China is a country of vast territory with complicated geographical environment and climate conditions. With the rapid progress of the Chinese BeiDou satellite navigation system (BDS); more accurate tropospheric models must be applied to improve the accuracy of navigation and positioning. Based on the formula of the Saastamoinen and Callahan models; this study develops two single-site tropospheric models (named SAAS_S and CH_S models) for the Chinese region using radiosonde data from 2005 to 2012. We assess the two single-site tropospheric models with radiosonde data for 2013 and zenith tropospheric delay (ZTD) data from four International GNSS Service (IGS) stations and compare them to the results of the Saastamoinen and Callahan models. The experimental results show that: the mean accuracy of the SAAS_S model (bias: 0.19 cm; RMS: 3.19 cm) at all radiosonde stations is superior to those of the Saastamoinen (bias: 0.62 cm; RMS: 3.62 cm) and CH_S (bias: −0.05 cm; RMS: 3.38 cm) models. In most Chinese regions; the RMS values of the SAAS_S and CH_S models are about 0.51~2.12 cm smaller than those of their corresponding source models. The SAAS_S model exhibits a clear improvement in the accuracy over the Saastamoinen model in low latitude regions. When the SAAS_S model is replaced by the SAAS model in the positioning of GNSS; the mean accuracy of vertical direction in the China region can be improved by 1.12~1.55 cm and the accuracy of vertical direction in low latitude areas can be improved by 1.33~7.63 cm. The residuals of the SAAS_S model are closer to a normal distribution compared to those of the Saastamoinen model. Single-site tropospheric models based on the short period of the most recent data (for example 2 years) can also achieve a satisfactory accuracy. The average performance of the SAAS_S model (bias: 0.83 cm; RMS: 3.24 cm) at four IGS stations is superior to that of the Saastamoinen (bias: −0.86 cm; RMS: 3.59 cm) and CH_S (bias: 0.45 cm; RMS: 3.38 cm) models.

An Earth's gravity field model IGGGRACE01S has been derived from 141 days of GRACE tracking data, including K‐band, accelerometer, and satellite orbit data. The model resolves the geoid with an accuracy of about 0.012m at a resolution of 500m half‐wavelengths, it improves the accuracy of the gravity field model in the long‐ to medium‐wavelength part (< 80 degree) in comparison with the pre‐CHAMP model. Comparing the coefficients of IGGGRACE01S, EIGEN‐GRACE02S, EIGEN‐CHAMP03S and EGM96 models, the result shows that the coefficients of IGGGRACE01S are much closer to those of EIGEN‐GRACE02S, and very different to those of the other two models. Comparing the geoid undulations and gravity anomalies derived from IGGGRACE01S, EIGEN‐GRACE02S and EGM96 models, the results indicate that the IGGGRACE01S solution is much closer to EIGENGRACE02S solution, and there exist large differences between IGGGRACE01S and EGM96 in Antarctica region. Comparing the gravity anomalies derived from IGGGRACE01S (72 degree) with NIMA gravity anomalies data (2.5° × 2.5°), the standard deviation is 4.8 mGal in China mainland region.

Firstly, the GRACE Level 1B measured data including the orbital position and velocity of GPS receiver, intersatellite range rate of K‐band ranging system, nonconservative force of accelerometer and attitude of star camera assembly between 2007‐06‐01~2007‐12‐31 provided by the American Jet Propulsion Laboratory (JPL) are processed effectively by orbital connection, gross error detection, linear interpolation, recalibration, coordinate transformation, error analysis, and so on. Secondly, the GRACE Earth's gravitational field complete up to degree and order 120 is recovered based on the improved energy conservation principle, the cumulative geoid height error is 25.313 cm at degree 120. Finally, the dependability of the Earth's gravitational field model IGG‐GRACE is verified in the paper, and the reasons why the accuracy of IGG‐GRACE is a little superior to the Earth's gravitational field model EIGEN‐GRACE02S provided by the German GeoForschungsZentrum Potsdam (GFZ) in the low frequency range and is slightly lower than that in the medium‐high frequency band are analyzed.