Tropical Synoptic Scale Moisture Fields Observed from the NIMBUS-7 SMMR
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
Pagination or Media Count:
Nimbus-7 SMMR brightness temperatures from 7 days in January 1979 and 3 day in May 1979 are used to estimate precipitable water and precipitation over the tropical eastern Pacific Ocean. The SMMR estimates are compared with moisture estimates from TIROS-N infrared moisture channels, TIROS-N outgoing longwave radiation, and the ECMWF model analysis. Comparisons are made within the context of five typical tropical synoptic scale features Tropical plumes TP synoptic scale disturbances viewed in the cloud field, linking the tropics and midlatitudes the Subtropical High STH, the dry region extending along the northwest flank of a TP the active Intertropical Convergence Zone AITCZ, banded equatorial convention over the eastern Pacific Ocean the quiescent Intertropical Convergence Zone QITCZ, areas with no convective cloud tops present along the ITCZ and the Equatorial Dry Zone EDZ, an area along and south of the equator between 100 W and 120 W. SMMR precipitable water estimates provide detailed information on the moisture structure in all areas of the tropics except in areas of heavy precipitation. Most of the information present in the TIROS-N and ECMWF data identifies the synoptic feature and not variations within a feature. SMMR data identified TP precipitable water content as statistically identical to QITCZ and the precipitation as statistically identical to AITCZ precipitation. Prediction of SMMR precipitable water using TIROS-N and ECMWF data explained 67 of the variance in SMMR data while ECMWF analysis alone explained 55 of the variance. Theses.