Analysis of the Orographic Influences of the Topography in the Structure of the Convective Precipitative Systems near the Tropical Andes of South America

This study uses radar reflectivity from the TRMM Precipitation Radar and brightness temperature from the GOES satellite in conjunction with high-resolution simulations from the Weather Research and Forecasting (WRF) model to better understand the physical factors that control the structure of convective precipitative systems that occur near the high elevation ranges of northern South America. This region is recognized to have frequent and widespread occurrence of deep convection that is favored by the convergence of cross-equatorial low-level flow towards the western slopes of the Andes ranges in the Pacific coasts of Colombia and Panamá. WRF model simulations using different microphysical parameterizations and initial conditions were explored in order to better simulate a previously observed convective storm with extreme characteristics, and which served as a control run. Then, different simulations modifying the model topography indicate that the orography of the Andes is critical in the generation of these convective storms. Reducing the elevation of the Andes ranges show a significant reduction of the horizontal and vertical extent, and the precipitation accumulation produced by the simulated storm. In the other hand, increasing the Andes elevations did not show a significant change in the conditions observed of the simulated storm. The results presented in this work provide a better understanding of the role of the topography in modulating the environments leading to the occurrence of convective storms in mountainous regions of the tropics.