Retrieval of Clear Sky Moisture Profiles using the 183 GHz Water Vapor Line

Abstract

A technique for retrieving vertical moisture profiles from downlooking radiometric measurements of atmospheric radiation near the 183 GHz water vapor line is described. A simulation experiment utilizing this retrieval technique and temperature and moisture profiles from tropical radiosonde stations has been carried out. Assuming the atmospheric temperature profile is known to 2K rms (state-of-the-art with present remote sensors) and the instrument noise is 1–2K rms brightness temperature (achievable with current technology), the humidity between the 700 and 1000 mb pressure levels was retrieved to ∼20% of true value over ocean and ∼45% of true value over land. The precipitable water content was retrieved to within ∼10% rms of true value over the ocean and within ∼45% rms of true value over land.