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One-dimensional var...
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von Engeln, AxelNaval Research Laboratory, Washington, DC
(author)
One-dimensional variational (1-D Var) retrieval of temperature, water vapor, and a reference pressure from radio occultation measurements : A sensitivity analysis
- Article/chapterEnglish2003
Publisher, publication year, extent ...
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2003
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electronicrdacarrier
Numbers
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LIBRIS-ID:oai:DiVA.org:ltu-11368
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https://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-11368URI
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https://doi.org/10.1029/2002JD002908DOI
Supplementary language notes
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Language:English
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Summary in:English
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Subject category:ref swepub-contenttype
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Subject category:art swepub-publicationtype
Notes
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Upprättat; 2003; 20070507 (pafi)
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A 1-D Var retrieval study of simulated radio occultation measurements is presented. Temperature and a water vapor profile are retrieved along with a reference pressure to generate the pressure profile by applying the hydrostatic equation. High-resolution European Center for Medium-Range Weather Forecasts (ECMWF) atmospheric fields are used by a ray tracing tool to calculate the exact positions of the tangent point. The 1-D atmospheric profiles following the calculated tangent point trajectory in the 3-D ECMWF fields are used to simulate bending angle measurements with a 1-D forward model. Assimilation of these bending angles in a 1-D Var tool employing the same 1-D forward model is performed. We analyze the sensitivity of the retrieval to changes in vertical resolution, horizontal smearing of the tangent point trajectory, and the assumption of hydrostatic equilibrium for a nonvertical atmospheric scan. We find that retrievals calculated without adequate vertical resolution can have significant errors in temperature and water vapor. Errors in the retrieval by assuming hydrostatic equilibrium for a nonvertical scan generally cause only minor errors in the retrieved profiles. A study into the occurrence of rays curving down toward the Earth surface indicates that about 5–10% of the profiles could experience so-called critical refraction at altitudes between 0.5 km and 2 km in case of the applied high-resolution ECMWF data.
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Nedoluha, GeraldNaval Research Laboratory, Washington, DC
(author)
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Kirchengast, GottfriedUniversity of Graz, Institute for Geophysics, Astrophysics and Meteorology
(author)
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Buehler, Stefan
(author)
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Naval Research Laboratory, Washington, DCUniversity of Graz, Institute for Geophysics, Astrophysics and Meteorology
(creator_code:org_t)
Related titles
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In:Journal of Geophysical Research108:11, s. 4337-0148-02272156-2202
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