Le jeudi 23 octobre 2025, Cécile PUJOL présentera l'examen en vue de l’obtention du grade académique de Docteur en Sciences (Collège de doctorat en Océanographie) sous la direction de Aida ALVERA AZCARATE et Alexander BARTH.

Cette épreuve consistera en la défense publique d’une dissertation intitulée :

« Study of Marine Heatwaves in a semi-enclosed coastal area: detection, formation, drivers and impacts, using a combination of satellite and in situ data ».

Le Jury sera composé de :

Mme S. GOBERT (Présidente), Mmes et MM. A. ALVERA-AZCARATE (Promotrice), A. BARTH (Co-promoteur), I. PEREZ-SANTOS (Universidad de Los Lagos), C. ROUGEOT (Secrétaire), R. SCHLEGEL (Sorbonne université).

Abstract

Marine heatwaves (MHWs) and marine cold spells (MCSs) are discrete temperature anomalies events that can persist for weeks or months, often causing severe ecological and socio-economic impacts. This thesis investigates the development, drivers and consequences of MHWs and MCSs in Central and Southern Chile (29°S-55°S), with a particular focus on Northern Patagonia, a region of oceanographic interest and of an economic importance due to intensive aquaculture activity. The main objective is to characterise the surface and subsurface dynamics of MHWs and MCSs, assess their spatial variability among large basins and narrow fjords, identify their drivers, and evaluate their ecological implications.

A multi-scale approach was applied, moving from offshore to coastal environments and from surface to subsurface layers. At large scale, satellite reanalysis data at low resolution (0.25°) were used to identify patterns, long-term trends and main drivers of MHWs in Central and Southern Chile, regions previously unexplored in this context. At finer scale, a novel methodology was developed, merging over three decades of in situ observations with satellite products to generate high-resolution (900 m) temperature fields for Northern Patagonia. This allowed the detection of extreme events across fjords and basins and the assessment of their spatial and temporal variability. Subsurface dynamics where also explored with a hydrodynamic model to evaluate the vertical extent of MHWs and MCS and the relation between surface and subsurface events. Additionally, the potential role of MHWs in promoting harmful algal blooms (HABs) was investigated.

This work provides the first integrated assessment of MHWs and MCSs in Central and Southern Chile, particularly in Northern Patagonia, demonstrating the importance of high-resolution approaches for capturing their complexity in coastal systems and highlighting implications for ecosystem functioning, fisheries and aquaculture management.

Lien Orbi

Lien Teams pour visio