On the basis of GPS data at stations of different climatic types in China, precipitable water vapor (PWV) products in year 2016 were obtained through precision data processing and water vapor inversion. On the basis of these products, the reliability of accuracy, annual variation, and diurnal variation of water vapor content for the first hourly resolution global reanalysis data ERA5 was systematically evaluated in China and compared with the previous generation of ERA-Interim analysis data. Results show that the annual and diurnal variation characteristics of PWV in different regions are mainly affected by monsoon and sunlight, respectively. The PWV accuracy provided by ERA5 is better than that of ERA-Interim. The two kinds of reanalysis data adequately reflect the annual variation characteristics of PWV, and the diurnal variation deviation of ERA5 is smaller than that of ERA-Interim in general, especially in the Qinghai-Tibet Plateau area.
This paper presents an investigation of the precise point positioning (PPP) performance of a combined solution from BDS-2 and BDS-3 satellites. To simultaneously process different BDS signal observations, i.e., B1/B1C, B2/B2a and B3C, undifferenced and uncombined observations with ionosphere delay constrained by the deterministic plus stochastic ionosphere model are used in the basic model. Special attention is paid to code bias and receiver clock parameters in the derivation of the observation model. The analysis is carried out using more than one-month data for BDS-2 and BDS-3 collected at the CANB, DWIN, KNDY and PETH stations in the Asia-Pacific region. The results suggest that compared with BDS-2 alone, the BDS-2 and BDS-3 solution provides significantly more accurate PPP, with increases of 28%, 21% and 5% in the up, north and east directions, respectively. In addition, the average root mean square error decreases to 0·21, 0·13 and 0·16 m for the three directions. Furthermore, the PPP convergence time for BDS-2 and BDS-3 is about 1·5 h and less than 1 h for the horizontal and vertical components, respectively, whereas that for BDS-2 alone is about 2·3 h for both directions.
With the continuous development of China's Beidou navigation and positioning system (BDS), Beidou widearea real-time precise positioning system is an important part of Beidou system, meeting the needs of the high-precision location service in various industries of the national economy. Based on the real-time high-precision orbit, clock and ionospheric products provided by Beidou wide-area real-time precise positioning service system, this paper uses mobile phone terminals which support Beidou wide-area real-time precise services to verify and evaluate real-time products accuracy and single frequency precise point positioning (PPP) accuracy. The experimental results show that the horizontal positioning accuracy of the realtime BDS single-frequency PPP of mobile phone terminal is 1 to 3 meters and the vertical positioning accuracy is 1.5 to 3.5 meters under the condition of good observation environment.
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