Date: Thursday Oct. 15th
Time: 10AM - 11AM
Location: IRP Conference Center - IRP2, 4211 Monarch Way
Title: Reconstructing Bottom Water Temperatures on the Middle Atlantic Continental Shelf
The Cold Pool on the Mid-Atlantic Bight (MAB) continental shelf is a recurring summer feature characterized by cold, dense bottom water that provides important habitat for boreal shelf species, including the long-lived bivalve ocean quahogs (Arctica islandica). Growth increments in ocean quahog shells preserve environmental signals that can be used to derive bottom water temperature (BWT), providing a proxy record of past ocean conditions over decadal to centennial timescales. This study develops a framework for reconstructing historical BWT fields on the MAB by combining shell-derived BWT records with spatial patterns of BWT variability derived from oceanographic reanalysis products. Empirical orthogonal function (EOF) analysis was applied to July–September BWT climatologies from the MOM6, GLORYS, and VIKING20X reanalysis products to identify dominant spatial patterns of BWT variability and evaluate their suitability for reconstruction. VIKING20X was subsequently selected for the historical BWT reconstructions based on this evaluation. These spatial patterns were combined with BWT time series to reconstruct historical BWT variability across the MAB. Results indicate a long-term reduction in Cold Pool area and warming of Cold Pool temperatures, with the most rapid warming occurring after 2000. The reconstruction framework captures the 2008 regime shift identified in previous studies and provides a basis for extending BWT reconstructions beyond the period covered by reanalysis products. Application of the framework to shell-derived BWT records extends the reconstructed temperature record into the nineteenth century. Relationships between shell-derived BWT variability and the North Atlantic Oscillation and Atlantic Multidecadal Oscillation further indicate connections between MAB BWT variability and large-scale North Atlantic climate variability. Together, these results demonstrate the potential of combining oceanographic reanalysis products and ocean quahog shell records to investigate long-term changes in MAB BWT and Cold Pool evolution.