Seeing Through the Smoke: How SWIR Satellite Imagery Detects Hidden Wildfires from Orbit

Why SWIR Matters in Remote Sensing

Short-wave infrared, or SWIR, refers to a portion of the electromagnetic spectrum typically ranging from 1.0 to 2.5 micrometers. This spectral window lies beyond the range of human vision and even beyond the near-infrared sensors commonly used in remote sensing. What makes SWIR particularly valuable is its ability to penetrate smoke and thin cloud cover. Unlike visible or NIR imagery, which can be obstructed by dense atmospheric particles, SWIR captures thermal signatures and material differences on the ground with clarity. It is especially sensitive to temperature variations, vegetation moisture levels and surface changes caused by combustion.

SWIR’s Role in Wildfire Detection and Assessment

During a wildfire event, SWIR imagery is indispensable. It can reveal the location of active fire fronts obscured by thick smoke, distinguish between hot ash and open flames and identify smoldering zones that may reignite. Beyond immediate detection, SWIR data also enables post-fire assessment by mapping burn scars and estimating the severity of damage to ecosystems. This information is critical for land managers, insurance assessors, and humanitarian responders who need accurate, high-resolution data under time pressure.

Maxar's WorldView-3: A High-Resolution SWIR Solution

Among the most capable satellites providing SWIR data is Maxar Technologies’ WorldView-3. Launched in 2014, WorldView-3 is the cutting-edge satellite offering eight SWIR bands at a ground resolution of 3.7 meters. This level of detail is exceptional in the SWIR domain and allows for precise fire detection even in complex terrains. The satellite's agility and frequent revisit make it ideal for monitoring rapidly evolving wildfire situations.

 SWIR in Action: California Wildfires 2018–2021

One of the most widely cited uses of WorldView-3 in wildfire management occurred during the catastrophic fires in California between 2018 and 2021, including the Camp Fire and Dixie Fire. In these cases, SWIR imagery from WorldView-3 allowed analysts to track the movement of fire lines, even as smoke choked the atmosphere and made visible-spectrum observations unusable. The satellite's data helped emergency services prioritize evacuation routes, assess structural damage and plan containment strategies based on up-to-date fire progression maps. High-resolution SWIR images also supported media coverage and post-disaster analysis by providing clear views of affected areas long before the smoke had cleared.

Sentinel-2: A Publicly Available SWIR Resource

While commercial platforms like WorldView-3 offer unparalleled resolution, publicly available missions such as the European Sentinel-2 have also proven essential in wildfire monitoring. Sentinel-2 carries SWIR bands (Band 11 and 12) at a spatial resolution of 20 meters, which are widely used to detect active fires, map burn scars and estimate post-fire vegetation stress. One of the key advantages of Sentinel-2 is its frequent revisit time – as short as five days globally – combined with its open-access policy. This makes it an invaluable source of data for governments, researchers and environmental agencies around the world. Using indices like the Normalized Burn Ratio (NBR), analysts can quantify burn severity and monitor ecosystem recovery over time. Although the resolution is coarser than commercial satellites, Sentinel-2’s consistency, multispectral range and global coverage make it a cornerstone of operational fire mapping workflows.

SWIR for Improved Fire Monitoring

In Australia’s Black Summer of 2019–2020, when vast portions of the continent were engulfed in flames, SWIR sensors again proved invaluable. Sentinel-2 satellites, which offer SWIR bands at 20-meter resolution, were used alongside commercial assets like WorldView-3 to monitor burned areas, estimate fuel moisture loss and evaluate the regeneration of vegetation weeks after the fires subsided. Though Sentinel-2 lacks the spatial resolution of WorldView-3, recent advancements in artificial intelligence have made it possible to enhance such data. In a 2019 study published on arXiv, researchers demonstrated how convolutional neural networks (CNNs) could be used to generate super-resolved SWIR imagery from Sentinel-2 data, effectively doubling its detail and improving fire detection at scale.

SWIR’s Contribution to Volcanic Hazard Management

SWIR technology also played a role during the 2021 eruption of the Cumbre Vieja volcano on La Palma in the Canary Islands. While the primary hazard was volcanic, the surrounding region experienced secondary fires caused by falling ash and lava. SWIR imagery was used to separate thermal anomalies from active fires, providing emergency teams with crucial information about where human intervention was needed most.

Limitations and Future of SWIR in Fire Response

Despite these successes, there are limitations. SWIR performance can still be affected by thick cloud decks or extreme weather conditions and the high cost of commercial imagery can restrict access in some regions. Nonetheless, as satellite technology advances and the frequency of extreme fire events increases, the demand for SWIR data in wildfire management is expected to grow.

Conclusion: SWIR’s Growing Importance in Earth Observation

For Earth observation professionals, researchers and crisis responders, the integration of SWIR sensors into operational monitoring frameworks represents a critical leap forward. Whether through ultra-high-resolution data from WorldView-3 or through AI-enhanced imagery from public satellites like Sentinel-2, SWIR is reshaping how we see and respond to fire on a warming planet.