1 aod to pm2.5 to aqc – an excel sheet exercise arset applied remote sensing education and...
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AOD to PM2.5 to AQC – An excel sheet exercise
ARSET
Applied Remote Sensing Education and Training
A project of NASA Applied Sciences
Pawan GuptaSalt Lake City, April 22-25, 2013
Exercise -1 – Converting AOD to PM2.5
Required Data
• PM2.5 mass concentration from ground monitors
• Satellite Derived Aerosol Optical Depth
• Meteorological Fields – only if working with multi-variable method
Exercise -1 – Converting AOD to PM2.5 to AQC …
STEP # 1 - Getting Satellite and Surface Data
• Obtained MODIS AOD data file from the NASA data server for your region/date/time of interest
(http://ladsweb.nascom.nasa.gov/) – from earlier exercise
• To get PM2.5 data for your region http://www.epa.gov/airdata/ad_maps.html)
Exercise -1 – Converting AOD to PM2.5 to AQC …
STEP # 2 – Collocating Satellite and Surface Data
•Run provided IDL code to obtained AOD at location of PM2.5 ground monitor --- from earlier exercise.
• Spatial and Temporal Collocation Methods• pick nearest pixel or average over 3x3 or 5x5 pixels• pick closest PM2.5 measurement from ground to satellite
over pass time
TerraMODIS (10:30)
AquaMODIS (1:30)
X XX X XXX
X XX X XXX
X XX X XXX
X XX X XXX
X XX X XXX
X XX X XXX
X XX X XXX
Temporal Collocation
Spatial Collocation
STEP # 2 Cont…
STEP # 3 - Developing Relationship between AOD and PM2.5
Exercise -1 – Converting AOD to PM2.5 to AQC …
Slope
Intercept
STEP # 4 - Estimating PM2.5 from Satellite AOD
0 10 20 30 40 50 60 700
10
20
30
40
50
60
70
f(x) = 0.561778050642814 x + 6.88390830600402R² = 0.559289151080337
Observed PM2.5 Mass Concentration
Estim
ated
PM
2.5
Mas
s Con
cent
ratio
n
Exercise -1 – Converting AOD to PM2.5 to AQC …
PM2.5= AOD*46.7 + 7.13
STEP # 5 - PM2.5 to Air Quality
Exercise -1 – Converting AOD to PM2.5 to AQC …
Online Tool
http://www.airnow.gov/index.cfm?action=resources.conc_aqi_calc
STEP # 5 - PM2.5 to Air Quality
Exercise -1 – Converting AOD to PM2.5 to AQC …
AQC - Est
AQC - Obs
Spatial Mapping of Pollution from Satellite
Creating Air Quality Category Map
Provide MODIS AOD file, slope and intercept to this code – will create AQC map
Spatial Distribution
July 4, 2012 --
For comparisons
http://www.airnow.gov/index.cfm?action=airnow.mapsarchivecalendar
Multiple Linear Regression Method
Required AOD and Meteorological Fields – more data processing, more expertise but
most of the time the product provides a more accurate PM2.5 estimation
Multiple Linear Regression Method
AOD, PM2.5 and Meteorological Data
Multiple Linear Regression MethodResults
0 5 10 15 20 25 30 350
5
10
15
20
25
30
35
f(x) = 0.88231112005876 xR² = 0.965752282966334
Observed PM2.5 Mass Concentration
Estim
ated
PM
2.5
Mas
s Con
cent
ratio
n
1 4 7 10 13 16 19 22 25 28 31 34 37 4005
101520253035
EPM2.5OPM2.5