Satellite-Based Fire and Pollutant Detection

Recently Space4Good engaged in a satellite based monitoring activity on air pollutants, with the World Bank. The Big Data NO2 Observatory, visualizes NO2 emissions for Indonesia and Vietnam and analyzes the effects of COVID-inflicted lockdowns in these countries. Coincidentally, upon stringent restrictions to human mobility, the NO2 emissions dropped around 25-30% in big cities. Nevertheless, in rural areas some further questions arise.

During the COVID-19 pandemic, one could expect to see a reduction in agricultural field activity akin to the decrease in urban activities. In this blog, Riau province serves to explain the rural dynamics.

Riau province is located in mainland Sumatra Island. Characterized by its riches in natural resources such as minerals and forest products, Riau contributes to a strong economy in the province. A large portion of Riau’s forested land (around 55% from 2002-2019 according to Global Forest Watch) has been lost to palm oil and coconut plantations. As a direct link to these deforestation activities are the annual forest fires set off on commercial agriculture plantations. Slash and burn agriculture practices are often utilized in plantations to clear off land, as they are cheaper than other methods. These fires take on particular strengths as many of the plantation lands coincide with peat soil types giving rise to highly combustible fires which are difficult to put out.

As a result, a large scale phenomenon called the Southeastern Asia Haze (SEAH) is often triggered in the dry seasons especially in the months of July-October resulting in considerably negative impact to air quality in these and neighboring regions. Both the fires and the haze open up other monitoring possibilities with Sentinel 5P and other satellites. The year 2019 was a particularly strong year for wildfires with 1.65 million hectares burned and a heavy phenomenon of the SEAH occurred. Figure 1 shows the active fires in Riau Province on Sep 11th, 2019.

Figure 1: Active fires Riau Province VIIRS 375m band Sep 11th 2019. Source: NASA FIRMS

Similarly, satellite-based-detection of aerosols are a useful proxy for detecting biomass burning. Figure 2 depicts the aerosols detected with Sentinel 5P’s TROPOMI instrument. This example shows the same satellite sensor data can be used for monitoring several events of a distinct nature, such as combustion from fossil fuels (NO2 in the case of the Big Data NO2 Observatory) and biomass burning (Aerosols AI).

Figure 2: Aerosols Riau Province Sentinel 5P TROPOMI Instrument UV Aerosol Index from 380 and 340 nm on Sep 12th 2019

For the year 2020, as the pandemic has receded activity in various sectors, the amount of fires have diminished. Nonetheless, fires have continued to spark in Sumatra Island and Kalimantan. In the COVID-19 context, most of the national budgets are allocated to the control of the pandemic; thus the control of fires are considered less economical and human resources for monitoring of the no-burn practices are not available (Singapore Institute of International Affairs, 2020). It can be assumed that less supervision, or economic pressures that prevent supervision, could imply the increase in slash and burn practices.

Check out our developments on the Big Data NO2 Observatory here. Would you like more information or are you interested in collaborating with Space4Good? Visit our website or contact us via