Spatial and seasonal variability of horizontal temperature fronts in the Mozambique Channel for both epipelagic and mesopelagic realms
Spatial and seasonal variability of horizontal temperature fronts in the Mozambique Channel for both epipelagic and mesopelagic realms
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DOI：
10.3389/fmars.2022.1045136
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发表时间：
2023-01
期刊：
影响因子：
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通讯作者：
F. Sudre;B. Dewitte;C. Mazoyer;V. Garçon;J. Sudre;P. Penven;V. Rossi
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文献类型：
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作者：
F. Sudre;B. Dewitte;C. Mazoyer;V. Garçon;J. Sudre;P. Penven;V. Rossi
海洋锋是在较冷和较暖沃茨的界面上形成的移动的短暂生物热点。在公海中，这里是海洋生物（从浮游生物到中层鱼类再到巨型动物）聚集的地方，也是大多数捕捞活动集中的地方。锋面是重要的生态系统，因此了解其时空变异性不仅对养护目标至关重要，而且对确保可持续渔业也至关重要。莫桑比克海峡（MC）是一个理想的实验室，研究海洋前沿的变化，由于其在次到中尺度，其高度的生物多样性和目前争论的保护举措的能量流。同时，锋检测仅仅依靠遥感海面温度（SST）不能访问的地下锋活动，可能是相关的了解生态系统动态的方面。方法采用Belkin和O 'Reilly算法对遥感SST和高分辨率嵌套海洋模式的后报资料进行反演，研究了MC不同深度温度锋的空间和季节变化。结果锋面活动的季节性空间分布特征可以解释为中尺度平均环流的主要特征。特别是，在水平方向上，温度锋强烈和频繁的沿着大陆架，在岛屿的尾迹，在涡流的边缘，并在东北马达加斯加电流（NEMC）和东南马达加斯加电流（SEMC）的路径。在南半球夏季，在MC的热锋主要与Angoche上升流和季节变化的莫桑比克电流。在南半球冬季，当NEMC、Seychelles-Chagos和南马达加斯加上升流环流增强时，MC的热锋更强烈。在垂直方向上，温度锋的强度在平均温跃层附近达到峰值。讨论考虑到锋面活动的显著季节性以及MC环流与赤道变率的动态联系，我们的研究呼吁解决更长时间尺度的变率，以研究海洋生态系统/锋面相互作用如何随着气候变化而演变。
Introduction Ocean fronts are moving ephemeral biological hotspots forming at the interface of cooler and warmer waters. In the open ocean, this is where marine organisms, ranging from plankton to mesopelagic fish up to megafauna, gather and where most fishing activities concentrate. Fronts are critical ecosystems so that understanding their spatio-temporal variability is essential not only for conservation goals but also to ensure sustainable fisheries. The Mozambique Channel (MC) is an ideal laboratory to study ocean front variability due to its energetic flow at sub-to-mesoscales, its high biodiversity and the currently debated conservation initiatives. Meanwhile, fronts detection relying solely on remotely-sensed Sea Surface Temperature (SST) cannot access aspects of the subsurface frontal activity that may be relevant for understanding ecosystem dynamics. Method In this study, we used the Belkin and O’Reilly Algorithm on remotely-sensed SST and hindcasts of a high-resolution nested ocean model to investigate the spatial and seasonal variability of temperature fronts at different depths in the MC. Results We find that the seasonally varying spatial patterns of frontal activity can be interpreted as resulting from main features of the mean circulation in the MC region. In particular, horizontally, temperature fronts are intense and frequent along continental shelves, in islands’ wakes, at the edge of eddies, and in the pathways of both North-East Madagascar Current (NEMC) and South-East Madagascar Current (SEMC). In austral summer, thermal fronts in the MC are mainly associated with the Angoche upwelling and seasonal variability of the Mozambique current. In austral winter, thermal fronts in the MC are more intense when the NEMC and the Seychelles-Chagos and South Madagascar upwelling cells intensify. Vertically, the intensity of temperature fronts peaks in the vicinity of the mean thermocline. Discussion Considering the marked seasonality of frontal activity evidenced here and the dynamical connections of the MC circulation with equatorial variability, our study calls for addressing longer timescales of variability to investigate how ocean ecosystem/front interactions will evolve with climate change.