Abstract Inter-relationships between physical ocean-atmosphere processes over the eastern Agulhas Bank are explored using data assimilation by the Hybrid Coordinate Ocean Model (HYCOM), which provides daily fields and time series off the south coast of South Africa (33.75–34.5S, 24.0–26.5E) in the period 2009–2017. Our objectives are: i) to describe and understand the sharp gradients over the shelf, ii) to quantify the temporal controls and lagged uptake of weather events and, iii) to analyze the spatial effects of capes on mesoscale oceanographic structure. Sea surface temperature (SST) and zonal winds (U-wind) were cross-correlated with salinity, currents, waves and atmospheric variables such as heat budget components, air pressure (SLP), air temperature. Correlations were made over daily and annual time scales to identify the leading ocean-atmosphere interactions and the strength of processes. At daily time scales weak correlations were found between SST and a variety of ocean-atmosphere parameters, suggesting that multiple processes affect the thermodynamic condition. SST showed most correlation with radiation and heat budget components (r = −0.35, 0.39), SLP (r = −0.30) and meridional currents (r = −0.26). In contrast, the simultaneous correlation of SST with U-wind was weak (r = −0.08). We attribute this to: i) delayed response, ii) opposing effects of coastal upwelling and summer heating, and iii) competing shelf-edge processes. Over the mean annual cycle, correlations between SST, U-winds, salinity, radiative fluxes and V-currents were strong, indicating how kinematic and thermodynamic controls conspire to induce seasonality. SST was well correlated (r Case studies of transient cold and warm events south of South Africa are described to reveal the large-scale atmospheric forcing of local SST. In addition, comparisons between the HYCOM reanalysis time series and independent insitu data are provided as a measure of confidence in global data assimilation systems, which open new opportunities for mesoscale oceanographic research in coastal zones.

中文翻译：

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来自再分析产品的南非大陆架上的物理海洋-大气变化

摘要 利用混合坐标海洋模型 (HYCOM) 的数据同化，探索了厄加勒斯岸东部物理海洋-大气过程之间的相互关系，该模型提供了南非南海岸 (33.75-34.5S, 24.0-26.5E) 在 2009-2017 年期间。我们的目标是：i) 描述和理解大陆架上的急剧梯度，ii) 量化天气事件的时间控制和滞后吸收，iii) 分析海角对中尺度海洋结构的空间影响。海面温度 (SST) 和纬向风 (U-wind) 与盐度、洋流、波浪和大气变量（如热预算分量、气压 (SLP)、气温）互相关。在每日和每年的时间尺度上建立相关性，以确定主要的海洋 - 大气相互作用和过程的强度。在每日时间尺度上，发现 SST 与各种海洋-大气参数之间的相关性较弱，这表明多个过程会影响热力学条件。SST 显示出与辐射和热预算分量 (r = -0.35, 0.39)、SLP (r = -0.30) 和子午流 (r = -0.26) 的最大相关性。相比之下，SST 与 U 风的同时相关性较弱（r = -0.08）。我们将此归因于：i) 延迟响应，ii) 沿海上升流和夏季加热的相反影响，以及 iii) 竞争性的陆架边缘过程。在平均年周期中，海温、U 风、盐度、辐射通量和 V 流之间的相关性很强，表明运动学和热力学控制如何共同导致季节性。SST 具有良好的相关性（r 描述了南非南部瞬态冷暖事件的案例研究，以揭示当地 SST 的大规模大气强迫。此外，还提供了 HYCOM 再分析时间序列与独立原位数据之间的比较作为衡量全球数据同化系统的信心，这为沿海地区的中尺度海洋研究开辟了新的机遇。