气温对西藏冰湖溃决事件的影响

Impact of Temperature on Glacier-Lake Outbursts in Tibet

西藏冰湖溃决是多因素引发的突发事件。由于溃决冰湖多位于高海拔、人烟稀少的地方,对于其独特的地貌因素、构造成分提取十分困难,所以作者仅研究气温这一易获取的重要因素对西藏冰湖溃决的影响。冰湖溃决与气候的波动变化有着密切联系,在全球平均地表温度持续上升的背景下,研究气温对于西藏冰湖溃决的影响,是十分重要的。考察了西藏的14次溃决事件,结合邻近12个溃决冰湖的9个气象站的年值气象资料和日值气象资料进行分析,发现冰湖溃决是年均温剧烈波动后区域响应的结果,波动越大,冰湖溃决发生的几率越大。还研究了溃决当年和溃决前一年的正积温值(T)和积温增长速度(积温拟合曲线指数a),发现溃决事件发生当年的正积温值和积温增长速度普遍大于溃决的前一年。根据正积温值与积温拟合曲线指数,建立幂函数曲线公式来界定易溃决事件和不易溃决事件。根据上述分析,推荐选择长序列的正积温值与积温曲线指数,作为考量指标以研究西藏冰湖溃决事件。

Glacier-lake outburst is closely related to temperature fluctuation.With the global warming,it is important to study the relationship between them.The authors try to find out the relationship based on the temperature data associated with 14 glacier-lake outburst events in Tibet.It is found that the outburst is sensitive to acute change in annual temperature.Most outbursts occur at the years with abnormal change in temperature.According to this study,the probability of outburst depends on temperature series in many years.According to the combination with positive accumulated temperature（T） and exponent（a） of fitting curve that is fitted for accumulated temperature,we can distinguish low-possibility outbursts and high-possibility outbursts by power function.The authors recommend long time series of total accumulated temperature and exponent of accumulated temperature curve is effective way to study glacier-lake outburst.