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.