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Proceedings Paper

Radiometric cross-calibration of the Terra MODIS and Landsat 7 ETM+ using an invariant desert site
Author(s): Taeyoung Choi; Amit Angal; Gyanesh Chander; Xiaoxiong Xiong
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Paper Abstract

A methodology for long-term radiometric cross-calibration between the Terra Moderate Resolution Imaging Spectroradiometer (MODIS) and Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM+) sensors was developed. The approach involves calibration of near-simultaneous surface observations between 2000 and 2007. Fifty-seven cloudfree image pairs were carefully selected over the Libyan desert for this study. The Libyan desert site (+28.55°, +23.39°), located in northern Africa, is a high reflectance site with high spatial, spectral, and temporal uniformity. Because the test site covers about 12 kmx13 km, accurate geometric preprocessing is required to match the footprint size between the two sensors to avoid uncertainties due to residual image misregistration. MODIS Level 1B radiometrically corrected products were reprojected to the corresponding ETM+ image's Universal Transverse Mercator (UTM) grid projection. The 30 m pixels from the ETM+ images were aggregated to match the MODIS spatial resolution (250 m in Bands 1 and 2, or 500 m in Bands 3 to 7). The image data from both sensors were converted to absolute units of at-sensor radiance and top-of atmosphere (TOA) reflectance for the spectrally matching band pairs. For each band pair, a set of fitted coefficients (slope and offset) is provided to quantify the relationships between the testing sensors. This work focuses on long-term stability and correlation of the Terra MODIS and L7 ETM+ sensors using absolute calibration results over the entire mission of the two sensors. Possible uncertainties are also discussed such as spectral differences in matching band pairs, solar zenith angle change during a collection, and differences in solar irradiance models.

Paper Details

Date Published: 20 August 2008
PDF: 12 pages
Proc. SPIE 7081, Earth Observing Systems XIII, 708110 (20 August 2008); doi: 10.1117/12.793829
Show Author Affiliations
Taeyoung Choi, Science Systems and Applications, Inc. (United States)
Amit Angal, Science Systems and Applications, Inc. (United States)
Gyanesh Chander, SGT, Inc. (United States)
Xiaoxiong Xiong, NASA Goddard Space Flight Ctr. (United States)


Published in SPIE Proceedings Vol. 7081:
Earth Observing Systems XIII
James J. Butler; Jack Xiong, Editor(s)

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