Each year in January and February, Earth-observing satellites detect fires and waves of smoke in the Lower Mekong River Region, an area that includes Thailand as well as the countries of Cambodia, Laos (officially the Lao People's Democratic Republic), and Myanmar. This activity increases through March and April, when the region's dry season reaches its peak, and then fades in May as the rainy season begins.
Although the fires are often short-lived and typically small (approximately 4 to 5 hectares or roughly 10 to 12 acres in size), there are often so many that they produce thick layers of what inhabitants of the region refer to as "smoke haze," a term for the atmospheric haze mainly due to smoke from fires ignited in forests and agricultural lands. This haze has a considerable impact on human health, as exposure to polluted air has been linked to premature death and the rise of respiratory illness throughout the region. It also impacts transportation networks, closes schools, and prompts government-issued burning bans.
According to Dr. Veerachai Tanpipat, a geographer, remote sensing expert, and advisor to the Director General of the Department of National Park, Wildlife and Plants Conservation (DNP), an agency in Thailand's Ministry of Natural Resources and Environment, humans are the primary cause of fires in Thailand.
"The major causes of forest fires are related to the activities of those who live in rural areas," said Tanpipat. "They are ignited by people for timber, growing of non-timber forest products, agricultural land preparation and land expansion, hunting, cattle grazing, drug trafficking, and local and political conflict."
In addition to generating smoke haze, these human-caused fires burn an estimated one to two million hectares (2.47 to 4.94 million acres) in Thailand each year. To address these impacts, hotspot detection and active fire data from NASA's Fire Information for Resource Management System (FIRMS) have become essential for detecting, managing, and mitigating fires and smoke haze in Thailand and throughout the region.
"The government relies on FIRMS for hotspot detection across the country," said Tanpipat. "The locations of fires and detection times are crucial information that they use to deploy the nearest units to suppress the fires and make decisions about firefighting resources."
The Use of Active Fire Data in Thailand
The use of satellite-derived active fire information in Thailand and the Lower Mekong River Region dates back to 1999, when the Asia Institute of Technology (AIT) began using World Fire Web, a system for globally mapping fires in vegetation that relied on data from the Advanced Very-High-Resolution Radiometer (AVHRR) instrument aboard NOAA's Polar-orbiting Operational Environmental Satellites (POES). In 2006, following the launch of the NASA Earth Observing System (EOS) satellites Terra (1999) and Aqua (2002), the DNP requested support from FIRMS and has been using it ever since.
To build confidence in its use of satellite-derived active fire products, the Thai government's Forest Fire Control Division carried out field validation campaigns in 2007, 2008, and 2009 to determine the accuracy of active fire data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard the Terra and Aqua satellites. In 2016, the field validation campaign was repeated to determine the accuracy of active fire data from the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard the joint NASA-NOAA Suomi National Polar-orbiting Partnership (Suomi NPP) satellite. These campaigns yielded highly accurate results, and natural resource managers at all levels of the Thai government now routinely rely on FIRMS data to manage fire and smoke haze throughout the country.
Managing Satellite-Detected Fires
That management process starts with three Thai government agencies—the DNP, the Royal Forest Department (RFD), and the Geo-Informatics and Space Technology Development Agency (GISTDA)—that receive near real-time (NRT) active fire information from FIRMS. The alerts are usually sent within three hours of a satellite observation for fires detected using data from MODIS and within four hours for fires detected using data from VIIRS, including the VIIRS instruments aboard the Suomi NPP satellite and the Joint Polar Satellite System (JPSS) NOAA-20 and -21 satellites.
"After the agencies receive the alerts, they combine it with information, such as the political or administrative boundaries a fire is in, the nearest forest fire control station, and the location of forest reserves or protected areas," Tanpipat said. "Then they redistribute the information through smartphone applications such as LINE [which is similar to Facebook Messenger or WhatsApp] to agency command posts, non-governmental organizations, and interested citizens."
This redistributed information also includes FIRMS fire maps in KML format, which easily can be viewed on a smartphone and used in conjunction with NASA Worldview and the FIRMS fire maps available online.
"FIRMS makes it much easier to monitor the progress of active fires and locate the previously burned areas, so we know what's happening during each fire season," Tanpipat said. "Because of [FIRMS'] easy-to-use interface, non-governmental organizations, academic researchers, government agencies, and the public use it to follow the situation of wildfires and open burning fires and inform local air quality networks."
The FIRMS fire map also allows users to view smoke haze by adding one of the corrected reflectance layers from MODIS or VIIRS to the map or by adding aerosol index data from the Ozone Mapping and Profiler Suite (OMPS) instrument aboard Suomi NPP. OMPS aerosol index data provide information about the density of smoke and suspended particles in the atmosphere.
For a detailed description of FIRMS data products, please see the recent NASA FIRMS Plays a Significant Role in Northwest Territories Fire Detection Earthdata article.
Spreading Throughout the Region
In addition to his role as advisor to the DNP, Tanpipat also promotes the use of FIRMS at the regional level through his association with numerous entities. These include the Association of Southeast Asian Nations (ASEAN), which provides research and technical training to its member states; the Asia Pacific Advanced Network (APAN), which promotes network-enabled research and education; and the Asian Forest Cooperation Organization (AFoCO), a treaty-based intergovernmental organization that promotes cooperation towards achieving shared sustainable development goals and regional and global forestry objectives.
"The AFoCO has an annual training that gives me a chance to present FIRMS to the participants. I let them know this is something they can use right now to monitor the fire situation in their country or area of interest and that they don't have to pay anything to use it. It's all free," he said. "I also introduce NASA Worldview because you can use it with FIRMS and it lets users make animated clips that show how an active fire may move within an area."
Tanpipat has been providing international FIRMS training since 2015, and during that time, he has seen its use expand throughout the region. Now, in addition to Thailand, FIRMS has users in Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, Vietnam, Bhutan, and Timor-Leste.
In addition to promoting the use of FIRMS, the trainings also give Tanpipat an opportunity to discuss the benefits and limitations of using active fire data from satellites.
Hotspot Detection Limitations
As Tanpipat notes in "Active Fire Monitoring of Thailand and Upper ASEAN by Earth Observation Data: Benefits, Lessons Learned, and What Still Needs to Be Known," a chapter in the 2023 book Vegetation Fires and Pollution in Asia: "Users sometimes need help understanding the caveats and limitations of using satellite-derived active fire information. The MODIS and VIIRS instruments are on polar-orbiting satellites, meaning active fires are only detected as the satellite passes overhead. Because they are optical instruments, clouds, smoke, and thick haze can obscure active fire detection. To this end, the number of active fire hotspots detected does not reflect the total picture of smoke haze, which affects air quality. [Further,] active fires detected in other countries mean additional sources of smoke haze that can be transported long distances to another country. Factors such as wind and air pressure are involved in the movement of smoke haze."
Acknowledging the limitations of MODIS and VIIRS hotspot detection and active fire data is not just an academic exercise. The accuracy of the results of the MODIS and VIIRS field campaigns prompted the Thai government to use the number of active fires detected by FIRMS during a fire season as key performance indicators (or KPIs) to evaluate the effectiveness of DNP and RFD fire control efforts. However, because the presence of clouds, smoke, and thick haze can negatively impact the ability of these sensors to detect active fires and burned areas, the annual fire season statistics from the DNP, RFD, and GISTDA may not agree.
To address this discrepancy, Tanpipat advised the agencies to use the MODIS Burned Area Product (MCD64A1) to identify fire season trends and then worked with Diane Davies, operations manager for NASA's Land, Atmosphere Near real-time Capability for Earth observations (LANCE), to ensure the product updates more frequently.
"[Thai government agencies] usually use burned area products from Landsat 8 and 9 and the ESA (European Space Agency) Sentinel satellites, but so far, they do it very slowly once every fire season. They plan to improve the frequency later," Tanpipat said. "Also, they have only 10-years of records and not for the whole country. So, if they would like to look back on the two decades of burned area history, they need to use MODIS 500m Burned Area Products to see any trends. They can look at Earth Map, which updates automatically when products are available, but FIRMS takes at least six months to update, which is too late. This year, I worked with Diane Davies to update it to last month."
FIRMS Future in the Lower Mekong River Region
Despite these limitations, Tanpipat says FIRMS has become an integral tool for monitoring active fires and smoke haze in the Lower Mekong River Region.
"The control, management, and mitigation measures used in Thailand are expanding and people all over the Lower Mekong River Region are using FIRMS," he said. "It is an international treasure for forest fire control and management."
NASA's Davies is not surprised that the use of FIRMS is expanding throughout the region.
"FIRMS provides tangible, real-world benefits to a variety of users around the world, so it's no surprise that we are seeing increasing numbers of users in the Lower Mekong River Region pull the active fire data via FIRMS's web services," Davies said. "The DNP, RFD, and GISTDA use of active fire data is a perfect example of this. They routinely pull data from FIRMS into a customized application and add value to it by combining it with other geospatial data, which enables them to expand their resources and be more effective on the ground."
Learn More
Data Tool in Focus: Fire Information for Resource Management System
Webinar: Discover Enhanced Wildfire System Capabilities with NASA's FIRMS (October 2023)
