectively, 2.9, 1.0 and 0.5 cm d-1 in 2013 and 0.8, 1.0 and 0.1 cm d-1 in 2014. Internal melting was realized in increase of ice porosity. In 2013 a rapid ice breakage event completed the ice breakup in short time when ice porosity had reached 40-50%. A lake ice melting model should include the thickness and porosity of ice, with porosity connected to an ice strength criterion. A cc ep te d A rti cl e

中文翻译：

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北极苔原基尔皮斯耶尔维湖的冰盖衰减和热平衡

为了更深入地了解湖冰融化过程，在 2013 年和 2014 年融化期在北极苔原湖 Kilpisjärvi（表面积 37.1 km2，最大深度 57 m）中进行了实地研究。冰盖的热量收支为以辐射平衡为主；2013年由于暖空气平流，湍流热通量较大，但2014年较小。2013年太阳辐射通过冰的透射率为0.25，2014年为0.10，2013年没有雪冰，但2014年占冰盖的50% . 2013 年熔化率为 4.4 cm d-1，2014 年为 1.9 cm d-1。表层、底部和内部熔化率分别为 2013 年的 2.9、1.0 和 0.5 cm d-1 和 0.8、1.0 和 0.1 cm d-1 于 2014 年。通过增加冰孔隙度实现了内部融化。2013年，一次快速破冰事件在冰孔隙度达到40-50%的情况下，在短时间内完成了破冰。湖冰融化模型应包括冰的厚度和孔隙度，孔隙度与冰强度标准相关联。接受条款