Polarization Surface-State Retrieval in the Presence of Atmospheric Perturbations

Mentor: Dr. Carol Bruegge (JPL)

By: Victor Chu

Who

• Funding: Non-NASA contract– ICATS project (Image Chain Analysis Technology for

Space)

• Orbiting Carbon Observatory (OCO)– OCO requires knowledge of surface polarization

properties for its retrieval algorithm– The task utilizes a retrieval code also used by OCO

• Multiangle SpectroPolarimetric Imager (MSPI)– JPL polarimeter built to study aerosols

Pre-Cursor

• Multi-angle Imaging SpectroRadiometer (MISR)

• Orbit since 1999

• 275m resolution

• 0º, 26º, 46º, 60º, and 70º fore and aft of nadir

• Spectral Bands - 446, 558, 672, 866 nm

• Multi-angle – Unique Capabilities

What it can doMISR generated image

Enhanced sensitivity to aerosols

Polarization

• MISR lacks Polarization Sensor

• Polarization Adds New Dimension

• New level of clarity

What it COULD do

• Camouflaged objects are difficult to detect with MISR

• Polarization makes objects appear extremely clear regardless

Do you see any trucks?

What about now?

See them now?

MSPI

• Follow-on instrument to MISR

• Many factors affect polarimetric accuracy

• Requires calibration

Radiative Programs• VLIDORT

• Few Polarization calculators– MODTRAN

• Developed by the Air Force Geophysical Laboratory (AFGL)

– MODTRAN 5– ICATS team has access to MODTRAN 4P beta

Effects of Aeresol

Ground Downwelling

Ground Upwelling

Satellite Upwelling

Degree of Linear Polarization

Effects of Gases

Ground Downwelling

Ground Upwelling

Satellite Upwelling

Degree of Linear Polarization

Future Plans

• Simulations of test scenes

• Identify surfaces given Stokes parameters

• Measurement capability

• Validation of both VLIDORT and MODTRAN 4P

Acknowledgements

• Dr. Carol Bruegge, Mentor

• Vijay Natraj, VLIDORT expert

• Rob Spurr, VLIDORT author

• SURF office for program organization

References

• D. Diner, A. Davis, R. Chipman, “Innovative Technology Approach for High-Accuracy Imaging Spectropolarimetry at Multiple View Angles,” project proposal for funding, 2006.

• Spurr, Robert J.D. VLIDORT: A linearized pseudo-spherical vector discrete ordinate radiative transfer model for forward model and retrieval studies in multilayer multiple scattering media. JQSRT 2006 in press.

• T. Takashima, K. Masuda, “Degree of radiance and polarization of upwelling radiation from an atmosphere-ocean system”, Applied Optics 24, 15, 2423 (1985)

• T. Cronin, E. Warrant, B Greiner, “Celestial polarization patterns during twilight”, Applied Optics 45, 22, 5582 (2006)

• G.N. Plass, G.W. Kattawar, “Polarization of the Radiation Reflected and Transmitted by the Earth’s Atmosphere”, Applied Optics 9, 5, 1122 (1970)

• J. S. Tyo, D. L. Goldstein, D. B. Chenault, J. A. Shaw, “Review of passive imaging polarimetry for remote sensing applications”, Applied Optics 45, 22, 5453 (2006