9:30 AM - 9:45 AM
[G07-3-05] Global and regional sea level budgets from joint analysis of space gravimetry and altimetry data sets
Partitioning of altimetric sea level change in contributions from ocean steric expansion, ice-sheet and glacier mass imbalance, the water cycle, and crustal uplift is important for developing sea level predictions at the regional scale, but as yet our understanding is incomplete even on the global scale.
Here we will present updated results following the ‘inverse' method developed at the University of Bonn, where budget closure is imposed on altimetric and gravimetric data in a least-squares forward modelling - inversion scheme (Rietbroek et al., 2016). Starting with GRACE normal equations and along-track binned Jason-1 and -2 altimetry, we derive an ocean mass rate at the lower end of the spectrum of contemporary studies (-0.3 mm/a hydrology, 1.4 mm/a ice sheets and glaciers, 2002-2014) that would suggest a larger steric rate than found from conventional ‘direct' GRACE ocean mass estimates before, but consistent with several modelling studies. As an aside, geocenter motion (difference between the center of common mass, CM, and the center of surface figure, CF) is resolved for within the method itself and can be extracted as a byproduct; i.e. we do not rely on external data for it.
In particular, we will discuss the sensitivity of these inversion results with respect to GRACE and altimetry data sets: we will present new results that incorporate Envisat altimetry and Swarm satellite gravimetry (which may be relevant in case a gap between GRACE and GRACE-FO cannot be avoided).
Rietbroek R. et al. (2016): Revisiting the contemporary sea-level budget on global and regional scales, Proc. Nat. Acad. Sci. U.S.A. 113(6):1504–1509
Here we will present updated results following the ‘inverse' method developed at the University of Bonn, where budget closure is imposed on altimetric and gravimetric data in a least-squares forward modelling - inversion scheme (Rietbroek et al., 2016). Starting with GRACE normal equations and along-track binned Jason-1 and -2 altimetry, we derive an ocean mass rate at the lower end of the spectrum of contemporary studies (-0.3 mm/a hydrology, 1.4 mm/a ice sheets and glaciers, 2002-2014) that would suggest a larger steric rate than found from conventional ‘direct' GRACE ocean mass estimates before, but consistent with several modelling studies. As an aside, geocenter motion (difference between the center of common mass, CM, and the center of surface figure, CF) is resolved for within the method itself and can be extracted as a byproduct; i.e. we do not rely on external data for it.
In particular, we will discuss the sensitivity of these inversion results with respect to GRACE and altimetry data sets: we will present new results that incorporate Envisat altimetry and Swarm satellite gravimetry (which may be relevant in case a gap between GRACE and GRACE-FO cannot be avoided).
Rietbroek R. et al. (2016): Revisiting the contemporary sea-level budget on global and regional scales, Proc. Nat. Acad. Sci. U.S.A. 113(6):1504–1509