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TitleAssessing global present-day surface mass transport and glacial isostatic adjustment from inversion of geodetic observations
 
AuthorJiang, YORCID logo; Wu, X; van den Broeke, M; Munneke, P K; Simonsen, S; van der Wal, W; Vermeersen, B
SourceGeophysical Research Letters vol. 126, issue 5, e2020JB020713, 2021., https://doi.org/10.1029/2020JB020713
Image
Year2021
Alt SeriesNatural Resources Canada, Contribution Series 20190309
PublisherBlackwell Publishing Ltd.
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf; html
Lat/Long WENS-180.0000 180.0000 90.0000 -90.0000
SubjectsScience and Technology; geodesy; gravity; inversion; mass change
Illustrationslocation maps; diagrams; tables
ProgramClimate Change Geoscience, Coastal Infrastructure
Released2021 04 22
AbstractSatellite gravity provide unprecedented spatial and temporal coverage to monitor present-day mass transport (PDMT). However, they contain signals from past ice sheet melting, preventing us from eLong-term monitoring of global mass transport within the Earth system improves our ability to mitigate natural hazards and better understand their relations to climate change. Satellite gravity is widely used to monitor surface mass variations for its unprecedented spatial and temporal coverage. However, the gravity data contain signals from visco-elastic deformation in response to past ice sheet melting, preventing us from extracting signals of present-day surface mass trend (PDMT) directly. Here we present a global inversion scheme that separates PDMT and visco-elastic glacial isostatic adjustment (GIA) signatures by combining satellite gravimetry with satellite altimetry and ground observations. Our inversion provides global dual data coverage that enables a robust separation of PDMT and GIA spherical harmonic coefficients. It has the advantage of providing estimates of Earth's long wavelength deformation signatures and their uncertainties. Our GIA result, along with its uncertainty estimates, can be used in future GRACE processing to better assess the impact of GIA on surface mass change. Our GIA estimates include a rapid GIA uplift in the Southeast Alaska and the Amundsen Sea Embayment, due to the visco-elastic response to recent glacial unloading. We estimate the average surface mass change rate from 2002–2010 to be -203 ± 3 GT·a-1 in Greenland, -126 ± 18 GT·a-1 in Antarctica and, -62 ± 5 GT·a-1 in Alaska. The GIA low degree spherical harmonic coefficients are sensitive to rheological properties in Earth's deep interior. Our low-degree GIA estimates include geocenter motion and (Formula presented.) which provide unique constraints to understand Earth's lower mantle and ice history.xtracting signals of current surface mass change directly from data. Here we present a global inversion scheme that separates PDMT and glacial isostatic adjustment (GIA) by combining satellite gravimetry with altimetry and ground observations. Our inversion provides global dual data coverage that enables a robust separation of PDMT and GIA low-degree spherical harmonic coefficients. We find rapid GIA uplift in the Southeast Alaska and the Amundsen Sea Embayment, likely due to the visco-elastic rebound in response to recent glacial unloading. We estimate the average mass change rate to be -198±4 GT/a in Greenland, -134±23 GT/a in Antarctica and -61±5 GT/a in Alaska from 2002 - 2010. Our low-degree GIA estimates including geocenter motion provide unique constraints to understand Earth's lower mantle and ice history.
Summary(Plain Language Summary, not published)
Surface mass exchange between the Earth's 'spheres' - atmosphere, hydrosphere, cryosphere, biosphere and pedosphere are enormous. Monitoring surface mass change helps to understand climate change and mitigate hazardous effects such as extreme drought or flooding. Measurements of surface mass change are perturbed by subsurface processes, such as mantle flow underneath the Earth's crust. Often, a model is introduced to correct the subsurface signals from observations, introducing un-modeled errors into the surface mass estimates. We use a data-driven method to extract present-day surface mass change directly from the data. We get a more accurate picture of the subsurface processes, that are mainly caused by the Earth's viscous response to past ice sheet melting. We find that the Earth's crust bounces back more rapidly and strongly after glacier melt than we assumed before, especially in places where the crust is weaker.
GEOSCAN ID315673

 
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