A comparison of atmospheric phase delay estimated by ASAR and MERIS over the Campania area

Propagation delay through the atmosphere is a key problem in coherent processing of synthetic aperture radar (SAR) data. Modern multitemporal interferometric techniques compensate the atmospheric phase delay contribution by analysing a stack of data. However, assessment of the achieved accuracy of the retrieved atmospheric component is still an open issue. In this work we report the results of an experiment carried out over a wide area aimed at comparing the zenith delay (ZD) estimated by radar and multispectral sensors. In particular, we refer to the instruments onboard the Envisat satellite and specifically to the Advanced Synthetic Aperture Radar (ASAR) and Multispectral Medium Resolution Imaging Spectrometer (MERIS) sensors that simultaneously acquire data along the same orbit. The study is preliminary to the possible exploitation of the MERIS water vapour product for compensating the atmospheric phase delay signals in a long series of acquisitions used in the multipass differential interferometric synthetic aperture radar (DInSAR) techniques to achieve higher accuracy and/or to extend the applicability of the technique to emergency situations, as well as to the possible use of SAR interferometry in meteorological applications.