High level smoke from Canadian wildfires, which started raging in early July 2017, could be seen as far as the Alps in August.
By Jochen Kerkmann (EUMETSAT), HansPeter Roesli (Switzerland) and Mike Fromm (US Naval Research Laboratory)
For more than a month, dozens of large fires raged in British Columbia, Canada. In July 2017 wildfires burned through coniferous forests stressed by heat, drought, and infestations of mountain pine beetles. In early August, another cluster of intense fires flared up in Northwest Territories when a cold front with powerful winds passed through the region.
As a result of the intense fires and persistent southerly winds huge amounts of smoke travelled north over Canada and across the Atlantic as far as the Alps.
According to NASA the smoke plumes were thick enough and high enough in the atmosphere to break a record. Colin Seftor, an atmospheric researcher for NASA’s Goddard Space Flight Center, the Ozone Mapping and Profiler Suite (OMPS) on Suomi NPP recorded aerosol index (AI) values as high as 49.7 on 15 August — more than 15 points higher than the previous record set in 2006 by fires in Australia.
The smoke plume streamed into the Atlantic at altitudes between 12–15 km, making it one of the most intense injections of smoke into the Upper Troposphere-Lower Stratosphere (UTLS) in many years.
This record breaking, high-level smoke could be seen in both the Meteosat-10 Dust RGB and in the new GOES-16 ABI 1.3 micron band.
The smoke was so thick and high that it could be detected in infrared-based Dust RGB, similar a case in Siberia in June 2017 (see Himawari-08 AHI True Color RGB and Dust RGB animated gif. Source JMA and CIRA).
Normally smoke is transparent in IR channels, but very dense smoke from forest fires is actually absorbed a bit in the IR channels, especially in the IR8.6 channel (less in the 11 and 12 micron channels). This means that the brightness temperature difference IR11.2–IR8.6 (green component of the Dust RGB) is positive — producing the green colour of the smoke, as seen on the Meteosat-10 Dust RGB (Figure 1, above right, click to expand), the GOES-16 Dust RGB (Figure 2) and the GOES-16 animation. The animation also includes a view of Hurricane Gert over the Atlantic, which peaked as a Category 2 system early on 17 August 17 an unusually high latitude of 40° N. Note the large, high-level outflow of Gert as shown by the upper level cirrus clouds in dark blue/black colours.
The smoke was well seen in the CIRA Geocolor product (typical brown color, True Color RGB from ABI, with Rayleigh correction and synthetic green band) and in the Natural Color RGB (typical cyan colour, RGB of NIR1.6, VIS0.8 and VIS0.5 bands), see Figure 3.
The new NIR1.3 ABI band (band 4) is also very useful for detecting high-level smoke plumes. As this band focuses on high level features (lower clouds are not seen because of the high water vapour absorption), it gives a very good view of the elongated smoke plume, with better contrast to the background than in other solar bands (see Figure 4)
In the early morning of 20 August a whitish sky could be seen from ground level over the Po Valley area. Usually the weather at the time, north foehn, would result in deep blue sky. The smoke from Canada caused the clouding of the sky.
Two distinct smoke streamers crossing the Alps could be seen on the Meteosat-10 image from 04:45 UTC (Figure 5). And on the Meteosat-10 HRV image from the same time (Figure 6) a clear line of smoke can be seen stretching from the north-east tip of Scotland down to Adriatic Sea.
Natural Colour RGB
High Resolution Visible
Note: NOAA's GOES-16 satellite has not been declared operational and its data are preliminary and undergoing testing.
Record-Breaking Smoke Over Canada (NASA Earth Observatory)
Canada's forests are burning, and the smoke is drifting into the Arctic (Mashable)
Canada wildfires: almost 40,000 evacuated in British Columbia amid state of emergency (The Guardian)
Record di altitudine per il fumo canadese (MeteoSwiss, in Italian)