AMT Atmospheric Measurement Techniques AMT Atmos. Meas. Tech. 1867-8548 Copernicus Publications Göttingen, Germany 10.5194/amt-3-1005-2010 The detection of cloud-free snow-covered areas using AATSR measurements Istomina L. G. 1 von Hoyningen-Huene W. 1 Kokhanovsky A. A. 1 Burrows J. P. 1 Institute of Environmental Physics, University of Bremen, Bremen, Germany 03 08 2010 3 4 1005 1017 Copyright: © 2010 L. G. Istomina et al. 2010 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://amt.copernicus.org/articles/3/1005/2010/amt-3-1005-2010.html The full text article is available as a PDF file from https://amt.copernicus.org/articles/3/1005/2010/amt-3-1005-2010.pdf

A new method to detect cloud-free snow-covered areas has been developed using the measurements by the Advanced Along Track Scanning Radiometer (AATSR) on board the ENVISAT satellite in order to discriminate clear snow fields for the retrieval of aerosol optical thickness or snow properties. The algorithm uses seven AATSR channels from visible (VIS) to thermal infrared (TIR) and analyses the spectral behaviour of each pixel in order to recognize the spectral signature of snow. The algorithm includes a set of relative thresholds and combines all seven channels into one flexible criterion, which allows us to filter out all the pixels with spectral behaviour similar to that of snow. The algorithm does not use any kind of morphological criteria and does not require the studied surface to have any special structure. The snow spectral shape criterion was determined by a comprehensive theoretical study, which included radiative transfer simulations for various atmospheric conditions as well as studying existing models and measurements of optical and physical properties of snow in different spectral bands. The method has been optimized to detect cloud-free snow-covered areas, and does not produce cloud/land/ocean/snow mask. However, the algorithm can be extended and able to discriminate various kinds of surfaces. <br><br> The presented method has been validated against Micro Pulse Lidar data and compared to Moderate Resolution Imaging Spectroradiometer (MODIS) cloud mask over snow-covered areas, showing quite good correspondence to each other. <br><br> Comparison of both MODIS cloud mask and presented snow mask to AATSR operational cloud mask showed that in some cases of snow surface the accuracy of AATSR operational cloud mask is questionable.

 References Ackerman, S. A., Strabala, K. I., Menzel, W. P., Frey, R. A., Moeller, C. C., and Gumley, L. E.: Discriminating clear sky from clouds with MODIS, J. Geophys. Res., 103, 32141–32157, 1998. Allen, R. C., Durkee, P. A., and Wash, C. H.: Snow/cloud discrimination with multispectral satellite measurements, J. Appl. Meteor., 29, 994–1004, 1990. Aoki, Te., Aoki, Ta., Fukabori, M., Hachikubo, A., Tachibana, Y., and Nishio, F.: Effects of snow physical parameters on spectral albedo and bidirectional reflectance of snow surface, J. Geophys. Res, 105, D8, 10219–10236, https://doi.org/10.1029/1999JD901122, 2000. Bréon, F.-M. and Colzy, S.: Cloud detection from the spaceborne POLDER instrument and validation against surface synoptic observations, J. Appl. Meteor., 38, 777–785, 1999. Campbell, J. R., Hlavka, D. L., Welton, E. J., Flynn, C. J., Turner, D. D., Spinhirne, J. D., Scott, V. S., and Hwang, I. H.: Full-Time, Eye-Safe Cloud and Aerosol Lidar Observation at Atmospheric Radiation Measurement Program Sites: Instruments and Data Processing, J. Atmos. Oceanic Tech., 19, 431–442, 2002. Delene, D. J. and Ogren, J. A.: Variability of aerosol optical properties at four North American surface monitoring sites, J. Atmos. Sci., 59, 1135–1150, 2002. Diner, D., Clothiaux, E., and Di Girolamo, L.: MISR Multi-angle imaging spectro-radiometer algorithm theoretical basis. Level 1 Cloud detection, Jet Propulsion Laboratory, JPL D-13397, 1999. Domine, F., Albert, M., Huthwelker, T., Jacobi, H.-W., Kokhanovsky, A. A., Lehning, M., Picard, G., and Simpson, W. R.: Snow physics as relevant to snow photochemistry, Atmos. Chem. Phys., 8, 171–208, https://doi.org/10.5194/acp-8-171-2008, 2008. Domine, F., Salvatori, R., Legagneux, L., Salzano, R., Fily, M., and Casacchia, R.: Correlation between the specific surface area and the short wave infrared (SWIR) reflectance of snow, Cold Reg. Sci. Technol., 46, 60–68, 2006. English, S. J., Jones, D. C., Hewison, T. J., Saunders, R. W., and Hallikainen, M.: Observations of the emissivity of snow and ice surfaces from the SAAMEX and MACSI airborne campaigns, Geoscience and Remote Sensing Symposium, 1995. IGARSS '95, "Quantitative Remote sensing for Science and Applications", International, vol. 2, 1493–1495, 1995. Gafurov, A. and Bárdossy, A.: Cloud removal methodology from MODIS snow cover product, Hydrol. Earth Syst. Sci., 13, 1361–1373, https://doi.org/10.5194/hess-13-1361-2009, 2009. Gerland, S., Winther, J.-G., Ørbæk, J. B., Liston, G. E., Øritsland, N. A., Blanco, A., and Ivanov, B.: Physical and optical properties of snow covering Arctic tundra on Svalbard, Hydrol. Process., 13, 2331–2343, 1999. Hori, M., Aoki, Te., Tanikawa, T., Motoyoshi, H., Hachikubo, A., Sugiura, K., Yasunari, T. J., Eide, H., Storvold, R., Nakajima, Y., and Tand akahashi, F.: In-situ measured spectral directional emissivity of snow and ice in the 8–14 um atmospheric window, Remote Sens. Environ., 100, 486–502, 2006. Istomina, L. G., von Hoyningen-Huene, W., Kokhanovsky, A. A., and Burrows, J. P.: Retrieval of aerosol optical thickness in Arctic region using dual-view AATSR observations, Proc. ESA Atmospheric Science Conference, Barcelona, Spain, 7–11 September 2009, ESA SP-676, 2010. Istomina, L. G., von Hoyningen-Huene, W., Kokhanovsky, A. A., Rozanov, V. V., Schreier, M., Dethloff, K., Stock, M., Treffeisen, R., Herber, A., and Burrows, J. P.: Sensitivity study of the dual-view algorithm for aerosol optical thickness retrieval over snow and ice, Proc. 2nd MERIS/(A)ATSR user workshop, ESRIN, Frascati, Italy, 22–26 September 2008, ESA SP-666, 2009. Key, J. and Barry, R. G.: Cloud cover analysis with Arctic AVHRR data. 1. Cloud detection, J. Geophys. Res., 94, D15, 18521–18535, 1989. Kokhanovsky, A. A.: Cloud Optics, Eds.: Mysak, L. A., Hamilton, K., Publ. Springer, 2006. Kokhanovsky, A. A, Rozanov, V. V., Aoki, T., Odermatt, D., Brockmann, B., Krüger, O., Bouvet, M., Drusch, M., and Hori, M.: Sizing of snow grains using backscattered solar light, Int. J. Remote Sens., in press, 2010. Krijger, J. M., Aben, I., and Schrijver, H.: Distinction between clouds and ice/snow covered surfaces in the identification of cloud-free observations using SCIAMACHY PMDs, Atmos. Chem. Phys., 5, 2729–2738, https://doi.org/10.5194/acp-5-2729-2005, 2005. Liu, Y., Key, J. R., Frey, R. A., Ackerman, S. A., and Menzel, W. P.: Nighttime polar cloud detection with MODIS, Remote Sens. Environ., 92, 181–194, 2004. Lotz, W. A., Vountas, M., Dinter, T., and Burrows, J. P.: Cloud and surface classification using SCIAMACHY polarization measurement devices, Atmos. Chem. Phys., 9, 1279–-1288, https://doi.org/10.5194/acp-9-1279-2009, 2009. Lyapustin, A., Tedesco, M., Wang, Y., Aoki, T., Hori, M., and Kokhanovsky, A.: Retrieval of snow grain size over Greenland from MODIS, Remote Sens. Environ., 113, 1976–1987, 2009. Lyapustin, A. and Wang, Y.: The time series technique for aerosol retrievals over land from MODIS, in: Satellite Aerosol Remote Sensing over Land, edited by: Kokhanovsky A. A., de Leeuw, G., Springer Praxis Publ. Chichester, 69–99, 2009. Lyapustin, A., Wang, Y., and Frey, R.: An automated cloud mask algorithm based on time series of MODIS measurements, J. Geophys. Res., 113, D16207, https://doi.org/10.1029/2007JD009641, 2008. Martins, J. V., Tanré, D., Remer, L., Kaufman, Y., Mattoo, S., and Levy, R.: MODIS Cloud screening for remote sensing of aerosols over oceans using spatial variability, Geophys. Res. Lett., 29(12), 8009, https://doi.org/10.1029/2001GL013252, 2002. Mendonca, B. G., DeLuisi, J. J., and Schroeder, J. A.: Arctic Haze and perturbation in the solar radiation fluxes at Barrow, Alaska, Proceedings from the 4th Conference on Atmospheric Radiation, Atm. Met. Sco., Toronto, Ontario, Canada, 95–96, 1981. Minnis, P., Chakrapani, V., Doelling, D. R., Nguyen, L., Palikonda, R., Spangenberg, D. A., Uttal, T., Arduini, R. F., and Shupe, M.: Cloud coverage and height during FIRE ACE derived from AVHRR data, J. Geophys. Res., 106, D14, 15215–15232, 2001. Quinn, P. K., Miller, T. L., Bates, T. S., Ogren, J. A., Andrews, E., and Shaw, G. E. : A three-year record of simultaneously measured aerosol chemical and optical properties at Barrow, Alaska, J. Geophys. Res., 107, D11, 15pp., https://doi.org/10.1029/2001JD001248, 2002. Rozanov, A. V., Rozanov, V. V., Buchwitz, M., Kokhanovsky, A. A., and Burrows, J. P.: SCIATRAN 2.0 – new radiative transfer model for geophysical applications in the 175–2400 nm spectral range, Adv. Space Res., 36, 1015–1019, 2005. Spangenberg, D. A., Chakrapani, V., Doelling, D. R., Minnis, P., and Arduini, R. F.: Development of an automated Arctic cloud mask using clear-sky satellite observations taken over the SHEBA and ARM NSA sites, Proc. 6th Conf. on Polar Meteor. and Oceanography, San Diego, CA, 14–18 May 2001, 246–249, 2001. Tedesco, M. and Kokhanovsky, A. A.: The semi-analytical snow retrieval algorithm and its application to MODIS data, Remote Sens. Environ., 110, 317–331, 2007. Tomasi, C., Vitale, V., Lupi, A., Di Carmine, C., Campanelli, M., Herber, A., Treffeisen, R., Stone, R. S., Andrews, E., Sharma, S., Radionov, V., von Hoyningen-Huene, W., Stebel, K., Hansen, G. H., Myhre, C. L., Wehrli, C., Aaltonen, V., Lihavainen, H., Virkkula, A., Hillamo, R., Ström, J., Toledano, C., Cachorro, V. E., Ortiz, P., de Frutos, A. M., Blindheim, S., Frioud, M., Gausa, M., Zielinski, T., Petelski, T., and Yamanouchi, T.: Aerosols in polar regions: A historical overview based on optical depth and in situ observations, J. Geophys. Res., 112, D16205, https://doi.org/10.1029/2007JD008432, 2007. Trepte, Q., Arduini, R. F., Chen, Y., Sun-Mack, S., Minnis, P., Spangenberg, D. A., and Doelling, D. R.: Development of a daytime polar cloud mask using theoretical models of near-infrared bidirectional reflectance for ARM and CERES, Proc. AMS 6th Conf. Polar Meteorology and Oceanography, San Diego, CA, 4–18 May , 242–245, 2001. Wald, A. E.: Modeling thermal infrared (2–14 <abbr>μm</abbr>) reflectance spectra of frost and snow, J. Geophys. Res., 99, B12, 24241–24250, 94JB01560, 1994. Warren, S. G.: Optical Properties of Snow, Rev. Geophys., 20(1), 67–89, 1982. Warren, S. G. and Wiscombe, W. J.: A model for the spectral albedo of snow. II: Snow containing atmospheric aerosols, J. Atmos. Sci. 37, 2734–2733, 1980. Welton, E. J., Campbell, J. R., Spinhirne, J. D., and Scott, V. S.: Global monitoring of clouds and aerosols using a network of micro-pulse lidar systems, Proc. Int. Opt. Eng. 4153, 151–158, 2001. Wiscombe, W. J. and Warren, S. G.: A model for the spectral albedo of snow, I. Pure snow, J. Atmos. Sci., 37(12), 2712–2733, 1980.