TY - GEN

T1 - Evaluation of EGM2008 by Comparison with Global and Local Gravity Solutions from CHAMP

AU - Weigelt, M.

AU - Sneeuw, N.

AU - Keller, W.

PY - 2010

Y1 - 2010

N2 - New gravity field models incorporate GRACE data for the long wavelengths since it is one of the best available data sources. However, considering e.g. the degree difference RMS between EGM2008 and GGM02s, also discrepancies between these models occur which cannot solely be explained by numerical inaccuracies. Their validation is difficult since comparisons with existing GRACE models will always be biased. Maybe the best independent data set on a global scale is the CHAMP data. One the other hand, it is known that the accuracy of these solutions is approximately one order of magnitude worse than GRACE-only solutions. In this research, it has been investigated if CHAMP can serve as an indicator in the comparison of EGM2008 and GGM02s. The primary data source of CHAMP is its position and velocity measurements derived from GPS. They are based on purely kinematic orbits, which are independent of any a priori information and are provided by the Institute for Astronomical and Physical Geodesy at the Technical University Munich for the period of April 2002 to February 2004. The comparison is based on a global solution and a local refinement with Slepian functions in order to further improve the quality of the CHAMP solution. The latter is adopted because it can make better use of information in high-latitude areas where the data density is higher. However, the solutions are solely based on GPS measurements which have a poorer quality compared to the K-band ranging system of GRACE and thus prevents a real statement about the quality of the EGM2008.

AB - New gravity field models incorporate GRACE data for the long wavelengths since it is one of the best available data sources. However, considering e.g. the degree difference RMS between EGM2008 and GGM02s, also discrepancies between these models occur which cannot solely be explained by numerical inaccuracies. Their validation is difficult since comparisons with existing GRACE models will always be biased. Maybe the best independent data set on a global scale is the CHAMP data. One the other hand, it is known that the accuracy of these solutions is approximately one order of magnitude worse than GRACE-only solutions. In this research, it has been investigated if CHAMP can serve as an indicator in the comparison of EGM2008 and GGM02s. The primary data source of CHAMP is its position and velocity measurements derived from GPS. They are based on purely kinematic orbits, which are independent of any a priori information and are provided by the Institute for Astronomical and Physical Geodesy at the Technical University Munich for the period of April 2002 to February 2004. The comparison is based on a global solution and a local refinement with Slepian functions in order to further improve the quality of the CHAMP solution. The latter is adopted because it can make better use of information in high-latitude areas where the data density is higher. However, the solutions are solely based on GPS measurements which have a poorer quality compared to the K-band ranging system of GRACE and thus prevents a real statement about the quality of the EGM2008.

KW - CHAMP

KW - Energy balance approach

KW - GRACE

KW - Slepian functions

KW - Spherical harmonics

UR - http://www.scopus.com/inward/record.url?scp=84884381110&partnerID=8YFLogxK

U2 - 10.1007/978-3-642-10634-7_66

DO - 10.1007/978-3-642-10634-7_66

M3 - Conference contribution

AN - SCOPUS:84884381110

SN - 9783642106330

T3 - International Association of Geodesy Symposia

SP - 497

EP - 504

BT - Gravity, Geoid and Earth Observation - IAG Commission 2

T2 - IAG International Symposium on "Gravity, Geoid and Earth Observation 2008"

Y2 - 23 June 2008 through 27 June 2008

ER -