Publications
Following publications have been announced by our department Physical-Biological Interactions. For further information please contact Dr. Paulo Calil, co-author of the publications:
Olivier, L., Reverdin, G., Boutin, J., Laxenaire, R., Iudicone, D., Pesant, S., Calil, P.H.R., Horstmann, J., Couet, D., Erta, J.M., Huber, P., Sarmento, H., Freire, A., Koch-Larrouy, A., Vergely, J.-L., Rousselot, P., & Speich, S. (2024): Late summer northwestward Amazon plume pathway under the action of the North Brazil Current rings. Remote Sensing of Environment, Vol 307, 114165, doi:10.1016/j.rse.2024.114165
Abstract:
The North Brazil Current (NBC) flows offshore of the mouth of the Amazon River and seasonally sheds anticyclonic rings (NBC rings) that propagate northwestward and interact with the Amazon River plume (ARP). Mesoscale features have a high temporal variability that is hard to monitor from current weekly and monthly sea surface salinity (SSS) satellite fields. Novel SSS fields with a higher temporal resolution analyzed together with satellite geostrophic currents, chlorophyll-a, and wind speed and in-situ data from the “Microbiomes cruise” on the SV Tara in August–September 2021 revealed a late summer freshwater pathway, which was not well documented in earlier studies. By combining these datasets, we improved the characterization of summer ARP pathways. In 2021, the ARP was a succession of freshwater patches cut off from the main plume by the NBC rings. A patch of about 200.000 km2 with salinity <33.5 pss was observed in September 2021, bringing 0.5 Sv of Amazon water northwestward in a period where the mean ocean currents lead to eastward transport. This patch was shallow, very stratified, and it created a surface steric-height anomaly that was identified as an anticyclonic feature in altimetric sea level products. Once separated from the NBC retroflection, it was mainly driven by Ekman currents. Other similar patches were observed during the 2021 summer, leading to a strong intermittency of the ARP transport. They strongly contributed to make 2021 the year with the largest northwestward freshwater transport in late summer within the 2010–2021 time-period investigated. This freshwater transport pathway is important for all plume-related phenomena, and show the ability of combined SMOS and SMAP data to accurately represent the day-to-day SSS variability.
Pedro W.M. Souza-Neto, P.W.M., da Silveira, I.C.A., Rocha, C.B., Lazaneo, C.Z., & Calil, P.H.R. (2024): The rio grande rise circulation: Dynamics of an internal tide conversion hotspot in the Southwestern Atlantic. Progress in Oceanography, 103264, doi:10.1016/j.pocean.2024.103264
Abstract:
The Rio Grande Rise (RGR) is a plateau located at 31°S in the Southwestern Atlantic, rising from 5916 m up to 161 m below the sea level. The RGR is an important site for future mining of Fe-Mn crusts and can lead to an expansion of Brazil’s Exclusive Economic Zone. The Cruzeiro do Sul Rift (CSR) fault cuts through the RGR from southeast to northwest. In this study we characterize the RGR circulation, showing that M2 tides are the main source of variability in the region, with an amplitude that can reach 0.3 m s−1, larger than the mean flow. These M2 tides are dominated by the baroclinic component and intensified near the bottom. The generation of M2 internal tides occurs mainly in the CSR slopes, with most energy converted from the barotropic tide being radiated away in the form of tidal beams. In addition, the impingement of the mean southern South Equatorial Current and tidal rectification generates anticyclonic circulations around the RGR peaks, with the latter mechanism being responsible for a bottom intensified anticyclonic circulation of 0.2 m s−1. Finally, our results reveal that the RGR is a hotspot of internal tide generation in the Southwestern Atlantic.
