3月巴伦支海海冰对中国东部8月气温偶极子型的影响及机制研究

利用NCEP/NCAR、ERA-Interim再分析资料以及观测资料,研究了3月巴伦支海海冰异常与中国东部8月“南暖北冷”的模态的联系及可能机制。结果表明,当3月巴伦支海海冰偏多(少)时,中国东部地表气温呈现“南暖北冷”(“南冷北暖”)的模态,东北上空对应气旋(反气旋)异常和上升(下沉)运动异常,华南上空对应反气旋(气旋)异常和下沉(上升)运动异常,地表净热通量表现为“南正北负”(“南负北正”)。进一步研究发现,“丝绸之路”遥相关型与中国东部环流异常密切相关,而3月巴伦支海海冰异常可以通过影响“丝绸之路”遥相关波列进一步影响中国东部的环流异常及偶极子温度异常。一方面,3月巴伦支海海冰偏多(偏少)的信号可以持续到8月,在喀拉海上空通过冰-气相互作用激发南传的波列,加强“丝绸之路”遥相关的负位相(正位相),影响中国东部地区的环流。另一方面,春季巴伦支海海冰偏多(偏少)使得同期欧亚大陆北部温度偏低(偏高),欧亚北部积雪呈“西多东少”(“西少东多”)、土壤湿度呈“西湿东干”(“西干东湿”)的空间格局。而土壤湿度异常的空间格局可一直持续到8月,使得“丝绸之路”遥相关波列的加强,进一步影响中国东部环流异常,最终影响中国东部8月气温偶极子型的分布。

Effect of the Barents Sea ice in March on the dipole pattern of air temperature in August in eastern China and the corresponding physical mechanisms

Based on the NCEP/NCAR reanalysis datasets,the ERA-Interim reanalysis datasets,and the observational data sets,this study investigates the relationship between the sea ice anomaly over the Barents Sea in March and the mode of "warm south-cold north"(WSCN) pattern in eastern China in August.The results indicate that the positive(negative) inconsistency of the Barents Sea ice in March corresponds to the mode of the "WSCN"("cold south-warm north",CSWN) pattern in eastern China in August.Further analyses suggested that the "WSCN"("CSWN") patterned was categorized by the atypical cyclone(anticyclone) and the ascending(sinking) motion over northeastern China as well as the uncharacteristic anticyclone(cyclone) and the sinking(ascending) motion over southern China.Besides,the surface net heat flux was mentioned as the "positive south-negative north"("negative south-positive north") pattern.Further analyses revealed that the "Silk Road" teleconnection pattern is closely related to the inconsistent atmospheric circulation in eastern China,which acts as a bridge to link the Barents Sea ice in March and the dipole temperature pattern in eastern China.Besides,the positive(negative) anomaly of the Barents Sea ice in March last until August,which accelerate the southward wave train over the Kara Sea,strength the negative phase(positive phase) of the "Silk Road" teleconnection,and further regulate the inconsistent atmospheric circulations in eastern China.On the other hand,the positive(negative) variance of the Barents Sea ice in spring results in lower(higher) temperature in northern Eurasia,which result in "positive western-negative eastern"("positive eastern-negative western") snow cover and "wet western-dry eastern"("dry western-wet eastern") soil moisture in northern Eurasia.The spatial pattern of soil moisture may last until August,which leads to the enhancement of the "Silk Road" teleconnection wave train,affecting the circulation anomaly in eastern China,and resulting in the dipole distribution of air temperature in eastern China in August.