A Composite Mesoscale Cumulonimbus Budget

Abstract Composite maps at levels from 950 to 150 mb of relative wind field (Vτ), mixing ratio (r), equivalent potential temperature (θE), and temperature perturbation (T′) from the growth and decay phases of a mean mesoscale cumulonimbus system (systems used had a maximum radar echo area >400 km2) were constructed using radar and one rawinsonde (experiment VIMHEX) for days having a similar synoptic-scale wind field. Echo area and track were measured from radar film, and relative winds calculated by subtracting a mean echo velocity; positions of radiosonde data points relative to the echo as center were computed, scaled by an echo radius, and plotted with echo motion vectors aligned along one coordinate axis. Mass flows into the mean system at all levels give vertical mass transports for growth and decay phases, and net mass balance. The net convergence of r closely balances a mean surface rainfall per echo, and the net enthalpy source by the cumulonimbus system. Fluxes of θE, into and out of the system f...