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A Molecular View of Vorticity & Turbulence Four Lectures at NCAR, 28-29 November 2007

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### A Molecular View of Vorticity & TurbulenceFour Lectures at NCAR, 28-29 November 2007

### CREDITS

### Key References

### Summary

Adrian Tuck

NOAA-ESRL/CSD6

Meteorological Chemistry Program

Slide 1

•Susan Hovde.

•Many people in the erstwhile NOAA Aeronomy Laboratory.

•Many people connected with the NASA ER-2 & WB57F, and the NOAA G4.

Slide 2

Alder & Wainwright (1970), Phys. Rev. A,1, 18-21.

[emergence of fluid flow from molecular dynamics]

Schertzer & Lovejoy (1987), J. Geophys. Res., 92, 9693-9714.

[generalized scale invariance, statistical multifractals]

Tuck et al. (2004), Q. J. R. Meteorol. Soc., 130, 2423-2444.

[scale invariance in jet streams]

Tuck et al. (2005), Faraday Discuss., 130, 181-193.

[correlation between temperature intermittency and ozone photodissociation rate]

Further references and bibliography are in slides 79-84

Some equations and text are in slides 70-78

Slide 3

Eady (1951), Q. J. R. Meteorol. Soc., 77, 316: Discussion remark. ‘I congratulate Dr. Batchelor on his scholarly presentation of the similarity theory of turbulence initiated by Kolmogoroff. The argument which derives the consequences of statistical “de-coupling” between the primary turbulence-producing processes and the secondary small-scale features of the turbulence appears to be sound but does it get us very far? In meteorology and climatology we are concerned principally with the transfer properties of the turbulence, determined mainly by the large-scale primary processes to which the similarity theory does not pretend to apply. It is the great virtue of similarity theories that no knowledge of the mechanism is involved and we do not have to assume anything about the nature of “eddies”; anything which has “size” (such as a Fourier component) will do in our description of the motion. But this emptiness of content is also their weakness and they give us very limited insight. It is true that a similarity theory that could be applied to the primary turbulence-producing processes would be of great value but there is no reason to expect that anything simple can be found; when several non-dimensional parameters can be formed, similarity theory, by itself, cannot do much.[continued]

Slide 4

Similarity theories are attractive to those who follow Sir Geoffrey Taylor in rejecting crude hypotheses regarding “eddies”, mixing lengths, etc. But those who try to determine the properties of turbulence without such (admittedly unsatisfactory) concepts must show that they have sufficient material (in the shape of equations) to determine the answers. If this is not the case it will be necessary to develop some new principle in addition to the equations of motion and the nature of this principle may be brought to light in a study of the mechanism of the primary turbulence-producing process i.e. by trying to refine or modify what we mean by an “eddy” rather than by completely rejecting the concept.’

A wider context for the importance of understanding the mechanisms of turbulence can be found in Eady and Sawyer (1951), Q. J. R. Meteorol. Soc.,77, 531-551: ‘Dynamics of flow patterns in extratropical regions’.

Slide 5

ER-2 flight into the polar night jet, Stavanger to Wallops Is.: √(u2+v2)

Slide 7

Slide 9

Scaling Calculation for19941005 Wind Speed(44°S,173°E) to (65°S,180°E)

Slide 11

Figure 8

Alder & Wainwright (1970): A flux applied to an

equilibrated population of Maxwellian molecules.

Vortices and fluid flow emerge in 10-12s and 10-9 m.

Slide 16

Intermittency, sharp gradients

Slide 17

Intermittency, sharp gradients

Slide 18

Intermittency, sharp gradients

Slide 19

Long-tailed PDFs of temperature: millions of 5 Hz points from

scores of ER-2 flight segments, Arctic summer 1997 & winter

2000.

Slide 20

All DC-8 ‘horizontal’ data, 44˚S - 90˚S, Aug-Sep 1987 (AAOE)

Slide 23

All DC-8 total water, ‘horizontal’, 44˚S - 90˚S, Aug-Sep 1987

Slide 24

All ER-2 ozone & nitrous oxide, 59˚N-70˚S, heavy SH weighting

Slide 26

All 261 dropsondes, Winter Storms 2004, 10˚N-46˚N, 140˚W-172˚W, 20040229 - 20040314, NOAA G4

Slide 27

All 261 dropsondes, Winter Storms 2004, 10˚N-46˚N,

140˚W-172˚W, 20040229 - 20040314, NOAA G4

Slide 28

Aircraft ascents and descents,Jan-Mar 2004,10˚- 60˚N,84˚- 158˚W

Gulfstream Ascents & Descents

WB57F Ascents & Descents

Slide 29

Correlation of H for dropsonde wind speed with jet strength, WS 2004

Slide 32

Dynamical stability [Ri>0.25] at 500 & 150 m(left),50 & 10 m(right)

Dropsonde (25˚N,157˚W) on 20040229. The ‘Russian doll’ structure.

Slide 33

Vertical scaling of horizontal wind, 235 dropsondes, Winter Storms

2004. Scaling is not Kolmogorov or gravity wave; Bolgiano-Obukhov

applies in lower troposphere, but none are correct at jet altitudes.

Slide 34

WB57F, Rocky Mountains 19980411. Severe turbulence & lee waves.

Isentropes observed by MTP.

Figure 22Slide 35

Scaling of WB57F and MM5, WAM Rocky Mountain Lee Wave Flight 19980411

Slide 38

Simulated monofractal signals: random, antipersistent & persistent.

Slide 39

Simulated statistical multifractal signal, with typical observed

values of generalized scale invariance exponents: conservation,

intermittency and Lévy.

Slide 40

ER-2 temperature data from SOLVE, Arctic Jan-Mar 2000. H1, C1 and . Archived (truncated) data spoils calculation of (T).

Slide 41

Scaling exponents H1, C1and for SOLVE ER-2, full precision at 5 Hz

Slide 42

Long-tailed PDFs of temperature, Arctic winter & summer, trop. trop.

Slide 45

Scaling & intermittency of temperature, ER-2, Arctic, 19970506

Slide 46

Correlation of the observed photodissociation rate of ozone with

the intermittency of observed temperature. Arctic summer 1997

and winter 2000.

Slide 47

Correlation of average temperature along an ER-2 flight segment with

its intermittency. Arctic summer 1997 and winter 2000.

Slide 48

ER-2, Arctic summer 1997. Racetrack segments in static air mass,

crossing terminator. Temperature changes between night and day,

nothing else does.

Slide 49

ER-2, Arctic summer 1997. Unlike temperature, wind speed and

nitrous oxide do not change across the terminator.

Slide 50

Shift to warmer temperatures on sunlit side of terminator, ER-2

racetrack flights in static air mass, Arctic summer 19970509.

Slide 51

Shift to warmer temperatures, sunlit side of terminator, ER-2

racetrack flights in static air mass, Arctic summer 19970911,14,15.

Slide 52

Lapse rate PDFs at different vertical resolutions, dropsondes from

NOAA G4, 20040229 - 20040315, eastern Pacific Ocean.

(a)

(b)

Slide 53

Maxwellian Velocity Distribution

Slide 54

Alder & Wainwright (1970): molecular dynamics simulation of

a flux applied to an equilibrated Maxwellian population results in

the emergence of vortices on scales of 10-12 seconds & 10-8 meters.

Figure 8Slide 58

O +

O

3

2

The correspondence and coupling of the microscopic and macroscopic

processes in the atmosphere.

Slide 59

Baloïtcha & Balint-Kurti (2005), PCCP, 7, 3829-3833.Speed

distribution of photofragments, O3 photodissociation, Hartley band.

Slide 60

Historical montane surface site observations of ozone:

Marenco et al. (1994),JGR, 99, 16617-16632.

Slide 61

ER-2 scaling exponents for ClO and NOy, Arctic vortex, January -

March 2000. An early ClO source & NOy sink from PSCs evolve

to a sink and to a passive scalar (tracer) respectively.

Slide 65

Figure 46

Scatterplot, scaling exponents of ClO & O3, Arctic vortex 2000.

1 = 20000120, 11 = 20000312. Ozone sink was present 20000120.

Slide 66

Figure 47

Evans & Searles (2002), Adv. Phys.,51,1529-1585. The high speed

molecules, a minority, produce order (‘flow’) while the average

majority produce dissipation (‘temperature’).

Slide 68

THEORY: Nonlinear interaction among high speed molecules subject to an anisotropy sustains vortices and the overpopulation of fast molecules in the PDF - fluid flow emerges from the Maxwellian ‘billiard balls’. Temperature remains defined but is not the mean of the Maxwell-Boltzmann distribution. The high speed molecules produce larger scale order (negative entropy), the ones near the mean are responsible for dissipation (positive entropy).

EVIDENCE: Correlation of H1(windspeed) with horizontal and vertical measures of jet stream strength. Correlation of temperature intermittency with ozone photodissociation rate.

Jet stream speeds reach Mach 0.7 - half the speed of the most probable speed of N2 molecules.

ATMOSPHERIC TURBULENCE: A Molecular Dynamics Perspective, Oxford University Press,

due to appear January 2008.

Slide 69

Slide 79

ATMOSPHERIC TURBULENCE: A Molecular

Dynamics Perspective

A F Tuck

Oxford University Press

Target: January 2008

Slide 84

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