Sensibilidade da camada limite atmosférica no litoral cearense ao crescimento urbano de Fortaleza.

Abstract

The current research has as main objective the investigation of the sensitivity of characteristics of the Atmospheric Boundary Layer (CLA) in response to the effects of urban growth, with possible formation of an Urban Heat Island (ICU) on the coast Brazilian, specifically in the city of Fortaleza. For this, profiles were analyzed virtual potential temperature verticals – θv and wind obtained from data from radiosonde for the identification of features within the CLA and the presence of signs that indicate the formation of the ICU. The experimental campaign was carried out during the month of April 2011 within the scope of the CHUVA Project. For the characterization of the ICU, Landsat 5 and Landsat 8 satellite images were used, in the years 1988, 1991, 1996, 2001, 2006, 2013 and 2017 to indicate urban growth in the study region through the surface albedo estimation results and the presence of signs of the formation of ICU through temperature estimation data. To quantify the intensity of the ICU, surface temperature data were used in the locality of Itaitinga, which is located in the interior of the state and has a lower urbanization content than Fortaleza. Data from ECMWF ERA5 reanalysis were used to expand the time series of data, increasing the study period to 1980 to 2018. The results found point to for the presence of the ICU formation signal in Fortaleza due to the existence of a layer thermodynamically unstable located up to an average height of 15.4 m with temperature virtual potential of 300.8 K, which indicates the non-cooling of the surface and the layers of air just above at night. With the reanalysis data, it was possible to verify that the ICU in Fortaleza has increased its intensity in the last two decades, so that the consequences of this within the CLA could be accentuated in the coming years. Per Finally, the presence of the ICU has considerable influence on the mean flow close to the surface, in order to suppress the formation of the land breeze at night when it is observed a wind intensity above 10 m/s. Even when the ICU signal is not observed, the land breeze still does not form as expected, which gives the possibility to conclude that the ICU influences the breeze circulation even when it does not have a signal strong. On the other hand, breeze circulation tends to shift the center of the ICU to the west.