Regional Haze is a Complex 8-Dimensional Problem

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• Regional Haze is a Complex 8-Dimensional Problem
• Aerosol Concentrations x Compositions x Size
  Distributions x Optical Properties x
  Latitude x Longitude x Altitude x Time,
• IMPROVE Data provide Site-Specific Information
  on Concentrations Compositions at the Surface,
• But Information on Particle Size, Optical
  Properties, (3D) Spatial
  Patterns Temporal Patterns is limited.
• Sources of Supplemental Regional Haze-Related
  Data
• Collected, Archived Distributed (with Other
  Objectives)
• Large Spatial Coverage (National - Global)
• High Spatial and/or Temporal Resolution
• Extractable Information Content Space, Time,
  Size, Optics, etc.

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• Collected, Distributed Archived with Other
  Objectives
• Large Domain Spatial Coverage (National -
  Global)
• High Spatial and/or Temporal Resolution
• Info on Aerosols Space, Time, Size Optical
  Properties

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IMPROVE Northeast Sulfate Event July 17, 1999
(Data available from VIEWS about 1 Year after
Event)
NAAPS Forecast Sulfate Aerosol July 17, 1999
Data Available from NRL about 5 Days Before Event)
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NAAPS Modeled Bext RH along JFK Jr. Flight
Path, 7/16/99
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NAAPS Model Data for Lye Brook IMPROVE site,
July 99 Sulfate Time Series and Vertical
Profile, Remodeled with Emissions Reductions
(Greater Midwest includes parts of Mane-VU,
VISTAS, CENRAP MRPO)
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Are There Areas of Common Interest between NRL
RPOs?
NAAPS Model is a Work in Progress
- For 7/17/99, SO4 formation
Underestimated, - Smoke Dust
Emissions Need Improvement, - Ground
Truth Evaluation Verification?
Under-estimates SO4
Over-estimates SO2
NAAPS Model - Our Current Work 1.
Improve the dust source function 2. Verify the
sulfate simulations
3. Identify/implement daily global
smoke emissions 4. Improve the microphysics
chemistry.
Sum is Just About Right
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Assessing Air Quality Using USDA
Shadow-band RadiometersJames SlusserUSDA UV-B
Monitoring and Research ProgramNatural Resource
Ecology LaboratoryColorado State University
http//uvb.nrel.colostate.edu/UVB/home_page.html
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Purposes of USDA UVB Monitoring and Research
Program

• Furnishes basic information necessary to support
  research on potential damaging effects of UVB on
  agriculture, forests, and livestock
• Provides UV climatology data to agricultural and
  scientific researchers
• Supplies ground truth for satellite retrievals
  and model development
• Establishes long-term record of UVB to assess
  trends

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USDA INSTRUMENTATION
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Three measures of aerosol and smoke
loading Aerosol optical depth (AOD) quantifies
the attenuation of the direct Solar beam. The
AOD is proportional to total column loading of
particles of the same size and related to
visibility. (Increases as Bext
Increases vertically) Angstrom exponent
(alpha) gives the wavelength dependence of the
AOD. Large particles (such as cloud drops or ice
crystals) are spectrally neutral (alpha close to
0). The very smallest particles , molecules,
have an inverse (wavelength) to the fourth
dependence (alpha equal to 4). Most aerosols
have alpha between 1 and 3. (Increases as
Particle Size Decreases) Single scattering
albedo (SSA) is the ratio of scattering to
scattering plus absorption. For non absorbing
(sulfate and water) particles SSA equals 1.0.
Aerosols with black carbon have SSA between 0.7
and 0.9. (Decreases as Particle Absorption
Increases)
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Direct, Indirect (Scattered), Total Solar
Radiation Available for 12 Wavelength Bands,
3-Minute Time Resolution For about 35 sites,
Distributed throughout US S. Canada Updated
Near-Real Time, every 24 hours
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Wavelength-Specific Aerosol Optical Depth at
Beltsville, MD for beginning of
Quebec Fire Smoke Event July 7, 2002 (note
Saturation for shorter wavelenths starting 1200)
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Sulfate Event Beltsville, MD 7/17/99
Most Radiation Diffuse, but Small Reduction of
Total High AOD High Bext (vertically) Single
Scat. Albedo 1, indicates non-adsorbing
(scattering-only) aerosol. Decreasing Angstrom
exp. Increasing Particle Size
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Smoke Event Baton Rouge, LA 5/15/98
Most Radiation Diffuse, Large Reduction of
Total High AOD High Bext (vertically) Angstrom
exp. gt 1 Small Particle Size. Single Scat.
Albedo lt 1, indicates adsorbing (and scattering)
aerosol.
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Logistics

• Basic cost around 12,500
• Requires 110 VAC and phone line OR batteries and
  memory card
• Can be polled in real time as Web site
• Calibration is established in situ during clear
  days
• Wind and ancillary instruments can be logged as
  well
• USDA would be willing to assist with data
  analysis on a per cost basis

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Are There Areas of Common Interest between
USDA-UVB RPOs?

• Visible Shadow-band radiometers provide aerosol
  and cloud information critical to forest fire and
  air quality studies.
• Low cost (12.5K) and automated operation are
  attractive features.
• This method provides fine temporal resolution
  useful for studying smoke and pollution plumes.
• Ancillary information (e.g. T, RH, wind speed and
  direction) can be logged simultaneously.
• USDA would be glad to work with State and Federal
  agencies on data analysis (would require about
  0.5 FTE for routine data processing).

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The ASOS Visibility Sensor

• The ASOS visibility sensor is a forward
  scattering instrument
• Replaced Hourly Human Observers in about
  1995-96
• Better Quality Extinction Data, But Need QA
  and Archived Data are Averaged,
  Binned, Truncated (Need Direct Access Routine
  Processing)

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ASOS Stations from FAA, NWS and Archived at NCDC
For this analysis (Husar, 2002) data for 220
stations were available from NCDC
These ASOS sites are mostly NWS sites, uniformly
distributed over the country (Imagine if we could
get the entire set, including the DOD sites, not
listed).
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Comparison of Sites with Duplicate ASOS Sensors

• Co-located ASOS sensors are installed at
  different runways of the same airport.
• Dual ASOS sensors (55) are distributed uniformly
  over the 800 station network
• Triple sensors are particularly useful for sensor
  calibration and consistency checking

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Duplicate Sensors Good Sites
Dallas-FW, TX
Erie, PA
San Diego, CA
Houston, TX

• At several duplicate sites the 2-sensor
  correlation is excellent and the absolute values
  also match.
• This indicates that the scattering sensor per se
  has high precision and temporal stability.

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Duplicate SensorsPoor Sites

• Duplicate sensors at some sites show significant
  deviation in scale and offset.
• The nature of these deviations indicate poor
  instrument calibration maintenance for the ASOS
  visibility sensors.

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ASOS Bext Threshold 0.05 km(-1)
Reported by NWS

• The Bext values below 0.05 km-1 are reported as
  0.05.
• For Koschmieder coeff K3.9, this threshold
  VR78km( 50 mile) for K2 VR40km(25mi)
• In the pristine SW US, the ASOS threshold
  distorts the cleaner day data
• Over the East and West, the (raw data) ASOS
  signal is well over the threshold most of the
  time (although Archived data are Truncated at 10
  mi.)

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Typical Diurnal Pattern of Bext, Temperature
Dewpoint

• Typically, Bext shows a strong nighttime peak due
  to high relative humidity.
• Most of the increase is due to water absorption
  by hygroscopic aerosols. At RH gt90 , the aerosol
  is mostly water
• At RH lt 90, the Bext is mostly influenced by the
  dry aerosol content the RH effect can be
  corrected.

Macon, GA, Jul 24, 2000
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Adopted RH Correction Curve (To be validated for
different locations/seasons)
RH is calculated from T Temperature, deg C and
D Dewpoint, deg C RH 100((112-(0.1T)D)/(112
(0.9T)))8

• The ASOS Bext value are filtered adjusted for
  high humidity
• Values at RH gt 90 are not used
• The Bext is also corrected for RH RHCorrBext
  Bext/RHFactor

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Seasonal Average Diurnal Bext Pattern

• For each minute of the day, the data were
  averaged over June, July and August, 2000
• Average Bext was calculated for
• Raw, as reported
• For data with RH lt 90
• RH lt 90 and RH Corrected
• Based on the three values, the role of water can
  be estimated for each location

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Location of ASOS and Nearby Hourly PM2.5 Sites

• There are no co-located ASOS and PM2.5 sites
• The stations are not co-located but in the same
  city
• Hourly PM2.5 data are compared to the filtered
  and RH-corrected one minute Bext

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ASOS-Hourly PM2.5 Allentown, PA

• RH-Adjusted Bext is a good surrogate for
  PM-2.5, and
• RH-Screened Bext is good surrogate for PM-2.5
  H2O

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Des Moines, IA
Grand Rapids, MI
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Islip, Long Island, NY
San Diego, CA
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• Are There Areas of Common Interest between ASOS
  Data Providers RPOs?
• ASOS Sites are Spatially Dense (1000 sites),
  Evenly Distributed (airports everywhere just out
  of town, and Have High Temporal Resolution
• Currently Archived Data are Averaged (1-hour),
  Truncated (at gt 10 miles) and Binned (into VR
  categories lt 10 mi.) but,
• Are Useful for evaluating Episodes, even in
  their current form, but
• Require Expert Processing to extract aerosol
  haze-relevant Info, and
• Could be extraordinarily Useful if
• We could access them in near-real time (
  historical),
• In their raw, uncensored form (1-minute
  uncensored Bext RH),
• From any all sites, and Processed for
  Haze-Relevant Info, and
• Merge them with other Haze-Related data