Speaker –  Ángel F. Adames-Corraliza, University of Michigan

Seminar Title – Insights on Large-scale Precipitation Evolution in the Tropics from the Perspective of Plume Buoyancy

Abstract – Tropical convection is highly sensitive by fluctuations in temperature and moisture in the lower-free troposphere as well as processes that occur in the planetary boundary layer (BL, 850-1000 hPa). It is shown that a semi-empirical framework precipitation-buoyancy relation can capture many of the processes that lead to convective onset and evolution in association with tropical motion systems. The following processes are of the same order of magnitude and contribute roughly equally to rainfall evolution: horizontal moisture advection, temperature advection, adiabatic lifting by gravity waves, ascent driven by radiative heating and surface energy fluxes. Through simplified equations it is shown that steady-state convection evolves towards a state of moisture quasi-equilibrium: moist convective instability is consumed while the free troposphere is moistened by convection in such a way that the mean free-tropospheric buoyancy is unchanged.