Non-gravitational force modelling and altimeter measurement modelling for SEASAT-A satellite

The SEASAT altimeter measurements have an accuracy of about 10 cm. In order to make best use of the altimeter measurements for oceanographic and other applications, the radial component of the satellite orbit must be known with an accuracy of about 10 cm. In the orbit computation, drag and solar radiation pressure are significant perturbations. Uncertainties in the reference which appear in these models along with errors in the atmospheric density model are primary error sources, limiting the orbit determination accuracy. In the case of SEATSAT, the effective areas vary considerably with time. In this research, models which account for the actual area variations are developed. To account for the atmospheric density model errors, a set of empirical density model parameters is defined and estimated in the data analysis process. These models are used to achieve laser range residual of 0.939 meter root mean square for a 16 day SEASAT orbit, a factor of about four improvement, over that obtained using the constant area models.