Inter-comparison of Atmospheric Boundary Layer Parameterizations Included in Simulations of Amazonian Convective Systems

Mesoscale convective systems (MCSs) are responsible for 2/3 of total precipitation in the tropics. Over the Brazilian Amazonian region, multi-scale and deep convective systems (0-100 km wide) develop and rapidly propagate across the rainforest. During the experiment Green Ocean Amazon (GOAmazon), surface and tower observations show MCSs promoting deep vertical mixing of gases and aerosols during the convective cycle. To simulate and forecast this convective activity in space and time, it is crucial to properly represent the meteorological conditions, then use a realistic convective parameterization scheme is needed. The Weather Research and Forecasting (WRF) model is used to simulate convective events using the Kain-Fritsch (KF) convective parameterization which is a low level controlled also a vertical mass flux scheme. The KF convective scheme is able to reproduce convective features such as updrafts, downdrafts, and deep vertical mass flux trough the cloud layer. The atmospheric boundary layer exerts an important role on the performance of the KF parameterization determining the source of convective energy to overcome the convective inhibition and release convective available potential energy by displacing air parcels from their conditional unstable level to free convection level. This study has two goals a) examines the sensitivity of the performance of KF convective scheme in WRF in being activated by three different planetary boundary layer (PBL)parameterizations: Mellor-Yamada-Janjic (MYJ), Yonsei University (YSU) and Bougeault–Lacarrére (BouLac). b) Verify the hability of KF convective scheme in produce the main convective elements expected in a SCM (updrafts, downdrafts, and deep vertical mass flux trough the cloud layer). The KF scheme simulated satisfactorily the vertical mass flux during the convective event, the BouLac PBL parameterization had the best performance keeping the convective activity lasting longer during the night period.