Simulating organized convection and precipitation in Northwestern South America at convection-permitting resolution

Abstract

ABSTRACT : Organized deep convection can trigger severe weather phenomena, compromising human life and impacting agriculture, infrastructure, and aviation. Convection-permitting (CP) models have emerged as useful tools to investigate the environments and mechanisms causing deep convection and precipitation. However, in Northwestern South America (NWSA), where organized convection is widespread and frequent, modeling studies at CP resolution are still limited. This research analyzes the representation of organized convection and precipitation in NWSA using CP simulations. A set of 4-km resolution simulations with the Weather Research and Forecasting (WRF) model covering the continental region of the NWSA are used to: study processes that cause high sensitivity to the selection of microphysics (MP) and boundary layer (PBL) schemes; assess the spatio-temporal representation of Mesoscale Convective Systems (MCSs) through an object-based approach; and identify mechanisms behind the diurnal cycle of rainfall and the organization of convection. The main results of this investigation strengthen the findings of earlier research and show advances in the modeling and understanding of convection in NWSA. In general, MP and PBL schemes strongly impact the simulation of rainfall, revealing key processes to improve the representation of rainfall in the region. On the other hand, CP simulations exhibit a good capacity to represent the main features of MCSs, including seasonality and diurnal frequency. Finally, the model unveils mechanisms that contribute to explaining the diurnal rainfall cycle and the organization of convection in different regions of NWSA. This research not only represents the first implementation of CP simulations to study convection in continental NWSA, but also highlights their potential to advance the study of convection in the region.