Global Ocean Tide Models – Assesment of Errors and their Impact on GRACE

gravity fields

Global Ocean Tide Models – Assesment of Errors and their Impact on GRACE

gravity fields

Roman Savcenko and Wolfgang Bosch

Deutsches Geodätisches Forschungsinstitut (DGFI) München

Email: savcenko@dgfi.badw.de

Joint International GSTM and DFG SPP Symposium, October 15-17,2007, PotsdamJoint International GSTM and DFG SPP Symposium, October 15-17,2007, Potsdam 22

Motivation Motivation Motivation Motivation

• The errors in global tide models are one of the possible causes of meridional striping The errors in global tide models are one of the possible causes of meridional striping in GRACE satellite-only gravity fields.in GRACE satellite-only gravity fields.

• Due to sampling characteristics of GRACE it is impossible to estimate the whole Due to sampling characteristics of GRACE it is impossible to estimate the whole residual tide signal from GRACE data. residual tide signal from GRACE data.

• The analysis of multi-mission-altimeter data can help to correct the global tide The analysis of multi-mission-altimeter data can help to correct the global tide models in order to improve the GARCE de-aliasing. models in order to improve the GARCE de-aliasing.

Joint International GSTM and DFG SPP Symposium, October 15-17,2007, PotsdamJoint International GSTM and DFG SPP Symposium, October 15-17,2007, Potsdam 33

Residual tides and their effect on the gravity Residual tides and their effect on the gravity potential in GRACE orbitpotential in GRACE orbitResidual tides and their effect on the gravity Residual tides and their effect on the gravity potential in GRACE orbitpotential in GRACE orbit

• The residual amplitudes of semidiurnal tidal constituents can extend 15 cm The residual amplitudes of semidiurnal tidal constituents can extend 15 cm level. level.

• The residual signal can exhibit the large-scale character. The residual signal can exhibit the large-scale character. • Caused by alias effects the residual tidal signals cause the meridional striping Caused by alias effects the residual tidal signals cause the meridional striping

and large-scale errors in the gravity field estimation.and large-scale errors in the gravity field estimation.

Residual tides [cm]Residual tides [cm]Potential differences [mPotential differences [m22/s/s22] / GRACE ephemeris ] / GRACE ephemeris

August 2003 August 2003