气象2016，Vol.42Issue(11)：1325-1334,10.DOI:10.7519/j.issn.1000-0526.2016.11.004
2014年8月西北太平洋和南海无TC生成之原因分析
Cause Analysis on the Lack of Tropical Cyclone’s Generation in the Northwest Pacific and South China Sea in August 2014
摘要
Abstract
Based on the conventional meteorological observation data,NCEP/NCAR 1°×1°monthly mean reanalysis data,the outgoing long-wave radiation (OLR)data observed by the NOAA satellite and the data from the Typhoon Yearbook of China Meteorological Administration,this paper analyzed the causes for the no generation of tropical cyclones (TCs)in the northwestern Pacific and South China Sea (SCS)in Au-gust 2014.The results show that the invading of the polar cold air led to the further eastward and south-ward movement of the subtropical high in northwestern Pacific during the first twenty days in August.In the last ten days the cold air became weaker,then the subtropical high moved westward and southward, driving the convergence zone between the easterly trade wind in the south side of the subtropical high and the equatorial westerly to be located abnormally further southward than normal.The weaker Miscarene high caused the Somali jet and the cross-equatorial flow over the eastern Indian Ocean to get weakened,and the low- and mid-level monsoon depression or monsoon trough over the Indian Peninsula to be ex-tremely inactive.Additionally,along with the weaker Australian high and its position deviation,the cross-equatorial flow over the southern SCS became weaker too.The SST of the tropical cyclone genesis was much lower than normal during the first dekad of August,so the warm and moist air in the area with lower SST could not form.In addition,the weak convection in the northwestern Pacific and SCS,the stable at-mosphere and large vertical wind shear were unfavorable for the generation and development of tropical cy-clone.In the lower level over the ocean between SCS and the east of Philippines,there was positive vortic-ity and negative divergence,but the convergence was not strong enough for the formation or development of TC.The weak updraft at the high-level troposphere caused by the South Asia high and the easterly dis-turbance south to the subtropical high could not accomplish the upper-level divergence process,being diffi-cult to support the maintenance and intensification of the upward flow.Hence,the four tropical disturb-ances in the abnormally southward ITCZ did not develop into tropical cyclones.关键词
TC/环流形势特征/季风低压/OLR/ITCZKey words
tropical cyclone (TC)/circulation characteristics/monsoon depression/outgoing long-wave ra-diation (OLR)/intertropical convergence zone (ITCZ)分类
天文与地球科学引用本文复制引用
李靓,胡啸,王小光,康志明..2014年8月西北太平洋和南海无TC生成之原因分析[J].气象,2016,42(11):1325-1334,10.基金项目
国家自然科学基金面上项目（41575104）资助 （）
