Kindel, Bruce: University of Colorado (Project Lead)
Project Funding:
2017 - 2019
NRA: 2016 NASA: Utilization of Airborne Visible/Infrared Imaging Spectrometer- Next Generation Data from an Airborne Campaign in India-AVRSNG
Funded by NASA
Abstract:
The atmospheric correction of hyperspectral imaging data remains the largest source of uncertainty in the derivation of surface reflectance and the data products created from surface reflectance. Despite the dramatic gains in signal-to-noise ratio of the AVIRIS instrument over the past two decades, the atmospheric radiative transfer modeling required to convert radiance to reflectance remains the greatest source of error because the atmospheric correction has not kept pace with the instrumental improvements. From an atmospheric correction standpoint, the AVIRIS dataset collected over India presents a unique opportunity. India is a very challenging environment in terms of the aerosol environment encountered by previous AVIRIS and future hyperspectral observations. India routinely reports large aerosol optical thicknesses and also contains an especially rich environment of different aerosol types. This makes the improvement of atmospheric correction critical to the future of hyperspectral imaging data in India. This proposal seeks to improve on atmospheric correction of imaging spectrometer data, focusing on the aerosol component of atmospheric radiative transfer modeling. Currently, nearly all of the standard atmospheric correction routines (e.g. ATCOR, FLAASH, etc) use the MODTRAN radiative transfer model as the basis for the calculation of the terms required for surface reflectance retrieval. The default aerosol types are restricted to very few aerosol types (e.g. “urban”, “desert”, “rural”, etc.) This proposal will generate a library of aerosol spectra (i.e. an AVIRIS-India Aerosol Spectral Catalog) based on a combination of aerosol properties retrieved from AVIRIS observations in 2015 and 2016, and aerosol properties measured by the Moderate Resolution Imaging Spectroradiometer (MODIS) experiment, aided by observations made within India from ground-based retrievals of aerosol optical properties (e.g. the AERONET network). Retrievals of AVIRIS 2015-2016 aerosol extinction spectra will be carried out by applying Clive Rodger’s optimal estimation methodology. This methodology includes retrievals and error analysis in a self-consistent framework. The error analysis will indicate the limitations of what can be retrieved from AVIRIS spectra in regards to aerosols. The ultimate product will be a suite of geographically specific aerosol spectra suitable for use in atmospheric correction for current 2015-1016 AVIRIS-India measurements and future imaging spectrometer data taken in India. A geographically specific model of aerosols for atmospheric correction of imaging spectrometer data has never, to our knowledge been produced and this would be the first of its kind. The catalog of aerosol spectra will be freely distributed to the AVIRIS community. More generally, we expect to achieve substantial improvements in atmospheric correction of hyperspectral data, due to our particular application of optimal estimation methodology that will utilize a priori data from multiple satellites and ground based sites.
More details may be found in the following project profile(s):