1. Increasing the accuracy of Arctic gravity field modelling using Cryosat-2 SAR altimetry. Ole B. Andersen, L. Stenseng and J. Maulik

2. EGU Vienna, April 2012 2DTU Space, Technical University of Denmark Outline Brief about satellite altimetry On Retracking Cryosat. The Baffin Bay test.

3. EGU Vienna, April 2012 3DTU Space, Technical University of Denmark The Sea surface height mimicks the geoid MSS = Geoid + Mean Dynamic Topography (MDT) Gravity from MDT corrected MSS (=Geoid) sea mount Gravity field

4. EGU Vienna, April 2012 4DTU Space, Technical University of Denmark Cryosat

5. EGU Vienna, April 2012 5DTU Space, Technical University of Denmark Cryosat SAR+LRM L2 in the Arctic

6. EGU Vienna, April 2012 6DTU Space, Technical University of Denmark SAR-In SAR LRM Hawaii

7. EGU Vienna, April 2012 7DTU Space, Technical University of Denmark 18 Hz Cryosat ”Noise” (Standard Dev)LRMSARSAR-In 2011 Proc 2.1 (20Hz)6.9 cm13.46 cm27.1 cm 2012 Proc 2.4 (20 Hz)10.1 cm9.9 cm14.3 cm SOUTH North Large ”jumps” at mode shift Different between processors LRMSAR SAR-In 2011 V 2.1 2012 V 2.4

8. EGU Vienna, April 2012 8DTU Space, Technical University of Denmark Baffin Bay Interesting because its partly icecovered. This enables comparison C2 SAR and LRM

9. EGU Vienna, April 2012 9DTU Space, Technical University of Denmark Cryosat SAR + LRM Entire 2011 LRM mode (summer) SAR mode (winter)

10. EGU Vienna, April 2012 10DTU Space, Technical University of Denmark Retracking of Cryosat-2 Experimenting with 5 retrackers on Level 1b SAR waveform (black) Entire waveform: OCOG + 5 parameter beta retracker with exponential tail (blue) and threshold retracking. Leading Edge retracking - OCOG and threshold retracking (50% for SAR, 75% for SarIn) (Se Poster XY348 by M. Jain today) 50% Th- reshold OCOG LE OCOG

11. EGU Vienna, April 2012 11DTU Space, Technical University of Denmark Retracking 20 Hz SAR data only SSH data in leads used. Std (ESA) = 36 cm Std (Leading Edge OCOG) = 22 cm

12. EGU Vienna, April 2012 12DTU Space, Technical University of Denmark Existing GM data (ERS-1)

13. EGU Vienna, April 2012 13DTU Space, Technical University of Denmark ERM ENVISAT/TP/GFO GEOSAT ICESAT

14. EGU Vienna, April 2012 14DTU Space, Technical University of Denmark Marine Gravity. 6696 datapoints used Within 67N to 75N 55W to 65 W

15. EGU Vienna, April 2012 15DTU Space, Technical University of Denmark Gravity comparison Identical parameter set to DTU10 for gravity comparison. No finetuning yet. 6696 obsstd EGM20085.51 DTU104.89 DTU (EIGEN 6C)5.87 CRYOSAT ESA L2 SAR4.66 Lead Edge OCOG - SAR4.01 Leading Edge Treshold3.96 LE OCOG (SAR & SAR-in)3.96 NOAA LRM (2 month)4.68

16. EGU Vienna, April 2012 16DTU Space, Technical University of Denmark Coastal regions heavily improved DTU 2012 Beta Including CRYOSAT LRM data (1.8 year from NOAA). Including CRYOSAT SAR data Currently testing Cryosat SAR-IN Updating all data. Particularly Ocean tide correction to GOT 4.7 Also SSB correction updated (na for Cryosat-2). StandardsDNSC08/DTU10DTU12 Beta Dry troposphereECMWF Wet troposphereECMWFRadiometer IonosphereAltimeter Dynamic AtmosphereIB (1013 mbar)MOG-2D_IB Ocean tidesGOT 00.2GOT4.7 Sea State BiasBM4Non-PARAM

17. EGU Vienna, April 2012 17DTU Space, Technical University of Denmark Summary Employes a Ph.d on retracking. Succesful retracking of SAR data. Trying SAR-IN now. This is certainly work in progress and we are really on the way Current Cryosat 2 data are comparable to existing GM altimetry Need to await new Cryosat 2 and the back processing. Will take time Rumours that Jason-1 will be changed to Geodetic Mission, but this will only improve up to 66N (no Arctic here).