Multiple scattering of laser pulses in snow over ice: modeling the potential bias in ICESat altimetry

The primary goal of NASA’s current ICESat and future ICESat2 missions is to map the altitude of the Earth’s land ice with high accuracy using laser altimetry technology, and to measure sea ice freeboard. Ice however is a highly transparent optical medium with variable scattering and absorption prope...

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Bibliographic Details
Main Authors: Davis, A. B., Várnai, T., Marshak, A.
Format: Report
Language:English
Published: Pasadena, CA : Jet Propulsion Laboratory, National Aeronautics and Space Administration, 2010 2015
Subjects:
Online Access:http://hdl.handle.net/2014/45128
Description
Summary:The primary goal of NASA’s current ICESat and future ICESat2 missions is to map the altitude of the Earth’s land ice with high accuracy using laser altimetry technology, and to measure sea ice freeboard. Ice however is a highly transparent optical medium with variable scattering and absorption properties. Moreover, it is often covered by a layer of snow with varying depth and optical properties largely dependent on its age. We describe a modeling framework for estimating the potential altimetry bias caused by multiple scattering in the layered medium. We use both a Monte Carlo technique and an analytical diffusion model valid for optically thick media. Our preliminary numerical results are consistent with estimates of the multiple scattering delay from laboratory measurements using snow harvested in Greenland, namely, a few cm. Planned refinements of the models are described. NASA/JPL