The role of the diurnal cycle on convective organization and resulting aerosol transport in the Maritime Continent

The influence of the Maritime Continent (MC) on larger scale convective features, such as the Boreal Summer Intraseasonal Oscillation (BSISO), is not well understood. The MC is characterized by complex terrain and surface inhomogeneity, with a variety land surface types. Each land surface category has a different roughness length, heat capacity, and porosity and therefore responds differently to diurnal heating, precipitation, and latent and sensible heat fluxes, all of which can affect the propagation of density currents (sea breezes, katabatic and anabatic mountain winds, and convective cold pools). The MC's complex terrain encourages interactions between mesoscale flow features such as mountain breezes, gap flows, and sea breezes, and larger scale meteorology. The goals of this study are to enhance our understanding of how the diurnally driven flow features feed into larger scale convective features and how these govern aerosol transport. In order to address this goal, we run a series of high-resolution idealized simulations with realistic topography of the Philippine's island Luzon and allow the simulations to evolve over several diurnal cycles. In the first simulation, we utilize a sounding from Baguio, taken on August 4, 2017, and set the u and v wind velocity components to zero. This serves as a control simulation in which there are no background winds, and all winds are initiated through thermal processes. The subsequent sensitivity tests include a realistic background flow from the aforementioned sounding, changes to surface characteristics, and eliminating the diurnal cycle by using a constant incoming solar radiation. In each simulation, we include a point emission source of passive tracers at Baguio. Comparisons between the simulations compare evaluation of convective intensity and organizational metrics, such as cloud top height and precipitation rates to determine the character of the convection. We also investigate how these convective characteristics govern the aerosol transport. Finally, we compare the differences between these simulations in order to understand how the diurnal cycle is affecting upscale growth of convective features and the subsequent aerosol distribution.