On the 12th of September HabWAVE’s team left Figueira da Foz’s port before dawn on board Instituto Hidrográfico’s NRP Auriga towards a previously established location, where a mooring was deployed earlier this week, at approximately 30 km offshore and about 100 m deep. This mooring contains an Acoustic Doppler Current Profiler (ADCP) 300 looking up and a 1200 looking down coupled with a LISST200x (Laser in situ transmissometer), together with a multiple thermistor vertical chain. The purpose of the mooring is to measure the temporal variability of currents (vertical profile), particle size distribution and the particle volume concentration in the benthic nepheloid layer (BNL). The coupled ADCPs will allow the understanding of the relationship between bottom physical forcing and sedimentary dynamics.
The work carried out at the fixed station comprises water sampling, collection of surface sediments, and CTD (conductivity-temperature-depth) surveys in order to characterize stratification conditions, spatial distribution of suspended particulate matter and turbidity (BNL), and cyst concentration. Successive temperature and salinity measurements at the same location are meant to try capturing fluctuations in the thermocline’s depth and thus inferring the passage of internal waves (internal tides characterization). Water samples are to be processed in the land lab, filtered for cyst concentration and phytoplankton enumeration.
Here are some photos provided by the team on board and the team on land standing by.