CASSIS-Malvinas: Southwestern Atlantic currents from in-situ and satellite altimetry data project

MARTIN SARACENO; PROVOST, C.; RAUL GUERRERO; PIOLA, A. R.

La Rochelle

Congreso; OSTST; 2016

This project has three main objectives: (i) to improve our understanding of the circulation on the Patagonian continental shelf (PCS) using satellite altimetry, (ii) to improve our understanding of the dynamics of a major western boundary current, the Malvinas Current (MC) and (iii) to improve our understanding of the interactions between the MC and the circulation on the continental platform. Because of the large size of the PCS and shelf-break regions, satellite altimetry data, combined with in-situ observations, offer a unique dataset to achieve our objectives. In-situ time-series measurements provide information on the vertical structure of the ocean and quantify the missing portion of the high-frequency variability that cannot be determined from the altimeter. As part of the project, we deployed an array of current meter moorings, bottom pressure recorders (BPR), conductivity-temperature (CT) sensors and a fully equipped oceanographic buoy during two years. During the first year (December 2014-November 2015) moorings were deployed below the Jason-2 satellite altimeter track #26, covering the northern portion of the MC and Patagonian shelf. In December 2015 instruments were recovered and redeployed for another year along a zonal section at 44.7ºS. The deployment scheme allows to simultaneously monitor the PCS and MC flows. Data are analyzed in conjunction with historical in-situ and satellite datasets. First results obtained from the northern section are analyzed here and in three complementary presentations (Paniagua et al, Ferrari et al and Artana et al). Overall in-situ data show large (>0.7) and significant correlation with satellite altimetry data. During specific events associated to mesoscale or passage of synoptic storms, differences between remote and in-situ data are largest. Over the continental shelf, the time series obtained are the longest record obtained to date. There, mean values are in agreement with model outputs but show unexpected variability at short (intraseasonal) time scales.We can affirm that results obtained help improving our understanding on the dynamics in both the shelf-break and continental Patagonian regions. In turn results will have an important socio-economical impact since the PCS and adjacent shelf-break are one of the most productive areas of the World Ocean. Furthermore, these regions have a significant impact on the balance of atmospheric CO2 and therefore possible fluctuations may impact the climate.The project use existing resources from two countries, France and Argentina. Deployment and recovery of the instruments is being carried out from R/V Puerto Deseado (CONICET, Argentina) and Guardacostas Tango (Prefectura Naval, Argentina). Instruments deployed were made available by INSU national park, LOCEAN-IPSL (France), SHN (Argentina), INIDEP (Argentina) and CIMA (Argentina). Participation of expert technicians from DT-INSU, LPO, SHN and INIDEP was essential to achieve the correct mooring deployment and recovery.