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IVS Contribution to ITRF2020 Update

Summary

Previously the ITRF was updated with a cadence of roughly once every 5-6 years, with the most recent update being ITRF2020. There is a general desire within the geodetic community to have more frequent updates. With this in mind the IVS and the other geometric services (IDS,IGS, ILRS) agreed to provide data from 2021 throught the end of calendar year 2023.

All IVS Analysis Centers are invited to contribute to this effort. The deadline for the final contribution is 2024-01-31. The IVS combination center will take the individual contributions and submit combined solutions by 2024-03-01. A detailied schedule is given below.

This web-page will be updated as information changes. A summary of the changes is given at the bottom of the web-page to help you identify things that might have changed since your last visit.

Status

The deadline for submissioon has passed. Twelve IVS Analysis Centers participated in this effort. On average, the submission rate was over 98% for the legacy S/X session, and 89% for the VGOS sessions. (One AC did not submit any VGOS sessions.) Details of which AC submitted which session can be found further below.

I thank all of the Analysis Centers which contributed to this effort.

Solution Setup

The solution setup is identical to what we are doing now. This is close to the setup for ITRF2020 with the following exceptions:

Note that the use of a new gravity deformation file will introduce discontinuities in the local Up at epoch 2021-01-01 for the following stations: KOKEE, NYALES20, ONSA13NE, ONSA13SW, WETTZELL, WETTZ13S WETTZ13N. The magnitude of the discontinuity is discussed near the bottom of this page.

Please note that in the SINEX files you must include additional information to allow users to remove loading effects. Many Analysis Centers include this information in their standard submissions, and won't need to make any changes. Other Analysis Centers will need to modify their solution setup to include this information.

Schedule

  • 2023-10-01: IVS Analysis Centers contribute sessions through ~2023-06-30 that were not in ITRF2020 submission. (e.g., from 2021 through 2023.05)
  • 2023-11-30: IVS Combination Center vets results and does combination.
  • 2024-01-31: IVS Analysis Centers submit remaining sessions to combination center (roughly last 6 months of 2023).
  • 2024-02-09: Exteded deadline!!
  • 2024-03-01: IVS Combination Center submits results.
Analysis centers are encouraged to submit there contributions as soon as possible. (You don't need to wait unitl 2024-01-31 to submit the last 6 months of 2023! Submit the sessions as soon as they are analyzed.)

IVS Analysis Centers Contributing to ITRF2020 Update

This section lists the IVS Analysis Centers which have agreed to contribute to the ITRF2020 update. The contributed SINEX files are available on the IVS Data Centers. The last two columns list the number of S/X and VGOS sessions submitted. The total number of sessions is now 568 for S/X and 100 for VGOS, which is based on the number of sessions which have been correlated. This is a reduction form the previous totals of 585 and 104 which was based on a prediction of the number of sessions which would be correlated.
Institution Software Code S/X (568) VGOS (100)
ASI Calc/Solve asi2023b 568 100
BKG Calc/Solve bkg2023b 568 100
DGFI DOGS-RI dgfi2023b 550 95
GFZ PORT gfz2022a 568 100
GSFC Calc/Solve gsf2023a 568 100
IGE Where ige2023b 559 97
NMA Where nma2023b 568 100
OPA Calc/Solve opa2020t 520 95
OSO ASCOT oso2023a 568 100
UAV VieVs@GFZ uav2023b 544 91
USNO Calc/Solve usn2023c 568 0
VIE VievS vie2023b 568 100
This table will be updated as new information becomes available.
  • 2024-02-08: Status through 2024-02-08
  • 2024-01-31: Status through 2024-01-31.
  • 2024-01-17: Status through 2024-01-10.
  • 2023-11-27: Status updated through 2023-11-27.
  • 2023-11-06: Software updated for IGE and UAV. Solution codefor ASI.
  • 2023-11-01: Session list information updated.

Sessions

Our goal is for all Analysis Centers that participate to submit all of the S/X and VGOS sessions from the start of 2021 through 2023. We exclude sessions from 2023 which include O'Higgins because these will not be correlated prior to the deadline because of issues in transporting the O'Higgins media.

Here are links to the S/X and VGOS sessions. These tables also indicate which ACs have submitted which sessions. Data is current as of 2024-02-08. These files are courtesy of the IVS Combination Center and will be updated periodically.

Future ITRF Updates

There is always a tension between frequent updates and using the best available models. An example occurs in this current effort where the antenna gravitional deformation changed between 2020 and now. This change introduces a discontinuity in local Up for stations with new models.

Going forward, we anticipate doing updates on annual basis. For these future updates we will ask all Analysis Centers to reprocess and resubmit SINEX files for all of the sessions.

Discontinuity in Local Up

We have studied the magnitude of the discontinuity for these stations and the results are summarizd below. The units are in mm and give the change in local Up. A positive sign indicates that using the new models will cause an INCREASE in the local up estimate.

The column label "Theoretical" was found by taking the predicted change in path-length and decomposing it into the basis functions: 1, sin(el), 1/sin(el) over the range 7 to 90 degrees. These functions are the partials of Clock, Up and (approximately) atmosphere.

The column labeled "Empirical" was found by doing two large global solutions using data from 1979 through 2022, one using the old gravity deformation file, and one using the new file, and taking the difference in the station positions.

Station Theoretical Empirical
KOKEE -1.1 -1.3
NYALES20 -1.1 -1.0
ONSA13SE 0.8 0.8
ONSA13NW 0.8 0.8
WETTZ13N -0.9 -0.7
WETTZ13S -0.9 -0.8
WETTZELL -3.8 -3.7
Note how close the last two columns are.

History of changes

This section lists major changes to this website to help you identify important changes since the last time you visited.
  • 2024-01-31: Session list updated. New deadline for submission.
  • 2023-11-27: Contributed session table update.
  • 2023-11-06: Added in ASI to table listing ACs that will contribute. >
  • 2023-11-01: Added table with ACs and solution codes. Added links to S/X and legacy sessions. Added section in discontinuity in Up.
  • 2023-10-31: Happy Halloween! First version of webpage.



The position of the IVS Analysis Coordinator is currently supported by NASA GSFC. NASA + Privacy Policy and Important Notices Last updated: 2023-11-27