iaa2021eopi.txt
Contact: Elena Skurikhina sea@iaaras.ru)
Last updated:  Feb 01, 2021


Technical description of solution iaa2019.eopi

1.  Purpose of solution:  Intensives UT1

2 - Analysis Center:  Institute of Applied Astronomy (IAA)

3.  Short narrative description of solution:

Sessions with the duration less than 2h are analyzed for this solution. Files in the
NGS format are used as source of observables.  Wet tropospheric delays and clock offsets are
modeled as random walk stochastic process and estimated using Kalman filter
technique.  Terrestrial reference frame ITRF2014 with the associated velocity
field is used for station coordinates.

The main differences with the previous solutions are:

- ITRF2014 is used for station positions, new statopns were added
- ICRF3 is used, GA applied 



4.  Estimated parameters:

    a. celestial frame:  No

    b. terrestrial frame:  No

    c. Earth orientation:  UT1-UTC

    d. zenith troposphere:  Random walk process

    e. troposphere gradient:  No

    f. station clocks:  Polynomial + random walk process

    g. baseline clocks:  No

    h. other:  No

5.  Celestial reference frame:

    a. a priori source positions:  ICRF3

    b. source positions adjusted in solution:  No

    e. solution identification or reference:  ICRF3

6 - Terrestrial reference frame:

    a. a priori station positions:  ITRF2014 

    b. a priori station velocities:  ITRF2014 

    c. reference epoch:  2010.0

    d. station positions/velocities adjusted in solution:  No

    l. solution identification or reference:  ITRF2014

7.  Earth orientation:

    a. a priori precession model:  IAU2000A

    b. a priori nutation model:  IAU2000A

    c. a priori short-period tidal variations in x, y, UT1:
            IERS Conventions (2006);
            zonal tidal variations are included in UT1;
            daily and subdaily variations are not included in EOP

    d. EOP estimation:  UT1-UTC for every session

8.  A priori geophysical models:

    a. troposphere: Saastamoinen model for HZD, VMF mapping function

    b. solid Earth tide:  IERS Conventions (2006)

    c. ocean loading:  IERS Conventions (2006)

    d. atmosphere loading:  GSFC time series

9.  Data type:  delays

10. Data editing:  Only data with zero quality flag  are used;
    supplemental editing of outliers is applied during adjustment when
    necessary

11. Data weighting:  Observations are weighted using std reported in VGOS
    file and a priori additive variance depending on session and/or station.
    Elevation depending weighting is applied to the observations made below
    10 deg.

12. Standard errors reported:  Reported formal errors are derived from
    Kalman filter adjustment without supplemental correction

13  Software:  OCCAM/GROSS

14. Other information:

    1. Supplement fields after standard IERS/IVS ones contain:

     - experiment name
     - number of stations
     - chi-square
     - number of rejected observations
     - three columns containing internal information
     - list of stations used for computation of reported EOP, clock reference
       station is listed first