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