3rd IGS Data Reprocessing Campaign
OBJECTIVE
By the start October 2019, the Analysis Centers (ACs) of the International GNSS Service will begin the third reanalysis of the full history of GPS data collected by the IGS global network since 1994 in a fully consistent way using the latest models and methodology.
CONVENTIONS
AND
MODELLING
FOR
REPRO3
Reference Frame
    Stations categorized by priority for Reference Frame Determination for repro3, provided by Paul Rebischung
      Antenna Information for each station
      Receiver information for each station
Antenna Modelling
    The ANTEX file to be used for repro3 can be downloaded from igsR3_2077.atx
    The antenna model was selected based on tests of different ANTEX files and assessing their impacts upon the reference frame for the period starting in 2017 through to the end of 2018
IERS Conventions (2010) Mean Pole tide
    As of early 2018, the IERS officially adopted a new (linear) mean pole for purposes of computing rotational deformation (pole tide). See the updated Chapter 7 at ftp://maia.usno.navy.mil/conventions/2010/2010_update/chapter7/ By adopting a linear mean pole, no corrections are required to C21/S21 going forward.
    • only to be implemented during the reprocessing run. Do not implement this in the operational stream otherwise a discontinuity in the velocities will be introduced
    • There is the possibility of applying this correction at the solution level, rather than at the observation level
    • Here is a presentation by John Ries outling the case for a linear mean pole model here
Sub-daily EOP model
    HF-EOP recommends the use of the Desai&Sibois/Egbert model for diurnal and sub-diurnal EOP variation. Coefficients for this model and software to generate EOP predictions can be obtained from https://ivscc.gsfc.nasa.gov/hfeop_wg/
Solar radiation pressure models
    The SRP model to be applied is dependent upon the constellation, and satellite block being processed.
    • ACs should upgrade from just ECOM1 modelling, with the exception of GPS Block IIF and IIR satellites
    • ECOM2 or JPL GSPM modelling should be used for other GPS Block Types, or a box-wing model
Earth albedo models
    Reflected (albedo) and retransmitted radiation from the Earth may cause scale (1 - 2 cm) and translational effects at GNSS altitudes; see:

    A recommended model for these effects,in the form of Fortran source code was originally developed within the scope of the IGS Orbit Modeling Working Group for repro2, this has recently been updated by Thomas Herring to include new values for GLONASS-M and GLONASS-K satellites (31 July 2019).
    • ERPFBOXW.f Computation of Earth Radiation Pressure acting on a box-wing satellite
    • SURFBOXW.f Computes the force on the satellite surfaces for a given radiation vector
    • PROPBOXW.f Provides the satellite dimensions and optical properties for different satellites blocks:
      • GPS: GPS-I,GPS-II,GPS-IIA,GPS-IIR,GPS-IIR-A,GPS-IIR-B,GPS-IIR-M,GPS-IIF,GPS-IIIA
      • GLONASS: GLONASS-M,GLONASS-K
      • GALILEO: IOV, FOC
Ocean Tide Model
    FES has recently been updated to FES2014b, a description of the products can be found here. A link to the spherical harmonic coefficients in geopotential be found at the bottom of the page.
Satellite Transmit Power (Antenna Thrust)
    Technicial note on satellite transmit power for GPS and GLONASS, by Peter Steigneberger is available from here
Third body effects
    — recommend ACs apply all planets into model
Time variable gravity
    Other ITRF observing techniques are considering the highest fidelity time-variable gravity model, this is not strictly required for GNSS orbits, but it will be important to stay consistent with their implementation.
Loading Models
    — should be consistent with the TVG model, and again consistent across all observing techniques
Data Products
    use RINEX3 in preference to RINEX2 Provide solutions in updated SINEX formats that support RINEX3


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