Surface <i>p</i> CO ₂ and hydrography in the dense water formation area of the southern Adriatic

Abstract. The rising CO2 concentration in the atmosphere leads to an increase in CO2 uptake by the ocean and to significant changes in seawater chemistry. These changes, in turn, exert profound effects on marine ecosystems across multiple trophic levels. The Mediterranean Sea is considered a hotspot for climate change. Despite such relevance, observations and studies on its carbonate system remain limited, especially in regions that play a crucial role in regulating air-sea CO2 exchange such as intermediate and dense water formation areas. The southern Adriatic Sea, a key site for dense water formation in the eastern Mediterranean, hosts the EMSO ERIC and ICOS ERIC South Adriatic observatory (EMSO-E2M3A), operated by the Italian National Institute of Oceanography and Applied Geophysics (OGS). This facility allows the study of physical and biogeochemical dynamics in the deepest area of the Adriatic Sea. The suite of sensors deployed on the surface buoy allows for the characterization of water mass properties, biogeochemical cycles, dense water formation process, and ocean acidification, particularly in relation to carbon sequestration dynamics. Here, time series of meteorological data (e.g., wind speed, wind direction), sea surface physical parameters (e.g., temperature, salinity), dissolved oxygen and partial pressure of CO2 (pCO2sw) and pH from 2014 to 2024 will be presented (https://doi.org/10.13120/y2hw-1j63, Cardin et al., 2025b). In particular, quality check, correction and post-processing methods applied to the data will be discussed. The validated surface dataset provides a consistent pCO2sw time series for the Adriatic Sea, with values and seasonal variability in agreement with previous observations across the Mediterranean. Associated temperature, salinity, oxygen, and wind measurements reproduce expected regional patterns, confirming the robustness and suitability of the presented dataset for further biogeochemical and climate-related analyses.