U.S. Air Quality

Special Feature: Fires and Smoke in MesoAmerica

On May 21, we received an email from colleagues with questions about air pollution that parts of MesoAmerica (specifically, Honduras, Costa Rica and Nicaragua) were experiencing, starting on Friday May 18. There was concern about toxics and about the possibility of Saharan dust crossing the Atlantic. We'd been watching the northern Gulf of Mexico pretty closely, since it had been very smoky from the fires in Florida. So, we looked a little further south to see if we could figure out what was happening.

MODIS true color images told us there were many fires in Central America that entire week; for example, on May 15 and May 16. The MODIS image from May 19 showed significant smoke and clouds in the entire northern part of the region (left image below). This is confirmed by the NOAA NESDIS smoke and fire detection Hazard Mapping System (right).

The GOES aerosol optical depth images from May 20 showed quite a bit of smoke and haze across the Gulf of Mexico, Caribbean Sea, and off Pacific coast (left image). The NRL model indicated smoke on May 21 (right image, bottom right panel). The back trajectories varied depending on start time and location, but 72 hours runs pointed to mostly local sources (e.g., see HYSPLIT for May 19 and May 20). NASA's Earth Observatory did a story on these fires in Mexico and Central America, including an image of the fires on May 21.

So, our conclusion is the air pollution in MesoAmerica May 18-21 was dominated by locally generated smoke. But, what about Saharan dust? Well, it seems dust was present in some quantity in the Atlantic, as far west as northern South America, as indicated by the NRL model runs on May 19 and a very messy SeaWIFS image from May 18. While we don't believe dust from the Sahara was a major contributor to this event, it is possible there was a slight influence.

Posted by Jill Engel-Cox at May 21, 2007 11:07 PM