| 摘要: |
| 采用1961—2016年西南区域4省（市）的地面观测资料、NCEP/NCAR再分析资料以及全球海温资料，对西南区域降水的时空分布特征以及其持续性干旱事件的气候特征及其环流成因进行了分析。结果表明：①西南区域的降水呈现东部南部多、西北少的空间分布特征，1986年为降水显著突变点，此点至今降水明显下降；西南区域的年降水存在显著的准3 a和准8 a的振荡周期；②近56 a西南区域共有8次持续性干旱事件发生，最多时段是20世纪60年代，春旱和冬旱最频繁，秋旱其次；③孟湾北部的异常反气旋环流和南海的异常气旋环流隔断了西南区域必要的水汽通道，水汽通量辐散；西南区域上空的异常反气旋环流，以及贝湖至中西伯利亚的异常气旋环流使得冷空气的活动区域被限制在中高纬地区，印缅南支槽偏弱，副高位置偏东偏南、强度偏弱，西南区域处于明显的下沉运动控制之下，配合海平面气压的负异常特征，使得温度持续偏高，从而导致西南区域持续性干旱的发生；前期中东太平洋的拉尼娜现象和中国近海地区的海温异常分布可作为西南区域持续性干旱事件的长期预测线索。 |
| 关键词: 西南区域；持续性干旱；成因分析 |
| DOI： |
| 投稿时间：2020-03-06 |
| 基金项目:国家自然科学基金项目（41865005）：贵州凝冻灾害事件特征和成因及其预报预测研究；中国气象局气候变化专项（CCSF201708）：西南区域持续性干旱特征及成因分析 |
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| Study on Precipitation Distribution and Persistent Drought in Southwest China in Recent 56 Years |
| YANG Chunyan,YAN Xiaodong,XIA Yang,LI Zhongyan,LIU Xiang,FAN Qian |
| (Meteorological Bureau of Qianxinan Buyei and Miao Nationality Autonomous Prefecture, Xingyi 562400 , China;Guizhou Climate Center, Guiyang 550002 , China;Liupanshui Meteorological Bureau, Liupanshui 553000 , China;Chongqing Meteorological Service Center, Chongqing 401147 , China) |
| Abstract: |
| Using the ground observation data of four provinces (cities) in Southwest China from 1961 to 2016, NCEP / NCAR reanalysis data and global sea temperature in recent 56 years, the spatial-temporal distribution characteristics of precipitation in southwest region and the characteristics and causes of persistent drought events in recent 56 years are analyzed. The results show that: ①The annual average precipitation in Southwest China shows the space distribution characteristics of being more in the east and south and less in the northwest. 1986 is the significant abrupt change point of precipitation, and the precipitation at this point up to now has declined significantly. The oscillation period of annual precipitation in Southwest China has significant quasi 3a and 8a characteristics. ②In recent 56 years, there are 8 persistent drought events in Southwest China. The most frequent period is 1960s. Spring drought and winter drought are the most frequent. Autumn drought is the second. ③The anomalous anticyclone circulation in the northern part of the Bengal Bay and the anomalous cyclone circulation in the South China Sea block the necessary water vapor channel in the southwest region, and the water vapor flux is divergent. The anomalous anticyclonic circulation over the southwest and the anomalous cyclonic circulation from central Siberia to Baikal Lake cause the cold air activity to be more concentrated in the high latitude area. The South Branch trough is obviously weakened. The subtropical high is located in the east by the South and the intensity is weak. The southwest region is the extreme center of obvious subsidence movement. The sea level pressure is negative, and the temperature is high. All kinds of abnormal conditions are very easy to cause the southwest region sustained drought event. The La Nina phenomenon in the early in the Middle East Pacific and the sea temperature abnormal distribution in China's offshore region can be used as the long-term prediction line of the southwest region sustained drought events. |
| Key words: Southwest region；persistent drought；cause analysis |
