Comparing Aircraft Measurements of Atmospheric Compounds with a Regional Photochemical Model

1. Comparing Aircraft Measurements of Atmospheric Compounds with a Regional Photochemical Model by Jennifer Schiffelbein CE 394K GISWR Fall 2003

2. Outline • Description of Model and Aircraft Data • TexAQS 2000 (Southeast Texas) • Completed Work • Creating grids & polygons with ArcInfo • CAMx Projection • Future Work • Spatial & Temporal issues • Interpolation

3. Description of Data:Aircraft • Electra aircraft • NOAA • Data collected • Position (GPS x,y,z) • Air analysis: CO, NOx, O3, PM, VOCs….. • Meteorological • Data frequency: 1 per second • Duration: 6-7 hours (~26,000 points!)

4. Description of Data:Model • Predicts chemistry of atmosphere over time • Inputs: emissions, temperature, meteorology… • Time scale: 1 hour • Structure: 3-D grid

5. Description of Data:Model • Structure • Chosen domain: Houston/Galveston (HG) • Box = 1 km x 1 km x variable height (m) • Horizontal extent: 74 cells x 74 cells • Vertical extent: 21 layers from 0 (ground) to 4106 m

6. Completed Work • Generate grid (“fishnet”) Example: 2x3 grid • ArcGIS/ArcInfo Workstation/Arc Arc: workspace mydirectory Arc: generate stockings Generate: fishnet Fishnet Origin Coordinate (X,Y): 0,0 Y-Axis Coordinate (X,Y): 0,2 Cell Size (width, height): 1,1 Number of Rows, Columns: 2,3 Generate: quit *Italics = prompts *mydirectory = z:\uteid, or c:\mystuff *red text = name of file you must specify

7. Completed Work • Generate grid • Make map displayable Arc: clean stockings drawer Arc: build drawer poly Arc: addxy drawer Arc: quit(to close Arc window) -Directory “drawer” contains “polygon” grid shapefile -“addxy” assigns x-y coordinate to center of each grid cell *Italics = prompts *mydirectory = z:\uteid, or c:\mystuff *red text = name of file you must specify

8. Completed Work • Generate grid • Example: 2x3 grid result

9. Completed Work • Generate polygon Example: 1000x1000 box Arc: generate bigbox Generate: polygons : ID, {AUTO | X,Y}: 1, auto X,Y: -1000,0; -1000, 1000; 0,1000; 0,0 X,Y: end ID, {AUTO | X,Y}: end Generate: quit *Clean “bigbox” & build as with grid

10. Completed Work • Generate polygon Example results

11. Completed Work • CAMx Projection • Projection type: Lambert Conformal Conic • First true latitude: 30°N • Second true latitude: 60°N • Latitude of origin: 40°N • Central meridian: 100°W *Earth datum: Perfect sphere, radius = 6370km *BUT ArcGIS only offers r ~6371 km -exact projection difficult to create

12. Future Work • Spatial issues: *Filter aircraft data points by 1.) Is aircraft within HG domain? 2.) Which vertical layer is aircraft in?

13. Future Work • Spatial issues: 1.) Exclude all points outside domain

14. Future Work • Spatial issue: 2.) Which vertical layer is aircraft in? -Horizontal slice -Vertical slice

15. Future Work • Spatial issues: 2.) Which vertical layer?

16. Future Work • Spatial issues: • 2.) Which vertical layer? • Decisiion – Assign points +½(hi+1-hi) & -½(hi-hi-1) to layer at hi

17. Future Work • Temporal issue: • Model hourly species concentration Example: 1:00 pm, CO conc. = 50 ppb 2:00 pm, CO conc. = 40 ppb • Aircraft second by second concentrtion Example: 1:32:08 pm, CO conc. = 46 ppb • How assign time intervals for comparison? • Aircraft points with time between *1:31 to 2:30 with 2:00 model *2:31 to 3:30 with 3:00 model

18. Future Work • Interpolation • Spatial Analyst – Interpolate to Raster *Try & compare 2-3 methods *Consider ~small, spatially concentrated points for each time interval and vertical layer

19. Concluding Remarks • Complex problem • 3 dimensions and time must be considered • Large volume of data • 74x74 cells = 5476 grid cells per layer • ~26,000 aircraft data points

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