SST analysesIn In--situ Measurementssitu MeasurementsError Analysis Methodology Error Analysis Methodology Table. Information on the sea surface temperature (SST) analyses used in this study, where the input data were investigated based on the SST analysis information on January 1, 2014, or on information from the respective database website. where 𝑥𝑖represents the SST analysis, 𝑦𝑖stands for the buoy temperature, and 𝑥and 𝑦represent the average values of the SST analysis and buoy temperature, respectively. N represents the number of the data • The data used in this study covered the period 2014–2018. • During the study period, water temperatures were measured at 35 coastal wave buoys located around the Korean Peninsula, with 10 of these located in the EJS, 15 buoys in the southern region, and 10 buoys in the Yellow Sea. • The precision and temporal resolution of their water temperature measurements were 0.1 K and 1 hour, respectively. Kyung-Ae Park1), Hye-Jin Woo1), Hee-Young Kim2) 1) Dep. of Earth Science Education, Seoul National University, Seoul, Korea, Email: kapark@snu.ac.kr 2) Dep. of Science Education, Seoul National University, Seoul, Korea. This study presents results from the validation of seven global blended sea surface temperature (SST) analyses using the in- situ temperature measured from the coastal wave buoy and inter-comparison of them in the seas around the Korean Peninsula from 2014 to 2018: OSTIA (Operational SST and Sea Ice Analysis) CMC (Canadian Meteorological Centre) analysis, OISST (Optimum Interpolation SST), REMSS (Remote Sensing System) analysis, MURSST (Multi-scale Ultra-high Resolution SST), and MGDSST (Merged Satellite and In situ Data Global Daily SST). Overall, the root-mean square error of each analysis for the in-situ measurements was relatively high at a range from 1.27°C (OSTIA) to 1.74°C (REMSS). All analyses had warm biases over 0.29°C, which were distinctive in the southwestern coastal region of the Korean peninsula with remarkable SST cooling due to strong tidal currents in summer. In the comparison of temporal variability, most analyses revealed low coherency (< 0.5) in the period shorter than 10 days. The SST analyses have been compared against each other by investigating the spatial distributions of RMSE and bias errors. While most SST analyses tended to show good agreement in the open ocean, the differences had tendency to be amplified at the coastal regions and frontal regions. We discussed potential factors that cause the errors of SST analyses at the coastal regions by presenting the effects induced by grid sizes, distance from the coast, energy spectra, wavelet coherence, and thermal fronts in the marginal seas of the Northwest Pacific. Inter-comparisons of Daily Sea Surface Temperature Data and In-Situ Temperatures at Korean Coastal Regions • Our results indicated that SST analyses had a positive bias errors ranging from 0.31 K to 0.77 K and RMSEs ranging from 1.27 K to 1.76 K, in the coastal region of the Korean Peninsula. • Temporal scales and similarity between the in-situ temperatures and satellite- based SST database were examined using comparison of the wavelet coherence. This coherence was high (>0.8) for long periods (>180 days) and much less for short periods (<30 days). • This study revealed the SST differences between onshore and offshore regions and addressed the importance of using as many coastal buoy measurements as possible in the production of the SST analysis database. This is particularly important for the coastal phenomena with small spatial scales, which exist over short time-scales in the coastal regions. [Acknowledgement] This study was supported by the National Research Foundation of Korea (NRF), grant funded by the Korean government (MSIT) (No. 2020R1A2C2009464).Study Area Study Area Fig. (a) Currents in the study area, where the color blue represents water depth; (b) enlarged bathymetry map for the seas around the Korean Peninsula. Blue, green, and ye