1. ATM S 542 Synoptic Meteorology Overview
Gregory J. Hakim
University of Washington, Seattle, USA
Vertical structure of the atmosphere.
Atmospheric phenomena by horizontal scale.
Potential vorticity.
Tropopause.

2. Gregory J. Hakim (U. Washington)
Overview
Asymptotic methods
expand dependent variables in a power series.
small parameters needed.
co-operative dialog between math & physics is helpful.
Role of asymptotics in atmosphere/ocean dynamics.
simplified equations for solution & understanding.
Goals
survey atmosphere/ocean structure & phenomena.
bias toward extratropics & atmosphere.
motivate asymptotic methods for these problems.
Gregory J. Hakim (U. Washington)

3. Gregory J. Hakim (U. Washington)
Jets, stirring, organized structures; waves, vortices, convection.
Gregory J. Hakim (U. Washington)

4. Atmospheric Structure
Atmosphere: very thin gas layer.
depth <<< radius earth.
Troposphere: “weather layer”
~ 10 km deep.
~ 80% mass of atmosphere.
~ all H2O vapor.
Tropopause: jet streams.
wave guide.
unstable: cyclones.
12:03 UTC, 25 kts sustained winds, gusting to 35 kts (125 knots = 144 mph) (1 knot = 1.15 mph)
Gregory J. Hakim (U. Washington)

5. Atmospheric Energy Spectrum
Energy increases with
horizontal length scale.
Gregory J. Hakim (U. Washington)

6. Atmospheric Phenomena by Scale
Planetary waves
L ~ km
H/L ~ .001
Ro ~ 0.01
Cyclones
L ~ 1000 km
H/L ~ .01
Ro ~ 0.1
Gravity waves
L ~ km
H/L ~ .1-1
Ro ~ 1
Convection
L ~ 10 km
H/L ~ 1
Ro > 1
Long, slow
Short, fast
Gregory J. Hakim (U. Washington)

7. Jet streams & planetary waves
Gregory J. Hakim (U. Washington)

8. Gregory J. Hakim (U. Washington)
Jet Streams
Gregory J. Hakim (U. Washington)

9. Jets: ~ Geostrophic Balance
Gregory J. Hakim (U. Washington)

10. Gregory J. Hakim (U. Washington)
Jet stream vorticity
Waves & particles
Waves:
Information flows through the medium by radiation.
Particles (vortices):
Information flows through the medium by material transport.
Gregory J. Hakim (U. Washington)

11. Cyclones & Anticyclones
Gregory J. Hakim (U. Washington)

12. Gregory J. Hakim (U. Washington)
Cyclone Structure
Center has lowest pressure.
~geostrophic winds.
Warm air moves poleward.
and upward.
warm front.
Cold air moves equatorward.
and downward.
cold front.
Clouds & precipitation.
~ “comma” shape.
Gregory J. Hakim (U. Washington)

13. North American Cyclone
Gregory J. Hakim (U. Washington)

14. Pacific Extratropical Cyclone
Intense vortex
Cold air: shallow cellular convection
Warm air: stratiform cloud
Sharp frontal boundaries L
Zoom in on cold front…
Gregory J. Hakim (U. Washington)

15. Gregory J. Hakim (U. Washington)
Scale collapse at cold front: “rope cloud”---narrow line convection.
Gregory J. Hakim (U. Washington)

16. Cyclone—Anticyclone Track Density
Hoskins & Hodges (2002)
Primary tracks coincide with time-mean jet stream locations.
Gregory J. Hakim (U. Washington)

17. Gregory J. Hakim (U. Washington)
Jet-Level 2.5—6 d Variance
Maximum variance in storm tracks.
Hoskins & Hodges (2002)
Gregory J. Hakim (U. Washington)

18. Baroclinic Waves & Packets
Cyclones & anticyclones often compose waves within larger wave packets.
Gregory J. Hakim (U. Washington)

19. Gregory J. Hakim (U. Washington)
Baroclinic Waves
Wavelength ~4000 km
Phase speed ~ 15 m/s.
Period ~ 3 d.
Due to baroclinic instability.
Organize into packets.
Lim & Wallace (1991)
Gregory J. Hakim (U. Washington)

20. Wave Packet Phase & Group Speed
phase speed
group speed
Chang & Yu (1999)
Gregory J. Hakim (U. Washington)

21. Gregory J. Hakim (U. Washington)
Wave Packet Tracks
Jet-stream wave guides.
Storm-track recycling.
Hakim (2003)
Gregory J. Hakim (U. Washington)

22. Mesoscale Phenomena & Smaller Scales
Fronts & frontal waves.
Gravity waves.
Convection.
Shear instabilities.
Gregory J. Hakim (U. Washington)

23. Gregory J. Hakim (U. Washington)
Frontal Waves
Paldor et al. (1994)
Wakimoto & Bosart (2000)
Gregory J. Hakim (U. Washington)

24. Tropopause Shear Line Instability
Gregory J. Hakim (U. Washington)

25. Tropopause Shear Line Instability
Gregory J. Hakim (U. Washington)

26. Tropopause Shear Line Instability
Gregory J. Hakim (U. Washington)

27. Tropopause Shear Line Instability
Gregory J. Hakim (U. Washington)

28. Gregory J. Hakim (U. Washington)
Moist Convection
tropopause
Strong vertical mixing
Gregory J. Hakim (U. Washington)

29. Kelvin—Helmholtz Instability
Gregory J. Hakim (U. Washington)

30. Gregory J. Hakim (U. Washington)
Gravity Waves
Wavelength ~10 km
Gregory J. Hakim (U. Washington)

31. Gregory J. Hakim (U. Washington)
Gravity Waves
Gregory J. Hakim (U. Washington)

32. How do we better understand cyclones & anticyclones?
Need to filter other disturbances from the equations…
Gregory J. Hakim (U. Washington)

33. Ertel Potential Vorticity
Gregory J. Hakim (U. Washington)

34. Gregory J. Hakim (U. Washington)
Vertical Profile of PV
Tropopause
Well-defined as PV jump.
Dynamics focus here.
Gregory J. Hakim (U. Washington)

35. Tropopause Topography (pressure)
High pressure over poles.
Low pressure over tropics.
Strong gradient in mid-latitudes.
Stronger gradient in winter.
source: Hoinka (1998)
Gregory J. Hakim (U. Washington)

36. Height-Latitude Tropopause Profile
Hoinka (1998)
Gregory J. Hakim (U. Washington)