Mountain Meteorology

Meteorology 5550

490 INSCC

TH 10:45 – 12:05

John Horel

Jim Steenburgh Photo: J. Horel

Mountains complement desert as desert complements city, as wilderness complements and completes civilization. Edward Abbey

Course Objectives and Content

Understand the influence of the earth’s orography upon weather and climate

First Half- John Horel Geographical controls of

mountain weather and climate Terrain-forced flows Flow interaction with complex

terrain

Photo: J. Horel

Course Content (cont.) Second half- Jim Steenburgh

Orographically modified cyclones Orographically trapped disturbances Orographic precipitation

Invited presentations Fire weather Air quality Avalanches Surface transportation

Houze 1993

Grading

40%: Homework, class participation, literature reviews

20%: Participation and writeup of results from field experiment

20%: 1st half quiz 20% 2nd half quiz

Source Material

Mountain Meteorology. D. Whiteman. 2000. Mountain Weather and Climate. R Barry. 1992. Atmospheric Processes over Complex Terrain. W.

Blumen 1990. Influence of Mountains on the Atmosphere. R.

Smith. 1979. Advances in Geophysics. 21. Additional Reading

Reading Assignments

Many available on-line. To save trees, you are to access them on-line from campus and print them as needed

http://ams.allenpress.com/amsonline/?request=index-html

First Reading Assignment First reading assignment: Barry, R. G. (1978): H. B. de

Saussure: the first mountain meteorologist. Bull. Amer. Meteor. Soc., 59, 702-5.

Summarize in a few paragraphs: (1) who Saussure was; (2) how did he make the measurements and what were his results regarding the decrease of temperature with height; (3) what other contributions to mountain meteorology did he make?

Due: via email at beginning of class on Aug. 30. Send to jhorel@met.utah.edu, Be prepared to discuss the reading during that class.

Field Project Analysis of wind circulations on ski-

jump slope Weather permitting

Set up on Friday September 28 Observations Saturday morning September

29 Takedown in afternoon

Requires planning in advance by class to design useful field project

Requires analysis of data after data collection completed

Photo: J. Horel

VTMX Workshop

September 10-12 Useful presentations on local wind circulations in

Salt Lake Valley Plan on attending a few hours at some point

instead of class on the 11th (and 13th?)

What is a mountain? Common usage:

600 m or more of local relief defines a mountainLess than 600m is a hill

High mountain/alpine areas (Troll 1973; Arct. Alp. Res., 5, 19-27):Relative to terrain featuresUpper timberlineSnow line

Himalayas: Photo credit: NASA/Science Photo Library

What are the effects of mountains? Substantial modification of synoptic or meso scale

weather systems by dynamical and thermodynamical processes through a considerable depth of the atmosphere

Recurrent generation of distinctive wx conditions, involving dynamically and thermally induced wind systems, cloudiness, and precipitation regimes

Slope and aspect variations on scales of 10-100 m form mosaic of local climates

(Barry 1992)

Effects of Mountains

Carruthers and Hunt 1990

Whiteman (2000)http://infoplease.lycos.com/ipa/A0001792.html

Precipitation

Barry 1992

Barry (1992)

Mountains % mountains as fraction of total land surface (land 30%) 0-1000 m 10% 1000-2000 m 3% 2000-3000 m 3% > 3000 m 4% Total 20%

Barry 1992 %mountain as fraction of earth 6%

Mt. Everest http://www.mteverest.com/ http://www.mnteverest.net/ http://www.m.chiba-u.ac.jp/class/respir/eve_e.htm http://www.newton.mec.edu/Angier/DimSum/

Him.Range Pix.html Height of Mt. Everest: 8848m(http://www.m.chiba-u.ac.jp/class/respir/hyoko_e.htm)

High Elevation Observatories Mt Washington

http://www.mountwashington.org/

Storm Peak Laboratoryhttp://www.dri.edu/Projects/SPL/

Geographical controls of mountain climate (Barry 1992)

Latitude Continentality Altitude Topography

Jeff Klein. SLC BLM)Jeff Klein. SLC BLM)

Thermally forced terrain circulations

Mountain-valley winds Slope flows Peter Sinks Experiment VTMX lake breeze

Flow Interaction With Complex Terrain

Photo: J. Horel

Buoyancy oscillations Flow over vs. around

obstacles Kinetic and potential energy

of flows Mountain waves Gravity wave drag Trapped lee waves

Downslope Windstorms

Conceptual models Observations Numerical studies Gap winds

L. Darby & R. Banta, ATDD/ETL

Other subjects

Orography and the General Circulation Mountain torque

Physiology of high altitude Climate change at high altitude

1st Homework Assignment Bring in a couple (to as many as you want) of

mountain and mountain weather related photos Be prepared to say a few words about 1-2 photos If you’re willing to allow use of the photos for this

class and future classes, scan the images on the PC in Rm 480 (details to be provided, but don’t leave them with me)

Due: whenever

Homework Assignment #2 (1) Find 5 interesting and useful internet web pages related to

mountain weather, mountain climates, or alpine environments (2) Send me in 1 email the web addresses with a 1-2 sentence

description of the content of each page (3) Provide at least 2 scientific, literary, or artistic (music/art)

definitions or descriptions of mountains. Not from dictionaries (4) Provide a reference/source for that definition and send it in

the same email as that used above Due August 30

Parameters used to define flow (Smith 1979)Parameter Symbol Units Typical Value

Mountain height h km 1

Width downstream Lx km 10

Width crossstream Ly km 100

Flow layer depth H km 1 PBL; 10 troposphere

Incoming windspeed u m/s 10

Incoming wind shear uz s-1 10-3

Stability frequency N s-1 10-2

Coriolis parameter f s-1 10-4

Buoyancy/reduced gravity

b = g m/s2 10-1