Atmospheric Chemistry and Physics www.atmos-chem-phys.net 1680-7316 1680-7324 7 24 2007 10.5194/acp-7-6145-2007 http://www.atmos-chem-phys.net/7/6145/2007/ http://www.atmos-chem-phys.net/7/6145/2007/acp-7-6145-2007.html http://www.atmos-chem-phys.net/7/6145/2007/acp-7-6145-2007.pdf 6145 6159 2007-12-18 Technical note: A new day- and night-time Meteosat Second Generation Cirrus Detection Algorithm MeCiDA W. Krebs H. Mannstein L. Bugliaro B. Mayer bernhard.mayer@dlr.de Deutsches Zentrum für Luft- und Raumfahrt (DLR) A new cirrus detection algorithm for the Spinning Enhanced Visible and Infra-Red Imager (SEVIRI) aboard the geostationary Meteosat Second Generation (MSG), MeCiDA, is presented. The algorithm uses the seven infrared channels of SEVIRI and thus provides a consistent scheme for cirrus detection at day and night. MeCiDA combines morphological and multi-spectral threshold tests and detects optically thick and thin ice clouds. The thresholds were determined by a comprehensive theoretical study using radiative transfer simulations for various atmospheric situations as well as by manually evaluating actual satellite observations. The cirrus detection has been optimized for mid- and high latitudes but it could be adapted to other regions as well. The retrieved cirrus masks have been validated by comparison with the Moderate Resolution Imaging Spectroradiometer (MODIS) Cirrus Reflection Flag. To study possible seasonal variations in the performance of the algorithm, one scene per month of the year 2004 was randomly selected and compared with the MODIS flag. 81% of the pixels were classified identically by both algorithms. In a comparison of monthly mean values for Europe and the North-Atlantic MeCiDA detected 29.3% cirrus coverage, while the MODIS SWIR cirrus coverage was 38.1%. A lower detection efficiency is to be expected for MeCiDA, as the spatial resolution of MODIS is considerably better and as we used only the thermal infrared channels in contrast to the MODIS algorithm which uses infrared and visible radiances. The advantage of MeCiDA compared to retrievals for polar orbiting instruments or previous geostationary satellites is that it permits the derivation of quantitative data every 15 min, 24 h a day. This high temporal resolution allows the study of diurnal variations and life cycle aspects. MeCiDA is fast enough for near real-time applications. Ackerman, S., Strabala, K., Frey, R., Moeller, C., and Menzel, W.: Cloud Mask for the MODIS Airborne Simulator (MAS): Preparation for MODIS, in: Eighths AMS conference on Satellite Meteorology and Oceanography, 28 January–2 February , 1996, Atlanta, Georgia, pp. 317–320, Am. Meteorol. Soc., 1996. Ackerman, S., Strabala, K., Menzel, W., Frey, R., Moeller, C., and Gumley, L.: Discriminating clear sky from clouds with MODIS, J. Geophys. Res., 103, 32 141–32 157, 1998. Anderson, G. and Hall, L.: Solar Irradiance between 2000 and 3100 Angstroms With Spectral Band Pass of 1.0 Angstroms, J. Geophys. Res., 94, 6435–6441, 1989. Chevallier, F., Cheruy, F., Scott, N., and Chedin, A.: A neural network approach for a fast and accurate computation of a longwave radiative budget, J. Appl. Meteorol., 37, 1385–1397, 1998. Derrien, M. and Le~Gleau, H.: MSG/SEVIRI cloud mask and type from SAFNWC, Int. J. Remote Sens., 26, 4707–4732, 2005. Feijt, A., de~Valk, P., and van~der Veen, S.: Cloud detection using Meteosat imagery and numerical weather prediction model data, J. Appl. Meteorol., 39, 1017–1030, 2000. Fu, Q., Lesins, G., Higgins, J., Charlock, T., Chylek, P., and Michalsky, J.: Broadband water vapour absorption of solar radiation tested using ARM data, Geophys. Res. Lett., 25, 1169–1172, 1998. Hansen, J., Sato, M., and Ruedy, R.: Radiative forcing and climate response, J. Geophys. Res., 102, 6831–6864, 1997. Hart, W., Spinhirne, J., Palm, S., and Hlavka, D.: Height distribution between cloud and aerosol layers from the GLAS spaceborne lidar in the Indian Ocean region, Geophys. Res. Lett., 32, doi:10.1029/2005GL023 671, 2005. Inoue, T.: On the temperature and effective emissivity determination of semitransparent cirrus clouds by bispectral measurements in the 10 μm window region, J. Meteor. Soc. Japan, 63, 88–98, 1985. IPCC: Climate Change 2007: The Scientific Basis, Tech. rep., Intergovernmental Panel on Climate Change (IPCC), IPCC Secretariat, c/o World Meteorological Organization, Geneva, Switzerland, 2007. Kidder, S. and Vonder~Haar, T.: Satellite Meteorology, Academic Press, 1995. King, M., Menel, W., Kaufman, Y., Tanre, D., Gao, B.-C., Platnick, S., Ackerman, S., Remer, L., Pincus, R., and Hubanks, P.: Cloud and aerosol properties, precipitable water, and profiles of temperature and water vapor from MODIS, IEEE Transactions on Geoscience and Remote Sensing, 41, 442–458, 2003. Kriebel, K.-T., Gesell, G., Kästner, M., and Mannstein, H.: The cloud analysis tool APOLLO: improvements and validation, Int. J. Remote Sens., 24, 2389–2408, 2003. Lynch, D., Sassen, K., Starr, D., and Stephens, G.: Cirrus, Oxford University Press, 3–10, 2002. Mahesh, A., Gray, M., Palm, S., Hart, W., and Spinhirne, J.: Passive and active detection of clouds: Comparisons between MODIS and GLAS observations, Geophys. Res. Lett., 31, doi:10.1029/2003GL018 859, 2004. 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, 2005. Mayer, B., Seckmeyer, G., and Kylling, A.: Systematic long-term comparison of spectral UV measurements and UVSPEC modeling results, J. Geophys. Res., 102, 8755–8767, 1997. Meerkötter, R., Schumann, U., Doelling, D., Minnis, P., Nakajima, T., and Tsushima, Y.: Radiative forcing by contrails, Ann. Geophys., 17, 1080–1094, 1999. Minnis, P. and Smith~Jr., W.: Cloud and radiative fields derived from GOES-8 during SUCCESS and the ARM-UAV spring 1996 flight series, Geophys. Res. Lett., 25, 1113–1116, 1998. Pierluissi, J. and Peng, G.-S.: New molecular transmission band models for LOWTRAN, Opt. Engin., 24, 541–547, 1985. Platnick, S., King, M., Ackerman, S., Menzel, W., Baum, B., Riedi, J., and Frey, R.: The MODIS cloud products: Algorithms and examples from TERRA, IEEE Transactions on Geoscience and Remote Sensing, 41, 459–473, 2003. Ricchiazzi, P. and Gautier, C.: Investigation of the effect of surface heterogeneity and topography on the radiation environment of Palmer Station, Antarctica, with a hybrid 3-D radiative transfer model, J. Geophys. Res., 103, 6161–6178, 1998. Rossow, W. and Schiffer, R.: Advances in understanding clouds from ISCCP, B. Am. Meteorol. Soc., 80, 2261–2287, 1999. Saunders, R. and Kriebel, K.: An improved method for detecting clear sky and cloudy radiances from AVHRR data, Int. J. Remote Sens., 9, 123–150, 1988. Schmetz, J., Pili, P., Tjemkes, S., Just, D., Kerkmann, J., Rota, S., and Ratier, A.: An introduction to Meteosat Second Generation (MSG), B. Am. Meteorol. Soc., pp. 977–992, 2002. 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. Opt., 27, 2502–2509, 1988. Van~Weele, M., Martin, T., Blumthaler, M., Brogniez, C., den Outer, P., Engelsen, O., Lenoble, J., Pfister, G., Ruggaber, A., Walravens, B., Weihs, P., Dieter, H., Gardiner, B., Gillotay, D., Kylling, A., Mayer, B., Seckmeyer, G., and Wauben, W.: From model intercomparisons towards benchmark UV spectra for six real atmospheric cases, J. Geophys. Res., 105, 4915–4925, 2000. World Meteorological Organization: International Cloud Atlas. Volume I – Manual on the observation of clouds and other meteors, WMO, 1975. World Meteorological Organization: International Cloud Atlas. Volume II – Plates, WMO, 1987. Wylie, D. and Woolf, H.: The Diurnal Cycle of Upper-Tropospheric Clouds Measured by GOES-VAS and the ISCCP, Mon. Weather Rev., 130, 171–179, 2002. Wylie, D., Jackson, D., Menzel, W., and Bates, J.: Trends in global cloud cover in two decades of HIRS observations, J. Clim., 18, 3021–3031, 2005.