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Correcting InSAR for tropospheric path effects over volcanoes using dynamic atmospheric models

Geoff Wadge(1) and Nicki Stevens(2)

(1) University of Reading, Harry Pitt Building, 3 Earley Gate, Reading, RG6 6AL, United Kingdom
(2) Institute of Geological and Nuclear Sciences, 69 Gracefield Road, Lower Hutt, New Zealand

Abstract

The benefits of applying independent models of atmospheric path effects over volcanoes on differential InSAR-measured ground motion are potentially considerable. The technique that has been developed consists of running a forward three dimensional mesoscale atmospheric model at high resolution over the volcano to simulate the state of the atmosphere at the time of radar image acquisition. The water vapour amounts and the resultant wave delays can be calculated along the radar lines of sight. Differencing two models gives the correction field to apply to the interferogram. We illustrate this approach with some ERS interferograms from Etna between 1995 and 2000. In some cases many centimetres of apparent ground motion can be modelled by water-vapour induced path delays. The availability of good initialisation data for the models is vital and the quality of the archived data for this purpose is less than ideal. However, the latest generation of operational mesoscale models promises major improvements in the ability to ingest timely data and to represent water phase transitions correctly.

 

Full paper

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry