Fig. 6: Schematic representation of the two seasonal extremes of equatorial Atlantic nitrate supply and productivity.
From: Seasonal productivity of the equatorial Atlantic shaped by distinct wind-driven processes
Shown are the mean conditions in the upper 150 m during the warm (April) and cold (July) seasons. In April, the nitracline is located below the shallow EUC core, resulting in no upward mixing of nitrate. A deep chlorophyll maximum is maintained at or below the EUC core. With the strengthening of equatorial easterlies, the nitracline in the eastern equatorial Atlantic moves upward, reaching its shallowest position in July. The EUC core independently moves downward due to the presence of the annual resonant basin mode superimposed on the mean EUC. Synchronously enhanced mixing in the shear zone between surface mixed layer and EUC core, driven by increased local winds, promotes upward nitrate supply, thereby enhancing productivity up to the surface.
