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GPS radio occultation: A potential new data source for improvement of antarctic pressure field

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Wuhan University Journal of Natural Sciences

Abstract

Radio occultation technique, first demonstrated by the GPS/MET experiment in 1995[1], has the potential to provide improved spatial and temporal resolution in the probing of the Earth’s neutral atmosphere, including pressure, temperature and water vapor profiles, in addition to traditional measurements (e.g., radiosonde, spacebome radiometers) and ground-based GPS networks for precipitable water vapor (PWV) measurements. This paper provides an overview of the radio occultation concept and retrieval procedure and current technical limitations including lower troposphere inhomogeneities, signal penetration, multipath, and water vapor ambiguity. The current limitations using atmospheric model pressure fields (ECMWF and NCEP) for the modeling of atmospheric mass load over Antarctica, for its separation from climate sensitive signals observed by gravity mapping satellite, GRACE, are quantified. Atmospheric pressure fields over Antarctica are poorly known and higher temporal variability of pressure causes an “aliasing” error in GRACE-observed climate-sensitive signals such as hydrology, mass balance and oceanic mass variations. In particular, comparison of ECMWF 6-hour data with the Automatic Weather Station (AWS) in Antarctica indicates mean differences of 5 hPa, and rms of 1.7 hPa, exceeding the accuracy requirement for GRACE. Aliasing effect manifests as high-frequency errors in GRACE-observed gravity signals and are more pronounced over Antarctica. The possibility of using current operating satellite (SAC-C, CHAMP and GRACE) occultation data to improve Antarctic surface pressure fields is proposed. Preliminary results indicate that in the absence of water vapor over Antarctica, retrieved CHAMP pressure profile agrees well with radiosonde data from Neumayer station, and that occultation signals reach near the surface.

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Authors and Affiliations

  1. Laboratory for Space Geodesy and Remote Sensing Research, The Ohio State University, 470 Hitchcock Hall, 2070 Neil Avenue, 43210, Columbus, Ohio, USA

    Ge Sheng-jie & C. K. Shum

  2. Division I, Kinematics and Dynamics of the Earth, Geo Forschungs Zentrum Potsdam (GFZ), Telegrafenberg, 14473, Potsdam, Germany

    J. Wickert & Ch. Reigber

Authors
  1. Ge Sheng-jie
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  2. C. K. Shum
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  3. J. Wickert
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  4. Ch. Reigber
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Corresponding author

Correspondence to Ge Sheng-jie.

Additional information

Foundation item: This Research (SJG & CKS) is Partially Supported by NASA’s Interdisciplinary Science Program (NAG5-9815)

Biography: Ge Sheng-jie(1973-), male, Ph. D. candidate, research direction: GPS occultation, orbit determination, gravity.

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Sheng-jie, G., Shum, C.K., Wickert, J. et al. GPS radio occultation: A potential new data source for improvement of antarctic pressure field. Wuhan Univ. J. Nat. Sci. 8, 636–648 (2003). https://doi.org/10.1007/BF02899829

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  • DOI: https://doi.org/10.1007/BF02899829

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