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SLODAR Turbulence Profilers

SLODAR Turbulence Profilers. Richard Wilson, Tim Butterley, James Osborn Durham University, UK. SLODAR (SLOpe Detection And Ranging). Shack-Hartmann wavefront sensor Observe double stars Recover C n 2 (h) from the time-averaged cross-covariance of the WFS data.

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SLODAR Turbulence Profilers

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  1. SLODAR Turbulence Profilers Richard Wilson, Tim Butterley, James Osborn Durham University, UK

  2. SLODAR (SLOpe Detection And Ranging) • Shack-Hartmann wavefront sensor • Observe double stars • Recover Cn2(h) from the time-averaged cross-covariance of the WFS data

  3. SLODAR Altitude Sampling  h  d/ h d (WFS sub-aperture size)

  4. SLODAR Altitude Sampling: Ground-Layer profiling Higher Altitude Total h

  5. SLODAR Turbulence Profile Sequence, Paranal

  6. SLODAR: Turbulent Layer Velocities • Movie shows the spatial cross-covariance with increasing time offset. • Motion of peaks => layer velocity (with altitude). Altitude

  7. SLODAR at ESO Paranal: Ground-Layer Characterization

  8. SLODAR Turbulence Profile Sequence, Paranal

  9. SLODAR Turbulence Profile Sequence: Paranal All quiet in the ‘gray zone’… Surface layer not resolved

  10. SLODAR at Paranal Mean Ground-Layer Turbulence Profile Free-Atmosphere Total ~ 45% of optical turbulence within ~70m of the ground

  11. SLODAR Cross-Verification MASS-DIMM Compare with MASS and DIMM SLODAR Cannot use the same targets for SLODAR and MASS-DIMM * SLODAR -- DIMM

  12. SLODAR Cross-Verification: Total Seeing versus DIMM (Paranal) SLODAR DIMM

  13. SLODAR Cross-Verification: Total Seeing versus DIMM (Paranal) Subtract 7x10-14 m1/3 for the first 5m ??? Need ~5m resolution to confirm this …

  14. SLODAR Cross-Verification: Free Atmosphere Seeing versus MASS (Paranal)

  15. SLODAR-LOLAS at Mauna Kea: Ground-Layer Characterization Campaign

  16. Ground-Layer Turbulence: Mauna Kea

  17. Ground-Layer Turbulence: Mauna Kea

  18. SLODAR at SALT: • Generalized Profiler - High Altitudes (~15km) • Characterize SALT site for AO • SLODAR Automation

  19. Meteorology: Turbulence Wind Speed Correlating surface layer turbulence speed with physical ground wind speed (Mauna Kea data, first try …) : Turbulence Speed (m/s) Wind Speed Physical Wind Speed (m/s) UT (hours)

  20. Optical Turbulence Forecasting: Model Verification ? Cn2(h) ? Wind Vw(h) MM5 Model, Cn2(h) and Wind Velocity Mauna Kea Weather Center

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