Anomalies of Ocean and Atmospheric Circulation in 2014 and Their Impacts on Climate over China
Based on the real time, historical observation data and NCEP/NCAR reanalysis data, anomalies of ocean and atmospheric circulation are analyzed and their impacts on climatic anomalies in 2014 over China are discussed. The results show that the intensity of East Asian winter monsoon and the Siberian high were weaker than normal during the 2013/2014 winter, with the center of polar vortex located in the Western Hemisphere, leading to the higher temperature than normal over China. While the East Asian winter monsoon exhibited intraseasonal variations, the surface air temperature over China had two stage variations last winter, warmer in the early winter and colder in late winter. It is found that a new El Ni〖AKn~D〗o event formed in the eastern and central equatorial Pacific in 2014, and significant positive phase persisted in the index of Basin Wide SSTA variation in the tropical Indian Ocean (IOBW) after March of 2014. As a response of circulations to above warm ocean conditions, the West Pacific subtropical high was stronger and extended further southward to its normal situation during summer and autumn, leading to the “more in South and less in North” feature for total precipitation over eastern China during the rainy season. In 2014, onset of the South China Sea summer monsoon was extremely later than normal, and its intensity was weaker than normal. The East Asian summer monsoon was weaker than normal, favorable for the main rain belt over the eastern China to hover southward and more precipitation in Meiyu season was seen over the Jiangnan and the middle and lower reaches of the Yangtze River while less precipitation was in most of the northern China during the summer 2014.