On the accuracy of integrated water vapor observations and the potential for mitigating electromagnetic path delay error in InSAR

[摘要] A field campaign was carried out in the framework of the Mitigation ofElectromagnetic Transmission errors induced by Atmospheric Water VapourEffects (METAWAVE) project sponsored by the European Space Agency (ESA) toinvestigate the accuracy of currently available sources of atmosphericcolumnar integrated water vapor measurements. The METAWAVE campaign tookplace in Rome, Italy, for the 2-week period from 19 September to 4 October2008. The collected dataset includes observations from ground-basedmicrowave radiometers and Global Positioning System (GPS) receivers, frommeteorological numerical model analysis and predictions, from balloon-bornein-situ radiosoundings, as well as from spaceborne infrared radiometers. Thesedifferent sources of integrated water vapor (IWV) observations have beenanalyzed and compared to quantify the accuracy and investigate the potentialfor mitigating IWV-related electromagnetic path delay errors inInterferometric Synthetic Aperture Radar (InSAR) imaging. The results, whichinclude a triple collocation analysis accounting for errors inherentlypresent in every IWV measurements, are valid not only to InSAR but also toany other application involving water vapor sensing. The present analysisconcludes that the requirements for mitigating the effects of turbulentwater vapor component into InSAR are significantly higher than the accuracyof the instruments analyzed here. Nonetheless, information on the IWVvertical stratification from satellite observations, numerical models, andGPS receivers may provide valuable aid to suppress the long spatialwavelength (>20 km) component of the atmospheric delay, and thussignificantly improve the performances of InSAR phase unwrapping techniques.

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