The units of the solutions in the "PreprocessingVariationalEquationOrbitFit" program

[ReubenLi1999]

Hello developers,

I'm currently working with the "PreprocessingVariationalEquationOrbitFit" program and have encountered a puzzling aspect related to the values in the solution file. I would appreciate some clarification from the developers to better understand the units of these values.

What I am doing now is using "PreprocessingVariationalEquationOrbitFit" program to generate integrated dynamic orbits of GRACE-FO satellites on a daily basis. I also want to get ACC calibration results and initial orbit states. Now, these parameters are estimated as a daily constant. However, I am puzzled about the units of these parameters.

If it helps, here's my results:

It appears that the initial position in the above picture is being treated incrementally from the last iteration, contrary to the expectation of a full initial position.

I appreciate your time and assistance in helping me gain clarity on this matter.

Cheers,

Haosi

[tmayerguerr]

Hi Haosi,

You are right: The program reads the inputfileVariational and estimates the fit parameters relative to this orbit (units m and m/s). We have never used these parameters before and GROOPS is not designed to calculate the absolute state vector.

regards
Torsten

[ReubenLi1999]

Thank you Torsten.

[ReubenLi1999]

One more thing. Could you kindly explain that there is any regularization applied in the estimation of these parameters? If so, what kind of regularization is applied? Thank you!

[tmayerguerr]

No regularization is applied

[ReubenLi1999]

@tmayerguerr OK. Thank you very much.