August 5, 2008

Special Feature: Beijing Aerosol Optical Depth

As the Olympic start approaches, so it seems does the haze. We have been using Rapidfire's subsetter with the .kmz feature, NOAA's HYSPLIT trajectory system, NOAA/NESDIS's host site for IDEA which is running MODIS AOD in near-real time and being captured and plotted by Hai Zhang of UMBC (this is not a publically available subset product, sorry). In the figure on the left, you can see the haze in a red-green-blue image (photograph-like) with overlays of three trajectories (red-500m above the surface, coming from the south; blue - 1500 m above the surface also coming from the south, and green - 3000 m above the surface coming from the east). The bubbles on the trajectories are spaced every six hours and arrive at Beijing at 0400 UTC on August 5. Unfortunately, the endpoint ended 23 miles west of Beijing but we'll fix that in the future posts.

On the right image, you can see the MODIS V5.27 AOD product (MOD04) run on the Aqua data. While there is a band of retrieved AOD ~ 1.0, the thickest part of the haze is interpreted as cloud by the processing system. There are clouds in the RGB image, certainly, but there also is just haze.

Posted by Ray Hoff at August 5, 2008 4:13 PM
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