Journal Article

Offsetting the noise: a framework for applying phenological offset corrections in remotely sensed burn severity assessments

Menick, Casey, Chastain, Robert, Vanderhoof, Melanie, Picotte, Joshua, Reiner, Alicia

2025

Overview

Background. Phenological correction of pre- and post-fire imagery is used to improve remotely sensed burn severity evaluations. Unburned offset values standardize greenness between image pairs, however, efficacy across diverse scenarios remains underexplored. Aims. We evaluated the impact of phenological offset correction methods to support analyst decision-making across fire-prone environments. Methods. We generated burn severity spectral index values for a dataset of Composite Burn Index (CBI) field plots across the conterminous U.S. The effectiveness of offset corrections was tested across image selection techniques, spectral indices, offset generation methods, and burn perimeter sources. We assessed the influence of offset corrections on the modeled relationship with CBI, agreement between burn severity thresholds, and potential bias. Key Results. Applying offset corrections consistently improved the modeled relationship with CBI by addressing extreme outlier severity values. However, automated offset corrections had the potential to introduce bias, systematically lowering severity values and reducing correspondence to observed burn severity categories. Conclusions. Offset corrections offer benefits but also pose tradeoffs to accurately representing remotely sensed burn severity. Implications. The utility of offset corrections depends on the environment, methods, and scale of analysis. We propose a decision-tree framework for analysts to consider when employing offset corrections given their study scope.