Schematic diagram of the interactions among tropical ocean basins and between tropics and mid-high latitudes (IMAGE)
Caption
The upper panel illustrates how ENSO influences the equatorial Atlantic and Indian Oceans, and how these two ocean basins in turn feed back to ENSO. On the right side of the panel, the schematic shows the meridional circulation pattern during an active phase of the Atlantic Meridional Overturning Circulation (AMOC), the zonal mean sea surface temperature (SST), and the climatological position of the Intertropical Convergence Zone (ITCZ).
The lower panel shows how Indian Ocean warming and ENSO influence the AMOC. It includes a plan-view schematic of AMOC and the meridional circulation pattern after AMOC weakens significantly, along with zonal mean SST anomalies and a southward shift of the ITCZ.
ENSO can modulate the Atlantic Niño, North Atlantic Meridional Mode, and Indian Ocean Dipole Mode by directly altering the zonal Walker circulation (black arrows in the figure). In turn, these three modes can feed back on ENSO (indicated by red, green, and blue arrows).
Warming in the Indian Ocean can alter the Walker circulation, leading to cooling in the equatorial Atlantic. It can also affect the North Atlantic Oscillation (NAO) via atmospheric teleconnections, thereby impacting AMOC. Additionally, warming-induced increases in Indian Ocean salinity can be transported to the North Atlantic by ocean currents, further influencing the AMOC. ENSO may also affect the NAO through atmospheric teleconnections and consequently modulate AMOC.
Credit
Ocean-Land-Atmosphere Research
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