Continuation model construction and application analysis of local gravity field based on least square collocation

Under the geodetic coordinate, the covariance model of gravity anomaly (GAC) and gravity disturbance (GDC) is respectively derived from the covariance model of disturbing potential (DPM) which is established by Forsberg, the results show that both model have the same expression formula. Two methods for parameter estimation of GAC model are described in detail. According to the actual airborne and land surveying, the accuracy of upward continuation based on the GAC model is about 1.8 x 10(-5) m . s(-2), and the accuracy of downward continuation is about 5 x 10(-5) m . s(-2). Based on the continuation result of different height, the model's application range is determined as about 7 kilometers. It can be generally concluded that the DPM model and GAC model can fulfill the continuation requirements of airborne surveying.