Surface Roughness Evaluation Methods - AWMA

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Dan Dix and Meghan Barber of All4 Inc. present "Surface Roughness Evaluation Methods." The presentation describes why surface roughness is important, evaluation methods, and what impact each evaluation method has on modeling results.

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Surface Roughness Evaluation Methods - AWMA

  1. 1. Surface Roughness Evaluation Methods Guideline on Air Quality Models: The Path Forward Meghan Barber and Dan Dix mbarber@all4inc.com | ddix@all4inc.com 610.933.5246 March 21, 2013 www.all4inc.com Kimberton, PA | 610.933.5246 Columbus, GA | 706.221.7688
  2. 2. Agenda   Why evaluate surface roughness? Which evaluation methods were used? • AERSURFACE (13016) • Site Survey • Meteorological Monitoring  Why are these evaluation methods important? • Impact on modeling results. • Data representativeness considerations. • Results and Conclusions.
  3. 3. Surface Roughness and AERMET   Surface roughness is used in estimating planetary boundary layer parameters. Surface roughness should be: • Evaluated within 1 kilometer of the measurement site. • Evaluated within 30-degree arcs (if land use is variable).  3 AERMOD is particularly sensitive to variations in surface roughness. Your environmental compliance is clearly our business.
  4. 4. Four Example Sites Evaluated Eastern Pennsylvania Site 4 Central Pennsylvania Site Your environmental compliance is clearly our business.
  5. 5. Four Example Sites Evaluated Eastern Virginia Site 5 Western North Carolina Site Your environmental compliance is clearly our business.
  6. 6. AERSURFACE    6 Uses 12 30-meter segments USGS 1992 Land Use Land Cover (LULC) data to estimate surface roughness. 21 land use categories, each with an assigned seasonal surface roughness. For each sector, surface roughness is calculated as an inverse distance-weighted geometric mean. Your environmental compliance is clearly our business.
  7. 7. USGS Land Use Patterns Eastern Pennsylvania Site 7 Central Pennsylvania Site Your environmental compliance is clearly our business.
  8. 8. USGS Land Use Patterns Eastern Virginia Site 8 Western North Carolina Site Your environmental compliance is clearly our business.
  9. 9. AERSURFACE Results Virginia Eastern Pennsylvania Central Pennsylvania North Carolina Wind Direction Sector Average AERSURFACE Surface Roughness (meters) 0° - 30° 0.118 0.217 0.474 30° - 60° 0.132 0.101 0.185 0.419 60° - 90° 0.344 0.133 0.186 0.523 90° - 120° 0.226 0.142 0.375 0.494 120° - 150° 0.162 0.189 0.227 0.448 150° - 180° 0.218 0.191 0.177 0.432 180° - 210° 0.161 0.273 0.229 0.439 210° - 240° 0.204 0.269 0.345 0.885 240° - 270° 0.154 0.204 0.297 0.838 270° - 300° 0.126 0.198 0.226 0.452 300° - 330° 0.169 0.185 0.302 0.188 330° - 360° 9 0.124 0.113 0.118 0.219 0.321 Your environmental compliance is clearly our business.
  10. 10. Overhead Photo/Survey    10 Site visit to assess actual land use patterns and height of surface elements. Calculate an inverse distance weighted geometric mean surface roughness for actual land use patterns. Calculation is similar to that performed by AERSURFACE using LULC data. Your environmental compliance is clearly our business.
  11. 11. Overhead Photo Approach 11 Your environmental compliance is clearly our business.
  12. 12. Site Survey Land Use Patterns Eastern Pennsylvania Site 12 Central Pennsylvania Site Your environmental compliance is clearly our business.
  13. 13. Site Survey Land Use Patterns Eastern Virginia Site 13 Western North Carolina Site Your environmental compliance is clearly our business.
  14. 14. Overhead Photo Results Virginia Wind Direction Sector Eastern Pennsylvania Central Pennsylvania North Carolina Average Site Survey Surface Roughness (meters) 0° - 30° 0.083 0.099 0.354 30° - 60° 0.213 0.058 0.150 0.410 60° - 90° 0.304 0.059 0.258 0.294 90° - 120° 0.240 0.042 0.402 0.220 120° - 150° 0.236 0.069 0.191 0.214 150° - 180° 0.210 0.084 0.079 0.379 180° - 210° 0.157 0.226 0.075 0.338 210° - 240° 0.184 0.121 0.218 0.621 240° - 270° 0.170 0.136 0.599 0.485 270° - 300° 0.158 0.412 0.423 0.613 300° - 330° 0.148 0.187 0.134 0.483 330° - 360° 14 0.217 0.204 0.069 0.138 0.757 Your environmental compliance is clearly our business.
  15. 15. Overhead Photo Advantages/Limitations  Surface roughness is based on site-specific data (potentially more defensible): • More direct correlation to actual land use patterns. • Potential to avoid dependence on generic surface roughness values.   15 Time considerations for site visit and surface roughness calculations. Human biases. Your environmental compliance is clearly our business.
  16. 16. Meteorological Monitoring 16 Your environmental compliance is clearly our business.
  17. 17. Meteorological Monitoring Results Virginia - 10m Average Wind Direction Gustiness Sector Equation Surface Roughness (meters) Eastern Pennsylvania - 10m Central Pennsylvania - 10m Count Average Gustiness Equation Surface Roughness (meters) Count Average Gustiness Equation Surface Roughness (meters) North Carolina - 10m Average Gustiness Equation Surface Count Count Roughness (meters) 0° - 30° 0.330 17 0.198 1,135 0.105 346 0.189 1 30° - 60° 0.204 11 0.187 679 0.099 520 0.269 5 60° - 90° 0.354 1 0.254 424 0.097 434 0.186 65 0 0.305 160 0.058 35 0.245 47 90° - 120° 120° - 150° 194 0.329 60 0.223 46 0.344 124 150° - 180° 0.231 448 0.250 218 0.166 85 0.323 7 180° - 210° 0.315 388 0.203 609 0.126 325 0 210° - 240° 0.311 231 0.185 503 0.160 769 0 240° - 270° 0.274 974 0.230 3,758 0.117 4,092 0.367 57 270° - 300° 0.265 1,256 0.268 7,372 0.102 5,985 0.250 1,131 300° - 330° 0.220 1,836 0.296 2,488 0.110 1,970 0.255 1,487 330° - 360° 17 0.211 0.225 1,087 0.258 1,561 0.140 313 0.343 38 Your environmental compliance is clearly our business.
  18. 18. Meteorological Monitoring Advantages/Limitations     18 Surface roughness values are based on monitored, quality assured meteorological data that are continuously recorded. Equation can be added to datalogger software and continuously calculated. Requires operation of a meteorological monitoring station. 5-minute wind speeds must be great than 5m/s, leading to data gaps. Your environmental compliance is clearly our business.
  19. 19. Comparison of Results Gust AERSURFACE Site Survey 0.500 Surface Roughness (meters) 0.450 0.400 0.350 0.300 0.250 0.200 0.150 0.100 0.050 0.000 Eastern Pennsylvania Site 19 Your environmental compliance is clearly our business.
  20. 20. Comparison of Results Gust AERSURFACE Site Survey 0.700 Surface Roughness (meters) 0.600 0.500 0.400 0.300 0.200 0.100 0.000 Central Pennsylvania Site 20 Your environmental compliance is clearly our business.
  21. 21. Comparison of Results Gust AERSURFACE Site Survey 0.800 Surface Roughness (meters) 0.700 0.600 0.500 0.400 0.300 0.200 0.100 0.000 Eastern Virginia Site 21 Your environmental compliance is clearly our business.
  22. 22. Comparison of Results AERSURFACE Site Survey Surface Roughness (meters) Gust 10m Western North Carolina Site 22 Your environmental compliance is clearly our business.
  23. 23. Conclusions   Surface roughness evaluation should be based upon the most recent land use patterns and available information. Overhead photo evaluations and meteorological analyses are based on site-specific data: • Diminishes the uncertainty associated with the use of default land use information. 23 Your environmental compliance is clearly our business.
  24. 24. Contact Information Meghan Barber and Dan Dix mbarber@all4inc.com | ddix@all4inc.com 610.933.5246 ext. 18 www.all4inc.com Kimberton, PA | 610.933.5246 Columbus, GA | 706.221.7688

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