Towards DTU13 Global Altimetric Marine Gravity Field. The impact of Cryosat-2 and Jason-1 "Geodetic Mission" Data
Andersen, Ole Baltazar1; Jain, Maulik1; Stenseng, Lars1; Knudsen, Per1; Kenyon, Stece2
1DTU Space, DENMARK; 2NGA, UNITED STATES
Data from the Cryosat-2 (369 days repeat mission) as well as Jason-1 end-of-life mission are the first new "geodetic mission" data sets released in nearly 2 decades since the ERS-1 and Geosat geodetic missions were conducted in the early 90'th and late 80'th. The new altimetric data also present geodetic mission data with "state of the art" altimeters with increased precision compared with the older altimeters and as such, should enable substantial improvement in gravity field determination with the use of these new geodetic mission satellites. One further advantage of the Cryosat-2 is its ability of provide new accurate sea surface height information for gravity field determination in the northernmost part of the Arctic Ocean where no altimeters have measured before. We aim at releasing the DTU13 global marine gravity field, based on one year of retracked data from each of the four geodetic missions (ERS-1, GEOSAT, CryoSat-2 and Jason-1). For Cryosat-2 we have derived a combined empirical/physical retracking system that uses physical retracking of the LRM data using a reduced parameter system in combination with empirical retracking of the SAR and SAR-In data in particularly high latitude regions. For Jason-1 we apply a similar two step retracking procedure using a tailored waveform smoothing technique to smooth the noisy part of the Jason-1 waveform to obtain more stable and hence more accurate sea surface height estimates.