Application of Curve Surface Fitting in Regional Ionospheric Delay Model with Sparse Station Distribution

Abstract

Ionospheric delay observations of regional satellite navigation system shows heterogeneity in space and time, and it brings difficulties to implement the ionospheric delay model. The Kloubuchar model in geographic coordinates assumes that the ionospheric delay at the same latitude have the consistent variation characteristics with local time. The constellation of COMPASS is mainly composed of GEO satellites. In order to achieve the regional ionospheric delay variation, we can use several GEO ionospheric observations. By selecting 5 observation stations with well-distributed in latitude from 24 stations with COMPASS observations through the year 2012, we adopt polyhedral function fitting and Delaunay triangulation fitting to complement ionospheric observations of the region and period of time without real observations. Then we compute the Kloubuchar model parameters by using the complemented data, and use all 24 stations observations to check the results. Analysis result shows that, in the solar activity peak year, the average correction accuracy of model is prior to 65 % in middle-low latitude area, and RMS (1σ) is better than 11 TECU. The precision improvement is obviously improved compared with results without data complement using polyhedral function fitting.