Estimation of sea level difference: velocities of movement of sea surface markers derived from ir images in comparison with satellite altimetry data

A quantitative comparison of sea level differences calculated from sea surface current velocities and satellite altimetry measurements was carried out. The velocities were calculated by the automatic method for tracing thermal inhomogeneities based оn a sequence of infrared images with a priori estimation of the calculation accuracy. Comparisons were carried out along the tracks of an altimetry satellite and at the points of the regular grid, to which the values from the tracks are interpolated. Ageostrophic components were estimated for the calculated velocities. At the distances of about 100 km, their contribution did not exceed the accuracy of altimetry measurements (2-4 cm). Along the tracks, the estimates of sea level differences calculated from the velocities were close to those computed from satellite altimetry. At the regular grid points, the estimates of sea level differences by velocities were significantly higher than the estimates of sea level differences by satellite altimetry, which is explained by the drawbacks of the optimal interpolation scheme used. It was concluded that the joint use of two types of measurements to retrieve the World Ocean circulation is reasonable.