2012年海洋和大气环流异常及其对中国气候的影响

文章主要对2011/2012年冬季至2012年秋季的海洋和大气环流异常进行分析,并讨论这些异常特征对中国气温和降水的主要影响。分析表明:2012年3月拉尼娜事件结束,赤道中东太平洋在7—8月出现明显暖水波动,之后进入正常状态。暖水波动使9—10月西太副高偏强偏西控制长江以南大部,造成该地温高雨少:8—9月,热带印度洋呈显著的偶极子正位相模态,在热带东太平洋激发出异常反气旋,其西北侧西南气流有利于暖湿气流影响中国华西南部出现明显秋雨。2012年南海夏季风爆发偏早1候,结束偏晚2候,强度偏弱;东亚夏季风为1951年以来第四强,使得东亚夏季风雨带位置偏北,中国北方大部夏季降水偏多。受海温和大气环流异常等的共同影响,我国出现了冬冷、春夏热、秋冷和夏季降水"北多南少"的气候特征。

Anomalies of Ocean and Atmospheric Circulation in 2012 and Their Impacts on Climate in China

Anomalies of ocean and atmospheric circulations were analyzed and their impacts on temperature and precipitation anomalies were discussed. It is found that the warm condition was observed in the tropical central eastern Pacific Ocean during July to August 2012 and then it changed into normal condition, following the La Nina event which ended in March 2012. As a response of circulations to the warm oceanic condition, the western Pacific subtropical high was stronger and extended further west, controlling most southern part of China and causing temperature higher and precipitation less than normal there during September to October. From August to September, significant Indian Ocean dipole with a positive phase persisted in tropical Indian Ocean. Then, an anomalous anticyclone was excited over eastern tropical Pacific Ocean, with southwest airflows along its northwest edge affecting Southwest China and resulting in obvious autumn rainy season in its southern part. In 2012, onset of South China Sea summer monsoon was 1 pentad earlier than normal and the ending was 2 pentads later than normal, and the intensity was weaker than normal. And East Asian summer monsoon was observed the 4th strongest since 1951. Under the impact of anomalies of ocean and atmospheric circulation, colder than normal winter of 2011/2012 and autumn of 2012, warmer than normal spring and summer of 2012 appeared in China. Summer precipitation distribution shows more than normal precipitation in northern China and less than normal precipitation in southern China.