Small-Scale Humidity Variations Inferred from Scanning Microwave Radiometer Measurements in the Tropics

Abstract:

Tropical convection is intimately connected to the accompanying environmental humidity field, with the role of humidity within convective transitions still under debate. The most reliable humidity measurements are made by radiosondes, but these do not resolve variability of less than a few hours, or spatial variability of less than tens of kilometers. Highly-resolved humidity measurements are particularly sparse within the Tropics. During the Dynamics of the Madden-Julian Oscillation (DYNAMO) field deployment to the equatorial Indian Ocean during October 2011-Febuary 2012, a 21-channel 22-30 GHz radiometer was operated at five frequencies, alternately pointing vertically and scanning horizontally. Humidities were retrieved using the radiosonde temperature profiles as input. In this presentation the retrieval is described and results shown for both vertical profiles and horizontal variability.