Abstract
Tropospheric correction models are receiving increasing attentions, as they play a crucial role in Global Navigation Satellite System (GNSS). Most commonly used models to date include the GPT2 series and the TropGrid2. In this study, we analyzed the advantages and disadvantages of existing models and developed a new model called the Improved Tropospheric Grid (ITG). ITG considers annual, semi-annual and diurnal variations, and includes multiple tropospheric parameters. The amplitude and initial phase of diurnal variation are estimated as a periodic function. ITG provides temperature, pressure, the weighted mean temperature (Tm) and Zenith Wet Delay (ZWD). We conducted a performance comparison among the proposed ITG model and previous ones, in terms of meteorological measurements from 698 observation stations, Zenith Total Delay (ZTD) products from 280 International GNSS Service (IGS) station and Tm from Global Geodetic Observing System (GGOS) products. Results indicate that ITG offers the best performance on the whole.
Highlights
Tropospheric correction models are receiving increasing attentions, as they play a crucial role in Global Navigation Satellite System (GNSS)
Zenith Wet Delay (ZWD) is used as an estimated parameter for higher accuracy[14,15], and can be transformed into precipitable water vapor (PWV) with Tm16
Numerical results indicate the proposed Improved Tropospheric Grid (ITG) outperforms the other models in terms of temperature, Zenith Total Delay (ZTD) and Tm
Summary
To further analyze the effectiveness and applicability of ITG, external references were used to compare the accuracy of the proposed ITG and the existing models . We used observations from 698 globally distributed stations provided by NOAA as a reference to validate ITG, GPT2 and GPT2w for temperature. 4(c),(e) indicate that the GPT2 series have a larger bias than ITG This results from different schemes for modeling, and ITG was found to be optimal. ITG had an average RMS of 3.73 cm, smaller than GPT2 and GPT2w of 5° × 5°, and its accuracy was similar to GPT2w of 1° × 1°. Comparison between GPT2w of 5° × 5° and GPT2w of 1° × 1° shows that higher horizontal resolution improves the ZTD RMS of only 0.05 cm. GPT2w of 1° × 1° had a higher horizontal resolution, the formula and modeling method of ITG was shown to be superior.
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