[IGSMAIL-3734]: GFZ Updated Analysis Center Description
Gerd Gendt
gend at gfz-potsdam.de
Fri Feb 8 09:55:48 PST 2002
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IGS Electronic Mail 08 Feb 09:55:52 PST 2002 Message Number 3734
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Author : Gerd Gendt
Subject: GFZ Updated Analysis Center Description
Dear colleagues,
Please find attached the update for GFZ analysis center
description.
The changes (effective from week 1149) concern the
new elevation cut-off angle (7 deg) and the elevation
dependent weighting.
(see ftp://igscb.jpl.nasa.gov/igscb/center/analysis).
Best regards
Gerd Gendt
==============================================================================
INTERNATIONAL GPS SERVICE FOR GEODYNAMICS
GFZ Analysis Strategy Summary
==============================================================================
| ANALYSIS CENTRE | GFZ, GeoForschungsZentrum Potsdam |
| | Dept. 1 |
| | D-14473 Potsdam |
|------------------------------------------------------------------------------|
| CONTACT PERSON(S) | Christoph Reigber |
| | (reigber at gfz-potsdam.de),ph.(0331) 2881100 |
| | Gerd Gendt (gend at gfz-potsdam.de), ph.(0331) 2881114 |
|------------------------------------------------------------------------------|
| SOFTWARE USED | EPOS.P.V2 developed at GFZ |
| -----------------------------------------------------------------------------|
| IGS PRODUCTS | GFZwwww0-6.sp3 GPS ephemeris/clock files in 7 daily files|
| GENERATED FOR | at 15 min intervals in sp3 format, |
| GPS WEEK 'wwww' | including acc. codes, which are assigned |
| | 25 cm nominally, and adjusted upward |
| | when indicated by orbit corrections |
| | GFZwwww7.erp ERP (pole, LOD) solutions |
| | GFZwwww7.sum Processing summary. |
| | GFZwwww7.snx Weekly combination of station coordinate |
| | and EOP solutions in SINEX format |
| | GFZwwww0-6.clk Daily clock files with 5 min sampling |
| | GFZwwww0-6.tro Daily trop estimates, 2 h sampling |
| | |
| RAPID PRODUCTS | GFZwwww0-6.sp3 same as above with 8h delay |
| (8h after 0h UT) | GFZwwww0-6.erp |
| | GFZwwww0-6.clk Daily clock files with 5 min sampling |
| | |
| ULTRA RAPID PROD. | GFUwwww0-6.sp3 same as above with 1h delay generated |
| | GFUwwww0-6.erp every 3 hours since March 2001 |
| | (containing 24h for data part and 24h prediction) |
| | GFUwwww0-6_hh.tro every 3 hours since August 2001 |
| | (containing 12h for data part) |
|------------------------------------------------------------------------------|
| Preparation Date | September 24, 2001 |
|------------------------------------------------------------------------------|
| Effective Date | August 1 , 1999 (for ITRF97) |
==============================================================================
---------------------------------------------------------------------------
| MEASUREMENT MODELS |
|---------------------------------------------------------------------------|
| Preprocessing | Rapid: DD-cleaning of phase data |
| | Final: PPP-cleaning of phase data using rapid products |
|---------------------------------------------------------------------------|
| Basic Observable | carrier phases ( pseudo-ranges normally used for |
| | ambiguity-fixing only) |
| |--------------------------------------------------------|
| | elevation cutoff: 15 degrees - no weighting |
| | 7 degrees starting week 1149 |
| | - elev.dep. weighting with |
| | unit weight until 30 deg, |
| | 1/2sin(ele) below |
| | sampling rate : 5 minutes |
| | no weighting |
|---------------------------------------------------------------------------|
| Modelled | undifferenced, corrected for ionosphere (L3, P3), |
| observable | CA pseudoranges not corrected for CA-P1 biases |
|---------------------------------------------------------------------------|
| RHC phase | applied (Wu at al., 1993) |
| rotation corr. | |
|---------------------------------------------------------------------------|
| Ground antenna | Model IGS_01 for phase center variations |
| phase centre cal.| (Rothacher, Mader 1996) |
|---------------------------------------------------------------------------|
| Troposphere | Met data input : standard met data, height-dependent P |
| |--------------------------------------------------------|
| | Zenith delay: adjusted in 4 hour- intervals |
| |--------------------------------------------------------|
| | Mapping function: Niell |
| | (standard met data are used to separate dry and wet) |
|---------------------------------------------------------------------------|
| Ionosphere | not modelled (ionospheric effects accounted for by |
| | dual frequency observations, see above) |
|---------------------------------------------------------------------------|
| Plate motions | Set of given sites agreed upon within IGS are fixed |
| | (in 2001 fixed to ITRF97 by 51 sites) |
|---------------------------------------------------------------------------|
| Tidal | Solid earth tidal displacement: applied, IERS 1992 |
| displacements | Both permanent and periodical parts: yes |
| | Wahr frequency dependent Love numnbers: yes |
| | Used Love numbers: h2=.609, dh2(K1)=-.089, l2=.085 |
| |--------------------------------------------------------|
| | Pole tide: applied, IERS 1992 |
| |--------------------------------------------------------|
| | Ocean loading: Model of Pagiatakis |
| |--------------------------------------------------------|
| | Permanent tidal term: applied in tide model, |
| | NOT included in site coordinates |
|---------------------------------------------------------------------------|
| Atmospheric load.| not applied |
|---------------------------------------------------------------------------|
| Earth Orientation| Tidal variations in UT1: applied for periods <= 32 days|
| | Subdaily UT and polar motion (IERS, 1996) |
|---------------------------------------------------------------------------|
| Satellite center | Block I x,y & z : (0.2100 m , 0 , 0.8540 m) |
| of mass |--------------------------------------------------------|
| correction | Block II/IIA x,y & z : (0.2794 m , 0 , 1.0229 m) |
| | Block IIR x,y & z : (0.0 m , 0 , 0.0 m) |
|---------------------------------------------------------------------------|
| Satellite phase | not applied |
| centre calibrat. | |
|---------------------------------------------------------------------------|
| Satellite clock | relativistic corrections applied |
| corrections | |
---------------------------------------------------------------------------
| GPS Attitude | GPS satellite yaw attitude model: applied |
| model | yaw rates : 1 parameter per arc estimated |
| | (Bar-Sever, 1995) |
---------------------------------------------------------------------------
---------------------------------------------------------------------------
| ORBIT MODELS |
|---------------------------------------------------------------------------|
| Geopotential | JGM2 degree and order 8 |
| | (C21, S21 modelled acc. to polar motion ) |
| |--------------------------------------------------------|
| | GM=398600.4418 km**3/sec**2 |
| |--------------------------------------------------------|
| | AE = 6378.137 km |
|---------------------------------------------------------------------------|
| Third-body | Sun, Moon , Venus, Jupiter (regarded as point masses) |
| |--------------------------------------------------------|
| | ephemeris: JPL DE200 |
| |--------------------------------------------------------|
| | Earth-Moon mass ratio = 81.300587 |
| |--------------------------------------------------------|
| | Sun-Earth mass ratio = 332946.045 |
|---------------------------------------------------------------------------|
| Solar radiation | direct radiation: T10 and T20 models for |
| pressure | Block I and II satellites, resp. |
| | |
| |--------------------------------------------------------|
| | direct-scale and y-radiation biases: taken into account|
| |--------------------------------------------------------|
| | Earth shadow model includes: penumbra |
| |--------------------------------------------------------|
| | GPS satellite yaw attitude model |
| | orbit dynamic effects : not applied |
|---------------------------------------------------------------------------|
| Tidal forces | solid earth tides: frequency dependent Love's |
| | numbers by Wahr-model ( nominal k2= 0.300 ) |
| |--------------------------------------------------------|
| | Ocean tides: Schwiderski-model |
|---------------------------------------------------------------------------|
| Relativity | not applied |
|---------------------------------------------------------------------------|
| Numerical | single step integrator from Everhart |
| integration | with direct integration of second-order equations |
| of orbit |--------------------------------------------------------|
| | integration step: variable, automatically controlled |
| |--------------------------------------------------------|
| | arc length: 24 hours |
|---------------------------------------------------------------------------|
| Numerical | multistep step integrator Stoermar-Cowell |
| integration | with direct integration of second-order equations |
| of var. equations|--------------------------------------------------------|
| | integration step: fixed |
| |--------------------------------------------------------|
| | start procedure: Cowell-Kulikov |
---------------------------------------------------------------------------
---------------------------------------------------------------------------
| ESTIMATED PARAMETERS (APRIORI VALUES & SIGMAS) |
|---------------------------------------------------------------------------|
| Adjustment | Helmert blocking method |
|---------------------------------------------------------------------------|
| Station | Set of given sites agreed upon within IGS are fixed |
| coordinates | (in 2001 fixed to ITRF97 by 51 sites) |
| |--------------------------------------------------------|
| | For producing the SINEX solution, all station coord. |
| | and velocities are estimated simultaneously with EOP |
|---------------------------------------------------------------------------|
| Satellite clock | solved for at each epoch (white noise process) |
| | |
|---------------------------------------------------------------------------|
| Receiver clock | solved for at each epoch (white noise process) |
| | One clock fixed and used as a time reference, |
| | usually ALGO. |
|---------------------------------------------------------------------------|
| Orbital | initial position and velocity, solar radiation pressure|
| parameters | scale, y-bias and yaw rate constant through the orbital|
| | arc. Stochastic impulses once per day (at noon). |
|---------------------------------------------------------------------------|
| Troposphere | estimated in steps of 4 hours |
|---------------------------------------------------------------------------|
| Ionospheric | not estimated |
| correction | |
|---------------------------------------------------------------------------|
| Ambiguity | real value |
| | apriori values from pseudorange observation |
| | constrained to about 50 meter; |
| | In a final step integer ambiguity resolution in global |
| | network with baselines up to 6000km |
|---------------------------------------------------------------------------|
| ERP | daily x & y pole and LOD. |
---------------------------------------------------------------------------
---------------------------------------------------------------------------
| REFERENCE FRAMES |
|---------------------------------------------------------------------------|
| Inertial | Geocentric; mean equator and equinox of 2000 Jan 1.5 |
| | (J2000.0) |
|---------------------------------------------------------------------------|
| Terrestrial | in 2001 ITRF97 was used |
|---------------------------------------------------------------------------|
| Interconnection | Precession: IAU 1976 Precession Theory |
| |--------------------------------------------------------|
| | Nutation : IAU 1980 Nutation Theory |
| |--------------------------------------------------------|
| | Tidal variations in UT1: applied for periods <= 32 days|
| |--------------------------------------------------------|
| | ERP: solved polar motion x,y and LOD |
---------------------------------------------------------------------------
References:
IERS (1992) Standards, IERS Technical Note 13, Observatoire de Paris,
(edited by McCarthy, D.)
IERS (1996) Standards, IERS Technical Note 21, Observatoire de Paris,
(edited by McCarthy, D.)
Wu J.,T. et al., (1993). "Effects of Antenna Orientation on GPS Phase,
Manuscripta Geodetica (1993)", 18, pp. 91-98.
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* Gerd Gendt Phone : ++49 331 288 1114 *
* _/_/_/ _/_/_/_/_/_/ GeoForschungsZentrum Fax : ++49 331 288 1111 *
* _/ _/ _/ Aufgabenbereich 1 E-Mail: gendt at gfz-potsdam.de *
* _/ _/_/ _/_/ _/ Telegrafenberg A17 *
* _/ _/ _/ _/ D-14473 Potsdam , GERMANY *
* _/_/_/ _/ _/_/_/ AFTP: //ftp.gfz-potsdam.de/pub/igsprod *
* www : //op.gfz-potsdam.de/S11/index_S11.html *
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