October 6, 2009
Another Quiet Air Quality Day for the U.S.; Interesting Set of Tropical Cyclones in Northwest Pacific
Today was yet another day of predominantly Code Green (Good) air quality conditions across the U.S., with a few scattered Code Yellow (Moderate) readings. AIRNow has updated their website, and unfortunately they decided to combine the previously separate maps of ozone and PM2.5 AQI values. The new combined loop of ozone and PM2.5 AQI values is below on the left. As a result of these changes, it's no longer straightforward for us at U.S. Air Quality (or anyone else) to analyze current air quality conditions. We are encouraging EPA to bring back the separate maps. In the interim, AIRNow makes maps of preliminary PM2.5 data; the loop of AQI values is below on the right. Based on these data, and the fact that the ozone season is over at most locations, the scattered Code Yellow (Moderate) values in the AIRNow loop are likely due to PM2.5.
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On Wednesday, air quality is expected to continue in the Code Green range for almost the entire nation. Much of the central and eastern portions of the country are under the influence of a strong extratropical cyclone (low pressure system) that is currently centered over the Upper Midwest. The location of the low pressure center, trailing cold front, and associated cloud cover are evident in today's MODIS Terra true color image, overlaid with the synoptic analysis and Wednesday's forecasted AQI values (below in Google Earth). The cloud cover, strong winds, and precipitation associated with this system will keep air quality conditions good for the next several days in the Eastern U.S.
Elsewhere, there is an unusual set of tropical cyclones in the northwestern Pacific Ocean. The NASA Earth Observatory is featuring a stunning combined Terra and Aqua MODIS true color image of the two storms, Typhoon Melor and Tropical Storm Parma. Parma was recently in the news because it made landfall in the Philippines and brought devastating rain and strong winds to the island nation. The tropical cyclones are unusual because the circulation of the stronger Melor has caused Parma to reverse course and move toward it. The current locations and tracks of the two storms (courtesy of GuiWeather) are below on the upper left, in Google Earth. Recent infra-red satellite images of the two storms are below on the lower left (Melor) and right (Parma), courtesy of the Joint Typhoon Warning Center.
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