1. Multi-Scale Physics Faculty of Applied Sciences The formation of mesoscale fluctuations by boundary layer convection Harm Jonker

2. Multi-Scale Physics Faculty of Applied Sciences Cold Air Outbreak Peter Duynkerke, IMAU Utrecht University Agee, Atkinson and Zhang ……

3. Stratocumulus Aircraft Observations log E(k) log k

4. Atmospheric Observations: Sc Nucciarone & Young 1991 w u q 

5. Multi-Scale Physics Faculty of Applied Sciences Sun and Lenschow, 2006

6. Multi-Scale Physics Faculty of Applied Sciences Sun and Lenschow, 2006

7. Multi-Scale Physics Faculty of Applied Sciences Sun and Lenschow, 2006

8. Multi-Scale Physics Faculty of Applied Sciences L = 25.6km Dx = Dy = 100m t = 1...16hr, liquid water path LES of Stratocumulus

9. L = 6.4km (8hr) Dx = Dy = 100m L = 12.8km (12hr) L = 25.6km (16hr) LES of Sc (ASTEX) Liquid water path “Large Eddy Simulations: How large is large enough?”, de Roode, Duynkerke, Jonker, JAS 2004 “How long is long enough when measuring fluxes and other turbulence statistics?”, Lenschow, et al. J. Atmos. Oceanic Technol., 1994

10. Multi-Scale Physics Faculty of Applied Sciences

11. w qtu lwp

12. Intermediate Conclusions 1) the formation of dominating mesoscale fluctuations is an integral part of PBL dynamics! - no mesoscale forcings - what is the origin (mechanism) ? - latent heat release - radiative cooling - entrainment - inverse cascade Atkinson and Zhang Fiedler, van Delden, Muller and Chlond, Randall and Shao, Dornbrack, ……

13. Multi-Scale Physics Faculty of Applied Sciences Convective Atmospheric Boundary Layer penetrative convection zizi heat flux entrainment tracer flux 

14. w  passive scalar c variance spectra LES FFT (2D) w c w  passive scalar c Jonker,Duynkerke,Cuypers, JAS, 1999

15. Saline convection tank Laser Induced Fluorescence (LIF) fresh water salt water (2%) fresh water + fluorescent dye buoyancy flux & tracer flux Laser  (z) digital camera pp Han van Dop, IMAU Mark Hibberd, CSIRO Jos Verdoold, Thijs Heus, Esther Hagen

16. Laser Induced Fluorescence

17. Laser Induced Fluorescence (LIF) “bottom-up” tracer boundary layer depth structure (Verdoold, Delft, 2001) (see also van Dop, et al. BLM 2005)

18. Intermediate Conclusions 1) the formation of dominating mesoscale fluctuations is an integral part of PBL dynamics! 2) latent heat and radiation are not essential - latent heat release - radiative cooling - entrainment - inverse cascade -

19. Multi-Scale Physics Faculty of Applied Sciences Inverse Cascade? P D k E(k) PD k P 2-D or not 2-D: that’s the question

20. Spectral variance budget scale by scale variance budget production dissipation spectral interaction

21. sink source 16 sections Scale Interaction Matrix C   passive scalar

22. sink source 16 sections Scale Interaction Matrix C   dynamics

23. k E(k) or pdf of spectral flow 

24. upscale transfer downscale transfer

27. Intermediate Conclusions 1) the formation of dominating mesoscale fluctuations is an integral part of PBL dynamics! 2) latent heat and radiation are not essential - latent heat release - radiative cooling - entrainment - inverse cascade 3) budgets show: no inverse cascade (significant backscatter on all scales)

28. Multi-Scale Physics Faculty of Applied Sciences Mechanism… PD k E(k) P P D k

29. Multi-Scale Physics Faculty of Applied Sciences PD k E(k) P weak production, weak transfer

30. mechanism (CBL) spectral large scales transport (Jonker, Vila, Duynkerke, JAS, 2004) weak production, weak transfer. w crucial! (Leith, 1967) (Corrsin, ‘68)

31. w qtu lwp

32. Multi-Scale Physics Faculty of Applied Sciences Spectral budget w buoyancy production subgrid dissipation pressure correlation spectral transfer

33. budget spectrum

34. Multi-Scale Physics Faculty of Applied Sciences Spectral budget u shear production subgrid dissipation pressure correlation spectral transfer

35. budget spectrum

36. budget spectrum

37. Multi-Scale Physics Faculty of Applied Sciences Spectral budget scalar spectral budget gradient production subgrid dissipation spectral transfer variance budget

38. spectrum

39. production buoyancy production pressure break the chain …

40. wlwpu reference w filtered test 1:

41. Multi-Scale Physics Faculty of Applied Sciences 41 reference

42. Multi-Scale Physics Faculty of Applied Sciences 42 test 1:

43. production buoyancy production pressure break the chain …

44. wlwpu reference q,  filtered test 2:

45. Multi-Scale Physics Faculty of Applied Sciences 45 reference

46. Multi-Scale Physics Faculty of Applied Sciences test 2:

47. Multi-Scale Physics Faculty of Applied Sciences Concluding: The spectral gap … (Stull)

48. Multi-Scale Physics Faculty of Applied Sciences Cold Air Outbreak time

49. Multi-Scale Physics Faculty of Applied Sciences Conclusions 1) the formation of dominating mesoscale fluctuations is an integral part of PBL convective dynamics! 2) latent heat and radiation are not essential (but speed up the process considerably) 3) budgets: no inverse cascade on average. significant backscatter (on all scales) 4) production: ineffective (slow), but spectral transfer is just as ineffective 5) the spectral behaviour of w at large scales is crucial

50. Multi-Scale Physics Faculty of Applied Sciences

51. Jonker,Duynkerke,Cuypers, JAS, 1999

52. Length scales of conserved quantities in the CBL at t=8h

53. Multi-Scale Physics Faculty of Applied Sciences dissipationproductionchemistryspectral transfer Spectral Model Leith (1967)

54. (Jonker, Vila, Duynkerke, JAS 2004)

56. Multi-Scale Physics Faculty of Applied Sciences dissipationproductionchemistryspectral transfer Spectral Model: scale analysis …at large scales