The TaiWan Ionospheric Model (TWIM) and its applications on radio wave propagation and ionospheric GPS L1 pseudorange correction

L. C. Tsai, G. H. Chen, M. H. Tian, Ernest P. MacAlalad

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

A three-dimensional ionospheric electron density (N e) model has been named the TaiWan Ionospheric Model (TWIM) and constructed from monthly-weighted and hourly vertical Ne profiles retrieved from FormoSat3/COSMIC GPS radio occultation (RO) measurements. The TWIM exhibits vertically-fitted α-Chapman-type layers, with distinct F2, F1, E, and D layers, and surface spherical harmonics approaches for the fitted layer parameters including peak density, peak density height, and scale height. These results are useful in investigation of near-Earth space and large-scale N e distribution. This way the continuity of N e and its derivatives is also maintained for practical schemes for providing reliable radio propagation predictions. We also present a numerical and step by step ray-tracing method on the TWIM. With the Earth's magnetic field and horizontal N e gradient effects included, efficient methods for calculating ray parameters such as phase path and group path are presented. The methodology has been successfully applied to a practical high-frequency transmitter for oblique incidence ray tracing and further evaluated by comparing synthetic vertical ionograms generated by the method with experimental ionosonde observations. Furthermore, the ray-tracing methodology also has potential applicability to ionospheric correction as applied to single frequency GPS receivers. In this paper, ionospheric delay correction for single-frequency GPS pseudoranges using the TWIM is presented. Its performance with respect with the ionospheric correction using other ionospheric model and the dual-frequency GPS receiver will also be presented.

Original languageEnglish
Title of host publication32nd Asian Conference on Remote Sensing 2011, ACRS 2011
Pages27-34
Number of pages8
StatePublished - 2011
Event32nd Asian Conference on Remote Sensing 2011, ACRS 2011 - Tapei, Taiwan
Duration: 3 Oct 20117 Oct 2011

Publication series

Name32nd Asian Conference on Remote Sensing 2011, ACRS 2011
Volume1

Conference

Conference32nd Asian Conference on Remote Sensing 2011, ACRS 2011
Country/TerritoryTaiwan
CityTapei
Period3/10/117/10/11

Keywords

  • GPS positioning
  • GPS radio occultation
  • Ionospheric electron density model

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