Puysségur, Béatrice and Michel, Rémi and Avouac, Jean-Philippe (2007) Tropospheric phase delay in interferometric synthetic aperture radar estimated from meteorological model and multispectral imagery. Journal of Geophysical Research B, 112 (5). Art. No. B05419. ISSN 0148-0227. http://resolver.caltech.edu/CaltechAUTHORS:20101115-105624515
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ENVISAT Medium Resolution Imaging Spectrometer Instrument (MERIS) multispectral data and the mesoscale meteorological model MM5 are used to estimate the tropospheric phase delay in synthetic aperture radar (SAR) interferograms. MERIS images acquired simultaneously with ENVISAT Advanced Synthetic Aperture Radar data provide an estimate of the total water vapor content W limited to cloud-free areas based on spectral bands ratio (accuracy 0.17 g cm^(−2) and ground resolution 300 m). Maps of atmospheric delay, 2 km in ground resolution, are simulated from MM5. A priori pertinent cumulus parameterization and planetary boundary layer options of MM5 yield near-equal phase correction efficiency. Atmospheric delay derived from MM5 is merged with available MERIS W product. Estimates of W measured from MERIS and modeled from MM5 are shown to be consistent and unbiased and differ by ~0.2 g cm^(−2) (RMS). We test the approach on data over the Lebanese ranges where active tectonics might contribute to a measurable SAR signal that is obscured by atmospheric effects. Local low-amplitude (1 rad) atmospheric oscillations with a 2.25 km wavelength on the interferograms are recovered from MERIS with an accuracy of 0.44 rad or 0.03 g cm^(−2). MERIS water product overestimates W in the clouds shadow due to mismodeling of multiple scattering and underestimates W on pixels with undetected semitransparent clouds. The proposed atmospheric filter models dynamic atmospheric signal which cannot be recovered by previous filtering techniques which are based on a static atmospheric correction. Analysis of filter efficiency with spatial wavelength shows that ~43% of the atmospheric signal is removed at all wavelengths.
|Additional Information:||© 2007 American Geophysical Union. Received 16 February 2006; revised 17 September 2006; accepted 27 October 2006; published 30 May 2007. We would like to thank Christophe Millet for his advice and discussions concerning the use and parameterization of MM5 and Ólafur Rögnvaldsson for MM5idl freeware. We also thank Eric Fielding and another anonymous reviewer for helpful comments, as well as Associate Editor Paul Tregoning. All ENVISAT images were provided by ESA through AO 425.|
|Group:||Caltech Tectonics Observatory, Seismological Laboratory|
|Subject Keywords:||InSAR; atmospheric delay; MM5|
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|Official Citation:||Puysségur, B., R. Michel, and J.-P. Avouac (2007), Tropospheric phase delay in interferometric synthetic aperture radar estimated from meteorological model and multispectral imagery, J. Geophys. Res., 112, B05419, doi:10.1029/2006JB004352.|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||15 Nov 2010 19:33|
|Last Modified:||11 Jun 2015 13:57|
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