Effects of Cumulus Cloud Activity on the Large-Scale Moisture Distribution as Observed in Reed-Recker's Composite Easterly Waves

Abstract

Based upon Reed-Recker's (1971) composite easterly wave and the associated cumulus cloud population determined by Cho and Ogura (1974), the effects of cumulus cloud on the large-scale moisture distribution are studied in this note. It has been found that the moisture contents in the upper troposphere increase almost linearly with increasing deep cloud activity. There is also a marked increase in moisture content in the lower troposphere when the weather changes from a relatively suppressed condition to a relatively disturbed condition. However, further intensification of deep cloud activity does not lead to any significant increase in moisture content in the lower troposphere. In the region of the wave where deep cloud activities are developing, the rate of moisture supply of the troposphere exceeds that of precipitation and the atmosphere is moistened. In other regions, where deep cloud activities are decaying, the rate of precipitation exceeds that of the moisture supply and the moisture content is depleted. An empirical method to determine the partition of moisture supplied to an air column into precipitation and storage is suggested.