Satellite remote sensing of primary productivity in the Bering and Chukchi Seas using an absorption-based approach

Ocean colour remote sensing has been utilized for studying primary productivity in the Arctic Ocean. However, phytoplankton chlorophyll a (Chl a) is not predicted accurately because of the interference of coloured dissolved organic matter (CDOM) and non-algal particles (NAP). To enhance the estimation accuracy, a phytoplankton absorption-based primary productivity model (ABPM) was applied to the Bering and Chukchi Seas. The phytoplankton absorption coefficient was determined correctly from sea surface remote sensing reflectance (R-rs) and reduced the effect of CDOM and NAP in primary productivity (PPeu) estimates. PPeu retrieved from in situ R-rs using the ABPM satisfied a factor of 2 of measured values. PPeu estimated from the Moderate Resolution Imaging Spectroradiometer R-rs data were within the range of historical values. These estimated PPeu values were less than half of those of the model based on Chl a, and the difference between the two models reflected the influence of CDOM and NAP absorptions. Interannual variation in August and September over the period 2002-2010 showed an increase in primary productivity. The increase in 2007 was especially large, by a factor of 1.51-2.71, compared with 2006. The significant temporal increase in productivity detected here differs from earlier studies that detected little, if any, change in the region.