elib
DLR-Header
DLR-Logo -> http://www.dlr.de
DLR Portal Home | Imprint | Contact | Deutsch
Fontsize: [-] Text [+]

Ionosphere induced higher order effects on GPS radio occultation measurements

Hoque, Mohammed Mainul and Jakowski, Norbert (2010) Ionosphere induced higher order effects on GPS radio occultation measurements. International Beacon Satellite Symposium 2010, BSS2010, 7-11 Jun 2010, Barcelona, Spain .

Full text not available from this repository.

Abstract

We have investigated higher order ionospheric effects on GPS radio occultation measurements onboard Low Earth Orbiting (LEO) satellites. Due to long ionospheric limb paths, GPS measurements are strongly affected by ionospheric refraction during radio occultation. Since the ionospheric refractive index depends mainly on the electron density, the inversion of the measured total electron content (TEC) from the radio occultation or limb sounding data provides the vertical electron density profile from the LEO height down to the bottom side of the ionosphere. In general, the TEC along a GPS-LEO path is calculated using the GPS dual frequency measurements. However, in the common practice only the first order ionospheric term in the expansion of the refractive index is taken into account for the TEC estimation, i.e., higher order ionospheric terms such as the second and third order terms, and ray path bending effects are ignored. The resulting error in TEC estimation leads thus to an erroneous reconstruction of the vertical profile of electron density. Additionally, due to the bending, the tangential height of the curved path deviates from that defined by the straight line of sight propagation. This leads to an erroneous determination of the reference height in the retrieval technique. Using a two dimensional ray tracing program, higher order ionospheric terms such as the second and third order ionospheric phase delays, and ray path bending related terms such as the ray path deviation, excess path length of the signal and TEC difference between the GPS L1 and L2 signal paths have been computed. In addition, higher order propagation effects on the dual-frequency range estimation and TEC estimation during occultation will be presented. We have found that during radio occultation the separation between the GPS L1 and L2 ray paths approaches the kilometer level if TEC exceeds 160 TECU. In this case the differences between the tangential heights of the curved path and LoS path exceed the kilometer level for both the L1 and L2 signals. Conclusions are drawn how to mitigate such higher order effects in radio occultation retrievals.

Document Type:Conference or Workshop Item (Poster)
Title:Ionosphere induced higher order effects on GPS radio occultation measurements
Authors:
AuthorsInstitution or Email of Authors
Hoque, Mohammed MainulUNSPECIFIED
Jakowski, NorbertUNSPECIFIED
Date:June 2010
Status:Published
Keywords:Higher order ionospheric effects, GPS radio occultation, Bending error
Event Title:International Beacon Satellite Symposium 2010, BSS2010
Event Location:Barcelona, Spain
Event Type:international Conference
Event Dates: 7-11 Jun 2010
Organizer:Technical University of Catalonia (gAGE/UPC)
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Space (old)
HGF - Program Themes:W EW - Erforschung des Weltraums
DLR - Research area:Space
DLR - Program:W EW - Erforschung des Weltraums
DLR - Research theme (Project):W - Vorhaben Weltraumwetter (old)
Location: Neustrelitz
Institutes and Institutions:Institute of Communication and Navigation
Deposited By: Mohammed Mainul Hoque
Deposited On:08 Jun 2010 11:51
Last Modified:26 Sep 2012 10:15

Repository Staff Only: item control page

Browse
Search
Help & Contact
Informationen
electronic library is running on EPrints 3.3.12
Copyright © 2008-2012 German Aerospace Center (DLR). All rights reserved.