Extremos de onda causados por ciclones no Oceano Atlântico Sudoeste: distribuição de casos e balanço de calor e vorticidade dos sistemas geradores

Abstract

Human activities over the ocean are greatly affected by environmental factors. As economic expansion advances towards the sea, there is a continuous search to understand its impacts, in order to resolve weather-related uncertainties. This work aims to study the region of extratro- pical cyclones, formed in the western portion of the South Atlantic Ocean, most prone to the formation of extreme waves, according to the large-scale atmospheric conditions. To this end, ERA5 hindcast data and atmospheric elds will be used in order to follow the evolution of systems in the cyclogenesis region, focusing on the most extreme events recorded in the last 42 years. Events will be selected within the domain, and grouped into latitude bands and secto- rally, in relation to cyclones. Observing the events, it is noted that there is a pattern between the distribution of extreme events in relation to the cyclone, varying between the seasons, and by latitude bands. It is also noted a a clear dependence of the extremes with respect to the cy- clone displacement speed. In order to investigate the processes of cyclone intensi cation up to the maximum signi cant height of the waves generated by them, heat and vorticity budgets were performed for all cyclones that generated wave extremes between 1979 and 2020, both during the instant of maximum signi cant height and in the intensi cation phase. Special at- tention was given to two cases with different characteristics, one in winter and one in summer, as well as subdivisions by seasons, by quadrants and also by the sector where the extreme is located in relation to the center of the cyclone. The heat and vorticity budgets showed us the important role of the advection of temperature and vorticity, and diabatic heating, among other terms; moreover the vertical variation of these terms, in addition to the unequal distri- bution in the quadrants, for the generation and intensi cation of extreme waves in the diffe- rent sectors and seasons.