Comparison of Convective Mass and Heat Transports in Tropical Easterly Waves Computed by Two Methods

Abstract

Convective fluxes of mass and beat in tropical easterly waves were computed by a slightly modified version of the method of Austin and Houze (1973). The input data for this method are radar and raingage observations of cloud heights and precipitation amounts. The computed fluxes were compared to convective fluxes inferred from budget studies of synoptic-scale rawinsonde data for the same easterly waves. Good agreement between the two methods was obtained for mass and heat fluxes in the middle troposphere. For the lower troposphere, our calculations showed smaller transports of man and heat than were indicated by large-scale budget studies. This result arises because many shallow convective clouds do not precipitate and thus axe not included in calculations based on precipitation data. When the effects of small clouds (tops below 6 km) were removed from the calculations based on large-scale budgets, excellent agreement was obtained in the lower as well as middle troposphere. This study shows that a particularly useful approach in future studies will be a combination of methods based on both precipitation and large-scale data.