Transcript PM 2.5 Exercise

AOD to PM2.5 to AQC –
An excel/IDL exercise
Pawan Gupta
Albany, NY, November, 2013
ARSET
Applied Remote Sensing Education and Training
A project of NASA Applied Sciences
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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
Temporal Collocation
Terra
MODIS
(10:30)
Spatial Collocation
Aqua
MODIS
(1:30)
STEP # 2 Cont…
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Exercise -1 – Converting AOD to PM2.5 to AQC …
STEP # 3 - Developing Relationship between AOD and PM2.5
Intercept
Slope
Exercise -1 – Converting AOD to PM2.5 to AQC …
STEP # 4 - Estimating PM2.5 from Satellite AOD
PM2.5= AOD*46.7 + 7.13
70
y = 0.5618x + 6.8839
R² = 0.56, R=0.75
Estimated PM2.5 Mass Concentration
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Observed PM2.5 Mass Concentration
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Exercise -1 – Converting AOD to PM2.5 to AQC …
STEP # 5 - PM2.5 to Air Quality
0 - 12.0
Online Tool
12.1 – 35.4
35.5 – 55.4
55.5 – 150.4
http://www.airnow
.gov/index.cfm?acti
on=resources.conc_
aqi_calc
Exercise -1 – Converting AOD to PM2.5 to AQC …
STEP # 5 - PM2.5 to Air Quality
AQC Obs
AQC Est
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=airno
w.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
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Estimated PM2.5 Mass Concentration
Multiple Linear
Regression
Method
Results
EPM2.5= OPM2.5*0.8823x
R² = 0.8582, R=0.93
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Observed PM2.5 Mass Concentration
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EPM2.5
OPM2.5
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