冬夏季节热带副热带OLR场的遥相关分析

A TELECONNECTION ANALYSIS OF OUTGOING LONGWAVE RADIATION IN TROPICS AND SUBTROPICS IN SUMMER AND WINTER

本文利用NOAA13年月平均格点资料分析了冬夏热带副热带射出长波辐射(OLR)的气候特征及其遥相关结构。结果表明,OLR场的高低值带有明显的季节变动,低值带中心从冬至夏由赤道西太平洋地区向西北移至孟加拉湾,高值带从冬至夏北移约10—15个纬度,但东南太平洋高值区的位置无明显季节变动。 遥相关结构分析表明,冬夏季节OLR场分别有8个遥相关关键区,它们之间存在着较强的同时性遥相关联系。冬季遥相关型主要由位于赤道低纬度“印度洋—西太平洋—东太平洋—大西洋”的纬向2波式遥相关和在太平洋中部、东亚地区,南北半球副热带与赤道地区的经向负遥相关型组成。夏季OLR遥相关关键区主要分布在孟加拉湾至赤道西太平洋、东太平洋与低纬度大西洋和中纬度东亚沿海与北美大陆,构成低纬度和中纬度两类纬向正遥相关型。进一步分析发现,冬夏OLR遥相关型的年际变化较好地揭示了OLR场异常与ENSO、低纬度Walker、Hadley环流等海—气系统异常的整体联系。

Thirteen years of mean monthly NOAA grid data are used to analyze the climatological characteristics of the tropical and subtropical outgoing longwave radiation (OLR) and their structure of teleconnection in summer and winter. The results show that high and low OLR belts have significant seasonal shifts in location as winter is replaced by summer. The low center moves to .the Bay of Bengal from equatorial West Pacific and the high center displaces itself 10-15 latitudes to the north, while the region of high OLR does not show any significant changes for the southeastern Pacific. Analyses of teleconnection structure show that there are 8 key regions in winter and summer OLR fields, which are highly teleconnected in a simultaneous manner among them. In winter the key teleconnection is mainly composed of a pattern of 2 zonal waves, which distributes across the equatorial latitudes of the Indian Ocean, West Pacific, East Pacific and Alantic, and a negative meridional pattern, which is active in the central Pacific, East Asia, both subtropical zones and equatorial regions. The key teleconnection for summer is made up of two positive zonal patterns, which locate from the Bay of Bengal to the equatorial West Pacific and East Pacific, and over low latitude Atlantic, middle latitude East Asia coastal areas and North America continent. Further study reveals that the interannual variations of summer and winter OLR teleconnection patterns are good indicators of the general association between OLR anomaly and air-sea systems such as ENSO, low latitude Walker and Hadley circulations.