The IbMa-CSV oceanographic station, composed of two autonomous moorings: a vertical profiler current meter (ADCP) and a wave-powered vertical profiler carrying a CTD and dissolved oxygen, turbidity and chlorophyll-a sensors; was deployed in late May in its regular location, ten nautical miles south of Cape São Vicente, at 200 m deep, over the continental shelf break. The upper 150 meters of the water column will be sampled continuously during the next four months, at a rate of 5 to 6 vertical profiles per hour, with 0.2 meters of vertical resolution. 

This deployment is intended to contribute to the continuous monitoring of the ocean in this region with strong mesoscale activity, where the waters of the Gulf of Cadiz interact with the Canary Current, the Mediterranean Outflow Water and the open North Atlantic. The gathered data will continue the long time-series of oceanographic variables, fundamental to accessing long-term variability and global change impacts in the water column structure and in the ecosystem functioning. The high resolution of the data will considerably improve the parametrisation of the numerical models, contributing to trustworthy digital twins of the ocean in the region. 

The observatory is jointly managed by CCMAR and IPMA, and this deployment was carried out onboard the Spanish R/V Ángeles Álvariño, in collaboration with the IEO (Spanish Institute of Oceanography).

A second identical set of vertical profiler current meter and wave-powered vertical profiler is already on the bench to replace the station on a rotating basis and thus avoid gaps in the data when the equipment needs maintenance. The goal is to sustain the IbMa-CSV station as permanently as possible in order to construct a long, high-resolution time series of essential oceanographic variables. 

Future plans include adding deeper, high-resolution long-term observations to the IbMa-CSV station to capture the Mediterranean Outflow Water (MOW). The MOW flows along the Iberian Margin of the Gulf of Cadiz, roughly between 800 and 1200 meters deep, although some shallower veins were already identified. The salty and warm MOW has a strong turbulent nature, giving origin to mesoscale eddies of Mediterranean water (meddies) that keep their TS identity while spreading in the North Atlantic. The salt balance in the North Atlantic is a key factor for the AMOC (Atlantic Meridional Overturning Circulation) variability, with significant climatic impacts. The MOW is a net salt contributor to this budget. It is critical to attain an enhanced long-term definition of the MOW, to assess trends and shorter-term variability, and contribute to the understanding of the mixing of the Mediterranean water in the North Atlantic, a precondition for the numerical modelling of the process.

 

 

Photo 1: Deployment of the ADCP mooring

Photo 2: Deployment of the wave powered vertical profiler (DMO Wirewalker).

Photo Credit: @Carlos Sousa

 

Authors: Carlos Sousa¹’², Paulo Relvas² and A. Miguel Santos¹’²

Affiliations: ¹IPMA – Portuguese Institute for the Sea and Atmosphere

² CCMAR (Centre of Marine Sciences) / University of Algarve, Portugal.