Ice Sheets GNSS (GPS, GLONASS, Galileo, Beidou, QZSS) Matt King

Ice Sheets - Needs –Contribution to sea level assessed at glacier level (20-50km, Antarctica; 1-5km smaller glaciers); 100,000+ glaciers globally –Model boundary conditions (bed topography <1km, geothermal heat flux ~km) –Paleo boundary conditions (bed topography on continental shelf <1-10km) a.k.a. modern warm-water pathways –Accumulation measurements –Past (paleo) changes of glacier level (<10m vertical) –Bedrock uplift (present-day; accuracy ~0.5mm/yr) FACULTY OF SCIENCE ENGINEERING AND TECHNOLOGY 2

Ice Sheets - Capabilities FACULTY OF SCIENCE ENGINEERING AND TECHNOLOGY 3

Ice Sheets - Capabilities FACULTY OF SCIENCE ENGINEERING AND TECHNOLOGY 4 Uncertainties still equivalent to 30% of sea level change. Not clear if East Antarctica stable or growing quickly.

Ice Sheets - Capabilities –GRACE (time-variable gravity ~300km; 2003-); GOCE (~220km; ) –Satellite altimetry (1992-present; ERS-1/2; EnviSat; CryoSat-2; ICESat) + ICESat-2 (2016-); ICESat laser; rest radar –SAR -> ice velocities FACULTY OF SCIENCE ENGINEERING AND TECHNOLOGY 5 Rignot et al., 2011

Ice Sheets - Capabilities –DEMs –TanDEM-X (X-band Radar); SRTM (limited due to latitudinal limit) –ASTER, SPOT, WorldView-1/2 (optical) FACULTY OF SCIENCE ENGINEERING AND TECHNOLOGY 6 Polar Geospatial Center

Ice Sheets - Capabilities –DEMs –TanDEM-X (X-band Radar); SRTM (limited due to latitudinal limit) –ASTER, SPOT, WorldView-1/2 (optical) –Optical imagery FACULTY OF SCIENCE ENGINEERING AND TECHNOLOGY 7 Polar Geospatial Center Khan et al., 2014

Ice Sheets - Capabilities –Bed topography –High expense airborne data –Offshore multibeam –Gravity (low res) –Geothermal heat flux –Geological sampling –Passive seismic –Hyperspectral? –Accumulation –Passive/active microwave FACULTY OF SCIENCE ENGINEERING AND TECHNOLOGY 8 BEDMAP2

Ice Sheets – Gaps & Possible Resolutions –Mission support $ lacking –e.g., ongoing GRACE/GRACE Follow-on analysis software development (ANU) – funding? –Need national-level pre & post launch support –Simulations suggest spoke-and-wheel constellation improves GRACE- type solutions of time-variable gravity –High resolution stereo optical that is available (WorldView-2 is $ and cloud means more sats very useful) –High-res hyperspectral for geological mapping of rock outcrops (high res, many bands) –P-band radar for ice bottom sounding (ESA Biomass mission?) FACULTY OF SCIENCE ENGINEERING AND TECHNOLOGY 9

GNSS- Background FACULTY OF SCIENCE ENGINEERING AND TECHNOLOGY 10

GNSS- Background FACULTY OF SCIENCE ENGINEERING AND TECHNOLOGY 11

GNSS- Needs –Need to position with accuracy 1mm and 0.1mm/yr at global scale –Ability to tie various GNSS and other geodetic measurement systems together is compromised –Potential need for use of ocean-reflected GNSS signals –Tsunami –Wind –Waves –High-resolution ocean dynamics FACULTY OF SCIENCE ENGINEERING AND TECHNOLOGY 12

GNSS - Gaps –Multi-GNSS/multi-satellite analysis software –Multi-technique alignment (inter-system ties) –Expertise in GNSS reflectometry FACULTY OF SCIENCE ENGINEERING AND TECHNOLOGY 13

GNSS – Possible Resolutions FACULTY OF SCIENCE ENGINEERING AND TECHNOLOGY 14

GNSS - Possible Resolutions –Surrey Satellite Technologies have demonstrated GNSS-R from space –SGR-ReSI (Space GNSS Receiver Remote Sensing Instrument) which is flying on-board TechDemoSat-1 –"For instance, a constellation of 18 SGR-ReSIs could cover most of the world's oceans every few hours providing a real time wind and wave height service. And these do not need to be dedicated satellites as the SGR-ReSI can be easily accommodated as a hosted payload on small satellites with a different primary mission. Our aim is to deploy such a constellation in the next two years." FACULTY OF SCIENCE ENGINEERING AND TECHNOLOGY 15