An improved Kloubuchar ionospheric correction model for single frequency GNSS receivers

Abstract The enhancement of positional accuracy of single frequency ionospheric correction models is an urgent need for low-cost and smartphone GNSS users. The available single frequency ionospheric correction models such as Klobuchar, NeQuick-G, NTCM, and Klob-BDS are providing ionospheric corrections for multi GNSS systems such as GPS, Galileo, BDS, and NAVIC systems. Otherwise, Global Ionospheric Map (GIM) Total Electron Content (TEC) corrections are also available to the GNSS users. In this letter, an improved Klobuchar ionospheric model is implemented. The slant TEC of dual Frequency GPS TEC observations is considered a reference. The Klobuchar model slant TEC observations are improved by taking the grid-based residual TEC corrections with the Adjusted Spherical Harmonic Function model. The Single frequency users can improve the ionospheric delay estimation using Klobuchar model and grid-based TEC residual corrections. The improved ionospheric correction model is tested under the biggest geomagnetic storm conditions during 24th Solar cycle that occurred in March 2015 over India. The proposed hybrid slant ionospheric TEC algorithms are evaluated with individual single frequency ionospheric models (Klobuchar, and GPS TEC) under adverse space weather conditions.