Seasonal constraints on the estimation of new production from space using temperature-nitrate relationships

[ 1] Inverse relationships between sea surface temperature and concentrations of the major inorganic nutrients have recently been exploited to estimate new production from remotely sensed data. In situ surface data collected in the Irminger Basin during four successive seasons in 2001/2 allow a robust examination of the conceptual processes behind temperature-nitrate relationships. The data confirm a simple model of the seasonal variation in the temperature-nitrate relationship. A strong inverse correlation between temperature and nitrate is found in both winter data sets, but no correlation is seen in spring or summer. Furthermore, the slope of the temperature-nitrate regression is found to be different for the two winter data sets. The results have implications for using temperature-nitrate relationships to derive new production estimates at high latitudes from satellite sea surface temperature measurements. However, the data allow a simple, lower-bound estimate of the region's new production to be made by exploiting Argo float data.