Fig. 1

North Atlantic GA03 aerosol Fe isotope sampling locations. Aerosol samples are a subset of those collected on the cruise, and are characterized as Saharan (gray), North American (blue), or European (red), according to HYPSLIT air mass back-trajectory analysis⁴³. 2010 and 2011 legs of the GA03 cruises (USGT10 and USGT11) are shown separately