Accuracy Assessment and Analysis for GPT2

doi:10.11947/j.AGCS.2015.20140356

Abstract

Abstract: GPT(global pressure and temperature) is a global empirical model usually used to provide temperature and pressure for the determination of tropospheric delay, there are some weakness to GPT, these have been improved with a new empirical model named GPT2, which not only improves the accuracy of temperature and pressure, but also provides specific humidity, water vapor pressure, mapping function coefficients and other tropospheric parameters, and no accuracy analysis of GPT2 has been made until now. In this paper high-precision meteorological data from ECWMF and NOAA were used to test and analyze the accuracy of temperature, pressure and water vapor pressure expressed by GPT2, testing results show that the mean Bias of temperature is -0.59℃, average RMS is 3.82℃; absolute value of average Bias of pressure and water vapor pressure are less than 1 mb, GPT2 pressure has average RMS of 7 mb, and water vapor pressure no more than 3 mb, accuracy is different in different latitudes, all of them have obvious seasonality. In conclusion, GPT2 model has high accuracy and stability on global scale.

Key words: tropospheric slant delay, GPT, GPT2, ECMWF, NOAA

CLC Number:

P228

YAO Yibin, CAO Na, XU Chaoqian, YANG Junjian. Accuracy Assessment and Analysis for GPT2[J]. Acta Geodaetica et Cartographica Sinica, 2015, 44(7): 726-733.

References

[1] SCHUELER T, HEIN G W, EISSFELLER B. A New Tropospheric Correction Model for GNSS Navigation[C]//Proceedings of GNSS. Sevilla, Spain: [s.n.], 2001: 8-11.
[2] QIAN Chuang, HE Changyong, LIU Hui. Regional Precise Troposphere Delay Modeling Based on Spherical Cap Harmonic Analysis[J]. Acta Geodaetica et Cartographica Sinca, 2014, 43(3): 248-256. (钱闯, 何畅勇, 刘晖. 基于球冠谐分析的区域精密对流层建模[J]. 测绘学报, 2014, 43(3): 248-256.)
[3] OU Jikun. Research on the Correction for the Neutral Atmospheric Delay in GPS Surveying [J]. Acta Geodaetica et Cartographica Sinica, 1998, 27(1): 31-36. (欧吉坤. GPS测量的中性大气折射改正的研究[J]. 测绘学报, 1998, 27(1): 31-36.)
[4] CHEN Yongqi, LIU Yanxiong, WANG Xiaoya, et al. GPS Real-time Estimation of Precipitable Water Vapor——Hong Kong Experiences[J]. Acta Geodaetica et Cartographica Sinica, 2007, 36(1): 9-12. (陈永奇, 刘焱雄, 王晓亚, 等. 香港实时 GPS 水汽监测系统的若干关键技术[J]. 测绘学报, 2007, 36(1): 9-12.)
[5] WANG Yong, LIU Lintao, HAO Xiaoguang, et al. The Application Study of the GPS Meteorology Network in Wuhan Region[J]. Acta Geodaetica et Cartographica Sinica, 2007, 36(2): 141-145. (王勇, 柳林涛, 郝晓光, 等. 武汉地区GPS气象网应用研究[J]. 测绘学报, 2007, 36(2): 141-145.)
[6] CHEN Junyong. On the Error Analysis for the Remote Sensing of Atmospheric Water Vapor by Ground Based GPS[J]. Acta Geodaetica et Cartographica Sinica, 1998, 27(2): 113-118. (陈俊勇. 地基GPS遥感大气水汽含量的误差分析[J]. 测绘学报, 1998, 27(2): 113-118.)
[7] DAVIS J L, HERRING T A, SHAPIRO I I, et al. Geodesy by Radio Interferometry: Effects of Atmospheric Modeling Errors on Estimates of Baseline Length[J]. Radio Science, 1985, 20(6): 1593-1607.
[8] BOEHM J, NIELL A, TREGONING P, et al. Global Mapping Function (GMF): A New Empirical Mapping Function Based on Numerical Weather Model Data[J]. Geophysical Research Letters, 2006, 33(7). DOI: 10.1029/2005GL025546.
[9] BOEHM J, WERL B, SCHUH H. Troposphere Mapping Functions for GPS and Very Long Baseline Interferometry from European Centre for Medium-range Weather Forecasts Operational Analysis Data[J]. Journal of Geophysical Research: Solid Earth (1978-2012), 2006, 111(B2). DOI: 10.1029/2005JB003629.
[10] NIELL A E. Global Mapping Functions for the Atmosphere Delay at Radio Wavelengths[J]. Journal of Geophysical Research: Solid Earth (1978—2012), 1996, 101(B2): 3227-3246.
[11] NIELL A E. Preliminary Evaluation of Atmospheric Mapping Functions Based on Numerical Weather Models[J]. Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy, 2001, 26(6-8): 475-480.
[12] YAO Y B, XU C Q, ZHANG B, et al. GTm-Ⅲ: A New Global Empirical Model for Mapping Zenith Wet Delays onto Precipitable Water Vapour[J]. Geophysical Journal, 2014, 197(1): 202-212.
[13] YAO Y B, ZHANG B, YUE S Q, et al. Global Empirical Model for Mapping Zenith Wet Delays onto Precipitable Water[J]. Journal of Geodesy, 2013, 87(5): 439-448.
[14] YAO Y B, ZHU S, YUE S Q. A Globally Applicable, Season-specific Model for Estimating the Weighted Mean Temperature of the Atmosphere[J]. Journal of Geodesy, 2012, 86(12): 1125-1135.
[15] YAO Y B, HE C Y, ZHANG B, et al. A New Global Zenith Tropospheric Delay Model GZTD[J]. Chinese Journal of Geophysics, 2013, 56(7): 2218-2227.
[16] SAASTAMOINEN J H. Atmospheric Correction for the Troposphere and Stratosphere in Radio Ranging Satellites[M]//The Use of Artificial Satellites for Geodesy. Washington DC: American Geophysical Union, 1972: 247-251.
[17] LIU Yanxiong, IZ H B, CHEN Yongqi. Precise Determination of Dry Zenith Delay for GPS Meteorology Applications[J]. Acta Geodaetica et Cartographica Sinica, 2000, 29(2): 172-180. (刘焱雄, IZ H B, 陈永奇. GPS 气象学中垂直干分量延时的精确确定[J]. 测绘学报, 2000, 29(2): 172-180.)
[18] SCHUELER T, HEIN G W, EISSFELLER B. On the Use of Numerical Weather Fields for Troposphere Delay Estimation in Wide Area Augmentation Systems[C]//Proceedings of GNSS. Edinburgh, Scotland: [s.n.], 2000: 1-4.
[19] BOEHM J, HEINKELMANN R, SCHUH H. Short Note: A Global Model of Pressure and Temperature for Geodetic Applications[J]. Journal of Geodesy, 2007, 81(10): 679-683.
[20] LAGLER K, SCHINDELEGGER M, BÓHM J, et al. GPT2: Empirical Slant Delay Model for Radio Space Geodetic Techniques[J]. Geophysical Research Letters, 2013, 40(6): 1069-1073.