【作者】 朱毓颖； 江静；

【Author】 Yuying Zhu Jing Jiang (School of Atmospheric Sciences,Nanjing University,210093)

【机构】 南京大学大气科学学院；

【摘要】 本文利用1979-2007年NCEP/NCAR逐日再分析资料数据集以及中国地面观测站共593站的站点温度资料,从气候意义上分析了热带地区低频振荡在北半球冬季的典型特征及其在各个位相与中国冬季持续性低温的一般性联系。伴随着热带异常对流活动的系统性东移,中国冬季的持续性低温事件发生频数也随之发生变化。当MJO处于位相4(即异常增强的对流活动处在印度洋上)时,中国持续性低温事件偏多,并主要出现在南部地区。通过对500hpa位势高度异常场、海平面气压异常场和1000hpa风场异常场的分析得到,中国南方的持续性低温事件总是伴随着加强的西伯利亚高压和东南亚地区持续的北风异常。前者提供了持续的冷空气爆发,而后者不断的将冷空气向南输送。而在中国北方,可能是MJO热带对流异常通过Rossby波列来影响持续性事件。更多还原

【Abstract】 Daily NCEP-NCAR reanalysis wind,temperature and geopotential height are used as major data in this study.Besides the grid data,we also make use of surface air temperature(SAT) data derived from 593 surface stations across China.We have examined the impact of the MJO on Chinese wintertime persisting cold anomaly. The influence of the MJO on the persisting cold anomaly occurs after the MJO is observed in Phases 4,when a tropical convection anomaly dipole reaches the eastern Indian Ocean.More persisting cold anomaly events happened in southern China while the MJO was detected in Phase 4,which correspond to an enhanced precipitation over the Indian Ocean and maritime continent and a reduced convective activity near the tropical central Pacific.An analysis of the evolution of the 500-hPa geopotential height,sea level pressure and 1000-hPa wind anomalies indicates that the persisting cold anomaly in Southern China is linked to an enhanced prolonged Siberian high(SH ) and a persistent northerly anomaly over Southeast Asia.The former provided the persistent cold air outbreak and the latter was crucial to lead to a continuous cold advection.In the Northern China,the persisting cold anomaly maybe related to the tropical convection anomaly of the MJO through a Rossby wave train.更多还原