Transcript GNSS

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)
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Ice Sheets - Capabilities
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Ice Sheets - Capabilities
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Ice Sheets - Capabilities
– GRACE (time-variable gravity ~300km; 2003-); GOCE (~220km; 20092012)
– Satellite altimetry (1992-present; ERS-1/2; EnviSat; CryoSat-2; ICESat) +
ICESat-2 (2016-); ICESat laser; rest radar
– SAR -> ice velocities
Rignot et al.,
2011
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Ice Sheets - Capabilities
– DEMs
– TanDEM-X (X-band Radar); SRTM
(limited due to latitudinal limit)
– ASTER, SPOT, WorldView-1/2
(optical)
Polar Geospatial Center
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Ice Sheets - Capabilities
– DEMs
– TanDEM-X (X-band Radar); SRTM
(limited due to latitudinal limit)
– ASTER, SPOT, WorldView-1/2
(optical)
– Optical imagery
Khan et al., 2014
Polar Geospatial Center
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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
BEDMAP2
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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 GRACEtype 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?)
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GNSS- Background
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GNSS- Background
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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
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GNSS - Gaps
– Multi-GNSS/multi-satellite analysis software
– Multi-technique alignment (inter-system ties)
– Expertise in GNSS reflectometry
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GNSS – Possible Resolutions
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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."
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