Abstract
We investigated the sensitivity of Fully-Focussed SAR
(FF-SAR) processing of CryoSat-2 altimeter data to Earth rotation and
exploit it to decontaminate waveforms in coastal zones. Earth's
rotation causes scatterers at varying cross-track locations to have a
different relative velocity with respect to the satellite. This second-order effect of Earth rotation on the phase is currently not corrected for in FF-SAR processing of altimetry data. The difference is largest near the poles, where the satellite flies parallel to the equator. We show when not
correcting for this second-order effect it yields a parabolic shape in
the counter rotated phase, which increases with the cross-track
distance. If the FF-SAR processor focusses on one point,
and there is a bright scatterer at another, then there is a residual
parabolic phase, whose sign and shape depend on the cross-track distance
and on whether the signal is left or right of the chosen focal point. In
theory, if the viewed scene only has few bright coherent scatterers,
then it might be possible to determine the cross-track position of each.
In practice though, natural targets are rarely coherent over the integration time. The
incoherent property of natural targets can, however, also be exploited
to decontaminate waveforms in coastal tracks from land signals, by
differencing two radargrams computed with two different focal points. If
the cross-track distance between the focal points is set correctly, the
speckle signal from the ocean becomes quasi-independent, while the land
signal is similar in both radargrams and can subsequently be removed.
Original language | English |
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Number of pages | 1 |
Publication status | Published - 2019 |
Event | AGU Fall Meeting 2019 - San Francisco, United States Duration: 9 Dec 2019 → 13 Dec 2019 https://www.agu.org/fall-meeting |
Conference
Conference | AGU Fall Meeting 2019 |
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Country/Territory | United States |
City | San Francisco |
Period | 9/12/19 → 13/12/19 |
Internet address |