热带对流和环流季内振荡强度与海表温度关系对比研究

利用外逸长波辐射(OLR）、风场和海表温度(SST)资料, 研究了热带大气季节内振荡(ISO)强度的季节变化特征, 发现热带印度洋和热带西太平洋区域是OLR和风场季内振荡最主要的共同活跃区。对比分析了OLR和风场季内振荡强度与海表温度异常之间的年际异常关系, 发现OLR季内振荡强度异常与海表温度异常之间存在显著局地正相关关系, 即在热带中东太平洋区域、热带西北太平洋区域和热带西南太平洋区域, 当海表温度正(负)异常时, OLR季内振荡增强(减弱),特别在冬春季节这一关系更清楚。除个别区域外, 风场季内振荡强度异常与海表温度异常不存在类似OLR的局地关系。OLR和风场季内振荡强度异常与海表温度异常之间局地和非局地关系的差异, 体现了两种要素特性的本质差异。但两种要素季内振荡强度在El Niño事件发展过程中的变化基本一致, 即在气候场中季内振荡活跃的区域, 事件发生之前季内振荡会增强, 并逐渐向东传播, 事件发生之后这些区域振荡减弱。

The Comparison between Relationships of Intraseasonal Oscillation Intensity of Tropical Convection and Circulation with Sea Surface Temperature

By using Outgoing Longwave Radiation (OLR, denoting convection), and wind (denoting circulation) and sea surface temperature (SST) data, the seasonal characteristics of intraseasonal oscillation (ISO) intensity of tropical atmosphere are studied, it is found that ISO is the most active in the tropical Indian Ocean and the tropical western Pacific for climatological OLR, 200-hPa and 850-hPa zonal wind fields. The relationships of intraseasonal oscillation intensity anomaly of tropical OLR and zonal wind with sea surface temperature anomaly (SSTA) are investigated individually, and their differences are compared. There is a notable local positive correlation between OLR intraseasonal intensity anomaly and SSTA, and the positive (negative) anomaly of OLR intensity lies in the areas where SSTA is positive (negative) in the tropical middle and eastern Pacific, the tropical northwestern Pacific and the tropical southwestern Pacific, which is clearer in the boreal winter and spring. There is no certain local relationship between ISO intensity anomaly of zonal wind and SSTA. The above conclusions reflect the intrinsical differences between two types of elements, which are local and nonlocal properties for OLR and zonal wind individually. The variations of intraseasonal oscillation intensity for two types of elements during El Niño events are basically consistent, that is, the ISO will strengthen before El Niño events and propagates eastward, then weaken subsequently in the active ISO areas of climatological fields.