Enhancement
of atmospheric aerosol research at the University of Wyoming
W. M. Keck Foundation,
$800,000, January 2000 - January 2003
PIs: Terry Deshler, Derek
Montague, Gabor Vali, Perry Wechsler
Principal scientist: Peter Liu,
June 2000 - July 2005
Support was received to accomplish two broad objectives.
1) To develop an aerosol
laboratory capable of
generating
aerosols of known size, number concentration, and composition in a
pressure/temperature controlled environment large enough to accommodate
balloon/aircraft
borne
instruments. 2) To add aerosol
instrumentation to the University of
Wyoming’s
research aircraft, a National Science Foundation facility, and to
the
aerosol laboratory to measure optical
scattering, black carbon, aerosol composition, and
aerosol
size distribution in the range from 10
- 10,000 nm.
Keck Atmospheric Aerosol Research
Laboratory:: The aerosol laboratory (~50 m2), dedicated in May
2004, is
available within the Department of Atmospheric Science of the
University of Wyoming for testing and characterizing aerosol
instruments. The
laboratory includes a filtered air supply for aerosol generation and
dilution, and vacuum ports for sample flow control via the use of
critical orifices. Flows are calibrated routinely with Gilian and
Bios flow meters. The laboratory is equipped with new aerosol
generation systems, capable of generating monodisperse aerosol of
various size (10 - 20000 nm), composition, and concentration.
Aerosol generation systems include a TSI 3940 Sub-micrometer
Monodisperse Aerosol Generation System and a TSI 3450 Vibrating Orifice
Aerosol Generator for producing super-micrometer particles. It
also contains several instruments for monitoring and measuring
aerosols, including an aerosol electrometer, used for calibrating
condensation particle counters, of which four (TSI model 3010) are
available. In addition, there are two Scanning Mobility Particle
Counters (SMPS) (TSI model 3936L10) for the measurement of
sub-micrometer particle mobility size distributions, and an aerodynamic
particle sizer (APS) (TSI model 3321) for the measurement of
aerodynamic and optical size distributions of particles in the 500 to
20000 nm range. Also available is a PMS optical particle counter
(PCASP100-X) that measures particle size distributions between 120 and
3000 nm. Particle composition is determined with an Aerodyne
aerosol mass spectrometer. Counting of cloud condensation nuclei
is achieved with two static thermal-gradient cloud condensation nucleus
counters, built in-house. Aerosol optical properties can be measured
with a Magee AE-16 single wavelength (880 nm) aethalometer for
absorption extinction, and three nephelometers for particle scattering,
two of which are Radiance M903 single wavelength (530 nm)
instruments. The third is a TSI 3563 high sensitivity
3-wavelength integrating nephelometer with backscatter feature.
The data from the various instruments are collected via a
Windows/Labview based data acquisition system or via proprietary
software from the instrument manufacturers. The laboratory also
contains a large environmental chamber capable of simulating
atmospheric conditions with pressures down to 1 Torr and temperatures
as low as -70ºC, for characterizing aerosol and other
instrumentation under ambient conditions likely to be experienced
throughout the troposphere and stratosphere. The Keck Laboratory is
situated on the top (6th) floor of the Engineering building of the
University of Wyoming, and is equipped with a rooftop inlet for ambient
air sampling.
Scientific results from the laboratory:
Causes of Concentration Differences
Between a Scanning Mobility Particle Sizer and a Condensation Particle
Counter, AAAR 2003
Liu, P. S. K., and T. Deshler, Causes
of
concentration
differences between a scanning mobility particle sizer and a
condensation particle counter, Aerosol
Sci. Technol., 37,
916-923, 2003.
Performance of a Scanning Mobility
Particle Sizer at pressures between 500 - 780 mbar, AAAR 2004
Experimental Determination of the
Collection Efficiencies of the Aerodynamic Lens in the Aerodyne Aerosol
Mass Spectrometer, AAAR 2004
Experimental Determination of
the Transmission Efficiency of the Aerodynamic Lens in the Aerodyne
Aerosol Mass Spectrometer, European Aerosol Conference, 2005