BRDF and Topographic Corrections Not Properly Applied to Reflectance Data for a Subset of Sites Collected in 2025

Summary

AOP has identified a processing issue affecting spectrometer data products for a subset of sites collected in 2025. For the affected acquisitions, the bidirectional reflectance distribution function (BRDF) and topographic corrections were not properly applied to most pixels. This issue impacts the spectrometer orthorectified surface bidirectional reflectance products as well as downstream hyperspectral products derived from them, including Albedo, LAI, fPAR, vegetation indices, and canopy water content.

Issue Description

During 2025 processing, a filter used to exclude non-vegetated pixels and shadows from the BRDF correction was configured too aggressively. As a result, too few pixels remained eligible for correction, causing the pipeline to skip BRDF and topographic correction for the vast majority of pixels in affected flightlines. See Tables 1 and 2 below for a summary of the sites and data products affected.

Impact

AOP Data users should use caution when working with affected bidirectional reflectance and downstream hyperspectral products (Table 2) from the sites and dates summarized in Table 1. Because BRDF and topographic corrections were not properly applied, reflectance values and derived products will not be directly comparable to correctly processed data. The AOP team recommends refraining from using these data products until they are re-processed. The flightline directional reflectance data product (DP1.30006.001) is still valid and can be used.

Timeline for data corrections

The AOP science team has begun to re-process affected datasets to properly apply the BRDF and topographic corrections. We expect to complete re-processing of all the affected sites by Sept 18, 2026. Once this issue has been resolved, we will generate another Data Notification and will update the related Issue Logs for each of the data products affected.

Table 1: Affected hyperspectral acquisitions with incomplete BRDF and topographic corrections applied.
 

Table 2: Affected data products with incomplete BRDF and topographic corrections

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