Interannual Variability of Winter-Spring Temperature in the Middle Atlantic Bight: Linkages to Large-Scale Atmospheric and Oceanic Changes

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The coastal ocean off the northeastern U.S. encompassing the Gulf of Maine and the Middle Atlantic Bight is a dynamic and highly productive system supporting economically important commercial fisheries. The ocean temperature in this region experienced an extreme warming event in 2012, which greatly impacted the coastal ecosystem and commercial fisheries. Therefore, understanding year-to-year variability of ocean temperature in this region, especially extreme change such as the 2012 warming, would provide the scientific basis necessary for ecosystem management and thus has important economic impacts for the commercial fishing industry. This project investigates the roles of large-scale atmospheric and oceanic processes in the interannual variability of winter-spring temperatures in the Middle Atlantic Bight, with a focus on the extreme warm and cold years. The investigators have been discussing this research with several scientists in the National Marine Fisheries Service and plan to share the results with them. The investigators will also be in close contact with the Commercial Fisheries Research Foundation in Rhode Island to communicate the results to the commercial fishing industry in the Northeast and participate in workshops dealing with management implications of the recent extreme interannual variability in the Northeast. Finally, the investigators have been, and will continue, presenting their work to the general public. The overall objective of this research is to better understand the mechanistic links between the large-scale atmospheric/oceanic processes and the interannual temperature anomalies on the Northeast U.S. Shelf, with an ultimate goal of identifying useful predictors of extreme temperature events. Recent studies indicate that Arctic warming increases the north-south amplitude of the polar jet stream and reduces its wind speed, resulting in slower-moving weather systems in mid-latitude regions and a higher probability of extreme events. A recent case study identified a direct link between the atmospheric jet stream variability and ocean temperature anomalies on the shelf in the Middle Atlantic Bight during the unusually warm winter of 2011-2012. This research will extend this case study from one winter to a longer period with multiple extreme warm/cold winter-springs to address the following scientific questions. What is the response of the coastal ocean in the northeastern U.S. to such extreme year-to-year variability of the climate system? To what extent is the interannual variability of temperature in the Middle Atlantic Bight due to the large-scale atmospheric forcing, e.g., jet stream variability? What are the relative contributions from oceanic processes versus atmospheric processes? To better understand the relative importance of the atmospheric and oceanic processes, a detailed local ocean heat budget analysis will be carried out based on both the observations and numerical simulations. The investigators will then explore the links between the interannual variability of each heat budget term associated with the temperature anomalies over the continental shelf and the large-scale atmospheric/ocean circulation. The analysis will focus on the winter-spring period, when inter-annual anomalies are the largest. This is also the seasonal time frame when the extreme warm anomaly in 2012 and the record-low temperatures in early 2014 occurred.