Decadal ocean observations in the Northwestern Mediterranean: insights from the MOOSE-GE cruises

Abstract. The annual MOOSE-GE cruise series is the backbone of the MOOSE regional ocean observing system providing a unique dataset to observe and understand large-scale physical, biogeochemical and biological processes in the northwestern Mediterranean basin, a key region that is responding to climate change faster than many other parts of the world. These cruises address major scientific challenges, such as monitoring the variability and impact of deep and intermediate convection, which plays a crucial role in deep-water ventilation, coastal–open ocean exchanges, and the evolution of phytoplankton production in this highly dynamic system. They also allow the assessment of climate change effects on ocean physics, marine biodiversity, biological resources, and seawater chemistry, including oxygen, nutrients, and dissolved carbon. Sustained observations are required to track rapid trends such as increasing temperature and salinity in intermediate and deep waters, declining oxygen concentrations, nutrients and carbonate system inter-annual variabilities, expected increased stratification of the water column and variations in heat and salt contents. These long-term datasets are indispensable both for climate model validation and process studies, as well as for assessing the environmental status of the Mediterranean Sea. The data can be accessed at https://doi.org/10.18142/235 (Testor et al., 2010), https://doi.org/10.17882/99825 (Bosse et al., 2024), https://doi.org/10.17882/44411 (Bosse et al., 2025), https://doi.org/10.17882/45980 (Durrieu de Madron et al., 2024), https://doi.org/10.17882/43749 (Coppola et al., 2025), https://doi.org/10.17882/99865 (Dimier et al., 2024).