FUTURE CLIMATE EVOLUTION IN THE CANARY CURRENT UPWELLING SYSTEM FROM A REGIONAL COUPLED MODEL

• Main Author: VAZQUEZ, RUBEN
• Other Authors: Vazquez, Ruben, COLTORTI, Massimo
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Università degli studi di Ferrara 2023
• Subjects: Coastal upwelling; Canary current; Regional model; Climate change; ROM; Settore GEO/12 - Oceanografia e Fisica dell'Atmosfera; North Atlantic
• Online Access: https://hdl.handle.net/11392/2512610

The Canary current upwelling system (CCUS) is one of the major eastern boundary coastal upwelling systems in the world, bearing a high productive ecosystem and commercially important fisheries. The CCUS has a large latitudinal extension, and it is divided into upwelling zones with different characteristics. Eddies, filaments and other mesoscale processes characterize upwelling dynamics and are known to have an impact in the upwelling productivity. Thus, for a proper representation of the CCUS, a high horizontal resolution is required. In this study we assess present and future climate of the CCUS using an atmosphere–ocean regionally coupled model. The regional coupled model consists of a global oceanic component with increased horizontal resolution along the northwestern African coast (reaching the 5 km in Cape Ghir) coupled to a high-resolution regional atmosphere (25 km), which extends its domain to the North Atlantic, including the whole CCUS region. We assess the model’s present-time performance over the CCUS against relevant reanalysis data sets and compared with an ensemble of global climate models (GCMs) and an ensemble of atmosphere-only regional climate models (RCMs) to evaluate the role of the horizontal resolution. The coupled system reproduces the larger scale pattern of the CCUS and its latitudinal and seasonal variability over the coastal band, improving the GCMs outputs. The model properly reproduces mesoscale structures and is able to simulate the upwelling filaments events off Cape Ghir, which are not well represented in most of GCMs. Our results demonstrate the ability of the regionally coupled model to reproduce both the larger scale and mesoscale processes over the CCUS. Under RCP8.5 scenario in summer (winter), the upwelling favourable winds increase (decrease) along the Iberian coast and decrease (increase) for the African region. The model simulations suggest that the Azores high is the main driver of these variations in winter, while in summer, the changes are attributed to the ...