The Role of Advective Heat Fluxes in Buffering Annual to Interannual Temperature Variability over U.S. Inner Shelves

大陆架内半部分的水温通常冬季寒冷，夏季温暖，这与大气表面热通量的年度循环一致。然而，对历史数据的初步分析和对以往区域研究的综合表明，年度周期的幅度存在很大的区域差异。例如，美国西海岸大部分地区8月至2月的平均温差不到5摄氏度，而东海岸的平均温差在15至20摄氏度之间。虽然地表热量的年循环也存在很大的区域差异，但地表热通量一般不能解释观测到的年度循环的幅度或区域差异。这些结果和前人的研究都表明，平流热通量在内陆架上是重要的，它们往往缓冲对地表热通量的响应，并导致重要的生物学和社会意义。热应激在生物体功能和群落生态中都发挥着关键作用，陆架内部温度的微小上升或控制它们的过程的改变可能会导致群落结构的戏剧性变化和/或大规模死亡事件。因此，清楚地了解平流的缓冲作用如何能够在未来气候情景中对生态和商业上重要的沿海海洋物种的潜在变化提供一些预测能力。这项研究项目旨在了解在年和年际时间尺度上控制内陆架水温变化的过程。该项目涉及对一名研究生的培训。这项研究将首次全面了解内大陆架的热量收支，包括其季节周期和年际变化。现有的温度和速度数据集将被用来研究一些可能的冷却来源如何维持热平衡，包括：由于深度相关的上升流而产生的跨陆架交换，沿陆架温度梯度的沿陆架平流，以及由于涡流而产生的跨陆架交换。这些结果将被综合起来，以确定美国大陆不同陆架地区热通量分量及其相关过程的相对贡献。该分析将能够评估陆架环境(例如宽度)与外部强迫(例如地表热通量、风应力)在驱动观察到的区域温度模式方面的作用。这些结果将提供关于陆架内环流、平流在控制或减缓陆架内加热方面的作用的新信息，并为以前关于沿海海洋跨陆架交换的研究提供更广泛的背景。

Water temperatures over the inner-half of continental shelves are typically cold in winter and warm in summer, consistent with the annual cycle of surface heat fluxes from the atmosphere. However, preliminary analysis of historical data and synthesis of previous regional studies indicate there are large regional differences in the amplitude of the annual cycle. For example, theaverage temperature difference between August and February is less than 5 C along much of the U.S. West Coast, but is between 15 and 20 C along the East Coast. While there are also large regional differences in the annual cycle of surface heat, the surface heat fluxes do not generally account for the observed amplitude of the annual cycle or the regional differences. Both these results and previousstudies indicate that advective heat fluxes are important over the inner shelf and that they tend to buffer the response to surface heat fluxes and lead to important biological and societal implications. Thermal stresses play a key role in both organism function and community ecology, and small increases in inner shelf temperatures or alterations in the processes that control them can lead to dramatic shifts in community structure and/or mass mortality events. Thus, a clear understanding of how buffering by advection functions would allow some predictive capacity for the potential changes in both ecologically and commercially important coastal marine species in future climate scenarios. This research project aims to understand the processes controlling water temperature variations over the inner shelf on annual and interannual timescales. The project involves training of a graduate student.This study will provide the first comprehensive look at the heat budget of the inner continental shelf, including its seasonal cycle and inter-annual variability. Available temperature and velocity data sets will be used to examine how the heat balance can be maintained by a number of possible sources of cooling including: across-shelf exchange due to depth-dependent upwelling, the along-shelf advection of an along-shelf temperature gradient, and the across-shelf exchange due to eddies. The results will be synthesized to determine the relative contributions of heat flux components and their associated processes for the different shelf regions of the continental US. The analysis will enable an assessment of the role of shelf environment (e.g. width) versus external forcing (e.g. surface heat flux, wind stress) in driving the regional temperature patterns observed. The results will yield new information about inner-shelf circulation, the role of advection in controlling or moderating inner-shelf heating, as well as give broader context to previous studies of across-shelf exchange in the coastal ocean.