The ocean circulation around and over the Seychelles Plateau (SP) is characterized using 35 months of temperature and velocity measurements along with a numerical model. The results here provide the first documented description of the ocean circulation atop the SP. The SP is an unusually broad (∼200 km), shallow (∼50 m) plateau, dropping off steeply to the abyss. It is situated in a dynamic location (3.5–5.5°S, 54‐57°E) in the south‐western tropical Indian Ocean where northwesterly winds are present during austral summer and become southeasterly in austral winter, following the reversal of the western Indian ocean monsoon winds. Measurements around the Inner Islands, on the SP, have been carried out since 2015. Velocity measurements show that most of the depth‐averaged current variance on the SP arises from near‐inertial oscillations and lower‐frequency variability. Lower‐frequency variability encompasses seasonal and intraseasonal variability, the latter of which includes the effects of mixed Rossby‐gravity waves and mesoscale eddies. A global 0.1° numerical ocean simulation is used in conjunction with these observations to describe the regional circulation around the SP. Atop the SP, circulation is dominated by ageostrophic processes consistent with Ekman dynamics, while around the SP, both geostrophic and ageostrophic processes are important and vary seasonally. Stratification responds to the sea surface height semiannual signal which is due to Ekman pumping‐driven upwelling (related to the Seychelles‐Chagos Thermocline Ridge) and the arrival of an annual downwelling Rossby wave.

中文翻译：

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塞舌尔高原地区海洋环流的观测和模拟

塞舌尔高原（SP）周围和上方的海洋环流使用35个月的温度和速度测量值以及一个数值模型来表征。这里的结果提供了SP顶部海洋环流的第一个文献记载。SP是一个异常宽广（〜200 km），浅（〜50 m）的高原，陡峭地下降到深渊。它位于西南热带印度洋的一个动态位置（3.5-5.5°S，54-57°E），在西印度的逆转期间，在夏季南方出现西北风，在夏季南方变成东南风。海洋季风风。自2015年以来，已经在SP上进行了内岛周围的测量。速度测量结果表明，SP上大多数深度平均电流方差都来自近惯性振荡和低频变化。低频变化包括季节和季节内的变化，后者包括混合的罗斯比重力波和中尺度涡旋的影响。结合这些观测资料使用了全球0.1°数值海洋模拟来描述SP周围的区域环流。在SP的顶部，循环由与Ekman动力学一致的年龄变迁过程控制，而在SP周围，地转和年​​龄变迁过程都很重要，并且随季节变化。