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Inverse problems in stellar occultation

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.author Sofieva, Viktoria
dc.date.accessioned 2012-02-17T06:54:27Z
dc.date.available 2012-02-17T06:54:27Z
dc.date.issued 2005-04-22
dc.identifier.isbn 951-22-7597-X
dc.identifier.issn 0782-6117
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/2552
dc.description.abstract Remote sensing plays a key role in monitoring the atmosphere, which becomes increasingly important for the Earth's changing environment. The stellar occultation technique is a novel method to monitor vertical distribution of ozone and other trace gases from the troposphere to the upper mesosphere. GOMOS (Global Ozone Monitoring by Occultation of Stars) flying on board the European Space Agency's ENVISAT satellite is the first operational stellar occultation instrument. Satellite measurements are indirect, and therefore inversion methods play a key role in the retrieval of atmospheric parameters. This dissertation is dedicated to inversion methods for stellar occultation measurements and to the optimization of retrievals. Optimization of retrievals by inclusion of a priori information about smoothness of atmospheric profiles is considered. Two methods are developed. One of them –"the target resolution method"– develops the classical Tikhonov regularization. The second method includes smoothness a priori information in the form of Bayesian optimal estimation. The methodology for creating a priori information about smoothness of atmospheric profiles is developed. This dissertation considers optimal selection of measurements based on information theory, aiming at optimal design of future instruments, as well as at improved efficiency of the current data processing. Two optimization problems, both taking the information content of the measurements as a criterion, are defined and discussed. The selecting procedures were developed, compared with each other and existing methodologies and applied to selection of the most informative channels for GOMOS measurements in the UV-Visible wavelength range. The dissertation presents a feasibility study for retrieval of temperature and density profiles from pointing measurements by stellar occultation instruments. This study introduces extra geophysical parameters that can be obtained from GOMOS measurements. The inversion methods developed are applied to GOMOS measurements. However, the methods are formulated in a general form that allows their application beyond the GOMOS mission. en
dc.format.extent 110
dc.format.mimetype application/pdf
dc.language.iso en en
dc.publisher Helsinki University of Technology en
dc.publisher Teknillinen korkeakoulu fi
dc.relation.ispartofseries Contributions / Finnish Meteorological Institute en
dc.relation.ispartofseries 49 en
dc.relation.haspart V. F. Sofieva, J. Tamminen, H. Haario, E. Kyrölä and M. Lehtinen. 2004. Ozone profile smoothness as a priori information in the inversion of limb measurements. Annales Geophysicae, Vol. 22, No. 10, pp. 3411-3420.
dc.relation.haspart V. F. Sofieva, E. Kyrö and E. Kyrölä. 2004. Smoothness of ozone profiles: analysis of 11-years of ozone sonde measurements at Sodankylä. Annales Geophysicae, Vol. 22, No. 8, pp. 2723-2727.
dc.relation.haspart V. F. Sofieva and E. Kyrölä. 2003. Information approach to optimal selection of the spectral channels. Journal of Geophysical Research, 108 (D16), 4513, doi: 10.1029/2002JD002980.
dc.relation.haspart V. F. Sofieva and E. Kyrölä. 2004. Abel integral inversion in occultation measurements. In: G. Kirchengast, U. Foelshe and A. Steiner (editors), Occultations for Probing Atmosphere and Climate. Springer-Verlag, pp. 77-86.
dc.relation.haspart V. F. Sofieva, E. Kyrölä, J. Tamminen and M. Ferraguto. 2004. Atmospheric density, pressure and temperature profile reconstruction from refractive angle measurements in stellar occultation. In: G. Kirchengast, U. Foelshe and A. Steiner (editors), Occultations for Probing Atmosphere and Climate. Springer-Verlag, pp. 289-298.
dc.relation.haspart V. F. Sofieva, E. Kyrölä, M. Ferraguto and GOMOS CAL/VAL team. 2003. From pointing measurements in stellar occultation to atmospheric temperature, pressure and density profiling: simulations and first GOMOS results. In: Proceedings of the 2003 IEEE International Geoscience and Remote Sensing Symposium (IGARSS 2003). ISBN 0-7803-7930-6.
dc.subject.other Environmental science en
dc.subject.other Electrical engineering en
dc.title Inverse problems in stellar occultation en
dc.type G5 Artikkeliväitöskirja fi
dc.description.version reviewed en
dc.contributor.department Department of Engineering Physics and Mathematics en
dc.contributor.department Teknillisen fysiikan ja matematiikan osasto fi
dc.subject.keyword inverse problems en
dc.subject.keyword atmospheric remote sensing en
dc.subject.keyword occultation of stars en
dc.subject.keyword GOMOS en
dc.subject.keyword ozone en
dc.subject.keyword information theory en
dc.identifier.urn urn:nbn:fi:tkk-005067
dc.type.dcmitype text en
dc.type.ontasot Väitöskirja (artikkeli) fi
dc.type.ontasot Doctoral dissertation (article-based) en
dc.contributor.lab Institute of Mathematics en
dc.contributor.lab Matematiikan laitos fi
local.aalto.digifolder Aalto_68466
local.aalto.digiauth ask

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