Winter Boundary Layer Experiment

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Winter Boundary Layer Experiment (WiBLEx)
Javier Fochesatto and Richard L.
Collins Atmospheric Science Group Geophysical
Institute. University of Alaska
Fairbanks Fairbanks, AK October 21, 2005
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Preliminary Objectives

• Preliminary running Experiment to Observe
• Stable BL Morphology
• Multi-Layered BL structure
• Waves and wave like propagation in Atmospheric
  waveguide structures
• Ice fog formation, intensification and
  dissipation
• Urban plume dispersion under stably-stratified
  multilayered conditions (in town power plant and
  University power plant)
• Cooling rate and development of near surface
  inversion
• Instrumental Site for ABL and Tropospheric
  Aerosols Monitoring

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Winter time BL morphology
Period December 1, 2004 to February 28, 2005
Potential temperature Vertical Profile (daily)
at 00Z - Fairbanks Airport Scale 240 300 K up
to 5 km.
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Lidar Ability to see waves and instabilities in
the BL
Evidence of the Dynamical Coupling between the
Residual Layer and the Developing Convective
Boundary Layer
Wave Activity between the Convective Boundary
Layer and the residual Layer. In Wave-like
phenomena during the morning transition in the
planetary boundary layer (pbl) a comparison with
water-tank experiments.
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Compact Eye Safe Backscatter Lidar System
Aerosols and Boundary Layer assessment in Arctic
Environment

• Laser wavelength 1.574 µm is in the Eye-Safe
  wavelength interval
• Adequate for Continuous Urban Environment
  Surveillance
• NIR wavelength is a merging technology between
  Communication and Atmospheric Science
• Higher Lidar Color Ratio than traditional
  wavelengths

Spectral Cross Section Ratio Aerosol/Molecules
for fine particulate matter PM 2.5
Eye-Hazard Factor Laser Fluence / MPE (?)
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CESBL (ESPDL) Characteristics
Current Instrument Specifications Operational Wave
length (NdYAGOPO) 1.574 ?m Peak
Energy 200 mJ PRF 10 Hz Pulse
Width 20 ns Beam Size 80 mm Beamwidths
Transmitter 1 mrad Receiver 0.5-3
mrad adjustable Receiver Diameter 30 cm
Detectors InGaAs-APD TEC
cooler Amplifiers Signal Conditioner gain
adjustable Maximum Scan Rate 5.0 deg.s -1  
Data Handling Number of Channels 2
(simultaneous at 100 MS/s) Sample Width
(resolution) 1.5 m maximum both channels Range
gates 20k points Pulses Averaged Selectable
Maximum throughput 1 M Sample/second Digitize
r Resolution 12 bits Storage PXI-1002
National Instrument On board digital processing
programmable digital filtering   Polarization
Properties Transmitted Vertical Polarization
gt 60 db purity Received Vertical
Horizontal 50 db accuracy Electrical and
physical characteristics Power
Requirements 110 VAC / 20 A Dimensions
Optical table 36 x 24 Scanning system
40x35x25 Weight 250 lbs
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Vertical and Horizontal deployment at the
Geophysical Institute

• Horizontal pointing measurements permits to
  determine the extinction in near surface and BL
  structure and aerosols dispersions in winter time

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CESBL Lidar Experiment BL Diurnal Cycle
Signatures on Summer time during Smoke Episode
June 29, 2005
GINA Modis Image Visible Channel June 29 , 2005
Birch Hill 1140 AM and 0330 PM
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Possible Experimental Sites
TVC - UAF Campus and Geophysical Institute (8th
floor)
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Instruments and Models that could be deployed
during the WiBLEx
1. LIDARS CESBL Scanning / deployable in any
platform / polarization diversity control
Multi-wavelength Aerosol / ABL Lidar 1,064 and
532 nm with polarization
channels, Raman Receivers for Water Vapor and
Nitrogen profiler 2. OP-FTIR Open Path FTIR
Spectroscopy Aerosol Microphysics and Gases in
the near surface 3. Turbulence Structure
Scintillometer, Doppler SODAR, Microbarograph
Array, sonic Anemometer 4. Basic Parameters
(P,T, RH, wind) 5. Radiation Measurements
Sun Photometer 1020, 940, 870, 670, 500, 440,
400, 340 Radiometers Visible (Total, Direct,
Diffuse), IR, UV-A, UV-B 6. Numerical Simulation
MM5 (WRF) CMAQ
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Previous Experiments

• Acoustic Soundings of the Fairbanks Temperature
  Inversions.
• Holgrem B., Spears L., Wilson C. and Benson C. in
  Climate of Arctic, pp 293-306. 1973
• Low Level Temperature Inversions in Fairbanks,
  Central Alaska.
• Wendler G. and Nicpon P. Mon. Wea. Rev. 103,pp
  34-44. 1974.
• Some measurements on the development of the
  surface inversion in Central Alaska during
  winter. Wendler G. and Jayaweera O. Pure and
  Applied Geophysics, 99, pp 209-221. 1972
• Relation entre la concentration en oxyde de
  carbone et les conditions météorologiques dans
  une communauté subarctique. Gerd Wendler. J.
  Rech. Atmos. IX, 3, pp 135-142. 1975
• Ice fog Low Temperature air pollution. C.
  Benson. Geophysical Institute Report. 1965.
• Radiative cooling rate in presence of ice crystal
  aerosols. Bowling A.S. PhD thesis, University of
  Alaska Fairbanks. (1970)
• Studies on ice fog, Geophysical Institute Report.
  Ohtake T. 1970.
• Lidar experiment in Fairbanks Ice Fog Glenn
  Shaw et al. Stanford Research Institute Report