This work is part of the MADRidge Project special issue which aims to describe pelagic ecosystems in the vicinity of three prominent shallow seamounts in the South West Indian Ocean: one here named MAD-Ridge (240 m below the surface) plus Walters Shoal (18 m) on the Madagascar Ridge, and La Pérouse (60 m) on the abyssal plain east of Madagascar. The three span latitudes 20°S and 33°S, some 1500 km. The study provides the background oceanography for the once-off, multidisciplinary snapshot cruise studies around the seamounts. As life on seamounts is determined by factors such as summit depth, proximity to the light layers of the ocean, and the ambient circulation, a first description of regional spatial-field climatologies (16–22 years) and monthly along-ridge gradients of surface wind (driving force), water column properties of sea surface temperature, mixed layer depth, chlorophyll-a and eddy kinetic energy, plus ocean currents is provided. Being relevant to many applications in the study domain, these properties in particular reveal contrasting environments along the Madagascar Ridge and between the three seamounts that should drive biological differences. Relative to the other two seamounts, MAD-Ridge is in the more extreme situation, being at the end of the East Madagascar Current, where it experiences sturdy, albeit variable, currents and the frequent passing of mesoscale eddies.

这项工作是MADRidge项目专刊的一部分，该专刊旨在描述西南印度洋三个著名浅海山附近的中上层生态系统：这里一个名为MAD-Ridge（海面以下240 m）加上Walters Shoal（18 m） ）位于马达加斯加山脊上，而LaPérouse（60 m）位于马达加斯加东部深渊平原上。这三个跨度分别为20°S和33°S，约1500公里。该研究为海山周围一次过的多学科快照巡航研究提供了背景海洋学。由于海山上的生活取决于诸如山顶深度，与海洋浅层的接近程度以及环境环流等因素，因此首次描述了区域空间场气候（16-22年）和地表每月沿山脊梯度风（驱动力），提供了涡旋动能和洋流。这些特性与研究领域中的许多应用相关，尤其揭示了马达加斯加山脊沿线以及三个驱动生物差异的海山之间形成对比的环境。相对于其他两个海山，MAD-Ridge处在更极端的情况下，位于马达加斯加东流的尽头，在那里经历了坚固，尽管多变的海流和中尺度涡旋的频繁通过。