Document Type

Thesis - Open Access

Award Date

2023

Degree Name

Master of Science (MS)

Department / School

Electrical Engineering and Computer Science

First Advisor

Larry Leigh

Keywords

bidirectional reflectance distribution function (BRDF), cross-calibration, Landsat, PICS, spectral band adjustment factor (SBAF), Underfly

Abstract

The Landsat 8 and 9 Underfly Event occurred in November 2021, where Landsat 9 flew beneath Landsat 8 in the final stages before settling in its final orbiting path. An analysis was performed on the images taken during this event, which resulted in a cross-referenced with uncertainties estimated to be less than 0.5%. This level of precision was due in part to the near-identical sensors aboard each instrument as well as the underfly event itself, which allowed the sensors to take nearly the exact same image at nearly the exact same time. This initial calibration was applied before the end of the on-orbit initial verification (OIV) period, which meant the analysis was performed in less than a month. While it was an effective and efficient first look at the data, a longer-term analysis was deemed prudent to have the most accurate cross-referenced with the smallest uncertainties. The three forms of uncertainty established in the initial analysis, dubbed “Phase 1”, were geometric, spectral, and angular. This paper covers Phase 2 of the underfly analysis, and several modifications were made to the Phase 1 process to improve the cross-referenced results, including a spectral correction in the form of a spectral band adjustment factor (SBAF) and a more robust filtering system that used the statistics of the reflectance data to better include important data compared to the more aggressive filters used in Phase 1. A proper uncertainty analysis was performed to more accurately quantify the uncertainty associated with the underfly cross-referenced. The final results of Phase 2 showed that the Phase 1 analysis was within its 0.5% uncertainty estimation, and the cross-referenced gain values in this paper were used by USGS EROS to update the Landsat 9 calibration at the end of 2022.

Library of Congress Subject Headings

Landsat satellites -- Calibration.
Artificial satellites in remote sensing -- Calibration.
Spectral reflectance.

Publisher

South Dakota State University

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Rights Statement

In Copyright