Understanding the interplay of ocean physics and biology at the submesoscale and below (<30 km) is an ongoing challenge in oceanography. While poorly constrained, these scales may be of critical importance for understanding how changing ocean dynamics will impact marine ecosystems. Fronts in the ocean, regions where two disparate water masses meet and isopycnals become tilted toward vertical, are considered hotspots for biophysical interaction, but there is limited observational evidence at the appropriate scales to assess their importance. Fronts around western boundary currents like the Gulf Stream are of particular interest as these dynamic physical regions are thought to influence both productivity and composition of primary producers; however, how exactly this plays out is not well known. Using satellite data and 2 years of in situ observations across the Gulf Stream front near Cape Hatteras, North Carolina, we investigate how submesoscale frontal dynamics could affect biological communities and generate hotspots of productivity and export. We assess the seasonality and phenology of the region, generalize the kilometer-scale structure of the front, and analyze 69 transects to assess two physical processes of potential biogeochemical importance: cold shelf filament subduction and high salinity Sargasso Sea obduction. We link these processes observationally to meanders in the Gulf Stream and discuss how cold filament subduction could be exporting carbon and how obduction of high salinity water from depth is connected with high chlorophyll-a. Finally, we report on phytoplankton community composition in each of these features and integrate these observations into our understanding of frontal submesoscale dynamics.

中文翻译：

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墨西哥湾流前沿千米级生物物理特征的证据

了解亚中尺度及以下（<30 公里）海洋物理和生物学的相互作用是海洋学中持续存在的挑战。虽然约束不充分，但这些尺度对于了解海洋动力学的变化将如何影响海洋生态系统可能至关重要。海洋前沿，即两个不同水团相遇且等密度向垂直方向倾斜的区域，被认为是生物物理相互作用的热点，但在适当尺度上评估其重要性的观测证据有限。墨西哥湾流等西部边界流周围的锋面特别令人感兴趣，因为这些动态的物理区域被认为会影响初级生产者的生产力和构成；然而，具体情况如何尚不清楚。利用卫星数据和两年来北卡罗来纳州哈特拉斯角附近墨西哥湾流锋面的现场观测，我们研究了亚尺度锋面动力学如何影响生物群落并产生生产力和出口热点。我们评估了该地区的季节性和物候，概括了锋面的公里级结构，并分析了 69 个样线，以评估具有潜在生物地球化学重要性的两个物理过程：冷大陆架丝状俯冲和高盐度马尾藻海俯冲。我们通过观察将这些过程与墨西哥湾流的曲流联系起来，并讨论冷丝俯冲如何输出碳，以及从深处的高盐度水如何与高叶绿素a相关。最后，我们报告了每个特征中的浮游植物群落组成，并将这些观察结果整合到我们对锋面亚中尺度动力学的理解中。