The Clustering Event Nr.1 took place on 11-12 March 2025 at the Institute of Oceanology, Polish Academy of Sciences (IOPAN), gathering project participants from both ObsSea4Clim and BioEcoOcean, and featuring an introduction from the third sister project, BioGeoSea.

We published the insights and lessons learned from the event in this article: (No) ocean between us: insights from ObsSea4Clim and BioEcoOcean Clustering Event, and now we supplement them with the official report (D6.1 Clustering Event Nr. 1) and presentations delivered during the event.

Deliverable 6.1 – Clustering Event Nr.1

Deliverable summary: ObsSea4Clim aims to maximise impacts and promote multidisciplinary ocean observing. One way of doing this is by organising clustering events with similar projects and promoting multidisciplinary ocean observation. This deliverable is a report on the Clustering Event Nr. 1 held on 11-12 March 2025, in Sopot, Poland, organised with the sister project, BioEcoOcean. Participants represented more than twenty relevant European and international initiatives and projects, such as BioGeoSea, TipESM, OCEAN ICE, among others. At the event, four sessions were organised to jointly discuss the Essential Ocean Variables (EOVs) concept and a joint contribution to their further development, their application to land-coast-ocean interactions and marine heatwaves. The last session focused on the key challenges in ocean observing.

Deliverable link: full deliverable can be accessed here under ObsSea4Clim community on Zenodo.

Presentations delivered at the Clustering Event Nr.1

The Clustering Event I consisted of the following sessions:

• Session 1: EOV Speed Dating
• Session 2: Bridging Land, Coastal, and Ocean Observing Systems – Integrating Physical, Biogeochemical, and Biological Data for Comprehensive Data Products
• Session 3: Marine Heatwaves in Space and Time – Understanding Thermal Anomalies at Ecologically Relevant Scales
• Session 4: Identifying Key Issues and Solutions in Ocean Observing

The resources related to sessions 1-3 are listed in the table below. Session 4 featured a hands-on workshop to consolidate learnings from sessions 1-3 and its results are presented in Deliverable 6.1 – Clustering Event I.

Session	Presentation	Lead speaker	Affiliation	Project	Zenodo
Session 1	EOV speed dating introduction	Lina Mtwana Nordlund	Uppsala University	BioEcoOcean	Slides – link
Session 2	Integrating land and coastal systems: Linking glacier runoff and atmospheric inputs with marine data – Arctic case studies	Katarzyna Draganska-Deja	IO PAN	BioEcoOcean	Slides – link
Session 2	Coast to open ocean data: Using the EOV concept to link physical, BGC and bio/eco data	Toste Tanhua	GEOMAR	BioGeoSea	Slides – link
Session 2	Links between temperature fluctuations and declining condition of Irish mussels	Gerard McCarthy	NUIM	ObsSea4Clim	N/A
Session 3	Marine heatwaves	Patrick Lehodey	Mercator Ocean	BioEcoOcean	Slides – link
Session 3	Assessing the Frequency and the Intensity of Marine Heatwaves in the Barents Sea	Ajith Joseph K	NERCI	ObsSea4Clim	Slides – link
Session 3	Marine heatwaves in the Baltic Sea	Veera Haapaniemi	FMI	ObsSea4Clim	Slides – link
Session 3	The Blob and Pyrosomes	Florian Lüskow	Uppsala University	BioEcoOcean	Slides – link
Session 3	Understanding marine heatwaves at relevant ecological scales	Lisandro Benedetti-Cecchi	University of Pisa	BioEcoOcean	Slides – link