17 
Longitude 
Longitude 
Fig. 10: Adjusted reference (red) and historical (blue) profiles. 
Multiplicative scale factors were calculated for oxygen and nutrients unlike additive corrections 
(biases) for salinity. As equation (2) deals with additive biases, the observed crossover 
differences D,y for oxygen and nutrients which were respectively recalculated for “standard” 
nutrient concentrations. There are several reasons to use multiplicative factors instead of biases. 
One reason is that multiplicative scale factors help to avoid negative nutrient/oxygen values for 
very low near-surface concentrations (see a more detailed discussion in Johnson et al., 2001).