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Circulation response to aerosol forcing of the 1970s and 2000s - the case of the North Atlantic warming hole
  • Stephanie Fiedler,
  • Dian Ariyani Putrasahan
Stephanie Fiedler
University of Cologne

Corresponding Author:[email protected]

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Dian Ariyani Putrasahan
Max Planck Institute for Meteorology
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We show how changes in the global distribution of anthropogenic aerosols favour different spatial patterns in the North Atlantic sea-surface temperature (NASST). The NASSTs largely show the expected decrease associated with the anthropogenic aerosols in the 1970s, but also a surprising warming response in the eastern sub-polar gyre, the region of the North Atlantic warming hole. The NASST response reversed for the anthropogenic aerosols in the 2000s against 1970s. The regional reduction in anthropogenic aerosols favoured (1) a strengthening of the warming hole and (2) a NASST increase at high latitudes associated with changes in the atmosphere-ocean dynamics. The gyre component of the northward Atlantic heat transport in mid- to high latitudes is an important driving mechanism. At least two-thirds of the NASST response is associated with the magnitude of aerosol-cloud interactions. Constraining the NASST response therefore depends on a better understanding of the uncertain aerosol effects on clouds.