Document Type

Thesis - University Access Only

Award Date

2011

Degree Name

Doctor of Philosophy (PhD)

Department / School

Geospatial Science and Engineering

Abstract

This study focuses on theoretical and applied understanding of radiometric cross-calibration of optical sensors over their entire missions in support of continued long-term studies of the Earth's land surfaces. The two sensors used for the study are the Terra Moderate Resolution Imaging Spectroradiometer (MODIS) and the Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM+) sensors. The Relative Spectral Response (RSRs) of the analogous ETM+ and MODIS spectral bands differ significantly, which gave the opportunity to explore, understand, quantify, and compensate for the differences in measurements as obtained from these two sensors. The investigation described in this study focused on using near-simultaneous observations from these two sensors over the Committee on Earth Observation Satellites (CEOS) Pseudo-Invariant Calibration Site (PIGS) locations in the reflective solar band spectral domain. The cross-calibration was initially performed by comparing the Top-of- Atmosphere (TOA) reflectances between the two sensors over their lifetimes. The average percent differences in intercept from the long-term trends ranged from 2.5% to 16% (obtained from the ETM+ TOA reflectance estimates as measured relative to MODIS TOA reflectance for the Libya 4 site). Spectral issues with this cross-calibration approach were investigated and Spectral Band Adjustment Factor (SBAFs) were developed for analogous ETM+ and MODIS spectral bands where the spectral signature of the target was simulated using Earth Observing-1 (EO-1) Hyperion data. The RSR adjusted ETM+ TOA reflectance (ETM+*) measurements were then found to agree with MODIS TOA reflectance to within 6% or better for all bands when Hyperion hyperspectral data was used to produce the SBAFs. These differences were later reduced to less than 1% for all VNIR bands (except Band 2) by using Environmental Satellite (ENVISAT) scanning Imaging Absorption SpectroMeter for Atmospheric CartograpHY (SCIAMACHY) hyperspectral data to produce the SBAFs. The cross-calibration results suggest the absolute calibration of Hyperion needs to be further investigated based on the assumption that ETM+ and MODIS sensors are accurately calibrated. To better understand the absolute limits of this type of cross-calibration, the uncertainties inherent in the process were quantified. These include contributions due to different spectral responses, spectral resolution (found to be within 0.25%), spectral filter shift (found to be within 2.5%), geometric misregistration (found to be within 0.35% ), and spatial resolution (found to be within 0.1 % ), effects. An overall net uncertainty was developed and was found to be within 2.5%, and the results from application of SBAFs to the visible and near infrared bands (except Band 4) were within the total uncertainties

Library of Congress Subject Headings

Landsat satellites -- Calibration

Earth resources technology satellites -- Calibration

Imaging systems -- Image quality

Format

application/pdf

Number of Pages

362

Publisher

South Dakota State University

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