Influência dos ciclones tropicais na formação dos fenômenos adversos no nordeste brasileiro entre 2013 e 2015

Abstract

This study analyzes the impact of Tropical Cyclones on adverse phenomena in the Northeast Brazil (BNE) within three years from 2013 to 2015. Due to the absence of tropical cyclones mentioned in previous papers as causing phenomena such as fog or thunderstorm on BNE, the main purpose of the study is to evaluate the existence of such influence and thus improve the weather forecasting in this area. The Tropical Cyclone’s information from the National Hurricane Center (NHC) of the National Oceanic and Atmospheric Administration (NOAA) was used. METAR data from the Brazilian Department of Airspace Control (DECEA), SYNOP maps from the Center for Weather Forecasting and Climate Studies (CPTEC/INPE) and images from the Lightning Image Sensor (LIS) aboard Tropical Rainfall Measuring Mission (TRMM) satellite were used for the Adverse phenomena study on BNE. Analysis of the synoptic systems was based on GOES 13 and METEOSAT 10 satellite’s Infrared images; and the streamline with the wind magnitude, divergence, and vertical speed wind maps. All maps were built by the GrADS software using reanalysis data from the European Center for Medium-term Meteorological Forecasting (ECMWF). A total of 10 tropical cyclones were studied. During their passage through the NEB longitude range, most phenomena associated to the stable atmosphere, especially mist with rain were observed. Tropical disturbances which did not develop in the tropical cyclones, were formed close to the tropical cyclones during this period. Ridge in the trade winds on BNE and a trough over the BNE’s coast were observed through the synoptic analysis, at the low levels (1000hPa). Two types of these troughs formation were identified. Type 1 results only from cyclones and tropical disturbances, while Type 2 also involves an extratropical cyclone in the southern hemisphere (HS). At the middle (500hPa) and high (300 / 200hPa) levels two types of the convergence were identified between the currents from the northern (HN) and southern hemisphere (HS). At the meddle levels, in the Type 1 events, the regions of divergence linked with the cyclones and tropical disturbances formed currents from the HN that cross the equator and converged with the trough associated to the extratropical cyclone on the HS. In the Type 2 events, convergence occurs with the HS anticyclone on the northern part of trough’s. Formation of 4 Middle Tropospheric Cyclonic Vortexes associated with cyclones and tropical disturbances was observed. At the high levels currents from the HN resulted from the same systems and from the Subtropical High at the east. In Type 1 events, the convergence occurred with the trough from HS, while in Type 2 events it occurs with the anticyclone from HS. At these levels, a region of lifting was observed over the centers of cyclones and tropical disturbances and a region of sinking over the NEB in the region of the convergence between two currents. The stable atmosphere phenomena occurred at the region of sinking. The results confirm that systems from HN influence to the systems in HS. This information is of the great importance for the improvement of the weather forecasting methods.