Understanding the linear response functions of shallow convection using a stochastic parcel model

A better understanding of the linear response functions of a shallow cumulus ensemble to large-scale temperature and moisture perturbations could be used to evaluate and to improve cloud parameterizations. A stochastic parcel model is used to investigate the physical processes behind such linear response functions. The undisturbed BOMEX case is used in the present study. The responses of the parcel model to temperature and moisture perturbations are able to match the results from the simulations of a cloud-resolving model. Analysis of the history of convecting parcels in the parcel model shows that the temperature perturbation can form a buoyancy barrier, inhibits convection, and changes the properties of convecting parcels. The response to moisture perturbation is much smaller, and the physical interpretation for that is still being investigated.