我国新疆北部地区雪面雨日数时空变化特征分析

Spatiotemporal variation of rain-on-snow days in northern Xinjiang

在全球变化背景下,雪面雨发生频次增加,致灾风险加大,认识雪面雨时空变化特征对于防洪减灾具有重要意义。基于我国新疆北部地区42个国家气象站1960—2015年逐日气温、降水、雪深、天气现象等气象观测数据,制定降水类型、地面状态、雪深等共同判定雪面雨事件的参数化方案,进而分析新疆北部地区雪面雨日数时空变化特征及其与气温、海拔的关系。结果表明:近56 a来新疆北部地区雪面雨日数以0.3 d·(10a)^(-1)的速率呈缓慢增加趋势;空间分布上,新疆北部地区雪面雨主要集中于塔城北部、伊犁河谷、乌鲁木齐河源地区,其中塔城裕民县最多,年平均雪面雨日数12.2 d;相关分析显示雪面雨日数及雪面雨量均与海拔呈显著正相关。该研究有望提升对新疆干旱区雪面雨事件这一诱发雨雪混合洪水重要现象的科学认识,为新疆地区致灾洪水过程分析以及洪水监测预警提供参考。

Many extreme floods are caused by the rain-on-snow(ROS)events in the world. Under global warming,the rain-on-snow(ROS)event and its flood have increased and would increase in the future. It is of great significance to understand the spatiotemporal variation of ROS for flood control and disaster reduction. Based on the daily temperature,precipitation,snow depth,weather phenomenon and other meteorological observation data of42 national meteorological stations in northern Xinjiang from1960 to2015,the parameterization scheme of rain-on-snow(ROS)events was determined by using precipitation type,ground state and snow depth records.On this basis,the spatiotemporal variation characteristics of ROS days and their relationship with temperature and elevation in northern Xinjiang were analyzed. The results show that during the last56 years,the rate of0.3 d·(10 )^(-1) of ROS days in northern Xinjiang has been increasing slowly;In terms of spatial distribution,ROS in northern Xinjiang is mainly concentrated in the north of Tacheng,Ili River Valley and the headwaters of Urumqi River. Yumin county has the most ROS events,with an annual ROS day of12.2 d;Correlation analysis showed there was a significant positive correlation between the number of ROS days,ROS amount and altitude. This study is expected to improve the scientific understanding of the snow surface rain event,which is an important phenomenon of inducing rain and snow mixed flood in arid area of Xinjiang,and provide a reference for the analysis of disaster causing flood process and flood monitoring and early warning in our region.