Throughout September and October 2025, 15 drifting buoys are due to be released into the Ionian Sea and central Mediterranean. These buoys provide valuable sea-level pressure observations in a region with few in situ observations and where recent extreme events have occurred, such as Storm Daniel in September 2023, which makes this an important deployment for weather forecasting activities. The buoys can operate for up to two years, depending partly on the ocean currents and eddies, and are a cost-effective component of the global observing system.
How the deployment came about
In February 2025, a meeting was hosted at ECMWF's data centre in Bologna, where partners from organisations in Italy, the Scripps Institution of Oceanography at the University of California, San Diego, and the EUMETNET Surface Marine programme (E-SurfMar) came together to discuss opportunities for augmenting the current observation network across the Mediterranean Sea. During the meeting, there were presentations about the current observation network in the Mediterranean, recent extreme events, E-SurfMar's role in coordinating European efforts to maintain and enhance marine surface observation networks, the Global Drifter Program (GDP; https://gdp.ucsd.edu/ldl/global-drifter-program/), and on the benefits to forecasts of sea-level pressure observations from drifting buoys. There was broad agreement on the necessity to increase the observation coverage in the Mediterranean and there were discussions around opportunities to make this possible.
During September, seven buoys were released as part of a new project named the Mediterranean Extreme Events Experiment (M3E), involving the Istituto Nazionale di Oceanografia e di Geofisica Sperimentale, Foundation Euro Mediterranean Center on Climate Change, E-SurfMar and Agenzia Italia Meteo. This included five buoys in the Ionian Sea from the research vessel Laura Bassi and two buoys in the open Ionian Sea by commercial shipping coordinated by E-SurfMar. Additional buoys will be deployed in October in the same area. The buoys launched were Surface Velocity Program Barometer drifters from the GDP (https://gdp.ucsd.edu/ldl/svpb/).
Potential for more skilful forecasts
The sea-level pressure observations from M3E buoys are available to all weather services, which brings benefits to the ECMWF Integrated Forecasting System and other modelling systems by providing more accurate initial conditions and therefore potential improvements to short- and medium-range forecasts in countries surrounding the Mediterranean. This deployment is timely with the forthcoming winter season and associated storm activity. It also forms part of a unique opportunity in January and February 2026 when observational campaigns, part of the Global Atmospheric River Reconnaissance Program in the Northern Hemisphere, will run, with the aim to investigate whether adding extra in-situ observations in the North Pacific and North Atlantic Oceans may increase weather forecast skill, both at sea and over land.