References

ACP

Atmospheric Chemistry and Physics

ACP

1680-7324

Copernicus GmbH

Göttingen, Germany

10.5194/acp-12-7135-2012

Fast cloud parameter retrievals of MIPAS/Envisat

Spang

¹ Arndt

¹ ⁸ Dudhia

² Höpfner

⁴ Hoffmann

¹ ⁷ Hurley

² Grainger

R. G.

² Griessbach

¹ ⁷ Poulsen

³ Remedios

J. J.

⁵ Riese

¹ Sembhi

⁵ Siddans

³ Waterfall

³ Zehner

⁶

Forschungszentrum Jülich, Institut für Energie and Klimaforschung, IEK-7, Jülich, Germany

University of Oxford, AOPP, Oxford, UK

Rutherford Appleton Laboratory, Chilton, Didcot, UK

Karlsruhe Institute of Technology, IMK, Karlsruhe, Germany

University of Leicester, EOS, Leicester, UK

ESA-ESRIN, Frascati, Italy

Forschungszentrum Jülich, Jülich Supercomputing Centre, JSC, Jülich, Germany

now at: Thinking Network AG, Aachen, Germany

07 08 2012

12 15 7135 7164

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.

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The full text article is available as a PDF file from http://www.atmos-chem-phys.net/12/7135/2012/acp-12-7135-2012.pdf

The infrared limb spectra of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board the Envisat satellite include detailed information on tropospheric clouds and polar stratospheric clouds (PSC). However, no consolidated cloud product is available for the scientific community. Here we describe a fast prototype processor for cloud parameter retrieval from MIPAS (MIPclouds). Retrieval of parameters such as cloud top height, temperature, and extinction are implemented, as well as retrieval of microphysical parameters, e.g. effective radius and the integrated quantities over the limb path (surface area density and volume density). MIPclouds classifies clouds as either liquid or ice cloud in the upper troposphere and polar stratospheric clouds types in the stratosphere based on statistical combinations of colour ratios and brightness temperature differences. Comparison of limb measurements of clouds with model results or cloud parameters from nadir looking instruments is often difficult due to different observation geometries. We therefore introduce a new concept, the limb-integrated surface area density path (ADP). By means of validation and radiative transfer calculations of realistic 2-D cloud fields as input for a blind test retrieval (BTR), we demonstrate that ADP is an extremely valuable parameter for future comparison with model data of ice water content, when applying limb integration (ray tracing) through the model fields. In addition, ADP is used for a more objective definition of detection thresholds of the applied detection methods. Based on BTR, a detection threshold of ADP = 107 μm2 cm−2 and an ice water content of 10−5 g m−3 is estimated, depending on the horizontal and vertical extent of the cloud. Intensive validation of the cloud detection methods shows that the limb-sounding MIPAS instrument has a sensitivity in detecting stratospheric and tropospheric clouds similar to that of space- and ground-based lidars, with a tendency for higher cloud top heights and consequently higher sensitivity for some of the MIPAS detection methods. For the high cloud amount (HCA, pressure levels below 440 hPa) on global scales the sensitivity of MIPAS is significantly greater than that of passive nadir viewers. This means that the high cloud fraction will be underestimated in the ISCCP dataset compared to the amount of high clouds deduced by MIPAS. Good correspondence in seasonal variability and geographical distribution of cloud occurrence and zonal means of cloud top height is found in a detailed comparison with a climatology for subvisible cirrus clouds from the Stratospheric Aerosol and Gas Experiment II (SAGE II) limb sounder. Overall, validation with various sensors shows the need to consider differences in sensitivity, and especially the viewing geometries and field-of-view size, to make the datasets comparable (e.g. applying integration along the limb path through nadir cloud fields). The simulation of the limb path integration will be an important issue for comparisons with cloud-resolving global circulation or chemical transport models.

References 1

Adams, S., Spang, R., Preusse, P., and Heinemann, G.: The benefit of limb cloud imaging for infrared limb sounding of tropospheric trace gases, Atmos. Meas. Tech., 2, 287–298, http://dx.doi.org/10.5194/amt-2-287-2009doi:10.5194/amt-2-287-2009, 2009.

Aumann, H. H., Chahine, M. T., Gautier, C., Goldberg, M. D., Kalnay, E., McMillin, L. M., Revercomb, H., Rosenkranz, P. W., Smith, W. L., Staelin, D. H., Strow, L. L., and Susskind, J.: AIRS/AMSU/HSB on the Aqua mission: design, science objectives, data products, and processing systems, IEEE Trans. Geosci. Remote Sens., 41, 253–264, 2003.

Baran, A. J., Francis, P. N., Labonnote, L.-C., and Doutriaux-Boucher, M.: A scattering phase function for ice cloud: Tests of applicability using aircraft and satellite multi-angle multi wavelength radiance measurements of cirrus, Q. J. Roy . Meteorol. Soc., 127, 2395–2416, 2001.

Davis, S., Hlavka, D., Jensen, E., Rosenlof, K., Yang, Q., Schmidt, S., Borrmann, S., Frey, W., Lawson, P., Voemel, H., and Bui, T. P.: In situ and lidar observations of subvisible cirrus clouds during TC4, J. Geophys. Res., 115, D00J17, http://dx.doi.org/10.1029/2009JD013093doi:10.1029/2009JD013093, 2010.

Drdla, K. and Müller, R.: Temperature thresholds for polar stratospheric ozone loss, Atmos. Chem. Phys. Discuss., 10, 28687–28720, http://dx.doi.org/10.5194/acpd-10-28687-2010doi:10.5194/acpd-10-28687-2010, 2010.

Dudhia, A., Morris, P. E., and Wells, R. J.: Fast monochromatic radiative transfer calculations for limb sounding, J. Quant. Spectrosc. Rad. Trans., 74, 745–756, 2002.

ESA: Candidate Earth Explorer Core Missions - Report for Assessment: PREMIER – PRocess Exploitation through Measurements of Infrared and millimetre-wave Emitted Radiation, SP-1313/5, ESA Publications Division, ESTEC, Keplerlaan 1, 2200 AG Noordwijk, The Netherlands, 2008.

Evans, K. F., Walter, S. J., Heymsfield, A. J., and Deeter, M. N.: Modeling of submillimeter passive remote sensing of cirrus clouds, J. Appl. Meteorol., 37, 184–205, 1998a.

Evans, K. F.: The spherical harmonics discrete ordinate method for three-dimensional atmospheric radiative transfer, J. Atmos. Sci., 55, 429–446, 1998b.

Ewen, G. B. L., Grainger, R. G., Lambert, A., and Baran, A. J.: Infrared radiative transfer modelling in a 3D scattering cloudy atmosphere: Application to limb sounding measurements of cirrus, J. Quant. Spectrosc. Rad. Trans., 96, 45–74, 2005.

Eyring, V., Butchart, N., Waugh, D. W., Akiyoshi, H., Austin, J., Bekki, S., Bodeker, G. E., Boville, B. A., Bruhl, C., Chipperfield, M. P., Cordero, E., Dameris, M., Deushi, M., Fioletov, V. E., Frith, S. M., Garcia, R. R., Gettelman, A., Giorgetta, M. A., Grewe, V., Jourdain, L., Kinnison, D. E., Mancini, E., Manzini, E., Marchand, M., Marsh, D. R., Nagashima, T., Newman, P. A., Nielsen, J. E., Pawson, S., Pitari, G., Plummer, D. A., Rozanov, E., Schraner, M., Shepherd, T. G., Shibata, K., Stolarski, R. S., Struthers, H., Tian, W., and Yoshiki, M.: Assessment of temperature, trace species and ozone in chemistry-climate simulations of the recent past, J. Geophys. Res. 111, D22308, http://dx.doi.org/10.1029/2006JD007327doi:10.1029/2006JD007327, 2006.

Fischer, H., Birk, M., Blom, C., Carli, B., Carlotti, M., von Clarmann, T., Delbouille, L., Dudhia, A., Ehhalt, D., Endemann, M., Flaud, J. M., Gessner, R., Kleinert, A., Koopman, R., Langen, J., López-Puertas, M., Mosner, P., Nett, H., Oelhaf, H., Perron, G., Remedios, J., Rudolfi, M., Stiller, G., and Zander, R.: MIPAS: an instrument for atmospheric and climate research, Atmos. Chem. Phys., 8, 2151–2188, http://dx.doi.org/10.5194/acp-8-2151-2008doi:10.5194/acp-8-2151-2008, 2008.

GEWEX, GEWEX cloud assessment, http://climserv.ipsl.Polytechnique.fr/gewexca/ presentation.html, last access: November, 2010.

Greenhough, J., Remedios, J. J., Sembhi, H., and Kramer, L. J.: Towards cloud detection and cloud frequency distributions from MIPAS infra-red observations, Adv. Space Res., 36, 800–806, 2005.

Hanson, R., Stutz, J., and Cheeseman, P.: Bayesian Classification Theory, NASA, Technical Report FIA-90-12-7-01, May, 1991.

Höpfner, M.: Study on the impact of polar stratospheric clouds on high resolution mid-IR limb emission spectra, J. Quant. Spectrosc. Radiat. Transfer, 83, 1, 93–107, 2004.

Höpfner, M., Luo, B. P., Massoli, P., Cairo, F., Spang, R., Snels, M., Donfrancesco, G. D., Stiller, G., von Clarmann, T., Fischer, H., and Biermann, U.: Spectroscopic evidence for NAT, STS, and ice in MIPAS infrared limb emission measurements of polar stratospheric clouds, Atmos. Chem. Phys., 6, 1201–1219, http://dx.doi.org/10.5194/acp-6-1201-2006doi:10.5194/acp-6-1201-2006, 2006a.

Höpfner, M., Larsen, N., Spang, R., Luo, B. P., Ma, J., Svendsen, S. H., Eckermann, S. D., Knudsen, B., Massoli, P., Cairo, F., Stiller, G., v. Clarmann, T., and Fischer, H.: MIPAS detects Antarctic stratospheric belt of NAT PSCs caused by mountain waves, Atmos. Chem. Phys., 6, 1221–1230, http://dx.doi.org/10.5194/acp-6-1221-2006doi:10.5194/acp-6-1221-2006, 2006b.

Höpfner, M., Pitts, M. C., and Poole, L. R., Comparison between CALIPSO and MIPAS observations of polar stratospheric clouds, J. Geophys. Res., 114, D00H05, http://dx.doi.org/10.1029/2009JD012114doi:10.1029/2009JD012114, 2009.

Hoffmann, L., Kaufmann, M., Spang, R., Müller, R., Remedios, J. J., Moore, D. P., Volk, C. M., von Clarmann, T., and Riese, M.: Envisat MIPAS measurements of CFC-11: retrieval, validation, and climatology, Atmos. Chem. Phys., 8, 3671–3688, http://dx.doi.org/10.5194/acp-8-3671-2008doi:10.5194/acp-8-3671-2008, 2008.

Hurley, J., Dudhia, A., and Grainger, R. G.: Cloud detection for MIPAS using singular vector decomposition, Atmos. Meas. Tech., 2, 533–547, http://dx.doi.org/10.5194/amt-2-533-2009doi:10.5194/amt-2-533-2009, 2009.

Hurley, J., Dudhia, A., and Grainger, R. G.: Retrieval of macrophysical cloud parameters from MIPAS: algorithm description, Atmos. Meas. Tech., 4, 683–704, http://dx.doi.org/10.5194/amt-4-683-2011doi:10.5194/amt-4-683-2011, 2011.

Kärcher B. and Spichtinger, P.: Cloud-controlling Factors of Cirrus, in: Clouds in the Perturbed Climate System: Their Relationship for Energy Balance, Atmospheric Dynamics and Precipitation, in the Strüngmann Forum Report, edited by: Heintzenberg, J. and Charlson, R. J., MIT Press, 235–267, 2009.

Kerridge, B. J., Siddans, R., Reburn, J., Jay, V., Latter, B., Lama, F., Dudhia, A., Grainger, D., Burgess, A., Höpfner, M., Steck, T., Emde, C., Eriksson, P., Ekstrom, M., and Baran, A.: Consideration of mission studying chemistry of the UTLS – Final Report, ESA Contract No 15457/01/NL/MM, 2004.

Kiefer, M., von Clarmann, T., Grabowski, U., De Laurentis, M., Mantovani, R., Milz, M., and Ridolfi, M.: Characterization of MIPAS elevation pointing, Atmos. Chem. Phys., 7, 1615–1628, http://dx.doi.org/10.5194/acp-7-1615-2007doi:10.5194/acp-7-1615-2007, 2007.

Lawson, R. P., Pilson, B., Baker, B., Mo, Q., Jensen, E., Pfister, L., and Bui, P.: Aircraft measurements of microphysical properties of subvisible cirrus in the tropical tropopause layer, Atmos. Chem. Phys., 8, 16090–1620, http://dx.doi.org/10.5194/acp-8-1609-2008doi:10.5194/acp-8-1609-2008, 2008.

Liao, X., Rind, D., and Rossow, W. B.: Comparison between SAGE~II and ISCCP high-level clouds, Part I: Global and zonal mean cloud amounts, J. Geophys. Res., 100, 1121–1135, 1995.

Luo, B. P., Peter, T., Fueglistaler, S., Wernli, H.,Wirth, M., Kiemle, C., Flentje, H., Yushkov, V. A., Khattatov, V., Rudakov, V., Thomas, A., Borrmann, S., Toci, G., Mazzinghi, P., Beuermann, J., Schiller, C., Cairo, F., Di Donfrancesco, G., Adriani, A., Volk, C. M., Strom, J., Noone, K., Mitev, V., MacKenzie, R. A., Carslaw, K. S., Trautmann, T., Santacesaria, V., and Stefanutti, L.: Dehydration potential of ultrathin clouds at the tropical tropopause, Geophys. Res. Lett., 30, 1557, http://dx.doi.org/10.1029/2002GL016737doi:10.1029/2002GL016737, 2003.

McFarquhar, G. M. and Heymsfield, A. J., Spinhirne, J., and Hart, B.: Thin and Subvisual Tropopause Tropical Cirrus: Observations and Radiative Impacts. J. Atmos. Sci., 57, 1841–1853, 2000.

Massie, S., Gille, J., Khosravi, R., Lee, H., Kinnison, D., Francis, G., Nardi, B., Eden, T., Craig, C., Halvorson, C., Coffey, M., Packman, D., Cavanaugh, C., Craft, J., Dean, V., Ellis, D., Barnett, J., Hepplewhite, C., Lambert, A., Manney, G., Strawa, A., and Legg, M.: High Resolution Dynamics Limb Sounder observations of polar stratospheric clouds and subvisible cirrus, J. Geophys. Res., 112, D24S31, http://dx.doi.org/10.1029/2007JD008788doi:10.1029/2007JD008788, 2007.

McCormick, M. P.: SAGE~II: An overview, Adv. Space Res., 7, 319–326, 1987.

Mergenthaler, J., Roche, A., Kumer, J., and Ely, G.: Cryogenic Limb Array Etalon Spectrometer observations of tropical cirrus, J. Geophys. Res., 104, 22183–22194, 1999.

Milz, M., von Clarmann, T., Fischer, H., Glatthor, N., Grabowski, U., Höpfner, M., Kellmann, S., Kiefer, M., Linden, A., Mengistu Tsidu, G., Steck, T., Stiller, G. P., Funke, B., López-Puertas, M., and Koukouli, M.: Water vapor distributions measured with the Michelson Interferometer for Passive Atmospheric Sounding on board Envisat (MIPAS/Envisat), J. Geophys. Res., 110, D24307, http://dx.doi.org/10.1029/2005JD005973doi:10.1029/2005JD005973, 2005.

Peter, Th., Luo, B. P., Wirth, M., Kiemle, C., Flentje, H., Yushkov, V. A., Khattatov, V., Rudakov, V., Thomas, A., Borrmann, S., Toci, G., Mazzinghi, P., Beuermann, J., Schiller, C., Cairo, F., Di Donfrancesco, G., Adriani, A., Volk, C. M., Strom, J., Noone, K., Mitev, V., MacKenzie, R. A., Carslaw, K. S., Trautmann, T., Santacesaria, V., and Stefanutti, L.: Ultrathin Tropical Tropopause Clouds (UTTCs): I. Cloud morphology and occurrence, Atmos. Chem. Phys., 3, 1083–1091, http://dx.doi.org/10.5194/acp-3-1083-2003doi:10.5194/acp-3-1083-2003, 2003.

Poulsen, C. A., Watts, P. D., Thomas, G. E., Sayer, A. M., Siddans, R., Grainger, R. G., Lawrence, B. N., Campmany, E., Dean, S. M., and Arnold, C.: Cloud retrievals from satellite data using optimal estimation: evaluation and application to ATSR, Atmos. Meas. Tech. Discuss., 4, 2389–2431, http://dx.doi.org/10.5194/amtd-4-2389-2011doi:10.5194/amtd-4-2389-2011, 2011.

Raspollini, P, Carli, B., Carlotti, M., Ceccherini, S., Dinelli, B. M., Dudhia, A., Flaude, J.-M., Hoepfner, M., Jay, V., Magnani, L., Oelhaf, H., Piccolo, C., Prosperi, M., Remedios, J. J., Ridolfi, M., and Spang, R.: SPIE Proc., Level 2 near-real-time analysis of MIPAS measurements on ENVISAT, Remote Sensing of Clouds and the Atmosphere VII, 4882, Agia Pelagia, Crete, Greece, 2002.

Raspollini, P., Belotti, C., Burgess, A., Carli, B., Carlotti, M., Ceccherini, S., Dinelli, B. M., Dudhia, A., Flaud, J.-M., Funke, B., Höpfner, M., López-Puertas, M., Payne, V., Piccolo, C., Remedios, J. J., Ridolfi, M., and Spang, R.: MIPAS level 2 operational analysis, Atmos. Chem. Phys., 6, 5605–5630, http://dx.doi.org/10.5194/acp-6-5605-2006doi:10.5194/acp-6-5605-2006, 2006.

Remedios J.J., Spang, R., Detection of cloud effects in MIPAS spectral data and implications for the MIPAS operational processor, Proceedings of the ENVISAT Calibration Review, 9–13 September 2002, ESA-ESTEC, Noordwijk, The Netherlands, 2002.

Remedios, J. J., Leigh, R. J., Waterfall, A. M., Moore, D. P., Sembhi, H., Parkes, I., Greenhough, J., Chipperfield, M. P., and Hauglustaine, D.: MIPAS reference atmospheres and comparisons to V4.61/V4.62 MIPAS level 2 geophysical data sets, Atmos. Chem. Phys. Discuss., 7, 9973–10017, http://dx.doi.org/10.5194/acpd-7-9973-2007doi:10.5194/acpd-7-9973-2007, 2007.

Ridolfi, M., Carli, B., Carlotti, M., von Clarmann, Thomas, Dinelli, B. M., Dudhia, A., Flaud, J.-M., Höpfner, M., Morris, P. E., Raspollini, P., Stiller, G., and Wells, R. J.: Optimized Forward and Retrieval Scheme for MIPAS Near-Real-Time Data Processing, Appl. Opt. 39, 1323–1340, 2000.

Riese, M., Preusse, P., Spang, R., Ern, M., Jarisch, M., Grossmann, K. U., Offermann, D.: Measurements of trace gases by the Cryogenic Infrared Spectrometers and Telscopes for the Atmosphere (CRISTA) experiment, Adv. Space Res., 19, 563–566, 1997.

Riese, M., Spang, R., Preusse, P., Ern, M., Jarisch, M., Offermann, D., and Grossmann, K. U.: Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) data Processing and atmospheric temperature and trace gas retrieval, J. Geophys. Res., 104, 16349–16367, 1999.

Riese, M., Friedl-Vallon, F., Spang, R., Preuße, P., Schiller, C., Hoffmann, L., Oelhaf, H., von Clarmann, Th., andHöpfner, M.: Global Limb Radiance Imager for the Atmosphere (GLORIA): Scientific Objectives, Adv. Space Res., 36, 989–995, 2005.

Rossow, W. B. and Schiffer, R. A.: Advances in understanding clouds from ISCCP, B. Am. Meteorol. Soc., 80, 2261–2287, 1999.

SAGE, SAGE~II information on data products at: http://www-sage2.larc.nasa.gov/Version6-2Data.html, last access: April, 2011.

Solomon, S.: Stratospheric ozone depletion: A review of concepts and history, Rev. Geophys., 37, 275–316, http://dx.doi.org/10.1029/1999RG900008doi:10.1029/1999RG900008, 1999.

Sassen, K., and Cho, B. S.: Subvisual-thin cirrus clouds lidar data set for satellite verification and climatological research, J. Appl. Meteorol., 31, 1275–1285, 1992.

Sassen, K., Griffin, M. K., and Dodd, G. C.: Optical scattering and microphysical properties of subvisible cirrus clouds, and climatic implications, J. Appl. Meteorol., 28, 91–98, 1989.

Sembhi, H., Remedios, J., Trent, T., Moore, D. P., Spang, R., Massie, S., and Vernier, J.-P.: MIPAS detection of cloud and aerosol particle occurrence in the UTLS with comparison to HIRDLS and CALIOP, Atmos. Meas. Tech. Discuss., 5, 1795–1841, http://dx.doi.org/10.5194/amtd-5-1795-2012doi:10.5194/amtd-5-1795-2012, 2012.

Spang, R., Riese, M., Eidmann, G., Offermann, D., Pfister, L., and Wang, P. H.: CRISTA observations of cirrus clouds around the tropopause, J. Geophys. Res., 107, 8174, doi:0/1029/2002JD000698, 2002.

Spang R. and Remedios, J., Observations of a distinctive infra-red spectral feature in the atmospheric spectra of polar stratospheric clouds measured by the CRISTA instrument, Geophys. Res. Lett., 30, 1875, http://dx.doi.org/10.1029/2003GL017231doi:10.1029/2003GL017231, 2003.

Spang, R., Remedios, J. J., and Barkley, M., Colour Indices for the Detection and Differentiation of Cloud Types in Infra-red Limb Emission Spectra, Adv. Space Res., 33, pp.1041–1047, 2004.

Spang, R., Remedios, J. J., Kramer, L. J., Poole, L. R., Fromm, M. D., Müller, M., Baumgarten, G., and Konopka, P.: Polar stratospheric cloud observations by MIPAS on ENVISAT: detection method, validation and analysis of the northern hemisphere winter 2002/2003, Atmos. Chem. Phys., 5, 679–692, http://dx.doi.org/10.5194/acp-5-679-2005doi:10.5194/acp-5-679-2005, 2005a.

Spang, R., Remedios, J. J., Tilmes, S., and Riese, M.: MIPAS observation of polar stratospheric clouds in the Arctic 2002/2003 and Antarctic 2003 winters, Adv. Space Res., 36, 868–878, 2005b.

Spang, R., Griessbach, S., Höpfner, M., Dudhia, A., Hurley, J., Siddans, R., Waterfall, A., Remedios, J. J., and Sembhi., H.: Technical Note: Retrievability of MIPAS cloud parameter, ESA-ESRIN Contract No. 20601/07/I-OL, March 2008.

Spang, R., Arndt, K., Dudhia, A., Grießbach, S., Höpfner, M., Hurley, J., Remedios, J. J., Sembhi, H., and Siddans, R.: Algorithm Technical Basis Document: Cloud Information Retrieval from MIPAS measurements, ESA-ESRIN Contract No. 20601/07/I-OL, Version 2.1, 10 June, 2010a.

Spang, R., Höpfner, M., Dudhia, A., Siddans, R., Waterfall, A., Poulsen, C., Remedios, J. J., and Sembhi, H.: Product Validation Report for the MIPAS cloud parameter processor, ESA-ESRIN Contract No. 20601/07/I-OL, Version: 10 June, 2010b. \hack

Spinhirne, J. D., Palm, S. P., Hart, W. D., Hlavka, D. L., and Welton, E. J.: Cloud and aerosol measurements from GLAS: Overview and initial results, Geophys, Res. Lett., 32, L22S03, http://dx.doi.org/10.1029/2005GL023507doi:10.1029/2005GL023507, 2005.

Stiller, G. P. (Editor), The Karlsruhe Optimized and Precise Radiative transfer Algorithm (KOPRA), Forschungszentrum Karlsruhe, Wissenschaftliche Berichte, Bericht Nr. 6487, 'http://www.imk-asf.kit.edu/english/312.php, last access: 21 July 2012, 2000.

Stubenrauch, C. J., Cros, S., Lamquin, N., Armante, R., Ch'edin, A., Crevoisier, C., and Scott, N. A.: Cloud properties from AIRS and evaluation with CALIPSO, J. Geophys. Res., 113, D00A10, http://dx.doi.org/10.1029/2008JD009928doi:10.1029/2008JD009928, 2008.

Stubenrauch, C. J., Cros, S., Guignard, A., and Lamquin, N.: A 6-year global cloud climatology from the Atmospheric Infra Red Sounder AIRS and a statistical analysis in synergy with CALIPSO and CloudSat, Atmos. Chem. Phys., 10, 7197–7214, http://dx.doi.org/10.5194/acp-10-7197-2010doi:10.5194/acp-10-7197-2010, 2010.

von Clarmann, T., Glatthor, N., Grabowski, U., H\" opfner, M., Kellmann, S., Kiefer, M., Linden, A., Mengistu Tsidu, G., Milz, M., Steck, T., Stiller, G. P., Wang, D. Y., Fischer, H., Funke, B., Gil-Lopez, S., and Lopez-Puertas, M.: Retrieval of temperature and tangent altitude pointing from limb emission spectra recorded from space by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), J. Geophys. Res., 108, 4736, http://dx.doi.org/10.1029/2003JD003602doi:10.1029/2003JD003602, 2003.

Wang, P. H., Minnis, P., McCormick, M. P., Kent, G. S., and Skeens, K. S.: A 6-year climatology of cloud occurrence frequency from SAGE~II observations (1985–1990), J. Geophys. Res., 101, 29407–29429, 1996.

Wang, P.-H., Veiga, R. E., Vann, L. B., Minnis, P., and Kent, G. S.: A further study of the method for estimation of SAGE~II opaque cloud occurrence, J. Geophys. Res., 106, 12603–12613, http://dx.doi.org/10.1029/2001JD900138doi:10.1029/2001JD900138, 2001.

Zhang, M. H., Lin, W. Y. Klein, S. A., Bacmeister, J. T., Bony, S, Cederwall, R. T., Del Genio,A., D. , Hack, J. J., Loeb, N. G., Lohmann, U., Minnis, P, Musat, I., Pincus, R., Stier, P., Suarez,M. J., Webb, M. J., Wu, J. B., Xie, S. C., Yao, M.-S., and Zhang, J. H.: Comparing clouds and their seasonal variations in 10 atmospheric general circulation models with satellite measurements, J. Geophys. Res. 110, D15S02, http://dx.doi.org/10.1029/2004JD005021doi:10.1029/2004JD005021, 2005.