Determination of Cloud Liquid and Precipitable Water Vapor by Ground-Based Microwave Radiometers

An algorithm has been developed for determining cloud liquid in the monsoon period from ground-based microwave radiometric observations over New Delhi. For cloud liquid measurements, 11- and 17.47-GHz frequencies are used. Calculations show that liquid content changes from 0.1 × 103 to 6.1 × 103 g/m2 and water vapor from 3 × 104 to 6 × 104 g/m2 in the monsoon period over New Delhi. Cloud liquid is found to be highly variable on a time scale and shows poor correlation (0.4) with water vapor content. The average liquid water density of cumulonimbus clouds is obtained as 1.2 g/m3 from these observations.