Contribution to IAG
Joint Study Group JSG0.3 (20112015)
Numerical comparisons between different approaches for regional gravity field modelling.
For regional gravity anomaly prediction in this study, two methods are used, one of them being LeastSquares Collocation (LSC) (developed by C. C. Tscherning, 1974) and the other the Reduced Point Mass (RPM) method (developed by Herceg, 2012).
Both methods show good agreement in prediction of the gravity anomaly residuals. Compared to the LSC method, the RPM method needs less time for calculation since LSC number of equations solved depends on the number of observations. When using RPM number of equations is dependent on the number of gridded point masses.
Prediction of T from GOCE Tzz gradient anomaly
(contribution up to spherical harmonic d/o 36 is removed):
Europe 


Observations 
Collocation 
Diff (ColObs) 
RPM 
Diff (RPMObs) 
Mean 
0.1141 
0.1454 
0.2594 
0.7152 
0.6011 
St. Dev. 
32.5489 
31.4413 
6.0328 
31.4973 
5.7783 
Pacific 


Observations 
Collocation 
Diff (ColObs) 
RPM 
Diff (RPMObs) 
Mean 
4.6159 
4.80 
0.18 
5.3564 
0.7405 
St. Dev. 
49.0739 
48.52 
6.66 
48.4749 
6.9177 
Prediction of Tr from GOCE Tzz gradient anomaly
(contribution up to spherical harmonic d/o 36 is removed):
Europe 


Observations 
Collocation 
Diff (ColObs) 
RPM 
Diff (RPMObs) 
Mean 
3.5638 
2.29 
1.27 
2.4206 
1.1431 
St. Dev. 
49.1310 
37.10 
29.44 
38.6243 
29.0696 
Pacific 


Observations 
Collocation 
Diff (ColObs) 
RPM 
Diff (RPMObs) 
Mean 
2.2160 
3.60 
1.39 
3.7367 
1.5207 
St. Dev. 
65.2483 
52.66 
38.24 
54.6542 
39.5912 
Prediction of T from terrestrial Tr
(contribution up to spherical harmonic d/o 240 is removed):
Europe 


Observations 
Collocation 
Diff (ColObs) 
RPM 
Diff (RPMObs) 
Mean 
0.0120 
0.02 
0.03 
0.0799 
0.0679 
St. Dev. 
4.0806 
4.19 
0.82 
3.8173 
1.4415 
Pacific 


Observations 
Collocation 
Diff (ColObs) 
RPM 
Diff (RPMObs) 
Mean 
0.1273 
0.0715 
0.0557 
0.2765 
0.4038 
St. Dev. 
4.8176 
4.7864 
0.2439 
3.7575 
2.9365 
Prediction of T from airborne Tr (Corsica)
(contribution up to spherical harmonic d/o 240 is removed):
Europe ( Corsica) 


Observations 
RPM 
Diff (RPMObs) 
Mean 
0.0953 
0.5383 
0.4429 
St. Dev. 
3.5330 
2.9636 
1.9740 