An accuracy assessment of the surface reflectance product from the EMIT imaging spectrometer

Red Willow Coleman*, David R. Thompson, Philip G. Brodrick, Eyal Ben Dor, Evan Cox, Carlos Pérez García-Pando, Todd Hoefen, Raymond F. Kokaly, John M. Meyer, Francisco Ochoa, Gregory S. Okin, Daniela Heller Pearlshtien, Gregg Swayze, Robert O. Green

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The Earth surface Mineral dust source InvesTigation (EMIT) is an imaging spectrometer launched to the International Space Station in July 2022 to measure the mineral composition of Earth's dust-producing regions. We present a systematic accuracy assessment of the EMIT surface reflectance product in two parts. First, we characterize the surface reflectance product's overall performance using multiple independent vicarious calibration field experiments with hand-held and automated field spectrometers. We find that the EMIT surface reflectance product has a standard error of ±1.0% in absolute reflectance units for temporally coincident observations. Discrepancies rise to ±2.7 % for spectra acquired at different dates and times of day, which we attribute mainly to changes in solar geometry. Second, we develop an error budget that explains the differences between EMIT and in-situ field spectrometer data. We find that uncertainties in spatial footprints, field spectroscopy, and the EMIT-reported measurement were sufficient to explain discrepancies in most cases. Our approach did not detect any systematic calibration or reflectance errors in the timespan considered. Together, these findings demonstrate that a space-based imaging spectrometer can acquire high-quality spectra across a wide range of observational and atmospheric conditions.

Original languageEnglish
Article number114450
JournalRemote Sensing of Environment
Volume315
DOIs
StatePublished - 15 Dec 2024

Keywords

  • Imaging spectroscopy
  • Remote sensing
  • Surface reflectance

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