Glider observations of the Northwestern Iberian Margin during an exceptional summer upwelling season

Glider observations from the Northwestern Iberian Margin during the exceptionally strong 2010 summer upwelling season resolved the evolution of physical and biogeochemical variables during two upwelling events. Upwelling brought low-oxygen Eastern North Atlantic Central Water from 190 m depth onto the shelf up to a depth of 50 m. During the two observed periods of upwelling, a poleward jet developed over the shelf break. The persistent upwelling favorable winds maintained equatorward flow on the outer shelf for 2 months with no reversals during relaxation periods, a phenomenon not previously observed. During upwelling, near-surface chlorophyll a concentration increased by more than 6 mg m ⁻³. Oxygen supersaturation in the near surface increased by more than 20%, 6 days after the chlorophyll a maximum.