The Research Scanning Polarimeter (RSP) is a multi-spectral scanning polarimeter with nine spectral channels centered between 410 and 2250nm. All channels are sensitive to polarization with the use of Wollaston prisms. The RSP scans in the along track direction, and views each scene at a 152+ view angles (roughly between +/- 60˚ of nadir) in a single pixel wide swath. Observations of a dark reference and a polarimetric calibration are also made with each scan. The RSP instrument has an IFOV of 14mrad and a pixel observation time of 1.875msec. For the ER-2 aircraft used during PODEX and SEAC4RS (altitude of 19800m, speed 207m/sec), this translates to a native pixel resolution is 277m with 277m of along track "smear".

The RSP is the airborne prototype of the Aerosol Polarimetry Sensor (APS), an instrument of the NASA Glory Mission. Glory failed to reach orbit during its launch in early 2011. Despite this, the pair of RSP instruments that have been manufactured continue to be deployed in field campaigns and serve as tools to investigate the design of future polarimetric orbital instrumentation.

Image: RSP data acquired on August 19, 2013 during the SEAC4RS field campaign. Each row of image data represents a single scan by the RSP. Columns thus represent slices of varying scan number (location) at fixed view zenith angle, while rows represent varying view zenith angle at a fixed measurement location. The 'tilt' of an image feature represents the distance from that object to the RSP. Objects far from the RSP require many scans to pass from fore to aft viewing angles, as is the case for the green and dark blue surface features in the scene shown at right. Closer objects, such as the bright clouds in the image, are observed with less scans.

More information:

• RSP instrument homepage
• Photopolarimetry group at NASA GISS
• NASA Glory Mission Science site
• APS Documentation

Data

RSP data are available in HDF5 format, along with TIF browse images. PODEX and SEAC4RS data (among other field campaigns) are available at the NASA Goddard Institute for Space Studies (GISS) FTP site, in addition to documentation and software tools.

Calibration

Radiometric calibration is performed in the calibration facilities of the NASA Goddard Space Flight Center and NASA Ames Research Center's integrating spheres. Polarimetric calibration is performed using wire grid polarizers on a rotating stage to provide fully polarized light at desired polarization angles.

Uncertainty

The analytical formulation of RSP Reflectance and Degree of Linear Polarization (DoLP) uncertainties are functions of both reflectance and DoLP, as described here. DoLP uncertainty is also minimally sensitive to the polarization angle. A simulation of these uncertainties as a function of scene reflectance are shown at left. ACE requirements are met for reflectances above about 0.025.

A detailed derivation and description of RSP uncertainty can be found here. A summary by K. Knobelspiesse is here.

Reference

Alexandrov, M. D., Cairns, B., and Mishchenko, M. I., 2012: Rainbow fourier transform. Journal of Quantitative Spectroscopy and Radiative Transfer, 113 (18), 2521-2535.

Alexandrov, M. D., Cairns, B., Emde, C., Ackerman, A. S., and van Diedenhoven, B., 2012: Accuracy assessments of cloud droplet size retrievals from polarized reflectance measurements by the research scanning polarimeter. Remote Sensing of Environment, 125 (0), 92 - 111.

Cairns, B., Waquet, F., Knobelspiesse, K, Chowdhary, J., and Deuzé, J.-L., 2009: Polarimetric remote sensing of aerosols over land surfaces. In Satellite Aerosol Remote Sensing over Land. A.A. Kokhanovsky, and G. De Leeuw, Eds., Springer-Praxis Books in Environmental Sciences. Springer, 295-325, doi:10.1007/978-3-540-69397-0_10.

Cairns, B., J.D. LaVeigne, A. Rael, and R.D. Granneman, 2004: Atmospheric correction of HyperSpecTIR measurements using the research scanning polarimeter. In Polarization: Measurement, Analysis, and Remote Sensing VI, 12 Apr. 2004, Orlando, Fla., Proc. SPIE, vol. 5432, 95, doi:10.1117/12.542194.

Cairns, B., E.E. Russell, J.D. LaVeigne, and P.M.W. Tennant, 2003: Research scanning polarimeter and airborne usage for remote sensing of aerosols. In Polarization Science and Remote Sensing, 3 Aug. 2003, San Diego, Cal., Proc. SPIE, vol. 5158, 33, doi:10.1117/12.518320.

Cairns, B. and Chowdhary, J., 2003: Aerosol and Cloud Environmental Data Records: Aerosol Polarimetry Sensor Algorithm Theoretic Basis Document. 

Cairns, B., E.E. Russell, and L.D. Travis, 1999: Research Scanning Polarimeter: Calibration and ground-based measurements. In Polarization: Measurement, Analysis, and Remote Sensing II, 18 Jul. 1999, Denver, Col., Proc. SPIE, vol. 3754, 186, doi:10.1117/12.366329.

Chowdhary, J., Cairns, B., Waquet, F., Knobelspiesse, K., Ottaviani, M., Redemann, J., Travis, L., and Mishchenko, M., 2012: Sensitivity of multiangle, multispectral polarimetric remote sensing over open oceans to water-leaving radiance: Analyses of RSP data acquired during the MILAGRO campaign. Remote Sensing of Environment, 118, 284--308.

Chowdhary, J., Cairns, B., and Travis, L. D., 2006: Contribution of water-leaving radiances to multiangle, multispectral polarimetric observations over the open ocean: bio-optical model results for case 1 waters. Appl. Opt., 45 (22), 5542--5567.

Chowdhary, J., Cairns, B., Mishchenko, M. I., Hobbs, P. V., Cota, G. F., Redemann, J., Rutledge, K., Holben, B. N., and Russell, E., 2005:Retrieval of Aerosol Scattering and Absorption Properties from Photopolarimetric Observations over the Ocean during the CLAMS Experiment.J. Atmos. Sci., 62, 1093-1117.

Chowdhary, J., Cairns, B., Mishchenko, M. I., and Travis, L. D., 2005: Using multi-angle multispectral photo-polarimetry of the NASA Glory mission to constrain optical properties of aerosols and clouds: results from four field experiments. Proceedings of SPIE, 5978 (59780G), 1-12.

Chowdhary, J., B. Cairns, M.I. Mishchenko, and L.D. Travis, 2004: Constraining aerosol single scattering albedos from multiangle multispectral photo-polarimetric observations over the ocean. In Remote Sensing of Clouds and the Atmosphere IX, 13 Sep. 2004, Maspalomas, Gran Canaria, Spain, Proc. SPIE, vol. 5571, 127, doi:10.1117/12.565705.

Chowdhary, J., Cairns, B., and Travis, L., 2002: Case Studies of Aerosol Retrievals over the Ocean from Multiangle, Multispectral Photopolarimetric Remote Sensing Data. J. Atmos. Sci., 59 (3), 383--397.

Chowdhary, J., Cairns, B., Mishchenko, M., and Travis, L., 2001: Retrieval of aerosol properties over the ocean using multispectral and multiangle photopolarimetric measurements from the Research Scanning Polarimeter. Geophys. Res. Lett., 28 (2), 243-246.

van Diedenhoven, B., Cairns, B., Fridlind, A. M., Ackerman, A. S., and Garrett, T. J., 2013: Remote sensing of ice crystal asymmetry parameter using multi-directional polarization measurements - Part 2: Application to the Research Scanning Polarimeter. Atmospheric Chemistry and Physics, 13 (6), 3185--3203.

van Diedenhoven, B., Cairns, B., Geogdzhayev, I. V., Fridlind, A. M., Ackerman, A. S., Yang, P., and Baum, B. A., 2012: Remote sensing of ice crystal asymmetry parameter using multi-directional polarization measurements - Part 1: Methodology and evaluation with simulated measurements. Atmospheric Measurement Techniques, 5 (10), 2361--2374.

Knobelspiesse, K., Cairns, B., Redemann, J., Bergstrom, R. W., and Stohl, A., 2011: Simultaneous retrieval of aerosol and cloud properties during the MILAGRO field campaign. Atmospheric Chemistry and Physics, 11, 6245-6263.

Knobelspiesse, K., Cairns, B., Ottaviani, M., Ferrare, R., Hair, J., Hostetler, C., Obland, M., Rogers, R., Redemann, J., Shinozuka, Y., Clarke, A., Freitag, S., Howell, S., Kapustin, V., and McNaughton, C., 2011: Combined retrievals of boreal forest fire aerosol properties with a polarimeter and lidar. Atmospheric Chemistry and Physics, 11, 7045--7067.

Litvinov, P., Hasekamp, O., Cairns, B., and Mishchenko, M., 2010: Reflection models for soil and vegetation surfaces from multiple-viewing angle photopolarimetric measurements. J. Quant. Spectrosc. Radiat. Transfer, 111 (), 529-539.

Mishchenko, M. I., Cairns, B., Kopp, G., Schueler, C., Fafaul, B., Hansen, J., Hooker, R., Itchkawich, T., Maring, H., and Travis, L., 2007:Accurate monitoring of terrestrial aerosols and total solar irradiance: introducing the Glory mission. Bull. Amer. Meteorol. Soc, 88, 687-691.

Ottaviani, M., Cairns, B., Chowdhary, J., Van Diedenhoven, B., Knobelspiesse, K., Hostetler, C., Ferrare, R., Burton, S., Hair, J., Obland, M. D., and Rogers, R., 2012: Polarimetric retrievals of surface and cirrus clouds properties in the region affected by the Deepwater Horizon oil spill. Remote Sens. Environ., 121, 389--403.

Peralta, R. J., Nardell, C., Cairns, B., Russell, E. E., Travis, L. D., Mishchenko, M. I., Fafaul, B. A., and Hooker, R. J., 2007: Aerosol polarimetry sensor for the Glory Mission. In MIPPR 2007: Automatic Target Recognition and Image Analysis; and Multispectral Image Acquisition", 15 Nov. 2007, Wuhan, China, Proc. SPIE, vol. 6786, 67865L, doi:10.1117/12.783307.

Persh, S., Shaham, Y., Benami, O., Cairns, B., Mishchenko, M. I., Hein, J. D., and Fafaul, B. A., 2010: Ground Performance Measurements of the Glory Aerosol Polarimetry Sensor. In Earth Observing Systems XV, 1 Aug. 1, 2010, San Diego, Cal., Proc. SPIE, vol. 7807, 780703, doi:10.1117/12.862029.

Waquet, F., B. Cairns, K. Knobelspiesse, J. Chowdhary, L.D. Travis, B. Schmid, and M.I. Mishchenko, 2009: Polarimetric remote sensing of aerosols over land. J. Geophys. Res., 114, D01206, doi:10.1029/2008JD010619.

More RSP and APS publications here