Atmospheric multiple scattering effects on GLAS altimetry. I.Calculations of single pulse bias
Duda, D.P.; Spinhirne, J.D.; Eloranta, E.W.
Geoscience and Remote Sensing, IEEE Transactions on
Volume 39, Issue 1, Jan 2001 Page(s):92 - 101
Digital Object Identifier 10.1109/36.898668
Summary:Estimates of the effect of pulse stretching on satellite laser
altimetry, such as planned for the Geoscience Laser Altimeter System
(GLAS), by cloud multiple scattering were made from an analytical method
and with Monte Carlo simulations. Altimetry is dependent on the time
required for a laser pulse to complete the roundtrip to the surface and
return to the transmitter. Since a transmitted Gaussian pulse will be
stretched by the effects of multiple scattering, the use of the pulse
centroid as the receive time will produce a biased measurement or an
apparent delay in the receive time. The magnitude of this delay was
found to be dependent on several factors including cloud height, cloud
optical depth, cloud particle size, particle shape, and receiver field
of view. The delay was found to be largest for low-level clouds with
particle radii of 3-20 μm, potentially amounting to altimetry biases
of tens of cm. Alternate methods for measuring the receive time, such as
a simple Gaussian fit of the return pulse peak reduce the path delay
estimates for all cloud conditions. Since GLAS is a dual mode instrument
that includes an atmospheric lidar channel, altimeter measurements that
are likely to be significantly contaminated by multiple scattering can
be identified
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