Figure 3 shows the hourly U.S. total mass of fire smoke emissions from FLAMBE in Gg-CO km-2 hr-1 gridded per 0.25˚ cell with a minimum threshold of 2,000 kg. From 8 August to 22 September 2013 the calculated total emissions were 1,060 Gg of CO. FLAMBE emissions depict a regional distribution pattern in known fire regions: agricultural and prescribed fires in the southeast U.S. (e.g. the Carolinas, Florida, and Georgia) and southcentral U.S. (e.g. Louisiana, Mississippi, and Arkansas); and the wildfires in the central plains and intermountain west U.S. (e.g. Wyoming, Idaho/Montana area, and California). A time series of the hourly emissions indicates that August contained almost all the major fire emissions (Figure 4). The duration of the largest fire emissions are indicated in the figure by arrows. Between 14 and 24 August 2013, on average ~6 Gg-CO hr-1 (∼1.2 x 104 FLEXPART particles where 1 particle = 500 kg = 0.5x10-3 Gg) was being emitted daily with a maximum hourly total of 11 Gg-CO hr-1 (∼2.2 x 104 FLEXPART particles). Regional fires emissions from the central U.S. were considerably lower than wildfires emissions in the intermountain west (3% compared to 70%).
Figure 4. A time series of FLAMBE emissions (mass/time) converted to particles released in FLEXPART-WRF (# of particles or particle count). Each 500 kg of mass is converted to 1 particle in FLEXPART-WRF simulations. Locations emitting less than 500 kg only emit a single particle. Arrows represent the duration of two of the largest wildfires (Rim Fire and Beaver Creek) with relevance to SEACIONS with other fires (Emigrant Fire and Pony/Elk Complex) contributing to those time frame emissions indicated. The dotted line is the California Rim Fire (37.85˚N, 120.083˚W) 17-31 August 2013, and the solid line is the Idaho Beaver Creek (43.593˚N, 114.684˚W) 7-21 August 2013. Note: Beaver Creek and Pony/Elk Complex occurred nearly at the same time and were fewer than 100 km apart in distance. While, the Emigrant Fire contributed a significant amount of emissions during its occurrence at the same time as the Rim Fire but was much smaller in magnitude.
Specifically, three large wildfires areas were identified that produced the most emissions and high-altitude smoke injection plumes. The Idaho Beaver Creek fire, caused by a lightning strike on 7 August 2013 in the Sawtooth National Forest, occurred in the lower southwestern edge of the Elk/Pony Complex (43.59˚N, 114.68˚W). This fire burned an area of 465 km2 (114,900 acres), emitting 54.6 Gg-CO of smoke emissions, and accounted for 14% of the Idaho and Montana states combined total fire emissions (392 Gg-CO km-2hr-1) during the months of August and September. The second fire area, led by a fire named the Montana Emigrant Fire, was a part of a small system of fires caused by multiple lightning strikes that spanned across Yellowstone National Park (45.20˚N, 110.69˚W) consuming <81 km2 (20,000 acres) starting 14 August emitting 9.4 Gg-CO of smoke emissions. Lastly, the largest of the three, the California Rim Fire, described in detail in Peterson et al. (2015), caused by an illegal campfire, occurred on 17 August 2013 in Yosemite National Park (37.85˚N, 120.08˚W). The Rim Fire burned an area of 1041 km2 (257,314 acres), emitted 224 Gg-CO of smoke, and accounted for over 66% of the California biomass burning emissions (341 Gg-CO km-2 hr-1) during SEAC4RS.
4.4. Residence time of particles over St. Louis