Statistical properties of a cloud ensemble: a numerical study

Abstract

An observed large-scale lifting and small amplitude random perturbations in the form of temperature fluctuations are imposed continuously in the model. The model then allows many clouds of different sizes to develop simultaneously. A 6-hour time integration is made to allow a large number of convective clouds to develop. After the model integration, horizontal and time averages of various relevant variables are computed to elucidate the statistical properties of clouds. The model is applied to the case of a well-organized intertropical convergence zone (ITCZ) rainband. Mass flux by cloud drafts and vertical velocity as well as condensation and evaporation associated with these cloud drafts are examined. The cloud drafts are further subclassified as inactive and active. Separate contributions to cloud statistics in areas of different cloud activity are then evaluated. The model results compared well with those obtained from aircraft measurements. -from Authors