Visualizations - Inscc.utah.edu - University of Utah

inscc.utah.edu

Visualizations - Inscc.utah.edu - University of Utah

Boundary Layer Meteorology


LES of passive scalar in a convective boundary layer

(grid size = 20 m)


(from Stevens 2005, after Arakawa 1975)


Time-lapse video of fog in Salt Lake Valley

Jan 26 and Feb 2, 2006


Acold-air pool (CAP), defined as a topographic depression filled with cold air,

occurs when atmospheric processes favor cooling of the air near the surface,

warming of the air aloft, or both. The resulting stable stratification prevents the

air within the basin from mixing with the atmosphere aloft while the surrounding

THE PERSISTENT COLD-AIR

POOL STUDY

BY NEIL P. LAREAU, ERIK CROSMAN, C. DAVID WHITEMAN, JOHN D. HOREL,

SEBASTIAN W. HOCH, WILLIAM O. J. BROWN, AND THOMAS W. HORST

Utah's Salt Lake valley was the setting for a wintertime study of

multiday cold-air pools that affect air quality in urban basins.


FIG. 2. Photos of key PCAPS instrumentation. See Fig. 1 for location of instruments. (a) NCAR ISFS, (b) University

of Utah automatic weather station, (c) University of Utah Hobo temperature dataloggers, (d) University of Utah

scanning Doppler lidar, (e) and (g) NCAR ISS sites, (f) University of Utah minisodar, (h) University of Utah mobile

radiosonde launch, (i) University of Utah mobile weather stations, and (j) instrumented motorized paraglider.


(NWS) soundings deployed at the nearby Salt Lake

International Airport (Fig. 1). The temporal interval


FIG. 2. Photos of key PCAPS instrumentation


FIG. 4. Photos of SLV inversions during PCAPS (photo credits are in parentheses): (a) 14 Jan 2011: combined fog

and pollutants (Sebastian Hoch); (b) 2 Dec 2010: cloud-free deep (~700 m) polluted layer (Chris Santacroce);

(c) 16 Jan 2011: thin surface layer (


king due to sharp vertical gradients in

d aerosols (e.g., Fig. 4c).

table layers were observed on many ocg

PCAPS (Fig. 5f, IOP 5), generally ariso

or more of the processes that control

ty. In this particular case, two elevated

surface local-scale forcing influenced its for

maintenance, and breakup. The thermod

signatures of these processes are summarized

which shows a time–height diagram of poten

perature within and above the SLV as measu

combination of ISS and NWS radiosondes.


METCRAX

(Meteor Crater Experiment)


METCRAX II Field Equipment!


Meteor Crater, 22-23 Oct 2006! • Strong 30-m

deep inversion

on crater floor !

• Isothermal

atmosphere in

remaining 75% of

crater depth!

• Temperature

jump develops at

rim level!

• Crater cools

while remaining

isothermal!

What physical process(es) produce the isothermalcy?!


Downslope-Windstorm-type Flow

Conceptual model - DWF!


Would you like to gain some meteorological field experience? The Meteor

Crater II (METCRAX II) experiment will be run this fall looking at nighttime

hydraulic flows and hydraulic jumps at Arizona's Meteor Crater. Helicopter

loading operations will be conducted in early to mid-September, the

equipment setup is scheduled for 25-29 September, the one-month field

experiment will be run from 30 September through 30 October, and

equipment takedown will take place 31 Oct - 2 November. We could use

assistance with all of these operations.

By participating, you could gain experience with hands-on operation of

tethersondes, rawinsondes, scanning Doppler LiDARs, automatic weather

stations, HOBOS, flux towers, tall instrumented towers, SoDARs and other

meteorological instruments. The field study is being supported by NCAR's

Earth Observing Laboratory, and they are providing some of this equipment

and bringing additional instruments and resources to the field. There will be

unique opportunities to enter the Meteor Crater to fly tethersondes at night

from the crater floor during Intensive Operational Periods.

If you would like to know more about the Meteor Crater, we have a webpage

at http://www.inscc.utah.edu/~whiteman/METCRAX/ where you can look at

photographs and other information from our previous experiment there in

October 2006.

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