## Reduction of the gravity vertical gradients to a spherical surface

The GOCE mission has produced gravity gradient data during 2009–2013 years. Various data sets were obtained, such as: tensor of second derivatives in different systems, satellite orbit parameters, the models of the gravitational field of the Earth. In contrast to the direct approach, space-wise-approach, and time-wise approach the construction of the spherical grid of gradients were orthogonality relationships are carry out, was developed via upward/downward continuation to sphere. This paper considers the vertical gravity gradients zz V (EGG TRF2 [Gruber Th., 2010]) in particular.