Page 73 - 卫星导航2021年第1-2合期

Cheng et al. Satell Navig (2021) 2:2 Satellite Navigation
https://doi.org/10.1186/s43020-020-00032-w
https://satellite-navigation.springeropen.com/

ORIGINAL ARTICLE Open Access

Update China geodetic coordinate frame

considering plate motion

1
1*
2
Pengfei Cheng , Yingyan Cheng , Xiaoming Wang and Yantian Xu 1

Abstract
China Geodetic Coordinate System 2000 (CGCS2000), as the formal national coordinate reference frame, has been
used for 20 years. The coordinates of all Global Navigation Satellite System (GNSS) stations in China need referring
to this system. To this end, the frst step is to align the coordinates of all stations, usually included in a regional GNSS
network, with a given International Terrestrial Reference Frame (ITRF), then these coordinates are corrected to the
CGCS2000 in consideration of plate movement. For a better alignment result, regional control stations are needed
and their coordinates were estimated from the combination of constraint-free normal equation systems provided by
several International GNSS Service (IGS) analysis centers. The efect in using these refned coordinates, which deter-
mine a regional coordinate datum, on the alignment result should be evaluated by the coordinate corrections of the
regional control stations to the regional coordinate datum, i.e. smaller corrections mean better alignments of the two
associated frames. The test results show that the refned coordinates are more accurate than the ones calculated from
the station’s velocity, and are well aligned with the ITRF2005. Moreover, for obtaining the coordinates of GNSS stations
in an updated CGCS2000 frame, a gridded linear velocity feld based on the estimated velocities at 1025 CGCS2000
stations was generated for mainland China using the optimal interpolation method, the inverse distance weighting,
which is selected from fve interpolation methods. The overall precisions of the constructed velocity feld at all stations
in the East (E) and, North (N) directions are 0.78 mm/a and 0.95 mm/a, respectively. For evaluating the accuracy of the
updated CGCS2000 frame, monthly solutions for the coordinates of some CGCS2000 CORS stations in the ITRF2014
during the period from 2000.0 to 2018 were obtained and the Root Mean Square (RMS) of the diferences between
the coordinates corrected to the CGCS2000 and the known coordinates at these stations are about 2–3 cm.
Keywords: Optimal reference frame alignment, Frame agreement, China’s grid velocity, CGCS2000 update

Introduction CGCS2000 transformation. Te CGCS2000 is a static
China Geodetic Coordinate System 2000 (CGCS2000) frame and maintained by the coordinates of all GNSS sta-
was released on July 1, 2008 (Chen 2008) as the formal tions, which are usually estimated from the observations
national reference frame. It was defned in the Interna- in diferent times and referred to diferent ITRFs, trans-
tional Terrestrial Reference Frame (ITRF) 97 at the ref- formed to the CGCS2000 frame.
erence epoch 2000.0 and maintained using 2600 Global A few approaches have considered the plate motions
Navigation Satellite System (GNSS) geodetic reference in the transformation of the coordinates of a regional
stations distributed over China (Cheng et al. 2008). Tere GNSS network from an ITRF to the CGCS2000. Two
are several newer ITRFs (Altamimi et al. 2002, 2012), common ones are as below. Te frst approach is using
shown in Table 1, which need to be considered in the the seven transformation parameters at a given epoch,
obtained from the parameters at the reference epoch, and
their rates between the ITRF and ITRF97 (Wang 2020),
*Correspondence: 504827709@qq.com; yycheng@casm.ac.cn together with the movement velocities of the selected sta-
1 Chinese Academy of Surveying and Mapping, 28 Lianhuachi West Road,
Beijing 100036, China tions. Te second one is tightly constraining the coordi-
Full list of author information is available at the end of the article nates of some stations to their known coordinates in the

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