Mixed Layer Depth computation
  • The Mixed Layer Depth (MLD) is computed on each density profile by using at threshold value of 0.03 difference from surface (10m) reference.

Chlorophyll processing
  • Fluorescence profiles acquired by floats are initially corrected by imposing zero fluorescence at the depth (Z > 800 m). The correction applies only if MLD is lower than 600m.
  • A quenching correction is applied, following the indication of Xing et al. 2012 . Briefly, fluorescence in the MLD is considered homogenous, keeping the fluorescence max value in the MLD.
  • The resulting fluorescence profile is corrected by an offset calculated comparing the first fluorescence profile of float and HPLC samples obtained at deployment. This correction applies only if HPLC samples exist.
  • Surface Chl (Chl Surf) is computed averaging the first 10 meters of the corrected profile.
  • Integrated Chl ("Chl Int") is calculated by integrating profile over the firsts 300m.

NO3 Concentrations processing
  • Raw spectrum in the UV is calibrated by imposing spectral reference (obtained before deployment).
  • NO3 concentrations are then obtained by fitting the resulting spectrum and considering salinity, temperature and deep influence (Johnson et al. 2013, "Long-term nitrate measurements in the ocean using the In Situ Ultraviolet Spectrophotometer: sensor integration into the Apex profiling float", Journal of Atmospheric and Oceanic Technology).
  • The resulting NO3 profile is finally adjusted, by imposing offset calculated by comparing NO3 concentrations at the deployment.
  • The NO3 concentration in the MLD ("NO3 MLD") is computed by arithmetically averaging the NO3 values in the MLD.
  • The nitracline depth ("Nitracline") is calculated by computing the first occurrence of the 2 μmol/liter along the profile (note that red lines in the plot indicate nitracline computed using 1 μmol/liter as threshold value).

Backscattering Coefficient computation
  • coming soon...