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A global barotropic ocean model forced by atmospheric disturbances is developed for the detection of seafloor vertical displacements from in situ ocean bottom pressure (OBP) data. The model accuracy is validated by deep-sea OBP data at more than 100 sites obtained over the global ocean. Parameters and boundary conditions including the horizontal resolution incorporated in the ocean model are tested in order to accurately simulate the nontidal (>2 days) OBP variations. The horizontal resolution is found to the factor that most significantly affects the simulated result. The finer the horizontal resolution applied, the smaller the model variability is. The model accuracy is highest when the horizontal resolution is 1/12°, but deteriorates when the horizontal resolution is finer than 1/12°. This may indicate a failure of the energy dissipation parameterization in the barotropic ocean model. Using the developed 1/12° model, the root-mean-square of the observed nontidal OBP component can be reduced by 18 % as an average of all the OBP data used. It is found that the 1/12° model is useful for the detection of a slow seafloor vertical displacement of centimeters related to the 2011 Tohoku-Oki earthquake from in situ OBP records near the hypocenter of the earthquake. [ABSTRACT FROM AUTHOR]