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Satellite geodesy (ge-2112)

Satellite geodesy (ge-2112). Applications E. Schrama. Applications. Global Positioning System Precise point positioning services Detection of platetectonics estimation of wet tropospheric delay International Earth Rotation Service Earth rotation parameters + LOD

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Satellite geodesy (ge-2112)

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  1. Satellite geodesy (ge-2112) Applications E. Schrama

  2. Applications • Global Positioning System • Precise point positioning services • Detection of platetectonics • estimation of wet tropospheric delay • International Earth Rotation Service • Earth rotation parameters + LOD • Interpretation of these Earth rotation variables (AAM) • Satellite altimetry • status 2002, where are we, how did it emerge, results • Results from gravity missions

  3. GPS: precise point positioning • Concept of differencing • Single differencing • Double differencing • Triple differencing • Software • Bernse software • GIPSY JPL • Other software

  4. Concept of differencing • In the GPS system, many observations are made at the “same” time by difference receivers. • All receivers collect pseudo range data, carrier phase data and navigation messages • The Pseudo range navigation allows you to get a approximate solution for receiver coordinates (approx 3 m) • More importantly is that the pseudo range navigation solution allows to synchronize all receiver clocks to the (approx 10 nano seconds, nsec). • The pseudo-range solution requires orbit information • The dual frequency concept results in ionospheric free ranges and carrier phase estimates • From this point on we start to work with “differencing techniques”,

  5. Broadcast Ephemeris GPS

  6. Broadcast ephemeris GPS (2)

  7. Single differences SAT(1) SAT(2) r1a r2a RCV(a) Single Difference = r1a - r2a

  8. Double differences SAT(1) SAT(2) r2b r1a r2a r1b RCV(b) RCV(a) Double Difference = (r1a - r2a) - (r1b-r2b)

  9. Difference data processing • Single differences (as shown two sheets before this one) are insensitive to receiver clock errors • Double differences are insensitieve to all receiver and satellite clock errors • Triple differences (= differences of double differences at consequetive epochs) reveal jumps in carrier phase data. • Differencing techniques as described above result in observation equations that allow one to solve for coordinate delta’s (improvements) • Available software to do this: GIPSY (JPL) + Bernese SW

  10. GPS to observedeformation around a vulcano on Hawaii Ref: http://www.unavco.org/research_science/science_highlights/kilauea/kilauea.html

  11. Plate Tektonics Source: Unavco Brochure

  12. GPS: Wet troposphere (cm) http://www.gst.ucar.edu/gpsrg/realtime.html

  13. Ionosphere from GPS (TEC) http://www.gst.ucar.edu/gpsrg/realtime.html

  14. IERS Earth rotation parameters

  15. X-pole solution

  16. Y-pole solution

  17. IERS: Length of day variations The atmosphere (left) and the ocean tides (right) correlate with space geodetic observations of the length of day (LOD) source: NASA

  18. Satellite Altimetry By means of a nadir looking radar we measure the reflection of short pulse in the footprint. This footprint is about 4 to 8 kilometer in diameter. Source: JPL

  19. Pulse reflection power Sent time power Received time

  20. Radar footprint simulation

  21. Significant wave height (JPL)

  22. Scalar wind speed (JPL)

  23. Ionospheric delay (JPL)

  24. Radiometric water vapor (JPL)

  25. Technical evolution • SKYLAB 1972 NASA 20 m • GEOS-3 1975-1978 NASA 3 m • SEASAT 1978 NASA 2 m • GEOSAT 1985-1990 US Navy 30 cm • ERS-1 1991-1996 ESA 4-10 cm • ERS-2 1995- ESA 4 cm • T/P 1992- NASA/CNES 2 - 3 cm • GFO 2000- US Navy • JASON 2001- NASA/CNES 2 - 3 cm • ENVISAT 2002- ESA

  26. ERS-1 1991-1996 Topex/Poseidon 1992 - ERS-2 1995- Geosat (1985-1990) Recent and operational systems

  27. Doris tracking network Source: CNES

  28. ERS-1/2 tracking + cal/val Source: DEOS

  29. 119 121 120 122 T/P sampling

  30. Topex/Poseidon groundtrack

  31. Mesoscale Variability

  32. Gulf stream (altimeter)

  33. Thermal image Gulf stream

  34. Permanent currents

  35. Schematic overview ocean currents

  36. Ship observations (1)

  37. To show how difficult it sometimes is at sea (2)

  38. More Detail in Gulf Steam

  39. Four Seasons from Altimetry

  40. El Niño Southern Oscillation

  41. Speed Kelvin/Rossby waves

  42. Kelvin and Rossby waves Equator: 2.8 m/s 20 N: 8.5 cm/s

  43. Pacific decadal oscillation Since 1999 1977-1999

  44. Examples of ocean tides This shows a 7 meter tidal height difference in Brittany France (Pentrez Plage)

  45. M2 tide observed by altimeter

  46. Tides in the South China Sea M2 wave

  47. K1 tidal component (23h 56m)

  48. Tide constants along the shores

  49. Tidal energy dissipation

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