1. Vancouver, June 20051 Models of the ground layer and free atmosphere at some sites A. Tokovinin, CTIO Need for OTP “models”: Adaptive Optics!

2. Vancouver, June 20052 Outline  Present MASS and DIMM  MASS “overshoots”  Free atmosphere model  SODAR and balloons  Ground layer model

3. Vancouver, June 20053 MASS = Multi-Aperture Scintillation Sensor  6 “layers” with triangular response  Good integrals  AO time constant  S/N~10% (better sensitivity at low turbulence) http://www.ctio.noao.edu/~atokovin/profiler MASS database: http://mass.ctio.noao.edu

4. Vancouver, June 20054 MASS-SCIDAR: MK2002 SCIDAR MASS PASP, 2005

5. Vancouver, June 20055 Combine MASS with DIMM  GL

6. Vancouver, June 20056 MASS-DIMM instruments

7. Vancouver, June 20057 MASS-DIMM + Meade

8. Vancouver, June 20058 “Overshoots” MASS DIMM ??? Strong scintillation should be saturated? Cerro Pachon, 2003

9. Vancouver, June 20059 Strong scintillation

10. Vancouver, June 200510 Index distortion… Some over-correction for exp. time remains! …and correction S AB  S AB0 /(1 + 0.7 S AB0 ) J  J 0 /(1 + 0.7 S AB ) Semi-empirical formula

11. Vancouver, June 200511 “Overshoots” corrected!

12. Vancouver, June 200512 MASS-DIMM: CP, 2005 MASS DIMM

13. Vancouver, June 200513 Histograms (CP, 2005) Total Ground Free

14. Vancouver, June 200514 FA and GL are independent! 1” Can model FA and GL separately Same plot for MK

15. Vancouver, June 200515 FA: calm or turbulent? When free atmosphere is calm, it is stable! When free atmosphere is calm, it is stable! Turbulence comes in bursts Turbulence comes in bursts

16. Vancouver, June 200516 CP data overview

17. Vancouver, June 200517 Data for Mauna Kea (2002)

18. Vancouver, June 200518 OTP model: Pachon h, km GoodTyp.Bad 02.22.73.3 0.50.20.40.7 10.030.10.2 20.020.10.4 40.20.40.6 80.150.20.3 160.250.3 All3.054.25.8 Integrals, 10 -13 m 1/3 MASS-DIMM, 2005 0.62” 0.75”0.91”

19. Vancouver, June 200519 Testing the model SAM AO system: Rayleigh LGS at 10km + 2 t-t NGS, 45 Zernike modes SAM AO system: Rayleigh LGS at 10km + 2 t-t NGS, 45 Zernike modes

20. Vancouver, June 200520 SODAR campaign at CP Goal: define the thickness of the Ground Layer Duration: Oct. 30 to Nov. 15, 2004 Equipment: XFAS from Scintec Altitude range: 40m – 800m Vertical resolution: 20m Time resolution: 20 min. Results: 505 profiles (168 hours)

21. Vancouver, June 200521 SODAR profiles Nov 3 Nov 4 Nov 5 Nov 6

22. Vancouver, June 200522 SODAR vs. MASS-DIMM (CTIO)

23. Vancouver, June 200523 GL model: SODAR best 25% typical worst 25% Split data in groups and average separately! C n 2 (h) = A e -h/h0 + B e -h/h1 Abahamid et al.: C n 2 (h) = A h -1.5

24. Vancouver, June 200524 GL model: balloons J, 10 -13 m 1/3 h(1/e), m Good0.9-1.215-30 Typical1.6-320-40 Bad6.5-1050-100 43 profiles

25. Vancouver, June 200525 What is “seeing”? Seeing is the HF power of optical turbulence (J) expressed in “arcseconds” [Kolmogorov] Seeing is the HF power of optical turbulence (J) expressed in “arcseconds” [Kolmogorov]  ” = (J / 6.8x10 -13 ) 3/5 Do not mix “seeing” with image quality!

26. Vancouver, June 200526 Atmospheric IQ at Pachon (2005) median worst 25% best 25% L 0 =25m Seeing Why do we use “seeing”? – to avoid a mess! CP site monitor Dec 2004-Apr 2005

27. Vancouver, June 200527 Conclusions  We know integrals in FA and GL and their variation  FA and GL are independent  Turbulence in FA: lower when stronger  Periods of calm FA: “sweet spot” for AO!  Profile models for CP: good, typical, bad  GL: exponential models