ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-10-1789-2010 Evaluation of Arctic cloud products from the EUMETSAT Climate Monitoring Satellite Application Facility based on CALIPSO-CALIOP observations Karlsson K.-G. 1 Dybbroe A. 1 Swedish Meteorological and Hydrological Institute, Norrköping, Sweden 16 02 2010 10 4 1789 1807 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/10/1789/2010/acp-10-1789-2010.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/10/1789/2010/acp-10-1789-2010.pdf

The performance of the three cloud products cloud fractional cover, cloud type and cloud top height, derived from NOAA AVHRR data and produced by the EUMETSAT Climate Monitoring Satellite Application Facility, has been evaluated in detail over the Arctic region for four months in 2007 using CALIPSO-CALIOP observations. The evaluation was based on 142 selected NOAA/Metop overpasses allowing almost 400 000 individual matchups between AVHRR pixels and CALIOP measurements distributed approximately equally over the studied months (June, July, August and December 2007). Results suggest that estimations of cloud amounts are very accurate during the polar summer season while a substantial loss of detected clouds occurs in the polar winter. Evaluation results for cloud type and cloud top products point at specific problems related to the existence of near isothermal conditions in the lower troposphere in the polar summer and the use of reference vertical temperature profiles from Numerical Weather Prediction model analyses. The latter are currently not detailed enough in describing true conditions relevant on the pixel scale. This concerns especially the description of near-surface temperature inversions which are often too weak leading to large errors in interpreted cloud top heights.

 References Ackerman, S. A., Holz, R. E., Frey, R., Eloranta, E. W., Maddux, B., and McGill, M. J.: Cloud detection with MODIS: Part II Validation, J. Atmos. Ocean. Tech., 25, 1073–1086, 2008. Bony, S., Colman, R., Kattsov, V. M., et al.: How well do we understand and evaluate climate change feedback processes?, J. Climate, 19, 3445–3482, 2006. Chevallier, M. M. F. and Tjemkes, S.: An improved general fast radiative transfer model for the assimilation of radiances observations, Technical Memorandum 345, European Center for Medium Range Weather Forecasting (ECMWF), 2001. Derrien, M., Lavanant, L., and Gleau, H. L.: Retrieval of the cloud top temperature of semi-transparent clouds with AVHRR, In: Proceedings of IRS'88, Lille, France, 199–202, 1988. Dybbroe, A., Thoss, A., and Karlsson, K.-G.: NWCSAF AVHRR cloud detection and analysis using dynamic thresholds and radiative transfer modeling – Part I: Algorithm description, J. Appl. Meteor., 44, 39–54, 2005a. Dybbroe, A., Thoss, A., and Karlsson, K.-G.: NWCSAF AVHRR cloud detection and analysis using dynamic thresholds and radiative transfer modeling - Part II: Tuning and validation, J. Appl. Meteor., 44, 55–71, 2005b. Eliasson, S., Tetzlaff, A., and Karlsson, K.-G.: Prototyping an improved PPS cloud detection for the Arctic polar night, SMHI Reports Meteorology, available from: SMHI, Folkborgsvägen 1, 601 76 Norrköping, Sweden), No. 128, 37 pp., 2007. Frey, R. A.; Ackerman, S. A., Liu, Y., Strabala, K. I., Zhang, H., Key, J. R., and Wang, X.: Cloud detection with MODIS: Part I Improvements in the MODIS Cloud Mask for Collection 5, J. Atmos. Ocean. Tech., 25, 1057–1072, 2008. Holz, R. E., Ackerman, S. A., Nagle, F. W., Frey, R., Dutcher, S., Kuehn, R. E., Vaughan, M., and Baum, B. A: Global MODIS cloud detection and height evaluation using CALIOP, J. Geophys. Res., 113, D00A19, doi:10.1029/2008JD009837, 2008. Inoue, T.: On the temperature and effective emissivity determination of semi-transparent cirrus clouds by bi-spectral measurements in the 10 \unit\mum window region, J. Meteorol. Soc. Jpn., 63(1), 88–98, 1985. IPCC4: 4th Assessment report Intergovernmental Panel on Climate Change: Climate Change 2007 – Synthesis report, Core Writing Team, edited by: Pachauri, R. K. and Reisinger, A., IPCC, Geneva, Switzerland, 104 pp., 2009. Karlsson, K.-G.: CMSAF Arctic cloud studies during the 2007 polar summer extreme sea ice anomaly event, in: Proceedings of 2008 EUMETSAT Satellite Conference, Darmstadt, Germany, 8–12 September 2008, 7 pp., 2008. Karlsson, K.-G., Willén, U., Jones, C., and Wyser, K.: Evaluation of regional cloud climate simulations over Scandinavia using a 10-year NOAA Advanced Very High Resolution Radiometer cloud climatology, J. Geophys. Res., 113, D01203, doi:10.1029/2007JD008658, 2008. Kay, J. E., L'Ecuyer, T., Gettelman, A., Stephens, G., and O'Dell, C.: The contribution of cloud and radiation anomalies to the 2007 Arctic sea ice extent minimum, Geoph. Res. Lett., 35, L08503, doi:10.1029/2008GL033451, 2008. Korpela, A., Dybbroe, A., and Thoss, A.: Retrieving Cloud Top Temperature and Height in Semi-transparent and fractional cloudiness using AVHRR, SMHI Reports Meteorology, available from SMHI, Folkborgsvägen 1, 60 176 Norrköping, Sweden, 100, NWCSAF Visiting Scientist Report. 2001. Li, J., Menzel, P., Yang, Z., Frey, R., and Ackerman, S.: High-spatial-resolution surface and cloud-type classification from MODIS multispectral band measurements, J. Appl. Meteor., 42, 204–226, 2003. Majewski D., Liermann, D., Prohl, P., Ritter, B., Buchhold, M., Hanisch, T., Paul, G., Wergen, W. and Baumgardner, J.: The operational global icosahedral-hexagonal grid point model GME: Description and high resolution tests, Mon. Weather. Rev., 130, 319–338, 2002. Platnick, S., King, M. D., Ackerman, S. A., Menzel, W. P., Baum, B. A. Riedi J., and Frey, R. A.: The MODIS cloud products: Algorithms and examples from Terra, IEEE T. Geosci. Remote, 41, 1–15, 2003. Reuter, M., Thomas, W., Albert, P., Lockhoff, M., Weber, R., Karlsson, K.-G., and Fischer, J.: The CMSAF and FUB Cloud Detection Schemes for SEVIRI: Validation with Synoptic Data and Initial Comparison with MODIS and CALIPSO, J. Appl. Meteorol. Clim., 48, 301–316, 2009. Rossow, W. B. and Schiffer, R. A.: Advances in understanding clouds from ISCCP, B. Am. Meteorol. Soc., 80, 2261–2288, 1999. Schulz, J., Albert, P., Behr, H.-D., et al.: Operational climate monitoring from space: The EUMETSAT Satellite Application Facility on Climate Monitoring (CMSAF), J. Atmos. Chem. Phys., 9, 1687–1709, 2009. Stephens, G. L.: Cloud feedbacks in the climate system: A critical review, J. Climate, 18, 237–273, 2005. Stephens, G. L., Vane, D. G., Boain, R. J., et al., and CloudSat Science team: The CLOUDSAT mission and the A-Train, B. Am. Meteorol. Soc., 83, 1771–1790, 2002. Weisz, E., Li, J., Menzel, W. P., Heidinger, A. K., Kahn, B. H., and Liu, C. Y.: Comparison of AIRS, MODIS, CloudSat and CALIPS cloud top height retrievals. Geoph. Res. Lett., 34, L17811, doi:10.1029/2007GL030676, 2007. Stubenrauch, C. J., Chédin, A., Rädel, G., Scott, N. A., and Serrar, S.: Cloud properties and their seasonal and diurnal variability from TOVS Path-B, J. Climate, 19, 5531–5553, 2006. Winker, D., Vaughan, M., and Hunt, B.: The CALIPSO mission and initial results from CALIOP, Proc. SPIE, 6409, doi:10.1117/12.698003, 2006.