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ATM S 542 Synoptic Meteorology Overview Gregory J. Hakim University of Washington, Seattle, USA Vertical structure of the.

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Presentation on theme: "ATM S 542 Synoptic Meteorology Overview Gregory J. Hakim University of Washington, Seattle, USA Vertical structure of the."— Presentation transcript:

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 08-21-03Gregory J. Hakim (U. Washington)2 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.

3 08-21-03Gregory J. Hakim (U. Washington)3 Jets, stirring, organized structures; waves, vortices, convection.

4 08-21-03Gregory 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 H 2 O vapor. Tropopause: jet streams. wave guide. unstable: cyclones.

5 08-21-03Gregory J. Hakim (U. Washington)5 Atmospheric Energy Spectrum Energy increases with horizontal length scale.

6 08-21-03Gregory J. Hakim (U. Washington)6 Atmospheric Phenomena by Scale Planetary waves L ~ 10 000 km H/L ~.001 Ro ~ 0.01 Cyclones L ~ 1000 km H/L ~.01 Ro ~ 0.1 Gravity waves L ~ 10--100 km H/L ~.1-1 Ro ~ 1 Convection L ~ 10 km H/L ~ 1 Ro > 1 Long, slowShort, fast

7 08-21-03Gregory J. Hakim (U. Washington)7 Jet streams & planetary waves

8 08-21-03Gregory J. Hakim (U. Washington)8 Jet Streams

9 08-21-03Gregory J. Hakim (U. Washington)9 Jets: ~ Geostrophic Balance

10 08-21-03Gregory J. Hakim (U. Washington)10 Jet stream vorticity Waves & particles Waves: Information flows through the medium by radiation. Particles (vortices): Information flows through the medium by material transport.

11 08-21-03Gregory J. Hakim (U. Washington)11 Cyclones & Anticyclones

12 08-21-03Gregory J. Hakim (U. Washington)12 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.

13 08-21-03Gregory J. Hakim (U. Washington)13 North American Cyclone

14 08-21-03Gregory J. Hakim (U. Washington)14 Intense vortex Cold air: shallow cellular convection Warm air: stratiform cloud Sharp frontal boundaries Zoom in on cold front… Pacific Extratropical Cyclone

15 08-21-03Gregory J. Hakim (U. Washington)15 Scale collapse at cold front: “rope cloud”---narrow line convection.

16 08-21-03Gregory J. Hakim (U. Washington)16 Cyclone — Anticyclone Track Density Primary tracks coincide with time-mean jet stream locations. Hoskins & Hodges (2002)

17 08-21-03Gregory J. Hakim (U. Washington)17 Jet-Level 2.5—6 d Variance Maximum variance in storm tracks. Hoskins & Hodges (2002)

18 08-21-03Gregory J. Hakim (U. Washington)18 Baroclinic Waves & Packets Cyclones & anticyclones often compose waves within larger wave packets.

19 08-21-03Gregory J. Hakim (U. Washington)19 Baroclinic Waves Wavelength ~4000 km Phase speed ~ 15 m/s. Period ~ 3 d. Due to baroclinic instability. Organize into packets. Lim & Wallace (1991)

20 08-21-03Gregory J. Hakim (U. Washington)20 Wave Packet Phase & Group Speed phase speed group speed Chang & Yu (1999)

21 08-21-03Gregory J. Hakim (U. Washington)21 Wave Packet Tracks Hakim (2003) Jet-stream wave guides. Storm-track recycling.

22 08-21-03Gregory J. Hakim (U. Washington)22 Mesoscale Phenomena & Smaller Scales Fronts & frontal waves. Gravity waves. Convection. Shear instabilities.

23 08-21-03Gregory J. Hakim (U. Washington)23 Frontal Waves Wakimoto & Bosart (2000)Paldor et al. (1994)

24 08-21-03Gregory J. Hakim (U. Washington)24 Tropopause Shear Line Instability

25 08-21-03Gregory J. Hakim (U. Washington)25 Tropopause Shear Line Instability

26 08-21-03Gregory J. Hakim (U. Washington)26 Tropopause Shear Line Instability

27 08-21-03Gregory J. Hakim (U. Washington)27 Tropopause Shear Line Instability

28 08-21-03Gregory J. Hakim (U. Washington)28 Moist Convection Strong vertical mixing tropopause

29 08-21-03Gregory J. Hakim (U. Washington)29 Kelvin—Helmholtz Instability

30 08-21-03Gregory J. Hakim (U. Washington)30 Gravity Waves Wavelength ~10 km

31 08-21-03Gregory J. Hakim (U. Washington)31 Gravity Waves

32 08-21-03Gregory J. Hakim (U. Washington)32 How do we better understand cyclones & anticyclones? Need to filter other disturbances from the equations…

33 08-21-03Gregory J. Hakim (U. Washington)33 Ertel Potential Vorticity

34 08-21-03Gregory J. Hakim (U. Washington)34 Vertical Profile of PV Tropopause Well-defined as PV jump. Dynamics focus here.

35 08-21-03Gregory J. Hakim (U. Washington)35 Tropopause Topography (pressure) source: Hoinka (1998) High pressure over poles. Low pressure over tropics. Strong gradient in mid-latitudes. Stronger gradient in winter.

36 08-21-03Gregory J. Hakim (U. Washington)36 Height-Latitude Tropopause Profile Hoinka (1998)

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