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Analysis of reflections in GNSS radio occultation measurements using the phase matching amplitude
Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.ORCID iD: 0000-0002-2856-6140
Molflow, Gothenburg, SWE.
RUAG Space AB, SWE.
Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.ORCID iD: 0000-0002-6643-312x
2018 (English)In: Atmospheric Measurement Techniques, ISSN 1867-1381, E-ISSN 1867-8548, Vol. 11, no 1, p. 569-580Article in journal (Refereed) Published
Abstract [en]

It is well-known that in the presence of super-refractive layers in the lower-tropospheric inversion of GNSSradio occultation (RO) measurements using the Abel trans-form yields biased refractivity profiles. As such it is problem-atic to reconstruct the true refractivity from the RO signal.Additional information about this lower region of the atmo-sphere might be embedded in reflected parts of the signal. Toretrieve the bending angle, the phase matching operator canbe used. This operator produces a complex function of theimpact parameter, and from its phase we can calculate thebending angle. Instead of looking at the phase, in this paperwe focus on the function’s amplitude. The results in this pa-per show that the signatures of surface reflections in GNSSRO measurements can be significantly enhanced when usingthe phase matching method by processing only an appropri-ately selected segment of the received signal. This signatureenhancement is demonstrated by simulations and confirmedwith 10 hand-picked MetOp-A occultations with reflectedcomponents. To validate that these events show signs of re-flections, radio holographic images are generated. Our resultssuggest that the phase matching amplitude carries informa-tion that can improve the interpretation of radio occultationmeasurements in the lower troposphere.

Place, publisher, year, edition, pages
Nicolaus Copernicus University Press, 2018. Vol. 11, no 1, p. 569-580
National Category
Remote Sensing Meteorology and Atmospheric Sciences
Identifiers
URN: urn:nbn:se:bth-15843DOI: 10.5194/amt-11-569-2018ISI: 000449173700001OAI: oai:DiVA.org:bth-15843DiVA, id: diva2:1178934
Funder
Knowledge Foundation, 20140192Swedish National Space Board, 241/15
Note

open access

Available from: 2018-01-31 Created: 2018-01-31 Last updated: 2019-01-10Bibliographically approved
In thesis
1. GNSS Radio Occultation Inversion Methods and Reflection Observations in the Lower Troposphere
Open this publication in new window or tab >>GNSS Radio Occultation Inversion Methods and Reflection Observations in the Lower Troposphere
2019 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

GNSS Radio Occultation (GNSS-RO) is an opportunistic Earth sensing technique where GNSS signals passing through the atmosphere are received in low Earth orbit and processed to extract meteorological parameters. As signals are received along an orbit, the measured Doppler shift is transformed to a bending angle profile (commonly referred to as bending angle retrieval), which, in turn, is inverted to a refractivity profile. Thanks to its high vertical resolution and SI traceability, GNSS-RO is an important complement to other Earth sensing endeavors. In the lower troposphere, GNSS-RO measurements often get degraded and biased due to sharp refractive gradients and other complex structures. The main objective of this thesis is to explore contemporary retrieval methods such as phase matching and full spectrum inversion to improve their performance in these conditions. To avoid the bias caused by the standard inversion, we attempt to derive additional information from the amplitude output of the examined retrieval operators. While simulations indicate that such information could be found, it is not immediately straightforward how to achieve this with real measurements. The approach chosen is to examine reflected signal components and their effect on the amplitude output.

Place, publisher, year, edition, pages
Karlskrona: Blekinge Tekniska Högskola, 2019. p. 77
Series
Blekinge Institute of Technology Licentiate Dissertation Series, ISSN 1650-2140 ; 4
Keywords
GNSS Radio Occultation (GNSS-RO)
National Category
Remote Sensing
Identifiers
urn:nbn:se:bth-17484 (URN)978-91-7295-368-0 (ISBN)
Presentation
2019-02-01, J1650, Blekinge Tekniska Högskola, Karlskrona, 09:00 (English)
Supervisors
Funder
Knowledge Foundation, 20140192Swedish National Space Board, 241/15
Available from: 2019-01-11 Created: 2019-01-10 Last updated: 2019-03-05Bibliographically approved

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Publisher's full texthttps://www.atmos-meas-tech.net/11/569/2018/

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Sievert, ThomasPettersson, Mats

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