Temperature and Composition

Transcription

1 Testing Theories of Gravity Wave Transports and Their Effects on Wind Temperature and Composition by Richard Walterscheid Aerospace Corporation 1995 CEDAR Workshop June 27,1995

2 Topics Waves Wave-mean-state interactions Observable phenomena Diagnostics Examples

3 Vertical Wave Fluxes Z A W W w w z A Nil X

4 Wave Mean State Interactions Wave Forcing ofthe Mean State Driven by wave fluxes Nonacceleration theorem Chemically induced forcing WMSI Phenomena in the Stratosphere and Lower Mesosphere Equatorial QBO and SAO Sudden Stratospheric Warmings WMSI Phenomena in the Upper Mesosphere and Lower Thermosphere Cold summer mesopause Pseudotides Wind, temperature and composition disturbances

5 Wave Fluxes Mean state changes induced by wave fluxes 13F^(\ /) at " p dz Fz( )=pwv Wave stress \ / = u Sensible heat flux \ / = CpT Species flux y = r, \ / = n

6 Nonacceleration Conditions Waves Linear Conservative Steady No critical level (u 56 c)

7 Forcing ofmean Wind by Momentum Flux c

8 Critical Levels Critical level: u c = 0 Critical level favored location for wave-mean-state interactions Strong enhancement ofwave dissipation as vertical wavelength and group velocity become small Orlanski-Bryan condition for wave breakdown satisfied for fairly small-amplitude waves E-P relation implies sign reversal for vertical momentum flux at critical level Wave dissipation forces decent of Critical level Orlanski-Bryan condition for wave breakdown u' ~c u E-P relation energy flux = (c- m)x momentum flux

9 o o o A II V I LU N

10 W - ^ TIME AFTER BREAKDOWN, hr Figure 7 Same as Figure 4 except " 10 ^break " TIW AFTER BREAKDOWN, hr Fligure 8. Sa^ as Figure 5 except 10 ^braak " -all TIME AFTER BREAKDOWN, hr Figure 9. Saae as Figure 6 except - 10

11 Chemical Forcing ofmean-state Minor Constituent Profiles Vertical flux ofconstituent mixing ratio is zero when. nonacceleration conditions apply and chemical production and loss are nil Vertical flux can be induced by chemistry even when nonacceleration conditions apply Strobel (1981) parameterized effects of chemistry in terms ofeddy diffusion coefficient Schoeberl et al. (1983) modified Strobel's parametization to incorporate turbulent mixing (Lindzen, 1981; Garcia and Solomon, 1985, Bjamason et al., 1987; LeTexier et al., 1987) Walterscheid and Schubert (1989) used five-reaction model ofwave-perturbed Os chemistry near the mesopause to calculatechemically inducedwave fluxes ofminor constituents

12 O cw Altitude (km) O X

13 Waves Obey characteristic dynamical and dispersion relations Characteristic frequencies, wavelengths (tides, planetary waves) Vertical phase propagation is opposite to vertical group propagation (except acoustic waves) Amplitude «= conservative waves for steady vertically propagating

14 Poker Flat, Alaska 11 October 1961 Horizontal Wind Profiles (one-hour average values) Northwurd 80 Eostwoni figure 4. Time sequence of the horizontal velocity profiles shown in rig. 3. Velocity scale shown in lower left corner of upper panel. Dashed lines indicate approximate height'of velocity extreme of the quasi-sinusoidal contours. (Note that left-to-right profile placements are not precisely uniform in time.)

15 Diagnostics Wave flux divergence Nonequilibrium conditions Anomalous or perturbed conditions Do not obey wave relations

16 Examples Vincent and Reid (1983) Fritts and Vincent (1987) Gille and Lyjak (1984) Czechowsky et al. (1979) Lieberman and Hays (1994) Hecht et al. (1995)

17 I /f r, a Vii»* ** ^ i / re // / /-a A ). V V ^ ' ' «ita -'. ^ QO 75 LATITUDE UTIBIDE (a) r2?; U (a) Wave flm (iiver,genoe (m s"^ day'^), for 29 January (h) Aoaeleration of zqnajl mean wind speed (m/s day), for 29 January 19?9.

18 r- 1 ^ r Ill Q t < L -5.'.,. / N ^ - m * ;.lo /. > i J ; ;t ; :. o ; ;!' 80 to- - i 70 E- r 1 I 1 1 " Jan Mar May Aug Oct Jan Mar May Figure 11

19 :0 r? Pff^f..-rrrrrz ^ ^ 90 MM... ^_4 L Jan Mar May May 1992 Figure 12

20

21 100 u 'w' / s'^ I 1 E JSC 90 *» P Jh O LiJ iw ^ / * P / X o o u'w' 80 F " ""'0 0 F / m s day Fig. 6. Height profiles of tl\e viipward flux of zonal mpmentiiin (u'w') for the period Um 1981 (open circles) and the as sociated body force F (solid

22 95-3km

23 >- q: J I L TIME(UT) 14

24 200 ohtempi 089.txt T I I [ I I r 190 LiJ q: 180 Q L I I 1 L 8 TIME(UT)

25 Conclusions Wave Mean State Interactions driven by wave fluxes Primary diagnostic is relationship between changes and fluxes Important to measure time and space variations of different quantities simultaneously