2017年秋季黄河源区连阴雨成因分析
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摘要
对黄河源区2017年9月22日—10月4日连阴雨过程的环流背景及水汽特征、能量场进行了分析,结果表明:南亚高压和副高的异常变化使得此次连阴雨过程中大气环流较同期发生了显著变化;北方冷空气不断分裂南下与西太平洋副热带高压外围暖湿气流持续交汇于黄河源区,导致了这次连阴雨天气的发生;副高西侧较强的偏南气流不断把来自西太平洋和南海的水汽输送到源区,并在500~400 h Pa高度层形成水汽辐合,当500 hPa层比湿>4 g/kg时,黄河源区容易出现较强降水;在整个连阴雨期间,源区低层(主要是400 hPa高度层以下)积累了大量不稳定能量,为连阴雨发生提供了有利的热力条件。
In this paper,the analysis was carried out for the circulation background,water vapor characteristics and energy field during a continuous autumn rain process from September 22 to October 4,2017 in the source region of the Yellow River. The results indicate that the anomalous changes in the south Asian high and the subtropical high made the atmospheric circulation change significantly over the same period. The continuous convergence of the northern cold air and the warm wet air that come from the periphery of the subtropical high led to the occurrence of this continuous rain weather. The strong southerly flow of the west side of the subtropical high continuously transport water vapor from the western Pacific and the South China Sea to the source region of the Yellow River and the water vapor convergence is formed on the 500-400 hPa layer. When the specific humidity of 500 hPa layer is more than 4 g/kg,strong precipitation is easy to occur in the source region of the Yellow River. During the continuous rain period,a large amount of unstable energy accumulates in the lower layer( mainly below 400 hPa),which provides advantageous thermodynamic conditions for the continuous rain.
In this paper,the analysis was carried out for the circulation background,water vapor characteristics and energy field during a continuous autumn rain process from September 22 to October 4,2017 in the source region of the Yellow River. The results indicate that the anomalous changes in the south Asian high and the subtropical high made the atmospheric circulation change significantly over the same period. The continuous convergence of the northern cold air and the warm wet air that come from the periphery of the subtropical high led to the occurrence of this continuous rain weather. The strong southerly flow of the west side of the subtropical high continuously transport water vapor from the western Pacific and the South China Sea to the source region of the Yellow River and the water vapor convergence is formed on the 500-400 hPa layer. When the specific humidity of 500 hPa layer is more than 4 g/kg,strong precipitation is easy to occur in the source region of the Yellow River. During the continuous rain period,a large amount of unstable energy accumulates in the lower layer( mainly below 400 hPa),which provides advantageous thermodynamic conditions for the continuous rain.
引文
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[13]周建琴,晏红明,郑建萌,等.2010年9—10月云南连阴雨发生的事实和成因分析[J].高原气象,2014,33(1):106-115.
[2]李晓英,姚正毅,王宏伟,等.近52 a黄河源区降水量和气温时空变化特征[J].人民黄河,2015,37(7):16-21.
[3]王欢,李栋梁.黄河源区径流量变化特征及其影响因子研究进展[J].高原山地气象研究,2013,33(2):93-99.
[4]谌芸,李强,李泽椿.青藏高原东北部强降水天气过程的气候特征分析[J].应用气象学报,2006,17(8):98-103.
[5]田成娟,朱平,马琼,等.青藏高原东北部两次区域性大到暴雨对比分析[J].高原山地气象研究,2017,37(1):1-6.
[6]李开明,李绚,王翠云,等.黄河源区气候变化的环境效应研究[J].冰川冻土,2013,35(5):1183-1192.
[7]封建民,王涛,谢昌卫.黄河源区生态环境退化研究[J].地理科学进展,2004,23(6):56-62.
[8]张宇,李耀辉,王式功,等.中国西北地区旱涝年南亚高压异常特征[J].中国沙漠,2014,34(2):535-541.
[9]张琼,钱正安,陈敏连.关于夏季南亚高压的进一步研究Ⅰ:与我国西北地区降水关系的统计分析[J].高原气象,1997,16(1):52-62.
[10]高登义,邹捍,王维.雅鲁藏布江水汽通道对降水的影响[J].山地研究,1985,3(4):239-249.
[11]林振耀,吴祥定.青藏高原水汽输送路径的探讨[J].地理研究,1990,9(3):33-40.
[12]梁宏,刘晶淼,李世奎.青藏高原及周边大气水汽资源分布和季节变化特征分析[J].自然资源学报,2006,21(4):526-534.
[13]周建琴,晏红明,郑建萌,等.2010年9—10月云南连阴雨发生的事实和成因分析[J].高原气象,2014,33(1):106-115.