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Comparison of spherical harmonic and B spline models for the vertical total electron content
Author(s) -
Schmidt Michael,
Dettmering Denise,
Mößmer Matthias,
Wang Yuanyuan,
Zhang Jiantong
Publication year - 2011
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/2010rs004609
Subject(s) - spherical harmonics , total electron content , geodetic datum , mathematics , ionosphere , mathematical analysis , geodesy , geometry , physics , computational physics , geology , tec , geophysics
Most of the geodetic ionosphere models describe the electron density of the Earth's atmosphere by global maps of the vertical total electron content (VTEC) for fixed time intervals (e.g., 2 h) assuming a single‐layer model and using a spherical harmonic expansion up to a specific degree n . However, it is well known that spherical harmonic models are not suited for representing data of heterogeneous density and quality. As a consequence, data gaps cannot be handled appropriately. In this paper we present a different approach for modeling VTEC generally depending on space and time defining the 3‐D system of base functions as tensor products of trigonometric B spline functions for the longitude and two sets of endpoint‐interpolating B spline functions for latitude and time, respectively. We compare this approach to a spherical harmonic expansion with similar resolution and show how data gaps influence the accuracy of VTEC maps even in areas with good data coverage.