Month: June 2023

A small wildfire near the town of Vestby broke out on the 13 June 2023. While it was very quickly extinguished on 14 June 2023, its impact could still be seen from space. Using this fire as a simple example, the figure below illustrates how we can determine the area that has been burned by a fire. Using 20 m resolution multispectral images from the Sentinel-2 satellite before and after the fire, a metric called “difference in normalized burn ratio (dNBR)” is derived, which is subsequently used for determining the total area that was burned in the fire. In the case of the Vestby fire this was estimated to be approximately 0.1 km², a negligibly small area compared to the large wildfire complexes that are typically burning in the fire season in Siberia or Canada.

Determining burned area from Sentinel-2/MSI data. False-color image before the fire (top left), false color image after the fire (top center), difference in normalized burn ratio (top right and bottom left), binary mask of the burned area determined from the difference in normalized burn ratio (bottom center), and vectorized polygon of the burned area derived from the binary mask (bottom right).

Updated calculations carried out by a team of atmosphere and climate scientists at NILU show that smoke from the forest fires in Canada is still drifting in over Norway.

The figure shows active fires (in red, from MODIS and VIIRS satellite instruments) and gray smoke plumes on June 4th over Canada and the USA. The white areas are regions with cloud-cover. (Image created using NASA Worldview.)

In the updated simulation, the smoke emission from Canada is shown as a cloud moving over a world map. The different colors of the cloud tell the amount of particles the cloud contains. The yellow areas of the cloud signal where there are the most soot particles in the air.

For more info see NILU’s website: https://www.nilu.com/2023/06/smoke-from-canada-still-coming-in-over-norway/

The atmosphere and climate scientists at NILU have used the model FLEXPART in forecast mode to predict how the smoke from the wildfires in Canada will move through the atmosphere.  

As the video below shows, the smoke has moved over Greenland and Iceland since 1 June before it reaches Norway today. The model is confirmed with observations in southern Norway (Birkenes Observatory) with increasing concentrations of aerosols. 

“We may be able to see some haze or smell smoke”, says senior scientist Nikolaos Evangeliou. “However, we do not believe that the number of particles in the air here in Norway will be large enough to be harmful to our health.”  

The concentration of smoke particles in the air in the affected areas of North America can certainly be harmful to health. In addition, smoke and soot particles from forest fires can float through the atmosphere and settle on ice and snow-covered surfaces on, for example, the Greenland ice sheet. There, they can contribute to making the surface darker, so that it absorbs solar radiation to a greater extent and contribute to warming the atmosphere.  

This effect is an important reason why climate and atmospheric scientists monitor particles in the atmosphere at Observatories all over the world, including Birkenes in Agder, Zeppelin on Svalbard and Trollhaugen in Antarctica.