Transformation of global satellite chlorophyll retrievals with a regionally tuned algorithm

“Global” algorithms for satellite remote sensing do not always provide accurate retrievals in all areas of the ocean, particularly in coastal areas and high latitudes. Our current arctic algorithm shows that low chlorophyll concentrations (∼0.6 mg m−3) are overestimated by the OC4V4 algorithm for Sea-viewing Wide Field-of-view Sensor (SeaWiFS), while higher concentrations common in blooms are underestimated almost twofold. Alternative algorithms or regionally tuned relationships can be used to produce more reliable chlorophyll retrievals; however, reprocessing of huge satellite data sets can be untenable. Several approaches were investigated to convert global products into regional values to improve accuracy while minimizing errors across the range of values. A simple, rapid transformation scheme employing linear interpolation circumvents reprocessing of entire data sets, but yields much more accurate regional values for the Arctic.