Inter-annual to decadal variability and response to anthropogenic forcing of the senegalo-mauritanian upwelling system
The oceanic region located off the Senegalese and Mauritanian coasts is one of the most productive one in the world ocean. This is due to the upwelling system, which occurs during the winter season in this region. This seasonality is very specific. In particular, it differs from the well-known upwel...
Main Author: | |
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Other Authors: | , , , , , , , , |
Format: | Doctoral or Postdoctoral Thesis |
Language: | French |
Published: |
HAL CCSD
2019
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Subjects: | |
Online Access: | https://theses.hal.science/tel-03717699 https://theses.hal.science/tel-03717699/document https://theses.hal.science/tel-03717699/file/SYLLA_Adama_these_2019.pdf |
Summary: | The oceanic region located off the Senegalese and Mauritanian coasts is one of the most productive one in the world ocean. This is due to the upwelling system, which occurs during the winter season in this region. This seasonality is very specific. In particular, it differs from the well-known upwelling systems located along the eastern coast of the tropical oceans but further poleward such as along Morocco and the Iberian peninsula, the Californian coast, the Peru-Chili and the Benguela. These upwelling systems are maximum in summer. Several studies have investigated their sensitivity to global warming. Early studies have suggested that their intensity may increase in the future, but recent observations do not clear give robust evidence of this behavior. The winter senegalo-mauritanian upwelling system has been largely excluded from these studies, in spite of its crucial role for the socio-economical development of the populations of the surrounding region, whose food and income strongly depend on the halieutic resources. In this context, this study proposes an evaluation of the representation of this system in the CMIP5 climate models, and its response to climate change. Our analysis is based on characteristics of the upwelling in terms of wind forcing and sea surface temperature signature. In spite of some diversity in the model’s ability to represent the senegalo-mauritanian upwelling system, the results suggest that its intensity may rather decrease in the future, primarily because of a reduction of the wind forcing. In a second hand we propose an analysis of the inter-annual to decadal variability of the intensity of the upwelling based on recent reanalyses. This study focuses on the link with the monsoon and with large scale climate modes such as the North Atlantic Oscillation (NAO), Atlantic Multi- decadal Oscillation (AMO). The link with the decadal variations of the West African Monsoon (WAM) during the opposite season is relatively clear. It is associated with anomalous trajectories of the ITCZ. The ... |
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