Precise Orbit Determination Strategy for GRACE and CYGNSS
| Estimated Parameters | Parameterization | a priori σ |
|---|---|---|
| Epoch State | ||
| 3D epoch position (X,Y,Z) | Bias per epoch | 10 km |
| 3D epoch velocity (X,Y,Z) | 1 km/s | |
| Empirical Acceleration (3 dynamic passes) | ||
| Drag Coefficient | 100 | |
| Once-per-rev cross-track (cos, sin) | Constant per 30-hr data set | 1 mm/s2 |
| Once-per-rev in-track (cos, sin) | 1 mm/s | |
| Empirical Acceleration (reduced-dynamic pass) | ||
| Cross-track | Stochastic with τ = 6 hrs, Δt = 30 min* | 1 nm/s2 |
| Radial | Stochastic with τ = 6 hrs, Δt = 30 min | 1 nm/s2 |
| In-track | Stochastic with τ = 6 hrs, Δt = 30 min | 1 nm/s2 |
| Once-per-rev cross-track (cos, sin) | Stochastic with τ = 6 hrs, Δt = orbital period | 1 nm/s2 |
| Once-per-rev in-track (cos, sin) | Stochastic with τ = 6 hrs, Δt = orbital period | 1 nm/s2 |
| Carrier Bias (GRAPHIC only) | Constant bias per continuous carrier track | 1e6 km |
| Clock | White-noise Process | 3e5 km |
↵* Δt is the update interval and τ is the correlation time.