An improved coastal upwelling index from sea surface temperature using satellite-based approach – The case of the Canary Current upwelling system

• An improved coastal upwelling index is derived from satellite sea surface temperature.
• The spatio-temporal variability of the upwelling is described from 1982 to 2011.
• The index is more accurate than previous ones based on SST.
• The method is generic for all Eastern Boundary Upwelling Systems and others.

A new methodology to derive an SST-based upwelling index was based on a rigorous spatial analysis of satellite SST fields and their variability, by referring to previous works, from Wooster et al. (1976) to Santos et al. (2011). The data was precautiously processed by considering data quality aspects (including cloud cover) and the best way to derive accurate coastal SST and its offshore reference. The relevance of the developed index was evaluated by comparing its spatial and seasonal consistency against two wind-based indices as well as with the previous SST-based indices, largely superseding these later ones in term of overall quality and spatio-temporal dynamic. Our index adequately describes the spatio-temporal variability of the coastal upwelling intensity in the Canary Current upwelling system and has the advantage of describing complementary aspects of the coastal dynamics of the region that were not covered by Ekman-based indices.The proposed methodology is generic and can be easily applicable to various coastal upwelling systems, especially the four major eastern boundary upwelling ecosystems.