内蒙古锡林郭勒牧区冬季降雪异常偏多季节预测信号研究

Disaster prevention and mitigation is a very important task in social services for meteorological organizations. The pastoral region of Xilin Gol League in Inner Mongolia locates in the mid-high latitude range of the North Hemisphere. Xilin Gol is one of very important animal husbandry bases in China. Although many researches focused on weather-scale snow forecasts in the past time, it is still a relatively difficult prediction area on climate-scale for seasonal precipitation. Serious White Disasters, which threaten the life of animals and human beings, may easily conducted by severe climate conditions of extraordinary snowfalls in wintertime. Selection of major influential factors is the most important basic step of the climate forecast. Therefore, it is a valuable to be focused and a crucial scientific project in seasonal climate forecast services to comprehensively investigating the major causes of the serious snow disasters, to analysis the evolutionary processes of the atmospheric circulations on large-scale and to explore seasonal forecast signals. The aims of this applied project is to find out the major circulation factors that lead to severe snowfall situations in wintertime, to study the dynamic functions of the ocean thermal energy and the teleconnection patterns on irregular evolutionary processes of the major influential circulation components, to test the stable, useful and predicting values of the forecast signals. Through the research of this project, we can deeply understand and get a clear recognition on the major circulation components for the serious snow seasonal predictions of the Xilin Gol pastoral region. It has academic values in climate predicting research fields. The methods of this project can be broadly used in other similar regions in North China and outcomes of it will promote our meteorological service quality of the short-term climate predictions, produce disaster prevention and mitigation plans and avoids losses of animal husbandry in advance.

防灾减灾是气象部门服务社会的重要任务之一。内蒙古锡林郭勒牧区是我国重要的畜牧基地，地处中高纬度，尽管天气尺度上对降雪过程已有不少研究，但在短期气候尺度上仍是降水预测相对困难地区。由于冬季持续偏多的降雪极易导致严重白灾，威胁人畜生存。选取预测因子是决定预测效果的关键基础，因此，针对冬季降水季节预测信号的研究是解决预测瓶颈、提高气候预测准确率需要深入研究的重要科学课题。此项目在分析冬季异常多雪气候事件的主要环流影响因子、海洋热力及大气遥相关对主要环流系统异常发展动力作用的基础上，探寻分析季节预测信号，检测信号的稳定性、可用性及效果。通过研究，使我们对引起冬季锡林郭勒牧区异常多雪气候事件影响因子的物理背景有更为清晰的认识，对短期气候预测研究具有学术价值，研究方法对北方其他地区具有推广价值，研究结果对提高锡林郭勒牧区冬季异常降雪的季节预测准确率、提前做好防灾减灾预案、减少牧业损失具有实际应用价值。

统计了59年(1961-2019年)锡林郭勒牧区及周边地区冬季日降水量及小、中、大、暴雪天气过程，建立了雪灾气候事件年谱；对比分析发现异常多/少雪年大气环流场差异显著，副高、极窝、印缅槽、贝加尔湖和乌拉尔山阻塞高压等是影响冬季降雪的主要系统；探析了环流系统从前期到同期与降雪之间的关联，研究了暴雪过程环流特征及机理；对海温变化研究结果显示夏季赤道中东太平洋海温偏高造成秋冬季Walker环流偏弱对应副高增强，有利于水汽输送；夏季SCAND模态与冬季乌山和贝湖阻高负关联显著，在分析了从海洋，大气、遥相关模态等前期状态对冬季主要环流系统影响的基础上，确定了经特征提取的一些因子信息可作为预测信号使用；多组多因子回报试验确定了最优因子组合，降雪异常偏多(R%≥25%)报出率达到76.5%，特别异常偏多(R%≥50%)达到83.3%，异常多雪A(R%≥25%) /降雪正常或偏少BN(R%＜25%)准确率达到66.1%，高于近年来对该地区的冬季预测评价得分，预测效果满意，对季节预测方法的研究具有学术价值。