A real time CTD record in the computer laboratory on the R/V Thompson as the rosett was being lowered to 10 meters above the seafloor at the International District vent field. The CTD vertical cast was done over the ~60 foot tall black smoker called "El Guapo". It record shows salinity (yellow), temperature (orange), Flourescence (blue-chlorophyll) and particulates in the water column (green).
A rosette with a suite of attached sensors was deployed during the VISIONs cruises. The sensors on the rosette include conductivity-temperature-depth (CTD) sensors, dissolved oxygen, chlorophyll fluorescence, transmissometer, pH, a Photosynthetically Active Radiation (PAR) sensor, and an altimeter. The CTD measures the salinity and temperature of seawater, which are fundamental properties needed to understand the physical structure of the ocean. A dissolved oxygen sensor measures the available oxygen present in the water, which gives clues to the ability of the ocean to sustain animal life. Chlorophyll fluorescence is a proxy for phytoplankton concentration and a transmissometer measures the amount of light absorbed or transmitted through water. pH is a measure of the total hydrogen ion concentration in the ocean. PAR sensors provide a measure of the amount of light available for photosynthesis by phytoplankton. The altimeter provides the distance above the sefloor.