Simulation Tool for GNSS Ocean Surface Reflections

Per Høeg, Hans-Henrik von Benzon, Tibor Durgonics

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    Abstract

    GNSS coherent and incoherent reflected signals have the potential of deriving large scale parameters of ocean surfaces, as barotropic variability, eddy currents and fronts, Rossby waves, coastal upwelling, mean ocean surfaceheights, and patterns of the general ocean circulation. In the reflection zone the measurements may deriveparameters as sea surface roughness, winds, waves, heights and tilts from the spectral measurements. Previous measurements from the top of mountains and airplanes have shown such results leading.The coming satellite missions, CYGNSS, COSMIC-2, and GEROS on the International Space Station, are focusing on GNSS ocean reflection measurements. Thus, simulation studies highlighting the assumptions for the data retrievals and the precision and the accuracy of such measurements are of interest for assessing the observational method.The theory of propagation of microwaves in the atmosphere is well established, and methods for propagation modeling range from ray tracing to numerical solutions to the wave equation. Besides ray tracing there are propagation methods that use mode theory and a finite difference solution to the parabolic equation. The presented propagator is based on the solution of the parabolic equation. The parabolic equation in our simulator is solvedusing the split-step sine transformation. The Earth’s surface is modeled with the use of an impedance model. The value of the Earth impedance is given as a function of the range along the surface of the Earth. This impedance concept gives an accurate lower boundary condition in the determination of the electromagnetic field, and makes itpossible to simulate reflections and the effects of transitions between different mediums. A semi-isotropic Philipsspectrum is used to represent the air-sea interaction.Simulated GPS ocean surface reflections will be presented and discussed based on different ocean characteristics.The spectra of the simulated surface reflections will be analyzed and compared with existing observations.The analysis of both the simulated surface reflection signals and the measured reflection signals will reveal spectral structures of the reflected signals leading to the extraction of sea surface roughness, ocean wave heights,surface wind speed and direction.
    Original languageEnglish
    JournalGeophysical Research Abstracts
    Volume17
    Number of pages1
    ISSN1607-7962
    Publication statusPublished - 2015
    EventEuropean Geosciences Union General Assembly 2015 - Austria Center Vienna , Vienna, Austria
    Duration: 12 Apr 201517 Apr 2015
    http://www.egu2015.eu/egu_today.html

    Conference

    ConferenceEuropean Geosciences Union General Assembly 2015
    LocationAustria Center Vienna
    Country/TerritoryAustria
    CityVienna
    Period12/04/201517/04/2015
    Internet address

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