C41C-0706
Potential Elevation Biases for Laser Altimeters from Subsurface Scattered Photons: Laboratory and Model Exploration of Green Light Scattering in Snow

Thursday, 17 December 2015
Poster Hall (Moscone South)
Adam Greeley1, Tom Neumann2, Thorsten Markus3, Nathan T Kurtz3 and William B Cook4, (1)University of Maryland College Park, College Park, MD, United States, (2)NASA Goddard Space Flight Ctr., Greenbelt, MD, United States, (3)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (4)NASA Goddard SFC, Greenbelt, MD, United States
Abstract:
Existing visible light laser altimeters such as MABEL (Multiple Altimeter Beam Experimental Lidar) – a single photon counting simulator for ATLAS (Advanced Topographic Laser Altimeter System) on NASA’s upcoming ICESat-2 mission – and ATM (Airborne Topographic Mapper) on NASA’s Operation IceBridge mission provide scientists a view of Earth’s ice sheets, glaciers, and sea ice with unprecedented detail. Precise calibration of these instruments is needed to understand rapidly changing parameters like sea ice freeboard and to measure optical properties of surfaces like snow covered ice sheets using subsurface scattered photons.

Photons travelling into snow, ice, or water before scattering back to the altimeter receiving system (subsurface photons) travel farther and longer than photons scattering off the surface only, causing a bias in the measured elevation. We seek to identify subsurface photons in a laboratory setting using a flight-tested laser altimeter (MABEL) and to quantify their effect on surface elevation estimates for laser altimeter systems. We also compare these estimates with previous laboratory measurements of green laser light transmission through snow, as well as Monte Carlo simulations of backscattered photons from snow.

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