Air-sea interaction at the Southern Brazilian Continental Shelf: In situ observations

TitleAir-sea interaction at the Southern Brazilian Continental Shelf: In situ observations
Publication TypeJournal Article
Year of Publication2016
AuthorsPezzi L.P, Souza R.B, Farias P.C, Acevedo O., Miller AJ
JournalJournal of Geophysical Research-Oceans
Volume121
Pagination6671-6695
Date Published2016/09
Type of ArticleArticle
ISBN Number2169-9275
Accession NumberWOS:000386913200007
Keywordsair-sea fluxes of heat; air-sea interaction; atlantic-ocean; boundary-layer; Continental shelf; cross-shelf; eastern equatorial pacific; instability waves; MABL stability; malvinas confluence; marine atmospheric boundary layer; numerical simulations; salinity signature; sardine sardinella-brasiliensis; satellite-observations; Southern Brazilian; surface-temperature; thermal gradients; tropical
Abstract

The influence of the cross-shelf oceanographic front occurring between the Brazil Current (BC) and the Brazilian Coastal Current (BCC) on the local Marine Atmospheric Boundary Layer (MABL) is investigated here. This front is typical of wintertime in the Southern Brazilian Continental Shelf (SBCS) and this is the first time that its effects are investigated over the above MABL. Here we analyze variability, vertical structure, and stability of MABL as well as heat fluxes at air-sea interface, across five oceanographic transects in the SBCS made during a winter 2012 cruise. Local thermal gradients associated with mixing between distinct water masses, play an essential role on MABL modulation and stability. Although weaker when compared with other frontal regions, the cross-shelf thermal gradients reproduce exactly what is expected for open ocean regions: Stronger (weaker) winds, lower (higher) sea level pressure, and a more unstable (stable) MABL are found over the warm (cold) side of the oceanographic front between the BC (warm) and coastal (cold) waters. Our findings strongly support the coexistence of both known MABL modulation mechanisms: the static and hydrostatic MABL stability. This is the first time that these modulation mechanisms are documented for this region. Turbulent fluxes were found to be markedly dependent on the cross-shelf SST gradients resulting in differences of up to 100 W.m(-2) especially in the southernmost region where the gradients were more intense.

DOI10.1002/2016jc011774
Short TitleJ Geophys Res-Oceans
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