Comparing Aircraft Measurements of Atmospheric Compounds with a Regional Photochemical Model

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Comparing Aircraft Measurements of Atmospheric
Compounds with a Regional Photochemical Model

• by Jennifer Schiffelbein
• CE 394K GISWR
• Fall 2003

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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

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Description of DataAircraft

• 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!)

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Description of DataModel

• Predicts chemistry of atmosphere over time
• Inputs emissions, temperature, meteorology
• Time scale 1 hour
• Structure 3-D grid

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Description of DataModel

• 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

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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

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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

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Completed Work

• Generate grid
• Example 2x3 grid result

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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

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Completed Work

• Generate polygon
• Example results

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Completed Work

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

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Future Work

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

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Future Work

• Spatial issues
• 1.) Exclude all points outside domain

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Future Work

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

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Future Work

• Spatial issues
• 2.) Which vertical layer?

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Future Work

• Spatial issues
• 2.) Which vertical layer?
• Decisiion Assign points ½(hi1-hi)
• -½(hi-hi-1) to layer at hi

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Future Work

• Temporal issue
• Model hourly species concentration
• Example 100 pm, CO conc. 50 ppb
• 200 pm, CO conc. 40 ppb
• Aircraft second by second concentrtion
• Example 13208 pm, CO conc. 46 ppb
• How assign time intervals for comparison?
• Aircraft points with time between
• 131 to 230 with 200 model
• 231 to 330 with 300 model

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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

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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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• ? Q ?
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