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Regional plots of MODIS aerosol optical depth (AOD), ta and cloud optical thickness

Sample regional plot of MODIS AOD

Sample MODIS ta plot

The Regional plots are defined by US EPA (Environmental Protection Agency) Regions, with Regions 1-3 combined into one view. Regions 4-10 are separate plots. The Regional plots show four parameters: daily MODIS (the Moderate Resolution Imaging Spectroradiometer) aerosol optical depth (in color contours), daily MODIS cloud optical thickness (in gray contours), and locations of in-situ continuous PM2.5 (Particulate Matter with a diameter smaller than 2.5 microns) monitors (white dots).

MODIS derived aerosol optical depth, ta

The MODIS ta used for these plot is based on the MOD04_L2 aerosol product (Kaufman and Tanré 1998) and is from the MODIS sensor aboard the Terra satellite and the Aqua satellites. Terra has a descending orbit and a 10:30am equatorial overpass time, while Aqua has an ascending orbit and a 1:30pm equatorial overpass time. The predicted and actual overpass time for a given day can be found at, and, respectively. The MODIS ta is at a 10 x 10 km^2 spatial resolution and is plotted on a scale of 0.0 to 1.0 with ta > 1.0 shown as dark red.

MODIS cloud optical thickness (COT)

The MODIS COT used for these plots is based on the MOD06_L2 cloud products (King et al., 1998) and is from the MODIS sensor aboard the Terra satellite with a descending orbit and a 10:30 equatorial overpass time. A ta is not derived for cloud filled pixels, therefore the clouds fields derived from MODIS are plotted to help define synoptic weather features important to the movement of aerosols.

In-situ continuous PM2.5 monitors

The geographic coordinates of each continuous PM2.5 monitor location from the State and Local Air Monitoring Stations (SLAMS) and National Ambient Monitoring Stations (NAMS) is represented by the symbol () on the map. These locations are plotted to help provide a visual geo-referenced location to nearby MODIS pixels.

MODIS aerosol optical depth and cloud optical thickness data is being obtained from NASA (National Aeronautics and Space Administration) through MODIS Direct Broadcast (DB).

In-situ PM2.5 mass concentration data is being obtained from the US EPA AIRNow Program in cooperation with State and Local Air Agency Partners

NAM meteorological data is being obtained from the Air Resource Laboratory of OAR/NOAA

We'd like to thank Liam Gumley at CIMSS of University of Wisconsin for helping us develop MODIS AOD images in KML and GEOTIFF format.

Kaufman & Tanre, 1998: Algorithm for Remote Sensing of Tropospheric Aerosol from MODIS. Products: MOD04, MOD08. ATBD Reference Number: ATBD-MOD-02.
King, Tsay, Platnick, Wang, & Liou, 1998: Cloud Retrieval Algorithms for MODIS: Optical Thickness, Effective Particle Radius, and Thermodynamic Phase. Products: MOD06, MOD08. ATBD Reference Number: ATBD-MOD-05.

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