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

包括缅因湾和中大西洋湾在内的美国东北部沿海海域是一个充满活力和高产的系统，支持着经济上重要的商业渔业。2012年，该地区海洋温度发生了一次极端变暖事件，对沿海生态系统和商业渔业造成了较大影响。因此，了解该地区海洋温度的年际变化，特别是2012年变暖等极端变化，将为生态系统管理提供必要的科学依据，从而对商业渔业产生重要的经济影响。本项目研究了大尺度大气和海洋过程在大西洋中部海域冬春气温年际变化中的作用，重点研究了极端温暖和寒冷年份。调查人员一直在与国家海洋渔业局的几位科学家讨论这项研究，并计划与他们分享结果。调查人员还将与罗德岛的商业渔业研究基金会保持密切联系，向东北地区的商业捕鱼业通报调查结果，并参加有关东北地区最近极端年际变化对管理影响的讲习班。最后，调查人员已经并将继续向公众展示他们的工作。本研究的总体目标是更好地了解大尺度大气/海洋过程与美国东北大陆架年际温度异常之间的机制联系，最终目标是确定极端温度事件的有用预测因子。最近的研究表明，北极变暖增加了极地急流的南北振幅并降低了其风速，导致中纬度地区天气系统移动速度变慢，极端事件发生的可能性更高。最近的一项案例研究发现，在2011-2012年异常温暖的冬季，大气急流的变化与大西洋中部大陆架上的海洋温度异常之间存在直接联系。本研究将本案例研究从一个冬季扩展到多个极端暖/冷冬春的较长时期，以解决以下科学问题。美国东北部的沿海海洋对这种极端的气候系统年复一年的变化有什么反应？中大西洋海域温度的年际变率在多大程度上是由大尺度大气强迫（如急流变率）造成的？海洋过程和大气过程的相对贡献是什么？为了更好地了解大气和海洋过程的相对重要性，将在观测和数值模拟的基础上进行详细的局部海洋热收支分析。然后，研究人员将探索与大陆架温度异常相关的每个热收支项的年际变率与大尺度大气/海洋环流之间的联系。分析的重点是年际异常最大的冬春期。这也是2012年极端温暖异常和2014年初创纪录低温发生的季节时间框架。

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.