CAsia GPS processing

Continuous processing results

Time series and sky plots of phase residuals are shown with this link.

NOTE: Suominet net sites SA09 and SA13 added 30 Jan 2002, see Processing changes at bottom of page.

The time series of station position estimates are generated in two analyses using globk/glorg from GAMIT runs which process both networks simulataneosly. The autcln command file is let unchanged each data and the sestbl. file is used to control the GAMIT runs. The main features here are use of 30 second data for cleaning which is decimated to 2 minutes for the final runs. The Use N-file feature in the sestbl. file set the use of a postfit, elevation angle dependent phase data noise model. The sittbl. template sets the apriori constraints on the station coordinates during the GAMIT run. These constraints are removed before processing in globk. During processing the atmospheric pressure, temperature and relative humidity are replaced by values computed from NCEP analysis fields. We used the Scripps Orbit and Permanent Array Center (SOPAC) final g-files obtained from the SOPAC combinations ftp area by GPS week number.

For the Californian network glorg is used to estimate daily translations of the network with the orienataion constrained to the IERS Bulletin A values. Over the 125 km extent of this network, 1 mas error in Earth orientation should change the relative coordinates by <1 mm. The California globk command file and glorg command file can be viewed with these hyper-links. globk.usesite contains the name of the sites used in the globk solution (used to eliminate un-wanted sites). glorg.cali.usesite and glorg.cont.usesite contain the names of the sites used for the origin constraint in the California and Central Asia glorg runs. The current California RMS scatters are updated daily.

For the Central Asia network which spans 1800 km we estimate only translation in glorg (same as the smaller California network). The Central Asia globk command file and glorg command file can be viewed with these hyper-links. The same rotational constraints are applied as California. (These constraints were previously 10-times larger). The current Central Asia RMS scatters are updated daily. These summary files include both the orginal larger Central Asia network (with translation and rotation) and the smaller network (with only translation).

In both analyses, the SIO orbits are constrained to +-100 mm in position and 0.01 mm/sec in velocity. Radiation parameter adjustments are constrained to 1% of the direct radiation pressure.

The data from Central Asia is collected in collaboration with the Russian Academy of Sceinces Institute for High Temperature Physics (IVTAN). The IVTAN web page contains more information about the continuous sites and the GPS campaigns that have been carried out in the region.

The results shown on these pages were made possible by support from the National Science Foundation (NSF), the National Aeronautics and Space Administration (NASA), the Southern California Earthquake Center (SCEC), and the University Navstar Consortium (UNAVCO).

Processing changes

Day 096, 1998 Introduced site-dependent data noise computed from postfit residuals with an elevation angle dependent model.

Day 119, 1998 Introduced estimation of atmospheric gradients with constraint of +-10 mm at 10 deg elevation angle.

Day 334, 1998 Changed the stations in the Central Asia Network to cover an 1800-km region only. (The original 6000-km network can be seen here.)

Day 072, 1999 Introduced site-dependent daily-mean-atmospheric delays into GAMIT processing. These delays are computed from the NCEP global forecast models. A new set of PNGs are included for each station showing the atmospheric delays since the beginning of 1999. The red-line on these plots shows the apriori delay being used in the processing. The green line is the RMS scatter of the phase residuals. The lower plot shows the results for the last 30 days.

Day 101, 1999 Reduced the elevation-angle cutoff from 15 degrees to 10 degrees. The elevation angle dependence of the phase noise means that the effective cutoff angle is still somewhat higher than 10 degrees.

Day 309, 1999 No data processing changes. We converted all of our GIF images to PNG (Portable Network Graphics) format so as not be in violation of the Unisys/Compuserve patent on GIF. Use of GIF images, without paying a licensing fee can result in $5000 fines. NOTE: Many of our images still use the .gif extension but are PNG format. Netscape shows the correct format type; Microsoft Internet Explorer, while correctly displaying the PNG image, reports the image as being a gif image. Viewing the page source of the images shows the PNG header.

Day 310, 1999 Modified the bias fixing sigma in sestbl. Increased values from 0.15 cycles to 0.25 cycles for both the WL and NL fixing. First analysis effected is day 292, 1999.

Day 314, 1999 Changed the "ionospheric constraint" in sestbl. to 8 ppm due to increasing solar activity. First analysis effected is day 297, 1999.

Day 161, 2000 Started to process with IGS Final orbit rather than the SOPAC final gfile. Also converted time series from days since 1998 to years.

Day 224, 2000 Started to apply ocean tide models based on Scherneck's tables to the processing. Stations not the standard tabular form are interpolated from grid values.

Day 030, 2002 Added two stations from the SuomiNet network. The sites are Trimble 4700 recievers with SA09 having a TRM33429.00+GP, L1/L2 microcentered Compact antenna with Ground plane, antenna and SA13 having a TRM29659.00 Choke ring antenna. These sites are distant from the California network we process (Map), and so geodetic quality of the positions is not our primary aim. Being at the end of a large lever aim to the rest of the network their position estimates are senstive to small Earth orientation errors.
The atmospheric delay plots for these sites show the 6-hourly estimates from the NCEP analysis field (in red; other sites show the daily mean value). We save the statistics of the RMS scatter of the phase residuals and the number of phase measurements as a function of elevation angle.
RMS phase residuals by date and elevation angles
Number of phase residuals by date and elevation angles
(Multiply fractional part of year by 365 to get day-of-year)

Day 189, 2002 Added a "Time Series Data" link to the results page to allow access to the time series in ascii form

Day 096, 1998	Introduced site-dependent data noise computed from postfit residuals with an elevation angle dependent model.
Day 119, 1998	Introduced estimation of atmospheric gradients with constraint of +-10 mm at 10 deg elevation angle.
Day 334, 1998	Changed the stations in the Central Asia Network to cover an 1800-km region only. (The original 6000-km network can be seen here.)
Day 072, 1999	Introduced site-dependent daily-mean-atmospheric delays into GAMIT processing. These delays are computed from the NCEP global forecast models. A new set of PNGs are included for each station showing the atmospheric delays since the beginning of 1999. The red-line on these plots shows the apriori delay being used in the processing. The green line is the RMS scatter of the phase residuals. The lower plot shows the results for the last 30 days.
Day 101, 1999	Reduced the elevation-angle cutoff from 15 degrees to 10 degrees. The elevation angle dependence of the phase noise means that the effective cutoff angle is still somewhat higher than 10 degrees.
Day 309, 1999	No data processing changes. We converted all of our GIF images to PNG (Portable Network Graphics) format so as not be in violation of the Unisys/Compuserve patent on GIF. Use of GIF images, without paying a licensing fee can result in $5000 fines. NOTE: Many of our images still use the .gif extension but are PNG format. Netscape shows the correct format type; Microsoft Internet Explorer, while correctly displaying the PNG image, reports the image as being a gif image. Viewing the page source of the images shows the PNG header.
Day 310, 1999	Modified the bias fixing sigma in sestbl. Increased values from 0.15 cycles to 0.25 cycles for both the WL and NL fixing. First analysis effected is day 292, 1999.
Day 314, 1999	Changed the "ionospheric constraint" in sestbl. to 8 ppm due to increasing solar activity. First analysis effected is day 297, 1999.
Day 161, 2000	Started to process with IGS Final orbit rather than the SOPAC final gfile. Also converted time series from days since 1998 to years.
Day 224, 2000	Started to apply ocean tide models based on Scherneck's tables to the processing. Stations not the standard tabular form are interpolated from grid values.
Day 030, 2002	Added two stations from the SuomiNet network. The sites are Trimble 4700 recievers with SA09 having a TRM33429.00+GP, L1/L2 microcentered Compact antenna with Ground plane, antenna and SA13 having a TRM29659.00 Choke ring antenna. These sites are distant from the California network we process (Map), and so geodetic quality of the positions is not our primary aim. Being at the end of a large lever aim to the rest of the network their position estimates are senstive to small Earth orientation errors. The atmospheric delay plots for these sites show the 6-hourly estimates from the NCEP analysis field (in red; other sites show the daily mean value). We save the statistics of the RMS scatter of the phase residuals and the number of phase measurements as a function of elevation angle. RMS phase residuals by date and elevation angles Number of phase residuals by date and elevation angles (Multiply fractional part of year by 365 to get day-of-year)
Day 189, 2002	Added a "Time Series Data" link to the results page to allow access to the time series in ascii form