The main natural source of iron to open ocean surface waters is continentally derived aeolian dust. This influences the aerosol optical depth (AOD) of the atmosphere, which can be measured by satellite-borne sensors such as SeaWiFS. Most of the iron present in remote marine aerosols is in the soluble Fe (II) form, which is readily utilised by phytoplankton. This suggests that phytoplankton biomass will respond rapidly to inputs of aeolian dust. These blooms will occur in the surface layer of the upper ocean where they are readily sensed by satellites. We examine the relationship between satellite-derived measures of AOD and chlorophyll at the global scale. Regions in which the atmosphere and ocean are coupled are identified and their significance discussed.