Agricultural fires in the Central Plains continue to burn, as shown in the MODIS Aqua "true color"/rgb image. Red dots in the image indicate the locations of today's active fires. Smoke associated with these fires yielded AOD values ranging between 0.1-0.3 over this region. The smoke was also visible over the Southeast coast states moving offshore into the Atlantic Ocean (bottom right image). PM2.5 AQI levels reached Moderate (Code Yellow) levels in Southern states as pollutant dispersion was limited by a surface high pressure that produced light winds.

A broad front extending from Canada to the Gulf of Mexico moved eastward today, carrying with it the aerosol load that gave rise to a broad band of Moderate Air Quality. Smoke continues to be generated in the upper midwest as spring moves north and farmers continue to clear their fields with stubble burning.

The USDA Large Incident Map shows the clusters of fires in the midwest and southeast which are largely agricultural in origin. There is only one wild fire in Arizona which is listed in the IMT2 category.

PM2.5 AQI levels reached Moderate levels today along the Great Lakes and Mid-Atlantic States.Humidity, light winds and transport aloft of smoke from agricultural fires in the Great Plains might have contributed PM2.5 formation. High AOD east of the Rocky Mountains and Central Plains states is associated with fire and smoke activity over this region and discussed here in past days.

Regarding Ozone AQI levels, we have Moderate AQI levels as well in the same locations as PM2.5. South Central California and Northeastern Ohio also experienced Code Orange AQI levels. Tropospheric NO2, an ozone precursor, satellite retrievals show high concentrations along metropolitan areas in the vicinity of Toronto, Detroit, Pittsburgh, Philadelphia, Baltimore, and Washington DC .

The first image, courtesy NOAA HMS, shows the widespread fire and smoke activity in the Great Lakes and Plains regions of the U.S. These fires are mostly concentrated within these regions and are producing a large smoke plume over the regions. Theses smoke plumes are increasing the AOD in the regions, as can be seen in the next image, courtesy MODIS Aqua. There is also a large increase in AOD in the Southwest region, which is mainly due to dust.

The first image below, courtesy NRL NAAPS, shows the total optical depth for 18:00 Z. There appears to be strong dust activity in some of the same regions in the MODIS AOD plot above. The next image is from GEOS-Chem, which shows the total AOD at 550 nm. This shows strong amounts of Saharan dust being transported towards the U.S. which may have been the cause for the dust aloft over the western part of the country.

Looking at the NOAA HMS Smoke and Fire Product (top left), the small red dots indicate currently burning fires, while the grey area in the Central Plains is a resulting smoke plume. This smoke is most likely coming from the persisting agricultural fires in the region, with the densest smoke occurring in northeastern Kansas and southeastern Nebraska. The MODIS Aqua image (top right) illustrates elevated AOD corresponding to the plume on the HMS as well as farther north into South Dakota, a possible result of migrating smoke.

The EPA AIRNow combined AQI loop (bottom left) depicts USG and unhealthy AQIs in the Central Plains, with the highest AQIs being found in the eastern Kansas-Nebraska area, the same place where the most dense smoke was observed . Thus, with higher AODs and AQIs, the agricultural fires and resulting smoke have deteriorated air quality in the Central Plains. Moderate and USG AQIs were also seen in the Great Lakes, and the NAAPS Aerosol sulfate model (bottom right) has increased concentrations over the eastern half of the United States, including this region. This projected increase in sulfates could be attributing to the increase in AQI today.

Looking at the NOAA HMS Smoke and Fire Product (top left), the small red dots indicate currently burning fires, and the small grey areas are meant to be smoke plumes. The HMS did not find any plumes of note, however, while MODIS Terra (top right) illustrates elevated AODs in the Central Plains, Great Lakes, and the Northwest near Montana. The fires could attribute to the AODs in the Central Plains and part of the Great Lakes, although the Northwest is not explained by the fires.

The EPA AIRNow combined AQI loop (middle left) shows moderate AQIs popping up across the United States, with USG AQIs popping up in Southern California sporadically throughout the day. The NAAPS Aerosol model (middle right) has increased sulfate surface concentrations over much of the East, with some of the higher values in the Great Lakes, which could be affecting the AOD in the region.

Yet the Northwest, namely around Montana, there were good AQIs, low sulfates, and no active fires. Looking in the region, the photo on the bottom left is from Grand Teton National Park at 6:00 PM MDT, with a visual range of 197 miles. The clear/hazy comparison to the bottom right has an example of a "good" visual range of 147 miles from the same webcam, so it really seems as though the air quality in this region is not as severe the MODIS Terra satellite image describes.

Air Quality Indices (AQI) peaked this afternoon in the Code Orange (Unhealthy for Sensitive Groups) range across the San Joaquin Valley in California. Elsewhere, Code Yellow (Moderate) AQIs were experienced in the Pacific Southwest, Central Plains and sporadically throughout the Southeast, Great Lakes, and Mid- Atlantic (top left). The area of concentrated fires in the Central Plains (Iowa/Nebraska/North Dakota) may have contributed to the elevated AQIs experienced there (top right). It appears the smoke layer associated with fires burning in Central America has dispersed, as it is no longer detected by the HMS analysis team. In terms of satellite imagery, MODIS suggested elevated aerosol optical depth (AOD) over western Texas, although there is no clear indication of smoke in this region (bottom).