Advances in fire science from a constellation of satellite sensors

The role of fire in the Earth system is changing in response to climate and human activity. Extended fire seasons under warmer and drier climate conditions promote more extreme fire behavior, including fast-moving fire storms with unprecedented impacts on ecosystems and people at the wildland-urban interface. The use of fire for agricultural management is also changing. Fragmentation of savanna and grassland biomes for agriculture reduces fire sizes, contributing to a 25% decline in global burned area in just the past two decades. Increases in cropland, on the other hand, result in numerous small and smoldering fires that go undetected by existing satellite sensors. Our understanding of the full scope of fire in the Earth system is therefore hampered by a lack of moderate resolution satellite coverage, particularly in the late afternoon when fires are most common and most extreme. These data gaps limit our understanding of sub-daily fire behavior and the climate drivers of variability in fire spread rates. The lack of active fire detection information in the late afternoon and early evening hours also prevents a complete accounting of small and short-lived fires in populated regions. Fires burning in the late afternoon contribute disproportionally to air quality issues in human-dominated landscapes as the nighttime collapse of the boundary layer traps fire emissions near the surface. Here, we explore the potential advances in fire science from a new constellation of active fire sensors. By observing global fire activity every three hours, a constellation for fire science would track the behavior of extreme fires, including the duration of both flaming and smoldering combustion, and quantify the magnitude of small fire activity. This new generation of measurement capabilities is critical to closing the data gap on global fire emissions and new extremes in wildfire behavior.