Dataset: CTD 1m averaged profiles
Deployment: B4-2008

CTD data are reported as cast number and not as station number.

Temperature and salinity (parameter names temp and sal): On the R/S Bjarni Saemundsson cruises, only one CTD unit was present, so salinity and temperature were de-spiked using a 21-point (3.5 s) median filter. An additional 81-point (13 s) median filter was applied where the signal was particularly variable. For more details on temperature and salinity processing, see Ship_TS_despiking-NAB08.pdf.

Dissolved oxygen, O2 (parameter name O2_uncal): The sensor was calibrated immediately before the 1 April 2008 cruise. The factory calibration was applied to SBE43 oxygen sensor voltage, with units of µmol kg-1. Although the sensor was calibrated immediately before the cruise, the absolute concentrations were not verified by Winkler oxygen.

Particulate attenuation coefficient, cp (parameter name beam_cp): C-Star s/n 284 did not have a recent factory calibration. On the subsequent R/V Knorr cruise in May, it was cross calibrated with the newly calibrated C-Star s/n 1090 through a series of simultaneous ship/Biofloat48 calibration profiles. The final product contains cross-calibrated cp coefficients (m-1) for all three C-Stars. Complete details of the transmissometer intercalibration procedure are in C-Star calibration report (C-Star_Calibration-NAB08.pdf).

Particulate backscattering coefficient, bbp (parameter name bbp700): Backscattering voltage was converted to ? at 140° by subtracting dark voltages (median in-situ dark voltage, 0.078 V) and multiplying by factory calibration scale factors, modified based on measurements and calculations of Sullivan et al. (subm.). The calibration factor did not change between pre-cruise and post-cruise factory calibration. ? at 140° was converted to bbp (m-1) by subtracting ? of seawater (Zhang et al., 2009) and multiplying by 2?? (where ? = 1.132). See calibration report for more details: Backscatter_Calibration-NAB08.pdf.

Chlorophyll fluorescence: Chlorophyll fluorescence (parameter name chl_raw) is reported as the raw instrument voltage output minus dark voltage (median in situ dark voltage = 0.083 volts).

Water column photosynthetically active radiation (PAR; parameter name par): The sensor was new and freshly calibrated before the cruise. For more details, see Radiometry_and_PAR_Calibration-NAB08.pdf.