DFG Research Unit:
Space-Time Reference Systems for Monitoring Global Change and for Precise Navigation in Space

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Models and Parametrization

Models

  Phenomenon Model References (in IERS Technical Note 36)
General Speed of light 299792458 ms^-1 Tab. 1.1
Gravitational constant of the Earth 3.986004418 × 10^14 m^3s^-2
Equatorial radius of the Earth 6378136.6 m
Dynamical flattening 3273795 × 10^-9
Time system terrestrial time: TT, barycentric time: TCB
Terrestrial reference frame (a priori) ITRF2008/IGb08/SLRF2008/VTRF2008 Chapter 4.2.4; Altamimi et al. (2011)
Celestial reference frame (a priori) ICRF2 Chapter 2.2; IERS Technical Note 35
Ephemerides JPL ephemerides DE421, if possible Folkner et al. (2009)
Station coordinates Solid Earth tides conventional routine from Dehant & Mathews Chapter 7.1.1.1
Permanent tide conventional tide free system Chapters 1.1, 7.1.1.2
Solid Earth pole tide polynomial trend for mean pole offsets (IERS2010) Chapter 7.1.4; Tab. 7.7
Ocean pole tide loading Desai (2002), if possible Chapter 7.1.5
Tidal ocean loading FES2004; HARDISP.F; CoM-corrected values Chapter 7.1.2
Non-tidal ocean loading not applied Chapter 7.2
Tidal atmospheric loading model (Bernese format) provided by J. Böhm applied Chapter 7.1.3
Non-tidal atmospheric loading model (Bernese format) provided by J. Böhm applied Chapter 7.2
Earth orientation parameters A priori EOP IERS 08 C04 Bizouard and Gambis (2011)
http://hpiers.obspm.fr/iers/eop/eopc04/eopc04_IAU2000.62-now
Interpolation of a priori polar motion linear interpolation  
Interpolation of a priori UT1 (1) reduction to UT1R and LODR Chapter 8.1; Tab. 8.1
(2) linear interpolation using UT1R and LODR  
(3) conversion to UT1 and LOD Chapter 8.1; Tab. 8.1
Interpolation of a priori nutation linear interpolation  
Subdaily ocean tidal effects IERS2010, Eanes (2000) Chapter 8.2
Atmospheric tidal effects not applied  
Precession-nutation model IAU 2006/2000A Chapter 5.6; Mathews et al. (2002)
Free core nutation not applied, if nutation parameters are estimated; IERS 08 C04 corrections, if nutation parameters are not estimated Chapter 5.5.5
Subdaily nutation IERS2010; Ray et al. (1994) Chapter 5.5.3.2
UT1 libration Brzezinski and Capitaine (2003) Chapter 5.5.3.3
Gravity field A priori terrestrial model EGM2008 Chapter 6.1; Pavlis et al. (2012)
A priori lunar model Konopliv et al. (2001)  
Solid Earth tides Mathews et al. (2002) Chapter 6.2.1
Permanent tide conventional tide free system Chapters 1.1, 6.2.2
Ocean tides FES2004 Chapter 6.3; Lyard et al. (2006)
Solid Earth pole tide IERS2010 Chapter 6.4
Ocean pole tide Desai (2002), if possible Chapter 6.5
S1/S2 atmospheric tides model (Bernese format) provided by J. Böhm applied  
Non-tidal atmospheric effect model (Bernese format) provided by J. Böhm applied  
Troposphere (microwave) Hydrostatic a priori model computed from 6-hourly ECMWF grids; account for the station and mean grid height differences Kouba (2008)
Hydrostatic mapping function hydrostatic VMF1 Chapter 9.2; Boehm et al. (2006)
Wet a priori model none; wet delay estimated  
Wet mapping function wet VMF1 = wet VMF Chapter 9.2; Boehm et al. (2006)
A priori gradients none; gradients estimated  
Gradient mapping function Chen and Herring (1997) Chapter 9.2
Trop. (SLR) A priori model Mendes and Pavlis (2004) Chapter 9.1
Ionosphere Earth's magnetic field IGRF-11 Finlay et al. (2010)
First order effect accounted for by linear combination of multi-frequency observations Chapter 9.4
Second order effect Fritsche et al. (2005) using IGRF-11
Third order effect
Ray bending IERS2010 Chapter 9.4.1; Equation (9.37)
Relativistic model Schwarzschild terms IERS2010 Chapter 10.3; Equation (10.12)
Lense-Thirring precession IERS2010, if possible
Geodesic (de Sitter) precession IERS2010, if possible
Gravitational time delay Shapiro (1969, 1971) Chapter 11.2; Equation (11.17)
GNSS effects Phase center corrections for satellite and receiver antennas ftp://igs.org/igscb/station/general/igs08_1711.atx Chapter 7.3.3
Receiver antenna heights IGb08.snx + IGSMAIL/IGSSTATION  
Horizontal antenna excentricities IGb08.snx + IGSMAIL/IGSSTATION  
Satellite attitude model nominal attitude; exclude shadow crossings  
A priori radiation pressure none  
Phase wind-up Wu et al. (1993)  
SLR effects Center of mass corrections (laser reflector array offsets) standard corrections from http://ilrs.gsfc.nasa.gov/missions/ spacecraft_parameters/ center_of_mass.html  
Range/time biases ILRS_Data_Handling_File.snx  
Arc length 7 days  
VLBI effects Thermal telescope deformations Nothnagel (2009) Chapter 7.3.2
A priori tropospheric gradients MacMillan and Ma (1997), provided in SINEX format, if available for a specific station; none otherwise  
Gravitational sag not applied  

 

Parameterization

Parameter Representation Resolution A priori values Stored in SINEX?
Station coordinates constant offset 1 d or 7 d ITRF2008/IGb08/SLRF2008/VTRF2008 yes
Pole coordinates piecewise linear or offset+drift 24 h IERS 08 C04; IERS subdaily ERP model yes
ΔUT1 piecewise linear or offset+drift 24 h IERS 08 C04; IERS subdaily ERP model yes
Nutation X, Y representation, if possible; 24 h none (parameters represent corrections to a priori model) yes
piecewise linear or offset+drift
Troposphere zenith delays (MW) piecewise linear 2 h hydrostatic VMF1 yes
Troposphere gradients (MW) piecewise linear 24 h none, except for VLBI yes
Quasar coordinates constant offset 1 d ICRF2 yes
Gravity field coefficients constant offset   EGM2008 yes