ORIGINAL RESEARCH article
Front. Remote Sens.
Sec. Multi- and Hyper-Spectral Imaging
Volume 6 - 2025 | doi: 10.3389/frsen.2025.1683919
This article is part of the Research TopicEarth Observations from the Deep Space: 10 Years of the DSCOVR MissionView all 12 articles
Size Matters: The Influence of Pixel Resolution on DSCOVR/EPIC Reflectance and Cloud Metrics
Provisionally accepted
- 1University of Maryland Baltimore County, Baltimore, United States
- 2NASA Goddard Space Flight Center, Greenbelt, United States
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Satellite‐derived reflectance and cloud retrievals are highly sensitive to spatial scale. Coarser pixels exaggerate cloud fraction and bias optical thickness and height estimates because unresolved subpixel variability violates plane–parallel assumptions. Here, we use DSCOVR/EPIC Level‐1 reflectance (317–780 nm) and Level‐2 cloud products (binary cloud mask, effective cloud height, ice/liquid optical thickness) to quantify these effects. Full‐disk images were downsampled to eight resolutions: 1024, 512, 256, 128, 64, 32, 16, and 8 pixels across the disk ~12, 25, 50, 100, 200, 400, 800, 1600 km per pixel, respectively). Reflectances were aggregated by simple averaging; cloud masks by five subpixel thresholds (≥1, ≥25, ≥50, ≥75, and 100 % cloudy); cloud height and optical thickness by mean values when ≥50 % of subpixels were valid. Global means of reflectance, cloud fraction, cloud height, and optical thickness were then calculated at each scale and threshold. While reflectance averages remained constant to within 1 % across all scales, cloud fraction rose steeply under permissive thresholds as resolution coarsened. Mean cloud height and optical thickness also increased, reflecting the dominance of taller, thicker clouds in coarse‐pixel averages. These results quantify resolution‐ driven biases in EPIC cloud products and underscore the value of high‐resolution observations and heterogeneity‐aware retrieval methods for robust cloud characterization.
Keywords: spatial resolution, Cloud fraction, plane-parallel biases, cloud optical thickness, Droplet effective radius, Earth observation instruments, exoplanet observations, disk-integrated data
Received: 11 Aug 2025; Accepted: 13 Oct 2025.
Copyright: © 2025 Delgado Bonal, Marshak and Yang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Alfonso Delgado Bonal, alfonso.delgado.bonal@gmail.com
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