Interannual Variability of Upper-Troposphere Water Vapor Band Brightness Temperature

A method for the intercalibration of the high-resolution infrared sounder (HIRS) upper-tropospheric water vapor band brightness temperature data is developed and applied to data from 1981 to 1993. Analysis of the adjusted anomaly time series show the location and strength of both the large-scale ascending and descending circulations in the Tropics as well as water vapor anomalies. Comparison of these HIRS data with outgoing longwave radiation and sea surface temperature anomalies reveals that both convection and increased upper-tropospheric moisture occur over anomalously warm water in the deep Tropics. The development and movement of deep convection and increased upper-tropospheric moisture can clearly be traced during the El Niño/Southern Oscillation warm events. These HIRS data are particularly useful in monitoring upper-tropospheric water vapor variability between the Tropics and subtropics.