How Does the North Atlantic SST Pattern Respond to Anthropogenic Aerosols in the 1970s and 2000s?

Abstract

We show how changes in the global distribution of anthropogenic aerosols favor 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 an unusual 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 favored as follows: (1) a strengthening of the warming hole and (2) a NASST increase at high latitudes associated with changes in the coupled atmosphere-ocean dynamics. We found that the gyre component of the northward Atlantic heat transport in mid-to high latitudes is an important driver for the heat convergence associated with the NASST patterns. At least two-thirds of the NASST response in MPI-ESM1.2 is associated with aerosol-cloud interactions, highlighting the need to better understand them.