IGS reprocessing, an exciting project!

After the IGS workshop which we recently concluded to great success, one of the most important and interesting activities for the near future is the reprocessing of all the historical IGS data using current state-of-the-art techniques.

Reprocessing of GPS data back to 1994 is a high-priority of the IGS since modern techniques can better estimate the IGS products of the past. The original products produced week to week continue to be the “gold standard” of GPS precision as they are store in Data Centers around the world. These products can be used by scientist, engineers and researchers as the best GPS orbit, clocks and ITRF values for their own research and post-processing. The reasons for the urgent need for reprocessing all of the IGS products are as follows:

  1. The IGS is now using absolute Antenna Phase Center calibrations for ground and space antennas (ANTEX), this has brought the IGS ITRF station position estimations closer to other techniques and reduced uncertainty. This jump introduced in GPS week 1400 (Nov, 2006) creates a discontinuity with the previous IGS products, which needs to be removed by reprocessing the older data with the new standards.
  2. The IGS product consistency and accuracy has improved over time as better processing methods and standards have been implemented at each of the Analysis Centers. This high-level of consistency and increased accuracy which now exists needs to be extended backwards in time for the benefit of all. With more precise past products better science can be produced by the users of the IGS products.
  3. The IGS has adopted many reference frame updates as the ITRF reference frame has been updated over time. This creates a set of products that is not continuous over time as each new ITRF realization introduces a new set of precise coordinates and velocities for the stations. The reprocessing will produce a consistent set of products using the latest ITRF05 reference frame.
  4. Data processing limitations of the past are removed. As computer speed and power has increased , it is now possible to include many more stations as available in the reprocessing of the IGS products. The inclusion of more data for the reprocessing allows for better products and for many more reference station coordinates to be estimated precisely.

The improvement of the IGS products over time can be best highlighted by the IGS Analysis Center Coordinator orbit quality plot:

IGS Final Orbits from each AC since the IGS start

IGS Final Orbits from each AC since the IGS start

The justification for the IGS reprocessing are therefore clear, and most of the IGS Analysis Centers have committed time and resources to contribute to this effort to reprocess the data for the time period between 01/1994 to 12/2007. The reprocessing efforts are being coordinated by the IGS ACC from this website which I encourage anyone interested to visit: ACC Reprocessing website.

The main output, apart from the much improved GPS products, will be the station positions to be used in the next realization of the International Terrestrial Reference Frame (ITRF).

Take care
Nacho Romero

One Response to “IGS reprocessing, an exciting project!”

  1. Soluciones Avanzadas Canarias S.L. » SAC helping ESA/ESOC Reprocessing Says:

    […] IGS Reprocessing is a fantastic activity which I have highlighted before in this […]

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