NATURAL HAZE LEVELS SENSITIVITY ASSESSMENT 3. Descriptive Analysis. Ivar Tombach

Transcription

1 NATURAL HAZE LEVELS SENSITIVITY ASSESSMENT 3. Descriptive Analysis Ivar Tombach Regional Haze Data Analysis Workshop 8 June 2005 (Minor revisions and corrections 13 June 2005) 1

2 Geographic Distributions of Current and Natural Hazes and Their Differences 2

3 Default Natural Conditions -- 20% Worst Days 3

4 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 4

5 Current ( ) 20% Worst Days 5

6 Ranking Current Conditions 20% worst days 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 6

7 Haze Reductions Required to Reach Default Natural Conditions 7

8 Rate of Haze Reduction to Reach Default Natural Conditions in

9 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 9

10 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.) 10

11 Current Annual Average AmmSO 4 Concentration Excess Over Default Natural Annual Concentration 11

12 Current 20% Worst Days AmmSO 4 Concentration Excess Over Default Natural Annual Concentration 12

13 Current Annual Average AmmNO 3 Concentration Excess Over Default Natural Annual Concentration 13

14 Current 20% Worst Days AmmNO 3 Concentration Excess Over Default Natural Annual Concentration 14

15 Current Annual Average POM Concentration Excess Over Default Natural Annual Concentration 15

16 Current 20% Worst Days POM Concentration Excess Over Default Natural Annual Concentration 16

17 Current Annual Average LAC Concentration Excess Over Default Natural Annual Concentration 17

18 Current 20% Worst Days LAC Concentration Excess Over Default Natural Annual Concentration 18

19 Current Annual Average Fine Soil Concentration Excess Over Default Natural Annual Concentration 19

20 Current 20% Worst Days Fine Soil Concentration Excess Over Default Natural Annual Concentration 20

21 Current Annual Average Coarse Matter Concentration Excess Over Default Natural Annual Concentration 21

22 Current 20% Worst Days Coarse Matter Concentration Excess Over Default Natural Annual Concentration 22

23 Summary -- Comparison of Component Concentrations Some current average concentrations are less than default natural concentrations Occurs for AmmNO 3, POM (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 23

24 Summary -- Comparison of Component Concentrations (cont d) 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/m 3 for AmmNO 3 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 24

25 Summary -- Comparison of Component Concentrations (cont d) 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. ==> Either current conditions for these components are already near natural levels or some default values are too high, or both. ==> Default concentrations need more regional variation than they have today 25

26 Regional Patterns of Current Reconstructed vs. Measured Fine and Total Mass Concentrations averages for Worst 20% Haze Days Goal: 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. 26

27 Difference Between Reconstructed and Measured Fine Mass 27

28 Ratio of Reconstructed to Measured Fine Mass 28

29 Difference Between Reconstructed and Measured Total Mass 29

30 Ratio of Reconstructed to Measured Total Mass 30

31 Summary -- Comparisons of Reconstructed and Measured Mass Concentrations Generally RCFM values are less than the measured quantities, except in Southern California (possibly because of large nitrate loss on weighed filter). The smallest ratios (RCFM/Measured FM < 0.8) are in Alaska and Hawaii. The largest (> 1.1) are in Southern California 31

32 Summary of Mass Comparisons (cont d) 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/m 3 ) occur at Great Smoky Mountains NP and nearby Class I areas (possibly because water retained on the filter is not accounted for in the reconstruction). 32

33 Summary of Mass Comparisons (cont d) 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). 33