Download - Mountain Waves entering the Stratosphere
Mountain Waves entering
the Stratosphere
Mountain Waves entering the Stratosphere: New aircraft data analysis techniques from T-Rex
Ronald B. Smith, Bryan WoodsYale University
New Haven, Connecticut
J. Jensen*, W. Cooper*, J. D. Doyle**, Q. Jiang**, V. Grubisic***[* National Center for Atmospheric Research, Boulder, CO;
**Naval Research Laboratory, Monterey, CA, ***Desert Research Institute, Reno, NV]
[Support from the National Science Foundation]
Outline• T-Rex Events (march/April 2006)• Potential and Kinetic energy• Sensitivity to Mountain Top Winds• Wave spectra with altitude• Wind and stability profiles• Layering of Mechanical Bernoulli and Ozone• Summary and future work
[Warning: Beware of speculation. This project is only a few weeks old.]
Microwave Limb ScannerJiang et al
Global pattern ofGravity Waves in the upperatmosphere
Frequency w > 1 m s-1 and Mean TKE> 2 m2 s-2
COAMPSClimate(Doyle)
Tropopause
Wind
Final GV Flight Table for T-Rex RF IOP Date JD Track
/actual Wmax**
Del WI
DWS MS Feature
01 1 M2 61 B 1.5 4 17 Smith 02 2 M5 64 C 1.5 18 Smith 03 3 M9 68 A/265 5 12 Smith Leg differences 04 4 M14 73 B/245 5 12 31 Smith 05 6 M25 84 B/260 9 17 32 Doyle Short Train & leg
diff 06 9 A2 92 B/245 1.5 3 Cooper Leg Diff 07 IC A7 97 IC* Grubisic 08 10 A9 99 B/245 3 8 Grubisic Periodic W& leg
diff 09 13 A15 105 B 2 6 Grubisic 10 13 A16 106 B/245 10 20 Grubisic Easter Event 11 14 A21 111 C Cooper? 12 15 A26 116 B/210
? 5 Cooper Easterly flow,
Jiang (* Intercomparison flight; ** eyeball)
Dashed Line = North Leg Solid Line = South leg
Note shorter wavelength ~15km
dxdyvuKH
)''()2/( 22
dxdywKZ 2')2/(
dxdyTgPE '')2/(
Wave Energy Components
)0()(
)()(
0
dssU
sws
s
Vertical Kinetic Energy (J/m2)
0
20
40
60
80
100
120
140
0 2 4 6 8 10 12 14
Research Flight (RF#)
Ve
rtic
al K
E
(times 1000) Each point is a leg
Sensitivity
0
10
20
30
40
50
60
70
80
0 5 10 15 20 25 30
Windspeed @700hPa (m/s)
Ver
tic
al
KE
(J
/m2
)Threshold?
Lemoore and Visalia soundings
Each point is a flight
Horizontal Kinetic Energy (J/m2)
0
100
200
300
400
500
600
700
800
900
0 2 4 6 8 10 12 14
Research Flight (RF#)
Ho
rizo
nta
l Kin
eti
c E
ne
rgy
Each point is a leg
Potential Energy (J/m2)
-2000
0
2000
4000
6000
8000
10000
0 2 4 6 8 10 12 14
Research Flight (RF#)
Po
ten
tia
l En
erg
y
Computed from the product of theta and displacement perturbation
BigWaves (RF4,5,10) Potential Energy (J/m2)
-5000
0
5000
10000
15000
20000
0 2000 4000 6000 8000 10000 12000 14000 16000
Altitude (m)
Po
ten
tia
l E
ne
rgy
(J/
m2
)
Wave Energy Comparison
• Observation – Vertical KE ~ 40 J/m2– Horizontal KE ~ 400 J/m2– Potential Energy ~ 4000 J/m2 (stratosphere)
• Interpretation– Wave energy concentrated in the stratosphere– Observations not consistent with vertically
propagating or trapped waves “rooted” in the troposphere
– Horizontal KE may be enhanced by Bernoulli layering
Wavelength 20 km
10km
VerticalVelocitySpectrum
9km 11km 13km
RF10
9km 11km 13km
RF10
North
South
9km 11km 13km
RF4
North
South
9km 11km 13km
RF4
North
South
Vandenberg Windspeed Profiles:Big Wave Events(RF4,5,10)
[Note oscillations in the stratosphere]
Vandenberg Theta Profiles:Big Wave Events(RF 4,5, 10)
Scorer Parameter from quadratic fits
0.00E+00
5.00E-08
1.00E-07
1.50E-07
2.00E-07
2.50E-07
3.00E-07
3.50E-07
4.00E-07
4.50E-07
5.00E-07
0 5000 10000 15000 20000 25000
Altitude (m)
Sc
ore
r P
ara
me
ter
(m-2
)
Ksquared for Lamda =15km
Gravity wave region
April 16, 2006
Scorer Parameter from quadratic fit
22 /)( UNzS
0ˆ)(ˆ 2 wkSwZZ
Conserved Variable Diagram for a racetrack
Dashed line = North Leg Solid line = South Leg
.)2/1()( 2 constgZUpPB
Mechanical Bernoulli Function for compressible steady flow
GPS altitudeMinor contributoras the A/C tries tofly at constant pressurealtitude
Dual Conserved Variable Plots(RF4; March 14, 2006; Leg @41kft)
Ozone Mechanical Bernoulli*
Wave #1 @41kft
352
354
356
358
360
362
364
366
368
370
372
0 50 100 150 200 250 300
Ozone (ppb)
Theta
(K)
Wave #1 @ 41kft
352
354
356
358
360
362
364
366
368
370
372
352300 352350 352400 352450 352500 352550 352600 352650 352700 352750 352800 352850
Bernoulli (m2/s2)
Theta
(K)
[using GPS altitude]
Conclusions• The new GV aircraft is effective in monitoring
stratospheric gravity waves. • March/April 2006 was an active period for storms hitting
the Sierras• 3 large gravity wave events out of 8 Track B flights• Wave energy is concentrated in the stratosphere• Typical wavelength there is ~15km• Wave location suggests Sierra causation• 2-D and steadiness are imperfect and variable• Wave amplitude very sensitive to mountain top winds• Strong wave events have similar wind environments
(with a stratospheric critical level)
Linear Theory
• Criterion for linear waves is nearly satisfied
2.0/50/02.0*500/2
smmUNPMAX
•Vertically propagating gravity waves should have KE = PE at each level (equipartition)
•Trapped waves should have PE concentrated in the active stable layer
Speculations on wave dynamics
• Waves are “rooted” in the stratosphere– Wave energy distributions are not consistent
with vertically propagating or conventional trapped waves.
– Potential energy is concentrated in the stratosphere
– Scorer parameter exceeds the wavenumber only in the stratosphere
– Generation mechanism unknown; probably non-linear
Free surface (Critical layer?)All the potential energy is here.
UMT website
Speculations on layering
• Vertical advection by waves allows diagnosis of ozone layering and dynamic “Bernoulli Layering”
• GPS altitude is required for Bernoulli function determination (new!)
• Bernoulli Layering correlates with ozone layering in the stratosphere
• Layering may represent isentropic interleaving of stratospheric air masses, prior to the wave encounter
• Bernoulli layering contributes a false signal to the horizontal wave kinetic energy.
Future work
• Improve GV instrument calibrations– Compute wave energy flux using GPS altitude– Improved wave energy density computations– Momentum fluxes– Improved Bernoulli computations
• PV computations using Crocco’s theorem• Analysis of soundings• Compare observations with linear wave theories• Test non-linear theories of wave regeneration, undular
bores, and critical level reflection and/or decoupling• Determine the role of the critical level
Big Waves (RF4,5,10)Vertical Kinetic Energy (J/m2)
0
20
40
60
80
100
120
140
0 2000 4000 6000 8000 10000 12000 14000 16000
Altitude (m)
Ver
tic
al
Kin
eti
c E
ne
rgy
(J
/m2
)
(Smith, 1985)
Other aircraft profiles:OzoneAir densityWater Vapor
Each point is a racetrack
delta WI
0
5
10
15
20
25
0 2 4 6 8 10 12 14
Flight number
Wm
ax-W
min
(m
/s)
Each point is one racetrack
Big Wave Events (RF4,5,10)Aircraft Racetrack Data
y = -3E-07x2 + 0.0043x + 33.241R2 = 0.3747
0
10
20
30
40
50
60
0 2000 4000 6000 8000 10000 12000 14000 16000
Altitude (m)
Ave
r. W
ind
spee
d (
m/s
)
Big Wave Events (RF4,5,10)Aircraft Racetrack Data
y = 2E-06x2 - 0.042x + 501.97R2 = 0.8289
310
320
330
340
350
360
370
380
0 2000 4000 6000 8000 10000 12000 14000 16000
Altitude (m)
Th
eta
(K
)
Aircraft Profiles:All Big Wave Events(RF4,5,10)
Each point is a racetrack