Phase Error Modeling and Its Impact on Precise Orbit Determination of GRACE Satellites

Table 3

Parameters estimated in orbit determination.

Estimated parameter	Description
Initial state vector	3D position and velocity estimated per day
Atmospheric drag coefficient	Estimated per 3 hour
Solar radiation pressure coefficient	Estimated per 12 hours
Empirical acceleration coefficient	𝑐𝑟, 𝑠𝑟, 𝑐𝑡, 𝑠𝑡, 𝑐𝑛, 𝑠𝑛 estimated per orbital revolution
LEO clock offset	Estimated epoch-wise
Ambiguity	Estimated per arc of continuous tracking of a single GPS satellite