Kemgang Ghomsi Franck Eitel, Raj Roshin P, Bonaduce Antonio, Halo Issufo, Nyberg Björn, Cazenave Anny, Rouault Mathieu, Johannessen Ola M
Department of Oceanography, University of Cape Town, Cape Town, South Africa.
Geodesy Research Laboratory, National Institute of Cartography, P.O. Box 157, Yaoundé, Cameroon.
Sci Rep. 2024 Feb 27;14(1):4759. doi: 10.1038/s41598-024-55170-x.
Coastal zones with dense populations, low elevations and/or inadequate adaptive capacity are on the frontline of unprecedented impacts from climate change. The Gulf of Guinea (GoG), stretching from Liberia to Gabon, is in particular vulnerable to coastal flooding caused by local and/or climate-induced sea level rise. In this region, interannual to decadal coastal sea level changes remain poorly understood, mainly due to a lack of tide gauge stations. Here we use nearly three decades (1993-2021) of satellite altimetry data to study the link between the Equatorial Atlantic and coastal GoG sea level variability. The rate of mean sea level rise increased from 3.47 to 3.89 ± 0.10 mm/yr from the Equatorial oceanic domain to the GoG coastal area, with an acceleration of 0.094 ± 0.050 mm/yr. This corresponds to a mean sea level rise of about 8.9 cm over the entire altimetry period, 1993-2021. We focus on the (extreme) warm/cold events that occur in both the GoG during Atlantic Niños, and along the Angola-Namibia coast during Benguela Niños. Both events are driven by remote forcing via equatorial Kelvin waves and local forcing by local winds, freshwater fluxes and currents intensifications. Analysis of altimetry-based sea level, sea surface temperature anomalies, 20 °C isotherm based PIRATA moorings, and the Argo-based steric and thermometric sea level allows us to follow the coastal trapped waves (CTWs) along the GoG, and its link with major events observed along the strong Equatorial Atlantic warmings in 2010, 2012, 2019 and 2021. Both 2019 and 2021 warming have been identified as the warmest event ever reported in this region during the last 40 years. A lag of 1 month is observed between equatorial and West African coastal trapped wave propagation. This observation may help to better anticipate and manage the effects of extreme events on local ecosystems, fisheries, and socio-economic activities along the affected coastlines. In order to enable informed decision-making and guarantee the resilience of coastal communities in the face of climate change, it emphasises the significance of ongoing study in this field.
人口密集、海拔较低和/或适应能力不足的沿海地区正处于气候变化带来的前所未有的影响的前沿。几内亚湾（GoG）从利比里亚延伸至加蓬，特别容易受到当地和/或气候引发的海平面上升导致的沿海洪水影响。在该地区，年际到年代际的沿海海平面变化仍知之甚少，主要原因是潮汐测量站不足。在此，我们使用近三十年（1993 - 2021年）的卫星测高数据来研究赤道大西洋与几内亚湾沿海海平面变化之间的联系。从赤道海洋区域到几内亚湾沿海地区，平均海平面上升速率从3.47毫米/年增加到3.89±0.10毫米/年，加速度为0.094±0.050毫米/年²。这相当于在整个测高时期（1993 - 2021年）平均海平面上升约8.9厘米。我们关注在大西洋尼诺期间几内亚湾以及本格拉尼诺期间安哥拉 - 纳米比亚海岸发生的（极端）暖/冷事件。这两个事件都是由通过赤道开尔文波的远程强迫以及当地风、淡水通量和洋流增强的局部强迫驱动的。基于测高的海平面、海表面温度异常、基于20°C等温线的PIRATA浮标以及基于Argo的比容和温度海平面分析，使我们能够追踪几内亚湾沿岸的沿岸捕获波（CTW），以及它与2010年、2012年、2019年和2021年赤道大西洋强烈变暖期间沿几内亚湾观察到的主要事件的联系。2019年和2021年的变暖都被确定为该地区过去40年有记录以来最暖的事件。在赤道和西非沿岸捕获波传播之间观察到1个月的滞后。这一观测结果可能有助于更好地预测和管理极端事件对受影响海岸线沿线当地生态系统、渔业和社会经济活动的影响。为了实现明智的决策并确保沿海社区面对气候变化时的复原力，它强调了该领域持续研究的重要性。
