Pezzi, L. P., R. B. Souza, P. C. Farias, O. Acevedo and A. J. Miller, 2016:
Air-sea interaction at the Southern Brazilian Continental Shelf: In situ
observations
Journal of Geophysical Research-Oceans, 121, 6671-6695.
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/m2 especially in the southernmost region where the
gradients were more intense.
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