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

The meridional coherence, connectivity, and regional inhomogeneity in long-term sea surface temperature (SST) variability over the Northwest Atlantic continental shelf and slope from 1982-2018 are investigated using observational data sets. 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 in North Carolina and Cape Chidley, Newfoundland and Labrador, Canada. The linear trends are 0.37 +/- 0.06 and 0.39 +/- 0.06 degrees 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 multiple longer observational data sets with records dating back to 1900. The coherence between the long-term meridionally averaged time series over the shelf and slope and basin-wide averaged SST in the North Atlantic implies approximately two thirds of the warming trend during 1982-2018 may be attributed to natural climate variability and the rest to externally forced change including anthropogenic warming.