摘要
2008年1月中下旬位于西北地区东部的陇东黄土高原出现近60 a罕见阴雪低温天气,利用NCEP/NCAR大气环流资料分析了环流背景和物理量特征。结果表明:西伯利亚脊强盛,青藏高原西部低槽和中国东部弱脊维持,东亚大槽偏北,青藏高原南支气流强,控制中亚、中国北方大部和西北地区的冷气团强盛活跃,500 hPa和700 hPa西北地区东部为负距平,700 hPa降温强。700 hPa相对湿度西北地区东部处于正距平中心,500 hPa相对湿度也在70%以上。700 hPa风场在98°～110°E、35°～40°N存在明显的切变,水汽通量和散度分析表明,降雪期间低层存在水汽输送和辐合。主要降雪时段700～500 hPa散度场表现为辐合,200 hPa表现为辐散;700～200 hPa涡度场表现为正涡度区,在降雪过程中有弱的动力抬升作用,降雪强度大。
By using NCEP/NCAR data,this paper analyzed the circulation background and the physical quantity characteristic of the rare snowy and low temperature weather event occurred on January 10 to 31 in 2008 in eastern region of Gansu province.The results indicated that during this weather process,the Siberia ridge was powerful,the trough in the west Qinghai-Tibet Plateau and the weak ridge in East China persisted,with the abnormally northerly location of East Asian trough and the strong south branch jet stream in Qinghai-Tibet plateau,the cold air mass was active which controlled the middle of Asia and the North China and Northwest China.The temperature at the level of 700 hPa decreased strongly.The center of 700 hPa relative humidity positive anomaly was located in the eastern of Northwest China,and 500 hPa relative humidity was more than 70%.The 700 hPa wind had obvious shear in the range of 98°-110°E and 35°-40°N.There was transfer and convergence of moisture at the lower level during the period of snow falling,but smaller than that of autumn precipitation.The vorticity was positive from700 to 200 hPa.
出处
《干旱气象》
2011年第4期478-482,共5页
Journal of Arid Meteorology
关键词
罕见降雪
低温
天气气候分析
the rare snowfall
low temperature
synoptic and climatic analysis
