Two-decade in-situ oceanographic and meteorological observations from Ieodo Ocean Research Station in the northern East China Sea.

The East China Sea (ECS) is a climate-sensitive region experiencing rapid oceanic and ecological changes, with warming rates approximately twice those of the global average. Sustained long-term observations are essential to detect and understand these changes. The Ieodo Ocean Research Station (I-ORS), established in June 2003 on the northern ECS continental shelf, serves as the first continental shelf platform in the global ocean observation network OceanSITES. Over two decades (2004-2023), I-ORS has continuously monitored oceanographic and meteorological variables in real time. Here, we present quality-controlled hourly datasets, including water temperatures at 5, 21, and 38 m, air temperature and pressure, winds, relative humidity, and precipitation, derived through systematic processing. Comprehensive validation demonstrates the dataset's quality, its capability to resolve variability from diurnal to decadal timescales, and its regional representativeness across the northern ECS. This openly available dataset supports studies of air-sea interactions and climate change impacts, with applications in forecasting, early warning systems, and disaster management for the region.