Ocean–Atmosphere Feedback during Extreme Rainfall Events in Eastern Northeast Brazil

Abstract

AbstractThe coupled ocean–atmosphere–wave–sediment transport model and the Weather Research and Forecasting (WRF) atmospheric model were used to simulate extreme rainfall events from 10 to 25 June 2010 in eastern Northeast Brazil (ENEB). The simulations aimed at investigating the improvements from using a coupled ocean–atmospheric model of meteorological systems as the ocean–atmosphere interactions intensified during the period when flood events occurred in ENEB. In June 2010, the sea surface temperature (SST) was warmer than 28.5°C in the western tropical South Atlantic Ocean with anomalies above 1°C, which are characteristics of a warm pool. The sensible and latent heat fluxes acted to moisten the lower troposphere and affected the height of the trade winds inversion layer (TWIL). The meteorological system that occurred at the low–midlevels during the period favored the weakening and even the breakdown of the TWIL. These atmospheric disturbances were associated with convergence, cyclonic vorticity, and upward water vapor motion to the midtroposphere levels. When the disturbances reached the coast of ENEB, they favored convection and intense rainfall over the region. Both coupled and uncoupled modeling experiments were performed with the same physical parameterizations and validated with in situ atmospheric and oceanic measurements. The results highlight that the predictions of extreme rainfall events were greatly improved with the coupled model.