Arctic gravity: improvements from new satellites such as Champ
Abstract
Progress is being made toward developing the accurate Arctic gravity field - and geoid - needed by geologists, geophysicists, geodesists as well as oceanographers and cryospheric scientists. For example the field just produced by the international Arctic Gravity Project (ARC-GP, c.f., Forsberg and Kenyon, 2002) using various surface data, airborne gravimetry, satellite altimetry and submarine data fills some of the large gaps in data coverage which existed heretofore. Despite the progress, large gaps in data coverage remain particularly in the northernmost Arctic Ocean. To fill in these gaps and underpin the detailed gravity fields, constraints on the long (>250 km) wavelength geopotential derived from satellite tracking data are essential. Data from the recently launched GRACE and CHAMP satellite missions will help significantly in providing these constraints and yielding the high accuracy marine geoid which will be needed, for example, to use ICESat data for estimating sea ice thickness. GRACE and CHAMP are in low altitude, near polar orbits and should greatly reduce long-wavelength gravity errors which, until now, peaked in the polar regions. Using the ARC-GP and the UCL/NOAA Arctic ERS gravity models (Laxon and McAdoo, 1998) we have evaluated the intermediate-to-long wavelength (> 200km), Arctic component of current satellite-only models such as EIGEN1S (from 3 months of CHAMP plus other satellite data) EIGEN2 (from 6 months of CHAMP data), GRIM5S, and EGM96S. We find discrepancies among, and apparent errors in, these satellite-only models in the high Arctic at wavelengths from 200 to 1500 km. New data from GRACE as well as additional data from CHAMP promise to resolve this outstanding difficulty with Arctic gravity.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA....12951M