摘要
利用中国西南地区云、贵、川、渝四省市95个气象台站1961—2017年逐日气温和降水量数据及NCEP/NCAR月平均再分析资料,计算了57 a来西南地区春季季节尺度标准化降水蒸散指数(SPEI),分析了西南地区春季干旱时空变化特征、干旱的异常环流特征及异常海温分布特征。结果表明,1961—2017年中国西南地区西部变暖变湿,东部变暖变干;SPEI指数存在明显的年代际变化特征;西南地区SPEI指数主模态呈整体一致分布,第二模态呈东西反相分布;对流层低层自西南地区的异常东北气流及青藏高原南侧的异常东风气流不利于源于印度洋和孟加拉湾的水汽向西南地区输送,200 hPa副热带西风急流异常对西南地区干旱有重大影响,200 hPa上西南地区表现异常辐合,配合中层显著的异常下沉运动,容易造成西南地区干旱;太平洋、印度洋海温异常,会影响大气环流,进而影响西南地区的旱涝情况。
Based on station temperature and precipitation data in the southwest of China during1961-2017 and monthly reanalysis data from NECP/NCAR,Standard Precipitation Evapotranspiration Index(SPEI)of spring in southwest of China from 1961 to 2017 have been obtained,which are used for analysis spatial-temporal variations of spring drought in the southwest of China,as well as the characteristics of anomalous circulation and the distribution characteristics of abnormal SST. Results show that the western area gets warmer and drier while the eastern area gets warmer and wetter.The SPEI has obvious interdecadal variation characteristics;The most significant mode of spring SPEI in southwest of China can be characterized by uniform distribution,the second mode is inversely eastern and western. The anomalous northeast flow from the southwest of China and anomalous easterly flow in the south of Tibetan Plateau in lower troposphere go against the water vapor from the Indian Ocean and the bay of Bengal transport to the southwest,the 200 hPa extratropical westerly jet anomaly has a great influence on the drought of southwest of China,the southwest region showed abnormal convergence in 200 hPa,with significant abnormal subsidence in the middle troposphere lead to drought in the southwest of China. SST anomalies in the Pacific and Indian oceans will affect atmospheric circulation and thus affect drought and flood conditions in the southwest.
作者
于凡越
靳立亚
李金建
YU Fanyue;JIN Liya;LI Jinjian(School of Atmospheric Science,Chengdu University of Information Technology,Chengdu 610225,China)
出处
《沙漠与绿洲气象》
2020年第6期68-76,共9页
Desert and Oasis Meteorology
基金
国家自然科学基金项目(41775070)。
