Configuração térmica horizontal e vertical do clima urbano do Central Business District (CBD) da cidade do Rio de Janeiro (RJ)

Abstract

This research aimed to analyze the influence of urban morphology on the thermal field, horizontal and vertical, at atmosphere of Central Business District (CBD) of Rio de Janeiro. Therefore, the methodological procedures involved three stages: pre-field, field experiment and post-field. In the pre-field stage, the mean of land surface temperature (LST) in the summer (2014 to 2019) and winter (2013 to 2019) was estimated and was prepared the urban climate susceptibility map, the UC-AnMAP, based on urban morphology. The confrontation between the LSTs and the UC-AnMAp brought to light the divergence of the results for Rio Branco avenue. Thus, for the field experiment, emphasize was given to the urban canyon of Rio Branco avenue by collecting data at seven points through two mobile transects, a meteorological control station in a free and grassed area at Santos Dumont Airport and vertical collections at Largo da Carioca with RPA, used to evaluate the vertical thermal profile of the initial 50 meters of the urban atmosphere. In this way, the field experiment combined horizontal and vertical collections at 6, 13 and 20 hours, which took place over ten summer days between 1/24/21 and 3/15/21. The mapping of the horizontal thermal field of the Rio Branco avenue, assessed that the urban morphology confers susceptibility to the configuration of heat islands that presented magnitudes that varied according to the different atmospheric processes: very strong (above than 6.1°C) in stable conditions; strong (4.1°C to 6°C) in unstable conditions; and moderate (2.1°C to 4°C) in post-instability conditions. The field data showed that the 13:00 happened the heat concentration, especially at the intersection of Av. Rio Branco/Rua do Ouvidor, with greater verticalization, and Praça Mauá, without vegetation. Another interesting aspect is that highest heat island intensity in the entire field experiment do not coincide with day (1/31 - Sunday) of highest recorded air temperature (29.5°C), but on a Monday. This Monday, the heat islands registered anomalies of 11.8°C at Av. Rio Branco/Rua do Ouvidor, and 8.3°C at Praça Mauá. Possibly the anthropic heat has contributed to the formation of these nuclei, which reinforces the importance not only of urban form, but of the rhythm of urban functions. Finally, for vertical analysis, the 13:00 pm time was also the one with the highest temperatures and highest gradients from the ground up to 50 meters. In the different synoptic conditions there were indicatives of thermal inversion, however, it was at night of the day with the highest air temperature (29.5°C), that the air temperature in 50 meters was 2.3ºC higher than ground. This result, when compared to the Galeão airport radiosonde monitoring, without occurrence of thermal inversion, indicates that, possibly, the roughness and volume of buildings present in the Rio Branco canyon may have forced the configuration of the phenomenon, revealing, perhaps, a new process that generates inversions.