CTD measurements over the Grimsey Hydrothermal Field (Northern Iceland) during cruise POS524 onboard RV Poseidon

The main objective of cruise POS524 to the Grimsey Vent Field (GVF), to the North of Iceland, was to study the suitability of electromagnetic (EM) systems for the characterization of an active hydrothermal system. As part of the EM measurements, a Microcat CTD sensor (Seabird) was attached to the mobile EM transmitter (MARTEMIS system), which was operated at an altitude of 5 - 10m above the seafloor. CTD measurements were collected alongside the EM measurements to serve as indicators for hydrothermal activity. CTD measurements with the Microcat CTD Sensor recorded conductivity [mS/cm], temperature [°C] and pressure [dbar] at a sampling rate of 4s, from which sound velocity [m/s] and salinity [psu] were derived using standard formulas (Chen and Millero formula; UNESCO Technical papers in Marine Science #44). Measurements were taken along profiles with a total length of about 18.5km crossing the GVF and surrounding areas during 24h of the 2nd deployment of the MARTEMIS system (station POS524_22-1) between 13.6.2018 6:00h - 14.6.2018 6:00h (UTC). The data are stored in an xls-file. Please note that on-deck measurements were cut from file. Details of the measurements and the cruise can be found in the cruise report (DOI 10.3289/CR_POS524)