From Environmental Moisture to Surface Precipitation in Mesoscale Convective Systems

Mesoscale convective systems (MCSs) are responsible for the majority of accumulated tropical precipitation and contribute disproportionately to extreme tropical precipitation. General relationships between environmental moisture and precipitation rates have been well established, but their sensitivities to MCS organization are less well known. Here, we investigate three moisture-precipitation relationships for tropical MCSs across three datasets: 1) an observational dataset of collocated ISCCP convective tracking, MSWEP precipitation intensities, and ERA-Interim synoptic conditions; 2) an idealized radiative-convective equilibrium simulation; and 3) a full complexity storm-resolving simulation from the DYAMOND model intercomparison. For each of these datasets, we examine 1) the rapid pickup in precipitation intensity beyond a threshold column saturation fraction; 2) the ability of the zero-buoyancy plume model to capture collocated saturation deficit-CAPE relations; and 3) the scaling of precipitation intensity with integrated condensation rate and the implied precipitation efficiency.