Gilerson, Alexander: CUNY (Project Lead)
Project Funding:
2013 - 2015
NRA: 2012 NASA: Ocean Biology and Biogeochemistry
Funded by NASA
Abstract:
Multi-spectral remote sensing reflectance data from Ocean Color satellites are suitable for the retrieval of absorption and backscattering coefficients but are insensitive to total scattering and attenuation coefficients because forward scattered light does not have any substantial impact on the measured radiances.
Our recent extensive vector radiative transfer simulations performed using realistic bio- optical models for coastal waters as well as related field measurements demonstrate potential for retrieval of scattering and attenuation coefficients from their polarization signatures. Specifically, we found that a strong relation exists between the subsurface degree of linear polarization (DoLP) and the attenuation/absorption ratio for viewing angles achievable from above water measurements of the Stokes vector components. The detailed analysis of such an approach is proposed which will be based on the generation of an expanded set of synthetic data for both ocean and coastal waters. This analysis is designed to provide a methodology for the retrieval of the attenuation coefficient as well as slopes of particle size distributions, concentrations of mineral particles, etc. from above water polarized multi-spectral / multi-angular observations.
To assess the potential of the approach for satellite observations, we will simulate the coupled atmosphere / ocean system using flexible vector radiative transfer codes over a wide variety of ocean and coastal water conditions to generate realistic top of the atmosphere (TOA) polarization signals. These simulations will be performed in a controlled manner to both assess the limitations due to uncompensated aerosols as well as to provide critical data to assess possible atmospheric correction schemes.
Our approach will be extensively validated through polarimetric measurements from a wide variety of existing instrumentation and platforms: 1) an underwater radiometric hyperspectral polarimeter - full Stokes vector imaging camera system, together with an integrated IOPs package of in-water instrumentation; 2) above water polarization measurements from our Long Island Sound Coastal Observatory (LISCO) including NASA AERONET aerosols retrievals from a SeaPRISM instrument and Stokes vector components measured by our extended version of HyperSAS and 3) coordinated Research Scanning Polarimeter (RSP) (NASA GISS) measurements from the aircraft. Developed methodology is expected to lead to the development, optimization and characterization of compact polarimeters suitable for both aerosol and water characteristics retrievals. The conceptual design of these satellite imaging polarimeters for such observations will be made based on a single band pushbroom imaging polarimeter small enough to fit into 3U CubeSats. These imagers would then be used in combination to cover multiple spectral bands, different polarization components, and
viewing angles to provide high SNR multispectral imaging polarimetry. This work directly responds to the item 2 of the NRA and related to future NASA missions: PACE and ACE in which multi-band multi-angular polarimeters will be a part of the sensor package.
The proposed project builds on the long term experience of researchers from the City College of New York, Raytheon and NASA GISS in polarimetric ocean and atmospheric studies, radiative transfer modeling of the ocean-atmosphere system, design of environmental polarimetric sensors and other space-based imaging instruments. CCNY is a minority serving institution and through several programs for Historically Black Colleges and Universities (HBCU) and other programs including the NASA - COSI center in 2003-2009, the remote sensing group was very successful in integrating student involvement. It is expected that the proposed project will attract new students with majors in Electrical and Environmental Engineering.
Publications:
Gu, Y., Carrizo, C., Gilerson, A. A., Brady, P. C., Cummings, M. E., Twardowski, M. S., Sullivan, J. M., Ibrahim, A. I., Kattawar, G. W. 2016. Polarimetric imaging and retrieval of target polarization characteristics in underwater environment. Applied Optics. 55(3), 626. DOI: 10.1364/AO.55.000626
More details may be found in the following project profile(s):
