Snow Accumulation, Surface Elevation, and Surface Roughness Across the Greenland Ice Sheet from Remote Sensing
Başlık:
Snow Accumulation, Surface Elevation, and Surface Roughness Across the Greenland Ice Sheet from Remote Sensing
Yazar:
Overly, Thomas Buckmaster, author.
ISBN:
9780438010659
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (108 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 79-10(E), Section: B.
Advisors: Robert L. Hawley Committee members: Jonathan W. Chipman; Veit Helm; Erich C. Osterberg.
Özet:
The Greenland Ice Sheet's sensitivity to climate change and potential contribution to sea-level rise make it of critical interest. This thesis measures snow accumulation, surface elevations, and surface roughness to improve understanding of the Greenland Ice Sheet. Chapter 2 uses GPS surface elevations from 2011 Greenland Inland Traverse (GrIT) to validate Digital Elevation Models (DEMs) derived from CryoSat-2 and NASA's Operation IceBridge (OIB) altimetry measurements and improves confidence in remotely measured elevations spanning Greenland. Chapter 3 reports annual snow accumulation from 1959 to 2004 along a 250 km segment of the Expeitions Glaciologiques Internationales au Groenland (EGIG) line across central Greenland using Airborne SAR/Interferometric Radar Altimeter System (ASIRAS) radar layers and neutron-probe (NP) density profiles. ASIRAS-NP-derived accumulation rates match in situ measurements, showing increased accumulation from 1985-2004 not captured by Regional Climate Models. Modeled density profiles produce accumulation rates nearly identical to ASIRAS-NP estimates in the dry snow region, indicating that radar layers detected in dry snow regions of ice sheets lacking detailed in situ density measurements may be calibrated with density models. Chapter 4 uses Kite Aerial Photography (KAP) to measure surface roughness (SR) at seven sites along the Greenland TRaverse for Accumulation and Climate Studies (GreenTRACS). KAP DEMs created using Structure-from-Motion (SfM) photogrammetry allow SR analysis at multiple length-scales and transect directions. SR scales with lengthscale by a power-law relationship that should be considered when assessing noise in accumulation records. GPS validated surface elevations (Chapter 2) and the roughness of the surface (Chapter 4) relate to preserved snow accumulation layers (Chapter 3). Quantifying ice-sheet surface roughness reduces uncertainty in radar altimetry and identifies noise preserved in accumulation records. Within the context of a warming climate and increasing extremes in variability, accurate accumulation records (Chapter 3) and surface roughness measurements (Chapter 4) are critical to interpreting the true climate signal versus variable noise. Accurate snow accumulation estimates, combined with spatially extensive GPS validated surface measurements from CryoSat-2 reduce uncertainty in remotely sensed measurements, improving understanding of the Greenland Ice Sheet.
Notlar:
School code: 0059
Tüzel Kişi Ek Girişi:
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(681881.1) | 681881-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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