Study of the variability of convective heating and moistening using Simplified Arakawa– Schubert convection scheme during INDOEX IFP-99

Abstract

A single column model (SCM) is used to study the thermodynamic characteristics of atmosphere over Indian ocean in two cases during INDOEX-99 (Sagar Kanya cruise). The first case represents a convectively- active (cloudy) day (4 February) and another convectively-suppressed (fair-weather) day (8 February). The objective of this paper is to study the variability of convective heating and moistening in the above two cases using Simplified Arakawa–Schubert convection scheme incorporated in the single column model. Vertical profiles of temperature, specific humidity, wind (u, v, w), sensible and latent heat fluxes, temperature and moisture advective forcings were used for the initialiazation of the SCM. The first three inputs of the above variables were obtained from the analysed data of the T80 Global Circulation Model in which INDOEX data were used for the data assimilation. The large scale advective forcings were also taken from the T80 GCM over the INDOEX observation points. The SCM has been integrated with 15 min time step in a fully prognostic way to obtain the convective heating, moistening, convective rainfall and cloud base mass flux for the above two dates. The results showed that the convective heating and moistening were larger on the cloudy day than those on the fairweather day. The distribution of hourly averaged values of convective heating and moistening showed the existence of multiple cloud types on the cloudy day.