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The T-REX experiment. Ralph Burton 1 , Stephen Mobbs 1 , Barbara Brooks 1. Harold Klieforth 2 , Martin Hill 1. 1 IAS 2 Desert Research Institute, Reno NV. 1. Motivation. 2. Rotors: brief overview. 3. T-REX. From. “ Hazardous Mountain Winds and their Visual Indicators ”

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The t rex experiment
The T-REX experiment

Ralph Burton1, Stephen Mobbs1, Barbara Brooks1

Harold Klieforth2, Martin Hill1

1 IAS 2 Desert Research Institute, Reno NV


1. Motivation.

2. Rotors: brief overview.

3. T-REX.


From

“Hazardous Mountain Winds

and their Visual Indicators”

Federal Aviation Authority,

U.S.Dept. of Transportation,

1988


severe wind events can be highly

localised, violent, and

short-lived


From “Hazardous Mountain Winds

and their Visual Indicators”,

1988

Accident rate 40% higher

in the 11 mountain

states

Accident rate less than 3 per 100,000

Accident rate greater than 3 per 100,000


DEM of the U.S. showing regions

of elevated terrain


From

http://adds.aviationweather.gov


From http://adds.aviationweather.gov


Extensive mountain

obscuration

For aviation weather reports,

see

http://adds.aviationweather.gov


Owens (dry) lake

  • Probably the largest single source of

  • PM10 dust in the United States

  • Dust plumes tracked to 3000m AGL,

  • 100 km north of the lake

  • Affects visibility and vegetation

  • in many neighbouring wilderness

  • areas

  • Dust storms regularly cause

  • suspension of operations at

  • China Lake Naval Weapons Center

From Reheis (1997)

See geochange.er.usgs.gov/sw/impacts/geology/owens


Sierra wave Project (1950s)

W

I

Looking South from 9800m/32000ft


Sierra Wave

Project (1950s)

Flight of

Feb. 16th 1952

From Holmboe

and Klieforth 1957


A: Type 1 rotor

B: Type 2 rotor

From Kuettner (1959)


Maximum rates of climb

Cessna 172: 720 ft/min

Ibis aerospace 270: 1791 ft/min

Boeing Chinook: 1840 ft/min


Sierra Wave

Project (1950s)

Flight of

Feb. 16th 1952

W=-31ft/s

w=+41ft/s

From Holmboe

and Klieforth 1957


Rotor: -1860ft/min

Maximum rates of climb

Cessna 172: 720 ft/min

Net

downward

Net

downward

Ibis aerospace 270: 1791 ft/min

Net

downward

Boeing Chinook: 1840 ft/min




“Inversion effects on

mountain lee waves”

Vosper, QJR 2003

Inversion height

Wind constant with height


Regime diagram

BLASIUS;

idealised ridge

H = hill height

zi = inversion

height;

Fi = U/(g’zi)1/2

g’ = g/0

U = background

wind


H/Zi > 0.3

Consider u=10 ms-1

surf temp = 200C,

Zi = 3600m,

then we have

U2 ~ 45

gives  ~ 2K


Climatology

of wave events

Based upon

satellite imagery,

1km resolution,

15 minute intervals

(visible channel)

From Grubišić,

T-REX proposal


Oct 29th 2000

GOES -Vis

From Doyle and Durran (2004)


Regime diagram

“Inversion effects on

mountain lee waves”

Vosper, QJR 2003

29/10/2000


Doyle and Durran (2004)

Coupled Ocean-Atmospheric Mesoscale

Prediction System (COAMPS)

  • Fully 3-d simulation using 5 nested grids, finest resolution x=333m

  • Fully compressible, nonhydrostatic

  • Mixing length scheme

  • Terrain-following coordinates




T-REX

The biggest field campaign ever mounted to study

rotors/gravity waves

ARL White Sands Missile Range

Scripps Institute of Oceanography

Colorado Research Associates

Cooperative Research in Environmental Science

Desert Research Institute

DLR

Lawrence Livermore National Laboratory

UK Met Office

NASA

NCAR

Naval Research Laboratory

NOAA

Arizona State University

Colorado State University

Harvard University

University of Houston

University of Innsbruck

University of Leeds

University of New Hampshire

North Carolina State University

Stanford University

University of Utah

Yale University





Roll cloud over Owens Valley March 24 2004

From Grubišić and Cohn (2004)


T-REX Phase I

From Grubišić and Kuettner (2004)

From Grubišić and Cohn (2004)


Location of proposed Leeds masts

National

Forest

Service

Inyo

Valley

Dept. of

Water

Resources

Sierra

Bureau of

Land

Management





Sonic anemometer

Temperature

sensors

GPS aerial

Solar panel

Logger box

Batteries


T-REX IOP: March – April 2006

  • At least 28 10m towers

  • Wind profilers

  • Lidars

  • Radiosondes

  • NCAR Gulfstream

  • Univ. of Wyoming King Air

  • FAAM BAe146

  • 50 temperature loggers

  • 3 x 30m flux towers

  • Univ. Innsbruck mobile

  • met system


T-REX Phase II

Map: V. Grubišić in collaboration with the UCAR Joint Office of Scientific Support


T-REX Phase II

Typical flight plans

Schematic: V. Grubišić and

J. Doyle


Rotors – some key scientific questions

Climatology:

- frequency,preferred location

Dynamics

  • to establish the conditions required

  • for the formation of rotors

Modelling

- Ability of current models to predict the occurrence

of rotor events

- Model validation


Summary

Rotors pose a severe aviation hazard and have been cited

as being responsible for several major accidents.

Still poorly understood.

  • Preparations in place for the most comprehensive

  • field campaign to study rotors/lee waves ever made,

  • using AWS, lidars, aircraft, flux towers, …

  • Permissions granted for installation of a further 12

  • 10m towers: deployment early 2005

  • Phase I completed; some case studies already being

  • undertaken in the US


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