Abstract
An application of the Arakawa-Schubert (1974) cumulus cloud parameterization model to the estimation of precipitation during the period of Baiu season is presented over the western part of Japan on July 5-12, 1970. The cloud sub-ensemble thermodynamic properties are determined from the conservation of mass, moist static energy and total water (vapor, suspended liquid water and precipitation). The cloud work function for each cloud type which is defined in the Arakawa-Schubert model is calculated from the observed data sets. Calculations of the large-scale forcing and the mass flux kernel in the discrete model are performed. The unknown cloud base mass flux is determined by the integral equation. Precipitations due to cumulus cloud in the parameterization model and large-scale condensation are calculated.
Results show that the cloud work function is large in the middle layer and small in the lower layer. It is emphasized that the choice of a particular value for M"B(j')Δt' of mass flux kernel is important to treat the precipitation of cumulus in middle latitudes such as that in Baiu season. In this paper, the particular constant value of M"B(j')Δt'=85kg m-2 is chosen as a reasonable one. Amounts of precipitation of cumulus cloud are variable when the constant of mass flux kernel changes. It is also shown that period of July 5-12, 1970 can be divided into two periods, i. e., the period when the precipitation of large-scale condensation is predominant and the period when the precipitation of cumulus cloud is predominant.
