Bushfires burning across Australia’s east coast captured on the 12th November 2019 by Copernicus Sentinel-3 mission. Image courtesy of ESA/Copernicus and contains modified Copernicus Sentinel data (2019), processed by ESA, CC BY-SA 3.0 IGO
Two weeks ago, we wrote about how the satellite industry was failing to deliver useful and actionable information, despite the huge increase in data, in relation to the Australian bushfires.
There have been a couple of interesting news reports issued over the last two weeks as to how this situation might be improved. Later we’ll examine how Copernicus satellites monitor the environment, but last week Australian scientists at the Australian National University in Canberra described a bespoke satellite mission that they think will be more accurate and useful in both identifying where bushfires may start, and the ones that could be difficult to contain.
During the most recent bushfire season, more than twenty per cent of Australia’s temperate woodlands have been burnt, which equates to ten million hectares of land. Just over a week ago, the New South Wales Rural Fire Service tweeted that the state was completely free of fires for the first time in two hundred and forty days! The importance of understanding these bushfires and their patterns is obvious.
The new mission proposed by the scientists will use sensors operating in the infra-red wavelengths specifically tuned to the highly flammable eucalypts, the most common vegetation in Australia, and they would detect small changes in the spectral signatures of trees, the leaf area index (which equates to the amount of leaves in the canopy), and the moisture content available to vegetation. These are all key factors in determining what ‘fuel’ there is available for any bushfires.
It’s hoped that this will eventually be a small constellation of satellites operating in a low-Earth orbit with a ground resolution of 10 m. It will, of course, take a few years to design, build and launch the satellites. In the interim, existing sources will need to be used such as the Copernicus missions; three of which potentially can provide helpful data.
Sentinel-2 mission’s high-resolution multispectral imager has been used to image the fires, and it is extremely good at showing the smoke generated but being an optical imager, it cannot see through the smoke to the events on the ground. Sentinel-3 has a sea and land surface temperature radiometer that can be used to record fire hotspots and an optical imager, but both suffering from the same deficiencies as Sentinel-2.
Research published last week suggests that the SAR data from Sentinel-1 can also be used to produce change maps for wildfires. The work was undertaken by Dietrich Heintz (Cropix) and Massimo Barbieri (Sarmap), observing the recent Australian bushfires. As Sentinel-1 uses radar data it means it’s not impacted by smoke from the wildfires themselves, or clouds.
The researchers compared Sentinel-1 data with Near Real-Time active fire data from the Fire Information for Resource Management System (FIRMS) which is based on MODIS (Moderate Resolution Imaging Spectroradiometer) and VIIRS (Visible Infrared Imaging Radiometer Suite) data, together with Normalised Difference Vegetation Index (NDVI) data from Sentinel-2 and they were able to map changes in vegetation due to the wildfires.
Whilst useful, as Sentinel-1 only passes over Australia every twelve days, it cannot provide ongoing information during the event. The CubeSat constellation suggested by the Australian team would, therefore, be valuable in providing useful and actionable information in a timely manner.
