Iron flux induced by Haida eddies in the Gulf of Alaska

Abstract

[1] Mesoscale anticyclonic Haida eddies are proposed to deliver a substantial amount of iron into the Gulf of Alaska (GOA) central gyre, where surface waters experience high-nitrate low-chlorophyll conditions. In this study we calculate an averaged upwelling flux of dissolved iron into the euphotic zone (100 m) of 1.17 μmol m−2 d−1 based on observed iron profiles and modeled eddy dynamics and resultant vertical velocities. This estimated eddy-derived iron supply rate is comparable with new estimates of pulsed iron fertilization rates from rare volcanic ash deposition events. Despite the relatively small area affected by Haida eddies, they are estimated to contribute about 4.6 × 106 moles of dissolved iron yearly to the GOA, which is equivalent to the annual atmospheric dust deposition. Haida eddies therefore represent a major iron source that should strongly influence the regional biological productivity and carbon budget of the GOA.