Main Characteristics and Possible Causes for the Climate in China During the Spring of 2014
During the spring of 2014, the air temperature over most China was above normal and tied for the second highest with the spring of 2013 during the corresponding period in history since 1961. The mean precipitation over China was slightly above normal, with significantly more precipitation over the Northeast China. Analysis shows that more precipitation in Northeast China occurred during 2-28 May, which was mainly caused by the active Northeast cold vortex (NECV). The NECV led to more cold air activities and also brought abundant water vapor from the Sea of Japan to Northeast China. Meanwhile, the intensified western Pacific subtropical high (WPSH), whose high ridge extended more westward, also brought more moisture from the western Pacific to Northeast China. In 2014, the South China Sea summer monsoon broke out on the 2 pentad of June, about 3 pentads later than normal, becoming one of the latest summer monsoons in history. The persistently strong and westward WPSH from late April to the end of May directly resulted in the later monsoon onset. Further analysis suggested that the strong and westward WPSH was possibly caused by the rapid warming over the tropical Indian Ocean.