Long-term SST Variability on the Northwest Atlantic Continental Shelf and Slope

The meridional coherence, connectivity and regional inhomogeneity in the long-term SST variability over the Northwest Atlantic continental shelf and slope from 1982-2018 are investigated using observational datasets. A meridionally concurrent large SST warming trend is identified as the dominant signal over the length of the continental shelf and slope between Cape Hatteras, North Carolina and Cape Chidley, Canada. The linear trends are 0.37±0.06 and 0.39±0.06 °C/decade for the shelf and slope regions, respectively. These meridionally averaged SST time series over the shelf and slope are consistent with each other and across different observational datasets over the longer period since 1900. The coherence between the long-term meridionally averaged time series over the shelf and slope and the basin-wide averaged SST of the North Atlantic implies ~2/3 of the warming trend during 1982-2018 may be attributed to natural climate variability and the rest to anthropogenic warming. Besides, two regions with prominent warming trends are found over the slope off Cape Hatteras and Gulf of Maine-Scotian Shelf. Possible ocean processes that mainly associated with the Gulf Stream variability (warm-core rings; destabilization point; main axis displacement) have been discussed to explain these warming patterns during recent decades.