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MASS LOSS FROM GLACIERS AND ICE SHEETS ARE MAJOR CONTRIBUTORS TO CURRENT SEA LEVEL RISE WITH ESTIMATED CONTRIBUTIONS OF ALMOST 2 MM PER YEAR BETWEEN 2002 AND 2014. THE RISE IS NOT UNIFORMLY DISTRIBUTED ACROSS THE EARTH S OCEANS BUT VARIES SUBSTANTIALLY FROM REGION TO REGION DUE TO LOADING AND CHANGES IN THE GRAVITY FIELD. THESE INCLUDE MAINLY CHANGES IN GRAVITATIONAL ATTRACTION OF LAND ICE MASSES AS THEY LOSE MASS AND THE REDISTRIBUTION OF WATER IN THE OCEANS (SELF-GRAVITATION) AND VERTICAL LAND MOTION AND GEOID CHANGE DUE TO GLACIAL ISOSTATIC ADJUSTMENT (GIA) THE VISCOELASTIC DEFORMATION OF THE EARTH IN RESPONSE TO CHANGES IN SURFACE LOAD. FOR THE PARTS OF THE EARTH WITH THIN LITHOSPHERE AND LOW VISCOSITY ASTHENOSPHERE THESE SEA LEVEL FINGERPRINTS FROM ONGOING ICE LOSS ARE NOT ADEQUATELY DESCRIBED BY AN ELASTIC EARTH MODEL BECAUSE THE RELAXATION TIME OF THE ASTHENOSPHERE IS SHORT; A VISCOELASTIC FINGERPRINT MODEL IS NEEDED. OUR OVERALL GOAL IS TO PROJECT THE 21ST CENTURY REGIONAL SEA-LEVEL CHANGES IN RESPONSE TO LAND ICE MASS CHANGES. SPECIFICALLY WE WILL A) PROJECT THE MASS CHANGES OF ALL GLACIERS OUTSIDE THE ICE SHEETS APPLYING A GLOBAL-SCALE MASS-BALANCE MODEL TO ALL 200 000 GLACIERS IN THE WORLD B) COMBINE THESE ESTIMATES WITH EXISTING PROJECTIONS FROM NASA S SEA-LEVEL RESPONSE TO ICE SHEET EVOLUTION (SEARISE) PROJECT FOR THE GREENLAND AND ANTARCTIC ICE SHEETS AND C) PROJECT THE RESULTING REGIONAL-SCALE RELATIVE SEA-LEVEL VARIATIONS IN RESPONSE TO GIA AND GRAVITATIONAL EFFECTS. THE GLACIER PROJECTIONS WILL BE DRIVEN BY OUTPUTS FROM GLOBAL CLIMATE MODELS (GCM) AND SUPPORTED BY EXTENSIVE USE OF REMOTE SENSING PRODUCTS IN PARTICULAR FROM NASA SATELLITE MISSION DATA. OUR APPROACH IS UNIQUE AND NOVEL SINCE IT FOR THE FIRST TIME USES DATA FROM THE GRAVITY RECOVERY AND CLIMATE EXPERIMENT (GRACE) AND SNOWLINE ELEVATION DATA DERIVED IN THIS PROJECT FROM LANDSAT IMAGERY TO CONSTRAIN MODEL PARAMETERS IN GLOBAL-SCALE GLACIER MODELING THUS REDUCING THE LARGE UNCERTAINTIES DUE TO POORLY CONSTRAINED MODEL PARAMETERS IN PREVIOUS STUDIES. OUR GIA MODELING APPROACH WILL ACCOUNT FOR REALISTIC 3D VARIATIONS IN THE VISCOELASTIC STRUCTURE OF THE EARTH. FOR ICE MASS CHANGES IN LOW-VISCOSITY REGIONS SUCH AS ALASKA PATAGONIA AND THE ANTARCTIC PENINSULA (AND MAYBE WEST ANTARCTICA) THE VISCOELASTIC COMPONENT OF THE FINGERPRINT IS SIGNIFICANT. LATERAL VARIATIONS IN LITHOSPHERIC THICKNESS AND ASTHENOSPHERIC VISCOSITY ALSO CHANGE THE GIA RESPONSE TO THE LAST GLACIAL MAXIMUM DEGLACIATION FOR EXAMPLE SHIFTING THE POSITION OF THE FOREBULGE AND THUS POTENTIALLY CHANGING THE PRESENT-DAY VERTICAL MOTIONS AT THE ~1-2 MM/YR LEVEL A SIGNIFICANT CHANGE FOR REGIONAL RELATIVE SEA LEVEL. OUR PROPOSAL IS DIRECTLY RESPONSIVE TO THE SEA LEVEL CHANGE SCIENCE TEAM RESEARCH ANNOUNCEMENT ADDRESSING SEVERAL OF ITS KEY OBJECTIVES.

$1,039,058FY2020National Aeronautics and Space AdministrationNASA

University Of Alaska Fairbanks, Fairbanks AK

Investigators

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