This manuscript presents an overview of NASA’s EXport Processes in the Ocean from Remote Sensing 2021 Field Campaign in the North Atlantic (EXPORTS NA) and provides quantitative and dynamical descriptions of the physical processes modulating water transformations during the study. A major programmatic goal was to conduct the sampling in a Lagrangian mode so that ocean ecological and biogeochemical changes can be observed independent from physical advective processes. To accomplish this goal, EXPORTS NA conducted a multi-ship, multi-asset field sampling program within a retentive, anticyclonic mode water eddy. Beneath depths of ∼ 100 m, Lagrangian sampling assets remained within the eddy core waters (ECWs) throughout the experiment, demonstrating that the ECWs within the mode water eddy were retentive. However, strong westerly winds from four storm events deepened the mixed layer (ML) of the surface core waters (SCWs) above the eddy’s mode water core by 25–40 m and exchanged some of the SCWs with surface waters outside of the eddy via Ekman transport. Estimates of flushing times ranged from 5 to 8 days, with surface exchange fractions ranging from 20 to 75 % and were consistent with particle tracking advected by combined geostrophic and Ekman velocities. The relative contributions of horizontal and vertical advection on changes in ECW tracers depended on the horizontal and vertical gradients of that tracer. For example, horizontal advection played a large role in ECW salinity fluxes, while vertical entrainment played a larger role in the fluxes of nutrients into SCW ML. Each storm injected nutrients and low oxygen waters into the ML, after which the surface ocean ecosystem responded by reducing nutrient concentrations and increasing %O₂ saturation levels. Overall, ECW values of chlorophyll and POC were the largest at the onset of the field program and decreased throughout the campaign. The analysis presented provides a physical oceanographic context for the many measurements made during the EXPORTS NA field campaign while illustrating the many challenges of conducting a production-flux experiment, even in a Lagrangian frame, and the inherent uncertainties of interpreting biological carbon pump observations that were collected in a Eulerian frame of reference.

本手稿概述了 NASA 2021 年北大西洋遥感实地考察活动 (EXPORTS NA) 的海洋出口过程，并提供了研究期间调节水转化的物理过程的定量和动态描述。主要的计划目标是以拉格朗日模式进行采样，以便可以独立于物理平流过程来观察海洋生态和生物地球化学变化。为了实现这一目标，EXPORTS NA 在保持性反气旋模式水涡中进行了多船、多资产现场采样计划。在~ 100 m深度以下，拉格朗日采样资产在整个实验过程中始终保留在涡流核心水域（ECW）内，这表明模式水涡流内的ECW具有保持性。然而，四次风暴事件产生的强西风使涡流模式水芯上方的地表核心水域（SCW）的混合层（ML）加深了25-40 m，并通过Ekman将一些SCW与涡流之外的地表水进行了交换运输。冲洗时间的估计范围为 5 至 8 天，表面交换分数范围为 20% 至 75%，并且与地转速度和埃克曼速度相结合的平流颗粒跟踪一致。水平和垂直平流对 ECW 示踪剂变化的相对贡献取决于该示踪剂的水平和垂直梯度。例如，水平平流在 ECW 盐度通量中发挥了重要作用，而垂直夹带在营养物进入 SCW ML 的通量中发挥了较大作用。每次风暴都会向 ML 中注入营养物质和低氧水，之后表层海洋生态系统会通过降低营养物质浓度和增加 %O ₂饱和度水平来做出反应。总体而言，叶绿素和 POC 的 ECW 值在实地计划开始时最大，并在整个活动期间下降。所提出的分析为 EXPORTS NA 现场活动期间进行的许多测量提供了物理海洋学背景，同时说明了即使在拉格朗日框架下进行生产通量实验的许多挑战，以及解释生物碳泵观测结果的固有不确定性收集在欧拉参考系中。