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Logo: Sonderforschungsbereich geo-Q
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B04 - Data analysis challenge for the GRACE-FO community

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Gravity field recovery missions such as GRACE, typically provide multiple data streams which need to be processed to extract the maximum information.

In GRACE, for example, five major signal streams

  • GPS ranging,
  • K-band ranging,
  • accelerometer data,
  • star camera data and
  • GPS occultation

measurements are recorded for use in the data analysis. Analyzing such complex data sets to extract the full science information requires development and testing of sophisticated algorithms. So-called “Mock data challenges” (MDCs) are an ideal platform under which to develop and test these algorithms under as realistic conditions as possible, especially before launch where no real data exists. By bringing together system and signal models from other members of the community, data streams can be produced which mimic the behavior of the entire system at a level which allows for rigorous testing of the data analysis algorithms under development. After producing simulated data streams, the entire GRACE community can analyze the data using their various algorithms. Analysis of the results can be used to compare the different algorithms and to help steer the development of future algorithms.

It turns out that, even now, more than 10 years after launch, improvements are still being found and new algorithms are being developed to extract the maximum science from these data streams. In GRACE Follow-On, there will be even more data streams, namely those from the joint U.S.-German Laser Ranging Instrument (LRI) that provides better ranging and pointing measurements, which add to the existing signals from the K-band µ-wave ranging, GPS receivers, clock information from the ultra-stable oscillators, the accelerometers and pointing information from several sensors.

Up to now, no such effort has been carried out in the GRACE community, resulting in groups working independently to solve similar problems. Through MDCs, the sharing of information and core algorithms can be improved, and broader working relationships can be created. Such challenges have already shown themselves to be extremely useful in the LISA community. There, a series of Mock LISA Data Challenges (MLDCs) was run over a number of years (see Arnaud et al. (2007a), Arnaud et al. (2007b), Babak et al. (2008), Babak et al. (2010)). Numerous institutions took part in these challenges and many working groups were formed as a result. This project planned several runs of Mock Data Challenges for the GRACE-FO and future satellite missions which were provided to the geodesy community. The goal was to initiate a basis for more data and methodology exchanges as well as searching answers to the existing questions in the field.

The simulated data for different challenges can be downloaded from the webpage of the project:

 

www.geoq.uni-hannover.de/mock

 

The deadline for basic challenge 1 is over and we have collected the solutions from different participants. A paper on the results and comparison is being prepared and scheduled to be submitted by end of April.

The basic challenge 2 contains the LRI data and realistic noise  provided by GRACE FO LRI sensor developers. The deadline for this challenge is 30th June 2017.

The advanced challenges 1 and 2 with more sophisticated simulation scenarios and full LRI noise model are now published and can be used.

Scientists working on this project

Dr. Neda Darbeheshti
email: neda.darbeheshtiaei.mpg.de

phone: +49 511 762-17534
details

Vitali Müller
email: vitali.muelleraei.mpg.de

phone: +49 511 762-14003
details

Selected Publications


Peer-Reviewed Literature

Shabanloui A. and Müller J. (2016): Mass variations in the Siberian permafrost region based on new GRACE results and auxiliary modeling, International Association of Geodesy Symposia, pp. 1–8.
DOI: 10.1007/1345_2015_186

Schütze D., Farrant D., Shaddock D. A., Sheard B. S., Heinzel G. and Danzmann K. (2014): Measuring coalignment of retroreflectors with large lateral incoming-outgoing beam offset, Review of Scientific Instruments, Volume 85, Issue 3, 035103
DOI: 10.1063/1.4866682

Schütze D., Müller V., Heinzel G. (2014): Precision absolute measurement and alignment of laser beam direction and position, Applied Optics, Vol. 53, Issue 28, page 6503-6507
DOI: 10.1364/AO.53.006503



Books

Naeimi M. and Flury J. (Editors) (2017): Global Gravity Field Modeling from Satellite-to-Satellite Tracking Data, Lecture Notes in Earth System Sciences, Springer
DOI: 10.1007/978-3-319-49941-3
ISBN: 978-3-319-49941-3


Presentations, Talks and Posters

Darbeheshti N., Müller V., Wegener H., Hewitson M., Heinzel G., Naeimi M. and Flury J. (2016): Instrument Noise Simulation for GRACE Follow-On, American Geophysical Union, Fall Meeting 2016, San Francisco, USA, 12 - 16 December, 2016

Darbeheshti N., Naeimi M., Hewitson M., Heinzel G. and Flury J. (2016): Introducing GRACE Follow-On mock data challenge project, European Geosciences Union, General Assembly 2016, Vienna, Austria, 17 - 22 April, 2016

Naeimi M., Darbeheshti N., Hewitson M., Flury J., Wegener H., Müller M., Goswami S. and Devaraju B. (2016): Introducing data analysis challenges for GRACE and GRACE Follow-on, American Geophysical Union, Fall Meeting 2016, San Francisco, USA, 12 - 16 December 2016

Darbeheshti N., Müller V., Hewitson M. and Heinzel G. (2015): On the Simulation of the Laser Ranging Instrument for GRACE Follow-on, American Geophysical Union Fall Meeting, San Francisco, USA, December more