1. Winds Yin (2000) JAM Annual mean winds

2. Annual Cycle in Wind Yin (2000) JAM Annual cycle amplitude

3. Peak Wind Season Yin (2000) JAM Time of peak wind

4. Diurnal Mountain Winds Diurnal mountain winds develop from terrain of all scales Circulations arise as a result of differential heating between the ground in regions of complex terrain and free atmosphere at the same elevation –During day, higher terrain is an elevated heat source –During night, higher terrain is an elevated heat sink

5. Sacramento Valley Zaremba and Carroll (1999) JAM

6. Grand Canyon Whiteman et al. 1999 JAM

7. Kali Gandaki Valley Egger et al. (2000) MWR

8. Mountain wind systems Slope winds- driven by horizontal temperature contrasts between air over valley sidewalls and air over center of valley Along-valley winds- driven by contrasts along valley’s axis and nearby plain Cross-valley winds- driven by contrasts between opposing sidewalls Mountain-plain winds- driven by contrasts between plateau and nearby plains

9. Mountain Wind Systems Whiteman (2000)

10. Terminology Katabatic wind: cold flow of air travelling downward or down a slope Anabatic wind: air current or wind rising up a slope

11. Slope Winds Whiteman (2000)

12. Slope flows Closed circulation driven by horizontal temperature contrasts between the air over the slope and the air at the same level over the center of the valley Speeds- 1-5 m/s with maximum a few meters above the ground Increase in speed as length of slope increases (Antarctica 14-30 m/s) Strongest downslope at sunset; strongest upslope in midmorning Depth of downslope ~5% of drop in elevation from top Upslope flows increase in depth as move upslope Stronger the stability, shallower the slope flows Downslope flows converge into gullies; upslope flows converge over higher ground between gullies

13. Slope flows Whiteman (2000) Cold Warm Cold Du’/dt = g’ (  en -  )/  =g’ (T-T en )/T en = g’ (  -  en )/  en g g’

14. Basin Circulations Enclosed terrain features develop slope flows but weak along-valley circulations Enhanced heating during the daytime and cooling at night as a result of absence of along-valley advection of cool/warm air Light winds

15. Night flows Whiteman (2000)

16. Thermal belt Whiteman (2000)

17. Slope Flows in Peter Sink Basin Record cold temperature in Utah: Peter Sinks –57C Clements (2001) conducted field program in remote basin in northern Utah to study slope flows Field program held 8-12 Sept. 1999

18. Peter Sinks

19. North Peter Sink Vegetation inversion

20. Peter Sinks Terrain

21. Perimeter

22. Instrumentation Layout

23. Net Radiation and Sonic Anemometer

24. Surface Energy Budget- Idealized Whiteman (2000)

25. Surface Energy Budget- Peter Sinks Strong net heating during day; surface losing energy during night

26. Surface Temperature Variation Coldest air in the basin- warm air on slopes

27. Tethersonde Operations

28. Vertical Structure in basin dw/dt = -g/  en (d  en /dz)dz Stability increases as evening progresses Winds weaken with time

29. Temperature Mast on Slope

30. Temperature Variation on Slope Strong inversion below 2 m; isothermal above

31. Vertical Structure on Slope Light drainage winds on slopes; nonexistent most of the time

32. Potential Temperature Profiles Along Slope Observations from Peter Sinks do not agree with classical model of relatively deep cold air on slopes draining down into basin

33. Morning Transition

34. dw/dt = -g/  en (  en /  z)dz Stability decreases as morning progresses Winds strengthen with time

35. Katabatic flow Poulos et al. 2000 MWR

36. Simulation of Katabatic Wind Poulos et al. (2000) MWR

37. Antarctica Katabatic Winds Bromwich (1989) BAMS

38. Divergence Salt Lake Valley: Interaction of Slope and Valley Winds Convergence Divergence October 2000. M. Splitt