New research on Marine Heatwaves: Unraveling driving mechanisms in the Mediterranean Sea

New research on Marine Heatwaves: Unraveling driving mechanisms in the Mediterranean Sea

Date
20/12/2024


We are pleased to share “The Role of Air–Sea Heat Flux for Marine Heatwaves in the Mediterranean Sea” —a fresh study from the POSEIDON team, focusing on driving factors for marine heatwaves (MHWs) in the Mediterranean Sea. This research explores how the air-sea heat exchange and oceanic processes contribute to the onset and decline of these extreme events, based on a joint analysis of satellite and modelled data spanning the past 4 decades.

 

Percentage of marine heatwaves (MHWs) primarily driven by air-sea heat flux (i.e., with more than half of the observed warming (cooling) attributed to heat flux during onset (decline)) for the entire Mediterranean Sea and sub-regions. Source: Denaxa et al. (2024).


Key Insights:

  • During the onset phase of MHWs, the air-sea heat flux plays a crucial role in warming the sea surface across the basin, especially during warmer months. This contribution becomes stronger in the Adriatic and Aegean Seas where heat exchange at the sea surface is the primary driver of the development of most events.

  • However, the air-sea interaction alone does not fully explain the temperature changes observed during the evolution of MHWs. While the surface heat exchange largely contributes to the temperature rise during the onset phase, the study reveals a significantly greater contribution of oceanic processes during the decline phase. Results suggest that horizontal advection likely drives the initial cooling of the sea surface as the events begin to decline. 

  • While strong stratification is observed throughout the evolution of MHWs, results suggest that, over time, vertical mixing helps dissipate excess heat from the sea surface, eventually contributing to the MHW decline.


This study offers new insights into mechanisms behind the evolution of MHWs across the Mediterranean Sea, highlighting differences across seasons, events of different duration, and Mediterranean sub-regions, while also discussing methodological limitations in this research field. It further reflects the benefit of combining multiple data sources, such as satellite observations and modelled data, to better understand complex ocean extreme phenomena in the basin.
 

Access the publication here! 

Denaxa, D., Korres, G., Bonino, G., Masina, S., and Hatzaki, M.: The role of air–sea heat flux for marine heatwaves in the Mediterranean Sea, in: 8th edition of the Copernicus Ocean State Report (OSR8), edited by: von Schuckmann, K., Moreira, L., Grégoire, M., Marcos, M., Staneva, J., Brasseur, P., Garric, G., Lionello, P., Karstensen, J., and Neukermans, G., Copernicus Publications, State Planet, 4-osr8, 11, https://doi.org/10.5194/sp-4-osr8-11-2024, 2024.