Environmental controls on N2 fixation by Trichodesmium in the tropical eastern North Atlantic Ocean-A model-based study

► Environmental controls on N2 fixation at TENATSO are studied in an 1D model. ► High temperature and DOP availability allow a maximal abundance of Trichodesmium in autumn. ► Newly fixed N fuels the growth of phytoplankton in autumn and winter. ► Dust deposition is required to support diazotrophy and the observed phytoplankton abundance. ► Higher deposition in autumn and winter switches N2 fixation from Fe- to P-limited.