1. Airborne Radar Observations of Breaking Waves/Rotors in the Lee of
13th Mtn Met, 13.6
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Airborne Radar Observations of
Breaking Waves/Rotors in the Lee of
the Medicine Bow Mountains in
SE Wyoming, USA
Jeffrey R. French1, Samuel Haimov1, Larry Oolman1, Vanda Grubisic2, and Dave Leon1
1University of Wyoming
2Desert Research Institute
This work supported by NASA Grant NCC5-578 (Geerts, Leon, Snider PI) and NSF ATM

2. Objective(s): Motivation:
13th Mtn Met, 13.6
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Objective(s):
Utilize data from the WCR and UWKA to investigate the internal structure of rotors
scales (temporal and spatial), amplitude, turbulence and sub-rotor features
Use the data to better understand rotor typology, including numerical modeling studies to augment and aid the interpretation of the observations.
Motivation:
Inability to penetrate some rotors with aircraft due to severe turbulence?
Use of WCR during TREX campaign to “see” into rotor clouds
Data mining for observations obtained in SE Wyoming

3. USE of NASA06 data- NASA06 Campaign-
13th Mtn Met, 13.6
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USE of NASA06 data-
Following the TREX campaign (Mar/Apr 06) we found that:
1. Under certain conditions the WCR can be very useful in investigating the internal structure of rotors
2. Closer examination of the earlier campaigns (NASA06) indicated data suitable of rotor/wave investigation to augment data collected in TREX
Wintertime data, collected in regions with significant snow cover, in the presence of strong surface winds provides environment rich with scatterers (small ice)!!!
NASA06 Campaign-
Investigate orographic precipitation formation over Med. Bow Mountains in SE Wyoming
In situ measures from UWKA and WCR

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5. Rapidly evolving Wave/Rotor system
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Case of 26 January:
Rapidly evolving Wave/Rotor system
Two passes over 30 minutes
Capture beginning of event
Strong vertical motion at UWKA flight level (>12 m s-1)

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11. Relatively stationary lee wave
13th Mtn Met, 13.6
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Case of 5 February:
Relatively stationary lee wave
4 passes over 1 hour
Multiple waves, weaker vertical motion (4 m s-1)

12. t = 0 min t = 14 min t = 48 min t = 59 min 13th Mtn Met, 13.6
15 August, 2008
t = 0 min
t = 14 min
t = 48 min
t = 59 min

13. Pass 1 t = 0 min Vertical Velocity from WCR and UWKA
13th Mtn Met, 13.6
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Pass 1
t = 0 min
Vertical Velocity
from WCR
and
UWKA

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Pass 1
t = 0 min

15. Pass 3 t = 48 min Vertical Velocity from WCR and UWKA
13th Mtn Met, 13.6
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Pass 3
t = 48 min
Vertical Velocity
from WCR
and
UWKA

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Pass 3
t = 48 min

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Summary:
two cases observed from which vertical x-sections of the two-dimensional velocity field were retrieved; one case evolved/changed rapidly, the other was rather stationary over the 1-hour observation period.
Observations at level of UWKA indicated moderate turbulence on Jan26, single wave-type feature, less turbulent on Feb05, with trapped lee waves evident.
Internal structure of the rotors/waves near the surface indicated very shallow (Jan26) strong downslope flow, with region of strong turbulence along the shear layer from the point of BL separation over the wave crest and downstream…sub-rotor scale features of hundreds of m in size evident on Jan 26.

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