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VIE_MOD

VIE_MOD. Lucia Plank. PART I: theory PART II: program / workflow PART III: usage. I. THEORY. computed delay τ . computed delay Vie_mod. adjustment ( lsm ). o- c. observed delay from NGS-card file, corrected for ionosphere . VieVS User Workshop 2011. I. THEORY.

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VIE_MOD

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  1. VIE_MOD Lucia Plank

  2. PART I: theory • PART II: program/workflow • PART III: usage VieVS User Workshop 2011

  3. I. THEORY computed delay τ • computed delay • Vie_mod adjustment (lsm) o-c • observed delay • from NGS-card file, corrected for ionosphere VieVS User Workshop 2011

  4. I. THEORY International Terrestrial Reference System BarycentricCelestial Reference System ITRS source BCRS GeocentricCelestial Reference System GCRS gravitationalretardation retardedbaselinecorr. Lorentz-transformation Lorentz-transformation BCRS in TT-frame VieVS User Workshop 2011

  5. I. THEORY models + EOP (oceanic & gravitational high frequency terms, nutation corrections) + solid Earth tides + troposphere delay (VMF / GMF / NMF) + ocean loading (FES2004 / EOT08a / GOT00 / AG06) + thermal antenna deformation + axis offset + atmosphere loading partial derivatives • computed delay • Vie_mod adjustment (lsm) in TT-frame o-c • observed delay • from NGS-card file, corrected for ionosphere VieVS User Workshop 2011

  6. II. WORKFLOW • 0. INPUT FILES (scan, parameter, antenna, sources) • EARTH ORIENTATION • read EOP | Interpolation | Add highfrequencymodels|Ephemerides| Transformation matrix TRS-CRS | Source vector • STATION COORDINATES • loopoverscans • loopoverstations • Station corrections (SET |oceanloading|atmosphereloading| pole tide|stationvelocity) |troposphericparameters • end stations • COMPUTED DELAY • loopoverbaselines • calculationofthe time delayfollowingtheconsensus model (incl. relativistic & gravitativecorr.) |troposphere|axisoffset|thermdef. • PARTIAL DERIVATIVES • wrt. EOP |wrt. sourcecoordinates|wrt. stationcoordinates|wrt. Love andShidanumbers • end baselines • STORE RESULTS • end scans • SAVE (scan, parameter, antenna, sources) VieVS User Workshop 2011

  7. III. USAGE VieVS User Workshop 2011

  8. III. USAGE • TRF: • storedat: ../TRF/VTRF2008.mat • stationcoordinates (TRS) • referenceepoch • stationvelocities • Other: - self-created TRF • - ../TRF/*.txt • - specifiedformat

  9. III. USAGE • CRF: • storedat: ../CRF/ICRF2.mat • rightascensionra • declination de • ++ (structureindex, …) • Other: - self-created CRF • - not finishedyet

  10. III. USAGE • Ephemerides: • storedat: ../EPHEM/jpl_421.mat • Earth, Sun, Moon, Planets • rememberedfor 2nd run (jpl_421_05SEP12XA_N004) • not critical for “normal” VLBI

  11. III. USAGE • Earth Orientation Parameters: • c04 08 (daily) seriesfromthe IERS webpage; ../EOP/C04_08_1962_now.txt; updatesmightbenecessary; • predefined EOP: ../EOP/*.txt; watchformat • dX, dY: include/excludefrom c04 table; mainlycontains FCN • highfrequency EOP • oceantides: interpf; • table 8.2 (xp,yp) & 8.3 (ut) diurnal & semi-diurnal • libration: table 5.1a (xp,yp) & 5.1b (ut) • DON‘T CHANGE ANYTHING, THEN YOU‘RE CONSISTENT WITH THE IERS CONVENTIONS !

  12. III. USAGE • Interpolation of EOP: • lagrange: • windowof 4 datapoints • - tidal UT variations: removedbeforeinterpolation, re-added • linear: • interpolationbetweenthemidnight before and after observation time. For a session from 18:00 to 18:00 this means, that there are 2 a priori lines and a break at midnight.

  13. III. USAGE • Precession/Nutation Model:

  14. III. USAGE • Station corrections: • hearmorefrom Hana • Thermdef: • [A. Nothnagel, J. ofGeodesy, 2008]

  15. III. USAGE • Pressureandtemperature: • Met datafrom NGS-file • GPT asbackup • External .trpfiles

  16. III. USAGE • A priori tropospheregradients:

  17. III. USAGE • Mapping function: • foratmosphericcorrections on thedelay • VM1: ../VM1/yyyy_VM1.mat • regular update! • GMF: • appliedwhenno VM1 available

  18. III. USAGE • Quality codelimit: • Acceptobservations < or = limit • Goodqualityobservationshavequalitycode 0

  19. III. USAGE • Externalionospherecorrection:

  20. III. USAGE • Cut-off Elevation angle: • all observationsbelowthislocalelevation [°, degrees] areskipped

  21. III. USAGE • Outliers: • use/dont‘tuseoutlierfile (chosen in init_qu)

  22. III. USAGE • PUSH

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