A partitioning analysis of tropical rainfall based on cloud budget

Precipitation in the deep tropical convective regime is investigated through the partitioning analysis of grid-scale data from a two-dimensional cloud-resolving model simulation based on cloud budget. The model is forced by large-scale vertical velocity, zonal wind, horizontal advection, and sea surface temperature observed and derived from TOGA COARE. In cloud budget, rainfall is associated with cloud microphysical processes denoted by the net condensation and dynamical processes denoted by hydrometeor change/convergence. Thus, three rainfall types are separated in this scheme. Time-mean analysis shows that the rainfall type associated with hydrometeor loss/convergence only accounts for 27% of total rainfall, which corresponds to downward motions and downward water vapor and hydrometeor mass flux in the mid and lower troposphere. The two other rainfall types associated with the net condensation contribute equally to total rainfall (36%), which are generally related to upward motions and upward water vapor and hydrometeor mass flux throughout the troposphere.

► The rainfall (cM) with hydrometeor loss/convergence accounts for 27% of total rain.
► cM shows downward motions in the mid and lower troposphere.
► The two rainfall types with net condensation contribute equally to total rain.
► These rainfall types show upward motions throughout the troposphere.