Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
Source: AGU Advances
Biological productivity in the ocean would rapidly wane if the nitrogen that is lost from the surface as a consequence of the marine biological pump was not resupplied back to the surface. However, the mechanisms responsible for the upward transport of this nitrogen are not well quantified.
Marshall et al. [2023] take advantage of the dual isotopic signature of nitrate (oxygen-18 and nitrogen-15) to trace the injection of new nitrate into the upper ocean. Using hydrographic survey data from the Agulhas Current, they find that mixing and upwelling associated with mesoscale eddies and other (sub)mesoscale processes are critically important pathways for providing this nitrate back to the surface.
The authors argue that similar processes are at play in the other western boundary currents, giving these regions an important role in enhancing biological productivity in the adjacent regions that are otherwise rather oligotrophic. This work further demonstrates the need for high-resolution approaches to capture the dynamics of the marine biological pump.
Citation: Marshall, T. A., Beal, L., Sigman, D. M., & Fawcett, S. E. (2023). Instabilities across the Agulhas Current enhance upward nitrate supply in the southwest subtropical Indian Ocean. AGU Advances, 4, e2023AV000973. https://doi.org/10.1029/2023AV000973
—Nicolas Gruber, Editor, AGU Advances