11:00 AM - 11:15 AM
[G07-4-03] Development of New Analysis Strategy for GNSS Observation Network in Japan
Geospatial Information Authority of Japan (GSI) has been operating Continuous Operating Reference Stations (CORS) called GEONET (GNSS Earth Observation Network System), since 1996. We currently operate more than 1,300 stations to cover whole Japan, with an average spacing of about 20km. With the total number and density, GEONET is one of the largest GNSS CORS systems in the world. After 20 years of successful operation, it becomes vital infrastructure for surveying and mapping, precise positioning, disaster management, and even for weather forecast in Japan.
We calculate the daily coordinates for each GEONET station by using Bernese GNSS software to monitor the crustal deformation in Japan. The analysis strategy was updated three times. Latest version was established in 2009. We are now developing new strategy because the software, reference frame, and other physical models have been obsolete.
In this paper, we focus on the GPS and GLONASS integration. Only GPS was used for older strategy. However, the receivers and antennas in GEONET were updated into the multi-frequency type in 2013. Furthermore, the final orbit for GLONASS provided by IGS has reached almost the same accuracy in comparison with the one for GPS. We process GPS and GLONASS data independently to estimate the ambiguities, and then combine the solutions with normal equations. The result based on GLONASS observations data show the apparent fluctuation with the period of 8 days that was not found on the GPS result. Which is significant for the stations apart from the reference station, but it is systematic which can explain, for example, frame rotation. IGS analysis centers using GLONASS observations reported the same phenomenon that seemed to be caused by the GLONASS constellation geometry (Ray et al., 2013, Rebischung et al., 2016). We have tried ways to set transformation parameters and absorb systematic fluctuation. We discuss the method to suppress the apparent fluctuation in our presentation.
We calculate the daily coordinates for each GEONET station by using Bernese GNSS software to monitor the crustal deformation in Japan. The analysis strategy was updated three times. Latest version was established in 2009. We are now developing new strategy because the software, reference frame, and other physical models have been obsolete.
In this paper, we focus on the GPS and GLONASS integration. Only GPS was used for older strategy. However, the receivers and antennas in GEONET were updated into the multi-frequency type in 2013. Furthermore, the final orbit for GLONASS provided by IGS has reached almost the same accuracy in comparison with the one for GPS. We process GPS and GLONASS data independently to estimate the ambiguities, and then combine the solutions with normal equations. The result based on GLONASS observations data show the apparent fluctuation with the period of 8 days that was not found on the GPS result. Which is significant for the stations apart from the reference station, but it is systematic which can explain, for example, frame rotation. IGS analysis centers using GLONASS observations reported the same phenomenon that seemed to be caused by the GLONASS constellation geometry (Ray et al., 2013, Rebischung et al., 2016). We have tried ways to set transformation parameters and absorb systematic fluctuation. We discuss the method to suppress the apparent fluctuation in our presentation.