Assessing SMAP for enhanced wildfire danger prediction in boreal-Arctic ecosystems

Document Type

Article

Publication Date

1-1-2026

Abstract

In boreal and Arctic regions, where organic soils act as wildfire fuel, NASA’s SMAP soil moisture products offer strong potential to improve drought and fuel (organic soil) moisture assessment beyond point-based weather station fire danger models. Since SMAP is not calibrated for organic soils, we evaluated its suitability using a network of fuel moisture stations we established across three SMAP grid cells, as well as fire weather station data across the North American boreal and Arctic. Comparison of SMAP products, brightness temperature, and reflectivity with in situ fuel moisture measurements revealed SMAP products to be dry-biased with low dynamic range (r = −0.03 to 0.40). In contrast, SMAP reflectivity showed good relationships to in situ fuel moisture at 6 cm depth in the Alaska tundra site (r = 0.62), and 10–18 cm depth for the Alberta (r = 0.46) and Ontario (r = 0.62) boreal sites. SMAP soil moisture products were then used to develop a statistical model to predict Drought Code (DC), a weather-based index of fuel availability in the deeper (10–20 cm) organic soil layers. The model, created using hundreds of weather stations across boreal and Arctic regions, explained 63 % of overall deviance (range 28–86 %). Additionally, incorporating SMAP retrievals flagged for dense vegetation increased spatial coverage without compromising model performance. These results indicate that an operational SMAP-derived deep organic fuel moisture (e.g. DC) product is feasible if future retrievals account for soil organic content. This would enhance fire danger monitoring and decision support across boreal and Arctic regions.

Publication Title

Remote Sensing Applications Society and Environment

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