Vertical hydrography profiles from CTD rosette downcasts during PolarFront cruise 2022-05

Hydrography data from CTD (SBE911plus, Seabird Inc.) profiles. Rosette equipped with the following sensors:

Conductivity

Temperature

Pressure

Fluorometer

Turbidity

PAR

Oxygen

Update December 2024

The salinity and temperature sensors were calibrated against another CTD from a moored instrument by Ragnheid Skogseth at UNIS, the University Centre in Svalbard. A relatively large drift in temperature was observed. To convert temperature (T) and salinity (S) to calibrated values apply the following equations to e.g. data from stnrxxxx_bin.cnv

T_new = T_old + 0.12S_new = 1.0115 * S_old – 0.5343

The following is quoted verbatim from chapter 1 in the cruise report (Basedow, 2022):

Hydrographic data were collected by a variety of sensors mounted on vertical profiling platforms, towed platforms and autonomous gliders. Combined, these platforms provided detailed information at stations, high-resolution measurements across the polar front, and longer-term measurements by the gliders. During the cruise, hydrographic measurements were taken at stations using the main rosette equipped with 12 5-L Niskin bottles, CTD-F, PAR and other sensors (Table 1.1) and using a smaller rosette frame equipped with CTD-F, LOPC, LISST and WBAT (Table 1.2, Fig. 1.1). Both platforms were deployed vertically until 5-10 m above the bottom for the main platform and down to 300 m for the platform with the LOPC, this rosette sampling three profiles at selected stations.

In total 14 vertical profiles were sampled by the rosette with the water bottles (Table 1.1) at our 6 main stations (PF1 to PF6). Water samples for biological analyses were taken from selected depths and a bottom water samples was collected at each station for calibration of the conductivity sensor ashore. Water samples for chlorophyll a will be used to calibrate the fluorescence sensor. CTD data from this rosette were processed using the SBEDataProcessing-Win32 software. Only the values from the CTD downcast were used to avoid turbulence caused by the rosette on the upcast. The data were convertedto physical units, filtered for outliers and bin-averaged over 1 m bins. 

References

Sünnje Basedow, Nicolas Gosset, Torkel Granaas, Eva Leu (2022). Hydrography. In: Malin Daase (ed.) (2022). PolarFront May 2022 Cruise Report. Zenodo. https://doi.org/10.5281/zenodo.7128746