Dataset: Nitrate plus raw spectral profiles from a Satlantic Nitrate Sensor on Biofloat 48 in the subpolar North Atlantic and Iceland Basin in 2008 (NAB 2008 project)

Nitrate (parameter names nitrate): The Satlantic in situ ultraviolet spectrophometer ISUS V3 sensor was deployed on Float 48.  Post calibration of the ISUS instrument and subsequent processing of the spectrophotometric data acquired by the ISUS incorporating in situ temperature and salinity measurements to correct for the temperature-dependent, ultraviolet absorbance by the bromide ion results in a precision of duplicate nitrate measurements of 0.1μM. These nitrate concentrations were then calibrated against bottle measurements collected during the R/V Knorr process cruise (April 17 through May16) and subsequently analyzed for nitrate plus nitrite (NO3-+ NO2-) concentration.  A simple linear regression was sufficient to make the ISUS nitrate concentrations (NO3ISUS) fit the bottle for nitrate plus nitrite measurements with a standard deviation of 0.6μM:
      nitrate = 1.1536 x NO3ISUS + 2.6227    (r2 = 0.927, n = 53)
Comparisons with water samples taken on the R/V Bjarni Saemundsson deployment cruise are inconclusive due to high spatial variability.  No obvious drift of the ISUS response with time or depth was apparent.  For more details, see ISUS_Nitrate_Calibration-NAB08.pdf.