Episodic analysis of a downburst on February 14, 2018, in de city of Rio de Janeiro

Abstract

Since the 18th century, Rio de Janeiro has been affected by extreme precipitation events, which cause a series of disturbances in the urban space, through floods and mass movements. Among numerous events, the one that occurred on February 14, 2018, has peculiar characteristics, as it precipitated 51 mm in 1 hour. Thus, the objective was, through rhythmic analysis, to understand the event dynamically, paying attention to the impacts caused in the Piraquê-Cabuçu river basin, in the municipality of Rio de Janeiro. For this, data were collected to characterize the genesis of the phenomenon, seeking to individualize the types of atmospheric weather, through the monitoring of their rhythms. To achieve the objective, with regard to the methodological framework, the study used meteorological and tide data, satellite images, meteorological radar, synoptic charts, reanalysis data and the Skew-T Log P Diagram, in addition to hemerographic data. However, most likely the flooding episode was associated with the occurrence of a downburst event, as the data corroborate the existence of an amalgam of meteorological conditions characteristic of such processes: loss of lift and consequent downward movement of a cumulonimbus parcel, the total concentrated rainfall and high levels of instability, such as the value of 1,198 J/kg for the CAPE index. Given the genetic characteristics of the event, in addition to the high degree of anthropization of the basin, as a consequence the impacts affected about 50,000 people and caused repercussions in the study area for at least 7 days.