A daily average dataset of temperature and salinity based on No. 23 buoy Qinhuangdao offshore during 2021–2023

In order to effectively prevent the frequent occurrence of various ecological disasters in the offshore waters of Qinhuangdao, such as red tide, green tide and jellyfish bloom, with the help of the Yellow and Dong Sea Station of the China Offshore Ocean Observation and Research Network, the Institute of Oceanology of the Chinese Academy of Sciences, deployed an integrated observation system of six-meter anchor buoy (No. 23) in the coastal waters near Qinhuangdao (39º40.88΄N，119º35.53΄E), Bohai Sea at the end of April 2021. Up to now, real-time observation data are still being collected and stored continuously. Among them, temperature and salinity, as important marine environmental factors, are of great significance for in-depth understanding of the characteristics of the sea area and marine ecological environment. In order to make better use of these valuable observational data, based on the time series data of the sea surface temperature and salinity of buoy No. 23 from May 2021 to April 2023, this paper adopted statistical methods for data preprocessing and quality control, and made a dataset of daily mean temperature and salinity for 24 consecutive months. This dataset can be used for the application download service of researchers, as well as for the development of local marine economy, fishery and tourism.