资源环境科技发展态势分析平台

Chlorophyll-a concentration (Chl-a) observed by satellite shows a marked seasonal and interannual variability in the Tropical Atlantic. This study analyzes how the remotely-sensed surface Chl-a responds to the leading boreal summer climate modes affecting the interannual Tropical Atlantic variability over 1998-2018, corresponding to a positive Atlantic Multidecadal Oscillation phase. We show that the Atlantic Zonal Mode (AZM) and the North Tropical Atlantic Mode (NTAM) significantly drive the interannual surface Chl-a variability in the equatorial Atlantic, with different timings and contrasted zonal modulation of the Cold Tongue. The AZM involves remotely-forced wave propagations favoring upwelling in the east and Chl-a modulation in the core of the Cold Tongue. Instead, the impact of the NTAM is mainly in the west, in response to locally-forced pumping that modulates the western extension of the Cold Tongue. Such conditions can affect the marine food web, inducing significant variations for ecosystem functioning and fisheries.