Variability of Deep Currents in the Western South Atlantic: Observations and modeling

CAMPOS, E. J. D.; MEINEN, C. S.; PIOLA, A. R.; GARZOLI, S. L.; CHIDICHIMO, M. P.; PEREZ, R. C.; DONG, S.

Praga

Simposio; 26th International Union of Geodesy and Geophysics (IUGG) General Assembl; 2015

International Union of Geodesy and Geophysics (IUGG)

Observations and outputs from a numerical experiment are analyzed to investigate the structure and variability of deep currents in the Southwestern Atlantic. The model is a 1/12-degree, 32 sigma2 layers, global implementation of the Hybrid Coordinate Ocean Model (HYCOM). The data were measured continuously, from Dec/2012 to Oct/2014, with two current-and-pressure-equipped inverted echo sounders (CPIES), deployed at 50.5ºW, 34.5ºS (site AA, 2885m) and 48.5ºS, 34.5ºS (and site BB, 4140m). The time series of the daily-averaged current meter data, measured 50m above the sea floor, show intense variability in a wide range of frequencies. At both sites, the meridional (N-S) component of the flow is less energetic than the zonal (E-W) component; particularly at Site BB. Preliminary calculations show values of mean and standard deviation as follows. Site AA: 1.7±4.8 cm s-1 for the zonal flow and 1.2±3.2cm s-1 for the meridional flow; Site BB: 7.1±14.0 cm s-1 and 0.4±3.2 cm s-1, respectively. Despite having lower mean values, the model shows standard deviations in good agreement with the observations at the two sites. Horizontal maps of the model?s results suggest that the deep flow in the region is dominated by intense mesoscale eddy-activity and is oriented alongshore.