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ITG: A New Global GNSS Tropospheric Correction Model.

Yao Y, Xu C, Shi J, Cao N, Zhang B, Yang J - Sci Rep (2015)

Bottom Line: 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).Results indicate that ITG offers the best performance on the whole.

View Article: PubMed Central - PubMed

Affiliation: 1] School of Geodesy and Geomatics, Wuhan University, 129 Luoyu Road, Wuhan, 430079, China [2] Key Laboratory of Geospace Environment and Geodesy, Ministry of Education, Wuhan University, 129 Luoyu Road, Wuhan, 430079, China.

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.

No MeSH data available.


Global distribution of temperature RMS difference for each model. The abscissa represents longitude, and the ordinate represents latitude. 698 globally distributed stations provided by NOAA are represented by colorful dots, the color of each dot represent the Bias or RMS value at this station. This figure is drawn using MATLAB software.(a) Bias of ITG (b) RMS of ITG.
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f4: Global distribution of temperature RMS difference for each model. The abscissa represents longitude, and the ordinate represents latitude. 698 globally distributed stations provided by NOAA are represented by colorful dots, the color of each dot represent the Bias or RMS value at this station. This figure is drawn using MATLAB software.(a) Bias of ITG (b) RMS of ITG.

Mentions: Figure 4(a) shows that the temperature in the northern of Central Asia and most of East Asia was lower than ever all year due to the influence of Arctic oscillation in 2012. Biases at many ​​stations were below -3 °C, and most stations in Europe exhibited negative biases. While biases in Arctic and North America were generally positive, some were larger than 2 °C. Fig. 4(b) shows that RMS increases as latitude increases. The majority of stations at low latitudes have an RMS of less than 3 °C. Most of the mid-latitude stations have an RMS of 3 °C ~ 6 °C. Some high latitude stations had an RMS larger than 6 ° C. Figs. 4(c) 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. Figs. 4(d) show that most stations had a negative RMS, indicating that ITG is superior to the GPT2 series. Results for ITG were striking: it was superior to GPT2 at 93.1% of the stations and superior to GPT2 w of 1° × 1°at 93.1% of the stations.


ITG: A New Global GNSS Tropospheric Correction Model.

Yao Y, Xu C, Shi J, Cao N, Zhang B, Yang J - Sci Rep (2015)

Global distribution of temperature RMS difference for each model. The abscissa represents longitude, and the ordinate represents latitude. 698 globally distributed stations provided by NOAA are represented by colorful dots, the color of each dot represent the Bias or RMS value at this station. This figure is drawn using MATLAB software.(a) Bias of ITG (b) RMS of ITG.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4508915&req=5

f4: Global distribution of temperature RMS difference for each model. The abscissa represents longitude, and the ordinate represents latitude. 698 globally distributed stations provided by NOAA are represented by colorful dots, the color of each dot represent the Bias or RMS value at this station. This figure is drawn using MATLAB software.(a) Bias of ITG (b) RMS of ITG.
Mentions: Figure 4(a) shows that the temperature in the northern of Central Asia and most of East Asia was lower than ever all year due to the influence of Arctic oscillation in 2012. Biases at many ​​stations were below -3 °C, and most stations in Europe exhibited negative biases. While biases in Arctic and North America were generally positive, some were larger than 2 °C. Fig. 4(b) shows that RMS increases as latitude increases. The majority of stations at low latitudes have an RMS of less than 3 °C. Most of the mid-latitude stations have an RMS of 3 °C ~ 6 °C. Some high latitude stations had an RMS larger than 6 ° C. Figs. 4(c) 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. Figs. 4(d) show that most stations had a negative RMS, indicating that ITG is superior to the GPT2 series. Results for ITG were striking: it was superior to GPT2 at 93.1% of the stations and superior to GPT2 w of 1° × 1°at 93.1% of the stations.

Bottom Line: 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).Results indicate that ITG offers the best performance on the whole.

View Article: PubMed Central - PubMed

Affiliation: 1] School of Geodesy and Geomatics, Wuhan University, 129 Luoyu Road, Wuhan, 430079, China [2] Key Laboratory of Geospace Environment and Geodesy, Ministry of Education, Wuhan University, 129 Luoyu Road, Wuhan, 430079, China.

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.

No MeSH data available.