References

ACP

Atmospheric Chemistry and Physics

ACP

1680-7324

Copernicus GmbH

Göttingen, Germany

10.5194/acp-12-3493-2012

Airborne hyperspectral observations of surface and cloud directional reflectivity using a commercial digital camera

Ehrlich

¹ Bierwirth

¹ Wendisch

¹ Herber

² Gayet

J.-F.

Leipzig Institute for Meteorology (LIM), University of Leipzig, Leipzig, Germany

Alfred Wegener Institute for Polar and Marine Research (AWI), Bremerhaven, Germany

Laboratoire de Météorologie Physique (LAMP), Université Blaise Pascal, Aubière Cedex, France

11 04 2012

12 7 3493 3510

This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

This article is available from http://www.atmos-chem-phys.net/12/3493/2012/acp-12-3493-2012.html

The full text article is available as a PDF file from http://www.atmos-chem-phys.net/12/3493/2012/acp-12-3493-2012.pdf

Spectral radiance measurements by a digital single-lens reflex camera were used to derive the directional reflectivity of clouds and different surfaces in the Arctic. The camera has been calibrated radiometrically and spectrally to provide accurate radiance measurements with high angular resolution. A comparison with spectral radiance measurements with the Spectral Modular Airborne Radiation measurement sysTem (SMART-Albedometer) showed an agreement within the uncertainties of both instruments (6% for both). The directional reflectivity in terms of the hemispherical directional reflectance factor (HDRF) was obtained for sea ice, ice-free ocean and clouds. The sea ice, with an albedo of ρ = 0.96 (at 530 nm wavelength), showed an almost isotropic HDRF, while sun glint was observed for the ocean HDRF (ρ = 0.12). For the cloud observations with ρ = 0.62, the cloudbow – a backscatter feature typically for scattering by liquid water droplets – was covered by the camera. For measurements above heterogeneous stratocumulus clouds, the required number of images to obtain a mean HDRF that clearly exhibits the cloudbow has been estimated at about 50 images (10 min flight time). A representation of the HDRF as a function of the scattering angle only reduces the image number to about 10 (2 min flight time). The measured cloud and ocean HDRF have been compared to radiative transfer simulations. The ocean HDRF simulated with the observed surface wind speed of 9 m s−1 agreed best with the measurements. For the cloud HDRF, the best agreement was obtained by a broad and weak cloudbow simulated with a cloud droplet effective radius of Reff = 4 μm. This value agrees with the particle sizes derived from in situ measurements and retrieved from the spectral radiance of the SMART-Albedometer.

References 1

Buriez, J.-C., Parol, F., Cornet, C., and Doutriaux-Boucher, M.: An improved derivation of the top-of-atmosphere albedo from POLDER/ADEOS-2: Narrowband albedos, J. Geophys. Res., 110, D05202, http://dx.doi.org/10.1029/2004JD005243doi:10.1029/2004JD005243, 2005.

Chepfer, H., Minnis, P., Young, D., Nguyen, L., and Arduini, R F.: Estimation of cirrus cloud effective ice crystal shapes using visible reflectances from dual-satellite measurements, J. Geophys. Res., 107, 4730, http://dx.doi.org/10.1029/2000JD000240doi:10.1029/2000JD000240, 2002.

Cox, C. and Munk, W.: Measurement of the roughness of the sea surface from photographs of the sun's glitter, J. Opt. Soc. Am. A., 44, 838–850, 1954.

Descloitres, J., Buriez, J C., Parol, F., and Fouquart, Y.: POLDER observations of cloud bidirectional reflectances compared to a plane-parallel model using the International Satellite Cloud Climatology Project cloud phase functions, J. Geophys. Res.-Atmos., 103, 11411–11418, http://dx.doi.org/10.1029/98JD00592doi:10.1029/98JD00592, 1998.

Dumont, M., Brissaud, O., Picard, G., Schmitt, B., Gallet, J.-C., and Arnaud, Y.: High-accuracy measurements of snow Bidirectional Reflectance Distribution Function at visible and NIR wavelengths – comparison with modelling results, Atmos. Chem. Phys., 10, 2507–2520, http://dx.doi.org/10.5194/acp-10-2507-2010doi:10.5194/acp-10-2507-2010, 2010.

Ehrlich, A., Bierwirth, E., Wendisch, M., Gayet, J.-F., Mioche, G., Lampert, A., and Heintzenberg, J.: Cloud phase identification of Arctic boundary-layer clouds from airborne spectral reflection measurements: test of three approaches, Atmos. Chem. Phys., 8, 7493–7505, http://dx.doi.org/10.5194/acp-8-7493-2008doi:10.5194/acp-8-7493-2008, 2008.

Gatebe, C., King, M., PLatnick, S., Arnold, G., Vermote, E., and Schmid, B.: Airborne spectral measurements of surface-atmosphere anisotropy for several surfaces and ecosystems over southern Africa, J. Geophys. Res., 108, 8489, http://dx.doi.org/10.1029/2002JD002397doi:10.1029/2002JD002397, 2003.

Gatebe, C K., King, M D., Lyapustin, A I., Arnold, G T., and Redemann, J.: Airborne spectral measurements of ocean directional reflectance, J. Atmos. Sci., 62, 1072–1092, 2005.

Gayet, J.-F., Mioche, G., Dörnbrack, A., Ehrlich, A., Lampert, A., and Wendisch, M.: Microphysical and optical properties of Arctic mixed-phase clouds. The 9 April 2007 case study., Atmos. Chem. Phys., 9, 6581–6595, http://dx.doi.org/10.5194/acp-9-6581-2009doi:10.5194/acp-9-6581-2009, 2009.

Gordon, H R. and Jacobs, M M.: Albedo of Ocean-atmosphere System – Influence of Sea Foam, Appl. Optics, 16, 2257–2260, 1977.

Haas, C., Lobach, J., Hendricks, S., Rabenstein, L., and Pfaffling, A.: Helicopter-borne measurements of sea ice thickness, using a small and lightweight, digital EM system, J. Appl. Geophys., 67, 234–241, http://dx.doi.org/10.1016/j.jappgeo.2008.05.005doi:10.1016/j.jappgeo.2008.05.005, 2009.

Hyer, E. J., Reid, J. S., and Zhang, J.: An over-land aerosol optical depth data set for data assimilation by filtering, correction, and aggregation of MODIS Collection 5 optical depth retrievals, Atmos. Meas. Tech., 4, 379–408, http://dx.doi.org/10.5194/amt-4-379-2011doi:10.5194/amt-4-379-2011, 2011.

Kaufmann, K.: CMOS Technology for Scientific Imaging, Spectroscopy, 25, 20–25, 2010.

Lampert, A., Ehrlich, A., Dörnbrack, A., Jourdan, O., Gayet, J.-F., Mioche, G., Shcherbakov, V., Ritter, C., and Wendisch, M.: Microphysical and radiative characterization of a subvisible midlevel Arctic ice cloud by airborne observations – a case study, Atmos. Chem. Phys., 9, 2647–2661, http://dx.doi.org/10.5194/acp-9-2647-2009doi:10.5194/acp-9-2647-2009, 2009.

Lebourgeois, V., Bégué, A., Labbé, S., Mallavan, B., Prévot, L., and Roux, B.: Can commercial digital cameras be used as multispectral sensors? A crop monitoring test, Sensors, 8, 7300–7322, http://dx.doi.org/10.3390/s8117300doi:10.3390/s8117300, 2008.

Litvinov, P., Hasekamp, O., and Cairns, B.: Models for surface reflection of radiance and polarized radiance: Comparison with airborne multi-angle photopolarimetric measurements and implications for modeling top-of-atmosphere measurements, Remote Sens. Environ., 115, 781–792, http://dx.doi.org/10.1016/j.rse.2010.11.005doi:10.1016/j.rse.2010.11.005, 2011.

Loeb, N. and Coakley~Jr., J.: Inference of marine stratus cloud optical depths from satellite measurements: Does 1D theory apply?, J. Climate, 11, 215–233, 1998.

Loeb, N. and Davies, R.: Angular dependence of observed reflectances: A comparison with plane parallel theory, J. Geophys. Res., 102, 6865–6881, 1997.

Loeb, N., Varnai, T., and Winker, D.: Influence of subpixel-scale cloud-top structure of reflectances from overcast stratiform cloud layers, J. Atmos. Sci., 55, 2960–2973, 1998.

Loeb, N., Parol, F., Buriez, J.-C., and Vanbauce, C.: Top-of-atmosphere albedo estimation from angular distribution models using scene identification from satellite cloud property retrievals, J. Climate, 13, 1269–1285, 2000.

Loeb, N., Kato, S., Loukachine, K., and Manalo-Smith, N.: Angular Distribution Models for Top-of-Atmosphere Radiative Flux Estimation from the Clouds and the Earth's Radiant Energy System Instrument on the Terra Satellite. Part I: Methodology, J. Atmos. Ocean. Tech., 22, 338–351, 2005.

Long, C N., Sabburg, J M., Calbo, J., and Pages, D.: Retrieving cloud characteristics from ground-based daytime color all-sky images, J. Atmos. Ocean. Tech., 23, 633–652, 2006.

Lyapustin, A., Gatebe, C. K., Kahn, R., Brandt, R., Redemann, J., Russell, P., King, M. D., Pedersen, C. A., Gerland, S., Poudyal, R., Marshak, A., Wang, Y., Schaaf, C., Hall, D., and Kokhanovsky, A.: Analysis of snow bidirectional reflectance from ARCTAS Spring-2008 Campaign, Atmos. Chem. Phys., 10, 4359–4375, http://dx.doi.org/10.5194/acp-10-4359-2010doi:10.5194/acp-10-4359-2010, 2010.

Mayer, B. and Kylling, A.: Technical note: The libRadtran software package for radiative transfer calculations – description and examples of use, Atmos. Chem. Phys., 5, 1855–1877, http://dx.doi.org/10.5194/acp-5-1855-2005doi:10.5194/acp-5-1855-2005, 2005.

Mayer, B., Schröder, M., Preusker, R., and Schüller, L.: Remote sensing of water cloud droplet size distributions using the backscatter glory: a case study, Atmos. Chem. Phys., 4, 1255–1263, http://dx.doi.org/10.5194/acp-4-1255-2004doi:10.5194/acp-4-1255-2004, 2004.

Nakajima, T. and King, M.: Determination of the optical thickness and effective particle radius of clouds from reflected solar radiation measurements. Part I: Theory, J. Atmos. Sci., 47, 1878–1893, 1990.

Nakajima, T. and Tanaka, M.: Effect of wind-generated waves on the transfer of solar radiation in the atmosphere-ocean system, J. Quant. Spectrosc. Ra., 29, 521–537, 1983.

Nicodemus, F., Richmond, J., Hsia, J., Ginsber, I W., and Limperis, T.: Geometrical Considerations and Nomenclature for Reflectance, vol. 160 of NBS Monograph, US Department of Commerce, Washington, D.C., National Bureau of Standards, 1977.

Olsen, D., Dou, C., Zhang, X., Hu, L., Kim, H., and Hildum, E.: Radiometric Calibration for AgCam, Remote Sensing, 2, 467–477, http://dx.doi.org/10.3390/rs2020464doi:10.3390/rs2020464, 2010.

Ovtchinnikov, M. and Marchand, R T.: Cloud model evaluation using radiometric measurements from the airborne multiangle imaging spectroradiometer (AirMISR), Remote Sens. Environ., 107, 185–193, http://dx.doi.org/10.1016/j.rse.2006.05.024doi:10.1016/j.rse.2006.05.024, 2007.

Schade, N. H., Macke, A., Sandmann, H., and Stick, C.: Total and partial cloud amount detection during summer 2005 at Westerland (Sylt, Germany), Atmos. Chem. Phys., 9, 1143–1150, http://dx.doi.org/10.5194/acp-9-1143-2009doi:10.5194/acp-9-1143-2009, 2009.

Schaepman-Strub, G., Schaepman, M E., Painter, T H., Dangel, S., and Martonchik, J V.: Reflectance quantities in optical remote sensing-definitions and case studies, Remote Sens. Environ., 103, 27–42, 2006.

Stamnes, K., Tsay, S., Wiscombe, W., and Jayaweera, K.: A numerically stable algorithm for discrete-ordinate-method radiative transfer in multiple scattering and emitting layered media, Appl. Optics, 27, 2502–2509, 1988.

Stramska, M. and Petelski, T.: Observations of oceanic whitecaps in the north polar waters of the Atlantic, J. Geophys. Res.-Oceans, 108, 3086, http://dx.doi.org/10.1029/2002JC001321doi:10.1029/2002JC001321, 2003.

Takashima, T.: Polarization Effect On Radiative-transfer In Planetary Composite Atmospheres With Interacting Interface, Earth Moon Planets, 33, 59–97, http://dx.doi.org/10.1007/BF00054709doi:10.1007/BF00054709, 1985.

Varnai, T. and Marshak, A.: View angle dependence of cloud optical thicknesses retrieved by Moderate Resolution Imaging Spectroradiometer (MODIS), J. Geophys. Res.-Atmos., 112, D06203, http://dx.doi.org/10.1029/2005JD006912doi:10.1029/2005JD006912, 2007.

von Schönermark, M., Geiger, B., and Röser, H.-P. (Eds.): Reflection Properties of Vegetation and Soil With a BRDF-Data base, vol 1, Wissenschaft und Technik Verlag, Berlin, 2004.

Wendisch, M. and Yang, P.: Theory of Atmospheric Radiative Transfer � A Comprehensive Introduction, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany, ISBN: 978-3-527-40836-8, 2012.

Wendisch, M., Müller, D., Schell, D., and Heintzenberg, J.: An airborne spectral albedometer with active horizontal stabilization, J. Atmos. Ocean. Technol., 18, 1856–1866, 2001.

Wendisch, M., Pilewskie, P., Jäkel, E., Schmidt, S., Pommier, J., Howard, S., Jonsson, H H., Guan, H., Schröder, M., and Mayer, B.: Airborne measurements of areal spectral surface albedo over different sea and land surfaces, J. Geophys. Res., 109, D08203, http://dx.doi.org/10.1029/2003JD004392doi:10.1029/2003JD004392, 2004.