关键词: 卫星, OLR, HIRS-T_b12, 赤道纬向环流, Walker环流

Abstract: The equatorial zonal circulation is an important component of the tropical general circulation. It's activity and variation are effected both on the anomalies of the mid-high latitudes and the global general circulation. Due to the lack of traditional observation, it is actually not true to describe the zonal circulation over the tropics with conventional data. The OLR observed by satellite observations is appropriate for indicating the convection upward motion over tropics but not for describing the descending motion. It is possible to describe the subsidence over tropics by using HIRS-T_b12 (High-resolution Infra-red Radiation Sounder—HIRS, channel 12, 6.7μm bright temperature T_b12) observed by NOAA satellite. So that the equatorial zonal circulation can be retrieved both with IR and WV channels on the satellite. The climatic characteristics of the equatorial zonal circulation are studied by using monthly 17 years (1979—1995) OLR, HIRS-T_b12 and NCEP/NCAR 2.5°×2.5°reanalysis data.Comparing the OLR, FWV (calculated by HIRS-T_b12 and 500hPa ω climatic mean map, it is further confirmed that it's a good approach to retrieve the equatorial zonal circulation by using the IR(indicate ascending branch) and WV(indicate descending branch) channels. The definition of the index of zonal circulation with the OLR and FWV are presented and the 17 years mean annual and seasonal equatorial circulation are drawn. The climatic characteristics of the equatorial zonal circulation are analyzed in detail. Consequently the fore results of the other observation are corrected.

Key words: satellite, OLR, HIRS-T_b12, equatorial zonal circulation, Walker circulation