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3-1. NCAR’s IBM SP4 `` Bluesky ” with 1600 Processors. 3-2. 3-3. 3-4. CLASSIFICATION OF CLEAR PBLs. 3-5. CLASSIFICATION OF CLEAR PBLs. Neutral. -10. -3. 0. 2. Strong convective forcing. Mix of shear and buoyancy forcing. Weakly stable continuous turbulence.

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  1. 3-1

  2. NCAR’s IBM SP4 ``Bluesky” with 1600 Processors 3-2

  3. 3-3

  4. 3-4

  5. CLASSIFICATION OF CLEAR PBLs 3-5

  6. CLASSIFICATION OF CLEAR PBLs Neutral -10 -3 0 2 Strong convective forcing Mix of shear and buoyancy forcing Weakly stable continuous turbulence Strongly stable globally intermittent or collapsed turbulence? 3-6

  7. Plumes visualized in laboratory convection 3-7

  8. 3-8

  9. VISUALIZATION OF VERTICAL VELOCITY IN X-Y PLANES Z = 47m 20km 3-9

  10. VISUALIZATION OF VERTICAL VELOCITY IN X-Y PLANES Z = 156m 3-10

  11. VISUALIZATION OF VERTICAL VELOCITY IN X-Y PLANES Z = 390m 3-11

  12. VISUALIZATION OF VERTICAL VELOCITY IN X-Y PLANES Z = 547m 3-12

  13. VISUALIZATION OF VERTICAL VELOCITY IN X-Y PLANES Z = 718m 3-13

  14. VISUALIZATION OF VERTICAL VELOCITY Narrow fast updrafts Wide slow downdrafts Horizontal convergence 3-14

  15. 3-15

  16. stationary period transient growth x-y average TKE in mid-pbl 3-16

  17. w-skewness, biased towards updrafts w-variance, mid-PBL maximum LES LES ? 3-17

  18. Mean KE Total KE Turbulent transport Shear production Buoyancy production Pressure transport Dissipation 3-18

  19. 3-19

  20. 3-20

  21. Overshoot and steeper gradient Initial profile Time 3-21

  22. VISUALIZATION OF T PERTURBATION IN X-Y PLANES Z = 47m Hot cores 20km 3-22

  23. VISUALIZATION OF T PERTURBATION IN X-Y PLANES Z = 718m Cold cores 3-23

  24. VISUALIZATION OF T PERTURBATION IN X-Y PLANES Z = 781m Cold cores 3-24

  25. VISUALIZATION OF T PERTURBATION IN X-Z PLANES Entrainment sites Stiff gradient at top of plumes 20km 3-25

  26. PBL ENTRAINMENT Entrainment “zone” 3-26

  27. 3-27 CLASSIFICATION OF CLEAR PBLs Neutral -10 -3 0 2 Coherent structures visualized in a neutral flat wall boundary layer in a wind tunnel. Entrainment hummocks in an x-z plane. Low-speed streaks in an x-y plane.

  28. Horizontal (x-y) slice of vertical velocity at z = 25m from an LES of a PBL driven by large scale forcing from the mesoscale code COAMPS. Atmospheric stability zi/L varies from strongly unstable to near neutral over the course of the 8 hour simulation. This changes the dominant coherent structure in the PBL from a hexagon to a streaky pattern. 3-28

  29. MEAN AND TURBULENT FLUX PROFILES FOR PBLS WITH VARYING STRATIFICATION LES RESULTS MOENG & SULLIVAN (1994) 3-29

  30. STABLE NIGHTTIME PBL Time series of sensible (turbulent) heat flux H from CASES-99 [Van de Wiel, 2003] Continuous turbulence Transient turbulence with collapse Radiatively cooled very weak turbulence Radiation sunrise sunset 3-30

  31. STABLE BOUNDARY LAYER Wind profile Low level jet Heat flux profile 400m KH mixing w contours 3-31

  32. 3-32

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