In August 2016 partially dense smoke veils covered extended areas of South America. The smoke was due to natural and man-made wildfires.
By HansPeter Roesli (Switzerland)
In the period of 18-28 August considered here the smoke appears to have initially originated from fires in Bolivia.
Download animation (MP4, 20 MB)
Wind and burning in other areas then helped to subsequently expand the smoke veils.
The position of Meteosat-10 relative to smoke and the sun produced strong forward-scattering in direction of the satellite at sunset.
The animated gif of Natural Colour RGBs taken each day at 20:30 UTC (Figure 1) gives an idea of the evolution of the bluish smoke screen over 11 days, even if the smoke disappeared under the white clouds every now and then.
A comparison between the Natural and True Color RGB of the scene, taken by VIIRS in the local early afternoon on 25 August, reveals that normal scattering from the smoke is very faint.
While the True Color RGB (Figure 2, right), which is sensitive to sunlight scattered by smoke particles, shows the smoke as light-blue wisps, on the strongly-enhanced Natural Color RGB (Figure 2, left), which is less sensitive due to using bands of longer wavelengths, the smoke signature is absent.
Late in the afternoon, the sun hits the west slopes of the Andes, which act as a screen to radiation. The result is the darkening of the Andes region. In the morning, sun and satellite are east of the Andes, and there is no such obstruction to radiation.
Smoke Over South America (NASA Earth Observatory)
Previous case studies
Smoke and dust streamers over Argentina as seen by Meteosat-10 (10 Sept 2013)
Large smoke plumes from fires over Bolivia (23 Aug 2010)
Dense smoke over Argentina and Uruguay (18 April 2008)
Fires and smoke in Brazil (2 Aug 2005)