HR: 1400h
AN: OS23C-02 [Abstracts]
TI: Seasonal Variability Of The Meridional Transport Along The Northeastern Brazilian Edge
AU: * Veleda, D
EM: doris.veleda@ufpe.br
AF: Laboratorio de Oceanografia Fisica Estuarina e Costeira, Departamento de
Oceanografia da Universidade Federal de Pernambuco LOFEC/DOCEAN/UFPE, Av. Arquitetura s/n, Cidade
Universitaria, Recife, PE 50740-550, Brazil
AU: Araujo, M
EM: moa@ufpe.br
AF: Laboratorio de Oceanografia Fisica Estuarina e Costeira, Departamento de
Oceanografia da Universidade Federal de Pernambuco LOFEC/DOCEAN/UFPE, Av. Arquitetura s/n, Cidade
Universitaria, Recife, PE 50740-550, Brazil
AU: Silva, M
EM: marcus@ufpe.br
AF: Laboratorio de Oceanografia Fisica Estuarina e Costeira, Departamento de
Oceanografia da Universidade Federal de Pernambuco LOFEC/DOCEAN/UFPE, Av. Arquitetura s/n, Cidade
Universitaria, Recife, PE 50740-550, Brazil
AU: Montagne, R
EM: montagne57@gmail.com
AF: Departamento de Fisica Teorica e Experimental da Universidade Federal do Rio Grande
do Norte, Caixa Postal 1641, Natal, RN 59078-970, Brazil
AB:
The dynamics of the southern band of the South Equatorial Current (sSEC) near to Brazilian shelf is investigated
using recent field observations and a regional numerical modelling approach. Ocean measurements were
obtained from five moorings deployed by German CLIVAR (Climate Variability and Predictability Program) cruises
(March 2000-May 2003) along a crossshore line at 11° S. The Regional Ocean Model (ROMS) is used to
simulate the circulation and thermohaline structures within the ocean area comprised between 5° S-25° S
and 20° W-47° W. This integration domain was covered by an isotropic 1/12° horizontal grid and 40
terrain-following layers. The numerical results confirm a seasonal migration of the core sSEC divergence along
the Brazilian edge, as well as its depth dependence with a maximum northward shift in July at 180 m layer, while
a maximum southward displacement occurs in November at this same depth. This intrannual variability
coincides with the North Brazil Undercurrent (NBUC) seasonality at 11° S such as moorings measurements,
Empirical Orthogonal Function (EOF) and numerical results show a minimum NBUC strength during November
(field data = 14.7 Sv; model = 19.1 Sv), a maximum northward transport in July (field data = 29.8 Sv; model = 29.8
Sv), and a quasi-semestral periodicity of the NBUC core (EOF1 = 97%). Furthermore the North Atlantic Deep
Water (NADW) variability observed at the deeper colder layers (and reproduced by the model) seems to be linked
to upstream instability from eddies passage in the Deep Western Boundary Current (DWBC). The variability is
decomposed into two separate modes accounting for 69% and 25% of the total variance in the lower and upper
NADW layers, respectively. Numerical results and EOF indicated a cycle of 60-70 days (EOF1 = 69%) for the core
of the DWBC at 1900 m depth. According to simulations the upstream DWBC flow is reinforced between 7° S-
10° S during austral winter, thus enhancing anticyclonic eddies generation along 10° S-17° S, whereas
upstream DWBC flow is reduced during the austral summer, when downstream eddies is less pronounced. A
counterflow offshore from NBUC was identified in the numerical results and EOF analysis at 500 m depth (EOF2
= 25%). The EOF for (T-V) fields exhibit temperature strongly coupled to the velocity current at the core of the
DWBC for the first year of data, which reveals that this two fields are synchronized each two months.
DE: 4500 OCEANOGRAPHY: PHYSICAL
DE: 4504 Air/sea interactions (0312, 3339)
DE: 4512 Currents
DE: 4534 Hydrodynamic modeling
DE: 4576 Western boundary currents
SC: Ocean Sciences [OS]
MN: 2007 Joint Assembly