提2009年以来，中国西南地区连续4年秋、冬、春季出现严重干旱，持续时间长、影响范围大、干旱程度重，给旱区农林业生产和人民生活带来严重影响，造成巨大的经济损失。本文利用多种资料从大尺度大气环流、水汽输送、太平洋及印度洋海温、平流层极涡等方面分析了此次连续干旱的原因。结果表明：南支槽强度偏弱、孟加拉湾水汽输送偏少以及弱极涡背景下，异常波活动造成的 AO 负异常引起的冷空气路径偏东是这4年持续干旱的共同特点。热带海表温度的异常变化对西南地区干旱的影响也不容忽视，主要表现在对孟加拉湾和南海水汽输送的阻碍上。La Nina 事件中，热带印度洋冬、春季海表温度的异常变化对干旱影响更为突出。冬、春季平流层和对流层的动力耦合作用结果使得 AO 位相发生变化，其中异常负位相的强度及持续时间对这4年西南地区秋、冬、春连旱的影响显著。
Analysis on Causes of Continuous Drought in Southwest China During 2009-2013
Severe droughts occurred in Southwest China continuously in 4 years’autumn,winter,spring beginning from 2009.Because of the long duration,large scope and heavy degrees,the drought has caused huge economic losses,seriously impacting on agroforestry production and people’s life in arid zones.In this paper,the causes of the continuous drought are analyzed from the impacts of the anomalies of large-scale atmospheric circulation,water vapor transportation,the Pacific and Indian Ocean SST,stratospheric polar vortex strength by analyzing a variety of data.The results show that the common backgrounds of the 4 years’continuous drought are weaker south branch trough,less water vapor transport over the Bay of Bengal and easterly cold air mass caused by AO negative anomalies which are produced by abnormal wave activities during weak polar vortex.The abnormal changes of tropical SST during the drought over South-west China play important roles in blocking water vapor transport over the Bay of Bengal and South China Sea.In the La Nina event,the effect of the tropical Indian Ocean SST changes in winter and spring is more outstanding.The phase of AO is always changed by the dynamic couple between stratosphere and tropo- sphere in winter and spring,and the intensity and duration of the abnormally negative phase of AO have significant effects on the drought that occurred in Southwest China in the autumn,winter and spring of 4 consecutive years.
国家科技期刊平台
NSTL
万方数据
维普
