Internal Solitary waves and Internal Tides off the Amazon Shelf and their impact on the sea surface temperature and on chlorophyll concentrations

– Carina de Macedo, Laboratoire d’Océanologie et de Géosciences, Wimereux, France –

Résumé :

The Amazon shelf is a key region for intense internal tides (ITs) and nonlinear internal solitary wave (ISWs) generation associated with them. The description of the seasonal and neap-spring tidal variability in the ISWs off the Amazon shelf is performed for the first time using a meaningful data set composed of 140 MODIS-Terra imagery from 2005 to 2021, where about 500 ISW signatures were identified in the sun glint region. Furthermore, the impact of the ITs on the sea surface temperature and chlorophyll concentration is analyzed for the same period. The main result is that IT mode 1 (and mode 2) signature can be found at spring neap tides frequency on the temperature and the chlorophyll offshore during propagation, and on the shelf, the mixing induced by the tides, allows to modify considerably the surface properties. Such signals at intra-seasonal time scale, might be of great importance for structuring the whole ecosystem and might have an impact on the mean state and variability of the tropical climate.