Tropospheric column ozone derived from Global Ozone Monitoring Experiment (GOME) measurements (GOME-O3) was validated using operational ozonesonde measurements over Japan and compared with Tropospheric Ozone Residual (TOR) derived from Total Ozone Mapping Spectrometer and Solar Backscatter Ultraviolet measurements. The GOME-O3 validation showed positive biases with a magnitude of less than 3 DU (∼10%) and random errors of 5 9 DU (∼15 30%) at collocated sonde stations. GOME-O3 showed better agreement with ozonesonde measurements over Japan than TOR did. The direct comparison between GOME-O3 and TOR showed the underestimation of TOR during winter and spring in the southern part of Japan (around 30°N).