Climatologia das brisas marítima e terrestre no Estado de Alagoas

Abstract

The breeze is an important factor in explaining the diurnal wind cycle in coastal regions, which, in turn, implies the advection of weather conditions from the sea to the land surface and vice versa. In the NEB region (Northeast Brazil) the winds are controlled by the circulation of trade winds and breezes. The magnitude of the large-scale wind flow, whether parallel or perpendicular to the orientation of the coast, where the differential heating between land and sea occurs, is decisive for the potential of breezes formation and their penetration into the continental interior. Some studies were carried out at NEB on the interaction of breezes with other systems, such as complex topographic systems, synoptic-scale wind, analysis of local precipitation variation and analysis of the territorial extent of the breeze. However, in Alagoas, there are few records of studies on breezes. In this sense, daily, seasonal and annual climatologies were used to analyze the diurnal cycle of breezes in this work, through surface meteorological observations from INMET (National Institute of Meteorology) stations in Alagoas, as well as data from the fifth generation of reanalysis surface from the European Center for Medium-Range Weather Forecasts (ECMWF), ERA5-Land. The ERA5-Land reanalysis was validated for Alagoas having as reference the 7 INMET surface stations. From these data, the comparative climatologies of the variables were generated: air temperature, surface pressure, relative humidity, precipitation, wind direction and speed in a period of 11 years, from mid-2008 to December 2019. The temperature and pressure were corrected with a bias of up to 0.7°C and 11.93 hPa and an RMSE of 0.34°C and 11.9 hPa. For the analysis of the breezes, the same meteorological parameters were used, except for precipitation, through the method of simultaneous alteration of the variables, to detect frontogenesis times. There were 450 days with breezes (average of detections for the 7 seasons) in the study period, being 21.42% in winter and 28.33% in summer, with maximum front development starting at 17h UTC and predominance of 28% of cases in March and April. It was observed that the closer to the coast, the sooner the formation of the FBM (Maritime Breeze Front) begins. It was also observed that the sea breeze has a significant potential to lower the temperature and increase the local relative humidity during the afternoon, as also seen in other studies. The results show the influence of breezes on the local climate, affecting thermal comfort, providing moisture to the atmosphere on the dispersion of pollutants etc., and indicates the need for representative wind reanalysis for regional and local scale, in order to spatially broaden the understanding of this system, in which there is a lack of observation data.