NATURAL HAZE LEVELS SENSITIVITY ASSESSMENT 3. Descriptive Analysis

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NATURAL HAZE LEVELS SENSITIVITY ASSESSMENT3.
Descriptive Analysis

• Ivar Tombach
• Regional Haze Data Analysis Workshop 8 June 2005

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Geographic Distributions of Current and Natural
Hazes and Their Differences
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Default Natural Conditions -- 20 Worst Days
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Default Natural Conditions (20 worst days)

• Mainly divided into East West regions,
  modulated by RH (no surprise!)
• All of East 11 dv
• Most of West 7 dv, except Pacific Northwest 8
  dv and Oklahoma 9 dv

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Current (1999-2003) 20 Worst Days
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Current Conditions20 worst days

• Ranking
• 1. (Clearest) Alaska, Rockies, Colorado Plateau,
  and Sonora Desert
• 2. Sierra Nevada/Cascades, except for
  substantially poorer visibility in southern half
  of California)
• 3. Northern Great Plains and West TX/eastern NM
• 4. New England, Upper Midwest, and Ozarks
• 5. (Haziest) New Jersey and inland Southeast,
  except that Southeast coasts are much clearer

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Haze Reductions Required to Reach Default Natural
Conditions
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Rate of Haze Reduction to Reach Default Natural
Conditions in 2064
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Needed Haze Reductions (current - default)

• Ranking
• 1. (Largest reductions needed) Southeast, next
  largest along Southeast coast and at Ozarks.
  Similar reductions needed in southern Sierra
  Nevada and some locations in Southern California
• 2. New England, northern border of the US,
  eastern OR, and West TX/eastern NM
• 3. Sierra Nevada, Sonora Desert, Idaho
• 4. (Smallest reductions needed) Alaska, Rockies
• Rate (dv/decade) (current - default)/6

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Comparison of Current Annual Average and 20
Worst Visibility Days Concentrations versus
Default Annual Averages, for Each Component of
Extinction in the IMPROVE Formula (Expressed as
concentrations in excess of the default annual
concentrations. Negative value means that default
concentration exceeds current measured value.)
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Current Annual Average AmmSO4 Concentration
Excess Over Default Natural Annual Concentration
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Current 20 Worst Days AmmSO4 Concentration
Excess Over Default Natural Annual Concentration
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Current Annual Average AmmNO3 Concentration
Excess Over Default Natural Annual Concentration
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Current 20 Worst Days AmmNO3 Concentration
Excess Over Default Natural Annual Concentration
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Current Annual Average OMC Concentration Excess
Over Default Natural Annual Concentration
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Current 20 Worst Days OMC Concentration Excess
Over Default Natural Annual Concentration
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Current Annual Average LAC Concentration Excess
Over Default Natural Annual Concentration
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Current 20 Worst Days LAC Concentration Excess
Over Default Natural Annual Concentration
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Current Annual Average Fine Soil Concentration
Excess Over Default Natural Annual Concentration
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Current 20 Worst Days Fine Soil Concentration
Excess Over Default Natural Annual Concentration
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Current Annual Average Coarse Matter
Concentration Excess Over Default Natural Annual
Concentration
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Current 20 Worst Days Coarse Matter
Concentration Excess Over Default Natural Annual
Concentration
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Summary -- Comparison of Component Concentrations

• Some current average concentrations are less than
  default natural concentrations
• Occurs for AmmNO3, OMC, fine soil, and/or coarse
  matter
• Occurs at areas in Alaska, Hawaii, mountains in
  West, near northern border of eastern half of US.
  Also, for soil and CM only, occurs in
  Appalachians from SW corner of NC northward

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Summary -- Comparison of Component Concentrations
(contd)

• Some current worst 20 day concentrations are
  also less than default natural concentrations
• Occurs for fine soil and/or coarse matter, and is
  within 0.01 µg/m3 for AmmNO3
• Occurs at areas in Alaska, north Pacific coast,
  northern Cascades, western Idaho, and in
  Appalachians from SW corner of NC northward
• Note though that soil and CM concentrations may
  not be very high (even less than average) on
  worst haze days, which are often driven by
  sulfates, nitrates, and RH

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Summary -- Comparison of Component Concentrations
(contd)

• If default concentrations represent averages for
  large areas of the country, one would expect that
  natural conditions averages at some sites would
  be below these regional averages. It is
  surprising how much this occurs with current
  conditions.
• gt Either current conditions for these
  components are already near natural levels or
  some default values are too high, or both.
• gt Default concentrations need more regional
  variation than they have today

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Regional Patterns of Current Reconstructed vs.
Measured Fine and Total Mass Concentrations
averages for Worst 20 Haze DaysGoal Look for
geographic patterns in the differences and ratios
that could be explained by missing or
misrepresented components (e.g., sea salt), which
could provide clues to refinements in the default
natural haze index calculations.
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Difference Between Reconstructed and Measured
Fine Mass
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Ratio of Reconstructed to Measured Fine Mass
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Difference Between Reconstructed and Measured
Total Mass
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Ratio of Reconstructed to Measured Total Mass
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Summary -- Comparisons of Reconstructed and
Measured Mass Concentrations

• Generally RCFM values are less than the measured
  quantities, except in Southern California. The
  smallest ratios (lt 0.8) are in Alaska and Hawaii.
  The largest (gt 1.1) are in Southern California
• The absolute differences are very nearly the same
  for fine and total mass, but the ratios are
  closer to 1 for total mass. The largest
  differences (nearly -4 µg/m3) occur at Great
  Smoky Mountains NP and nearby Class I areas.

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Summary of Mass Comparisons (contd)

• There is no obvious indication, except for
  Southern California, that the ratio of
  reconstructed to measured fine mass has any
  geographic biases. The total mass ratio appears
  to be lower in the western mountains (Rockies,
  Cascades, Sierra Nevada) than in regional lower
  terrain (discounting the southern Sierra Nevada).