Variations in Cloud Cover and Cloud Types over the Ocean from Surface Observations, 1954–2008

Ryan Eastman Department of Atmospheric Sciences, University of Washington, Seattle, Washington

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Stephen G. Warren Department of Atmospheric Sciences, University of Washington, Seattle, Washington

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Carole J. Hahn Department of Atmospheric Sciences, The University of Arizona, Tucson, Arizona

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Abstract

Synoptic weather observations from ships throughout the World Ocean have been analyzed to produce a climatology of total cloud cover and the amounts of nine cloud types. About 54 million observations contributed to the climatology, which now covers 55 years from 1954 to 2008. In this work, interannual variations of seasonal cloud amounts are analyzed in 10° grid boxes. Long-term variations O(5–10 yr), coherent across multiple latitude bands, remain present in the updated cloud data. A comparison to coincident data on islands indicates that the coherent variations are probably spurious. An exact cause for this behavior remains elusive. The globally coherent variations are removed from the gridbox time series using a Butterworth filter before further analysis.

Before removing the spurious variation, the global average time series of total cloud cover over the ocean shows low-amplitude, long-term variations O(2%) over the 55-yr span. High-frequency, year-to-year variation is seen O(1%–2%).

Among the cloud types, the most widespread and consistent relationship is found for the extensive marine stratus and stratocumulus clouds (MSC) over the eastern parts of the subtropical oceans. Substantiating and expanding upon previous work, strong negative correlation is found between MSC and sea surface temperature (SST) in the eastern North Pacific, eastern South Pacific, eastern South Atlantic, eastern North Atlantic, and the Indian Ocean west of Australia. By contrast, a positive correlation between cloud cover and SST is seen in the central Pacific. High clouds show a consistent low-magnitude positive correlation with SST over the equatorial ocean.

In regions of persistent MSC, time series show decreasing MSC amount. This decrease could be due to further spurious variation within the data. However, the decrease combined with observed increases in SST and the negative correlation between marine stratus and sea surface temperature suggests a positive cloud feedback to the warming sea surface. The observed decrease of MSC has been partly but not completely offset by increasing cumuliform clouds in these regions; a similar decrease in stratiform and increase in cumuliform clouds had previously been seen over land.

Interannual variations of cloud cover in the tropics show strong correlation with an ENSO index.

Corresponding author address: Ryan Eastman, Department of Atmospheric Sciences, University of Washington, Box 351640, Seattle, WA 98195-1640. E-mail: rmeast@atmos.washington.edu

Abstract

Synoptic weather observations from ships throughout the World Ocean have been analyzed to produce a climatology of total cloud cover and the amounts of nine cloud types. About 54 million observations contributed to the climatology, which now covers 55 years from 1954 to 2008. In this work, interannual variations of seasonal cloud amounts are analyzed in 10° grid boxes. Long-term variations O(5–10 yr), coherent across multiple latitude bands, remain present in the updated cloud data. A comparison to coincident data on islands indicates that the coherent variations are probably spurious. An exact cause for this behavior remains elusive. The globally coherent variations are removed from the gridbox time series using a Butterworth filter before further analysis.

Before removing the spurious variation, the global average time series of total cloud cover over the ocean shows low-amplitude, long-term variations O(2%) over the 55-yr span. High-frequency, year-to-year variation is seen O(1%–2%).

Among the cloud types, the most widespread and consistent relationship is found for the extensive marine stratus and stratocumulus clouds (MSC) over the eastern parts of the subtropical oceans. Substantiating and expanding upon previous work, strong negative correlation is found between MSC and sea surface temperature (SST) in the eastern North Pacific, eastern South Pacific, eastern South Atlantic, eastern North Atlantic, and the Indian Ocean west of Australia. By contrast, a positive correlation between cloud cover and SST is seen in the central Pacific. High clouds show a consistent low-magnitude positive correlation with SST over the equatorial ocean.

In regions of persistent MSC, time series show decreasing MSC amount. This decrease could be due to further spurious variation within the data. However, the decrease combined with observed increases in SST and the negative correlation between marine stratus and sea surface temperature suggests a positive cloud feedback to the warming sea surface. The observed decrease of MSC has been partly but not completely offset by increasing cumuliform clouds in these regions; a similar decrease in stratiform and increase in cumuliform clouds had previously been seen over land.

Interannual variations of cloud cover in the tropics show strong correlation with an ENSO index.

Corresponding author address: Ryan Eastman, Department of Atmospheric Sciences, University of Washington, Box 351640, Seattle, WA 98195-1640. E-mail: rmeast@atmos.washington.edu
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  • Bajuk, L. J., and C. B. Leovy, 1998: Are there real interdecadal variations in marine low clouds? J. Climate, 11, 29102921.

  • Bengtsson, L., S. Hagemann, and K. I. Hodges, 2004: Can climate trends be calculated from reanalysis data? J. Geophys. Res., 109, D11111, doi:10.1029/2004JD004536.

    • Search Google Scholar
    • Export Citation
  • Bony, S., and J.-L. Dufresne, 2005: Marine boundary clouds at the heart of tropical cloud feedback uncertainties in climate models. Geophys. Res. Lett., 32, L20806, doi:10.1029/2005GL023851.

    • Search Google Scholar
    • Export Citation
  • Bromwich, D. H., and R. L. Fogt, 2004: Strong trends in the skill of the ERA-40 and NCEP–NCAR reanalyses in the high and midlatitudes of the Southern Hemisphere, 1958–2001. J. Climate, 17, 46034619.

    • Search Google Scholar
    • Export Citation
  • Cermak, J., M. Wild, R. Knutti, M. I. Mishchenko, and A. K. Heidinger, 2010: Consistency of global satellite-derived aerosol and cloud data sets with recent brightening observations. Geophys. Res. Lett., 37, L21704, doi:10.1029/2010GL044632.

    • Search Google Scholar
    • Export Citation
  • Clement, A. C., R. Burgman, and J. R. Norris, 2009: Observational and model evidence for positive low-level cloud feedback. Science, 325, 460464, doi:10.1126/science.1171255.

    • Search Google Scholar
    • Export Citation
  • Dee, D. P., E. Kallen, A. J. Simmons, and L. Haimberger, 2011: Comments on “Reanalysis suitable for characterizing long-term trends.” Bull. Amer. Meteor. Soc., 92, 6570.

    • Search Google Scholar
    • Export Citation
  • Deser, C., A. S. Phillips, and M. A. Alexander, 2010: Twentieth century tropical sea surface temperature trends revisited. Geophys. Res. Lett., 37, L10701, doi:10.1029/2010GL043321.

    • Search Google Scholar
    • Export Citation
  • Eastman, R., and S. G. Warren, 2010a: Arctic cloud changes from surface and satellite observations. J. Climate, 23, 42334242.

  • Eastman, R., and S. G. Warren, 2010b: Interannual variations of Arctic cloud types in relation to sea ice. J. Climate, 23, 42164232.

  • George, R. C., and R. Wood, 2010: Subseasonal variability of low cloud radiative properties over the southeast Pacific Ocean. Atmos. Chem. Phys., 10, 40474063, doi:10.5194/acp-10-4047-2010.

    • Search Google Scholar
    • Export Citation
  • Hahn, C. J., and S. G. Warren, 2009a: A gridded climatology of clouds over land (1971–96) and ocean (1954–97) from surface observations worldwide (2009 update). Carbon Dioxide Information Analysis Center Rep. NDP-026E, 71 pp. [Available online at http://cdiac.ornl.gov/ftp/ndp026e/.]

    • Search Google Scholar
    • Export Citation
  • Hahn, C. J., and S. G. Warren, 2009b: Extended edited cloud reports from ships and land stations over the globe, 1952–1996 (2009 update). Carbon Dioxide Information Analysis Center Numerical Data Package NDP-026C, 79 pp.

    • Search Google Scholar
    • Export Citation
  • Hahn, C. J., S. G. Warren, and J. London, 1995: The effect of moonlight on observation of cloud cover at night, and application to cloud climatology. J. Climate, 8, 14291446.

    • Search Google Scholar
    • Export Citation
  • Hamming, R. W., 1989: Digital Filters. Prentice Hall, 284 pp.

  • Hansen, J., R. Ruedy, M. Sato, and K. Lo, 2010: Global surface temperature change. Rev. Geophys., 48, RG4004, doi:10.1029/2010RG000345.

  • Kalnay, E., and Coauthors, 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc., 77, 437471.

  • Kato, S., 2009: Interannual variability of the global radiation budget. J. Climate, 22, 48934907.

  • Klein, S. A., and D. L. Hartmann, 1993: The seasonal cycle of low stratiform clouds. J. Climate, 6, 15871606.

  • Lanzante, J. R., 1996: Resistant, robust and non-parametric techniques for the analysis of climate data: Theory and examples, including applications to historical radiosonde station data. Int. J. Climatol., 16, 11971226.

    • Search Google Scholar
    • Export Citation
  • Marshall, J. G., and S. A. Harangozo, 2000: An appraisal of NCEP/NCAR reanalysis MSLP data viability for climate studies in the South Pacific. Geophys. Res. Lett., 27, 30573060, doi:10.1029/2000GL011363.

    • Search Google Scholar
    • Export Citation
  • Meyers, S. D., J. J. O’Brien, and E. Thelin, 1999: Reconstruction of monthly SST in the tropical Pacific Ocean during 1868–1993 using adaptive climate basis functions. Mon. Wea. Rev., 127, 15991612.

    • Search Google Scholar
    • Export Citation
  • Mitchell, T. P., and J. M. Wallace, 1992: The annual cycle in equatorial convection and sea surface temperature. J. Climate, 5, 11401156.

    • Search Google Scholar
    • Export Citation
  • Norris, J. R., 1999: On trends and possible artifacts in global ocean cloud cover between 1952 and 1995. J. Climate, 12, 18641870.

  • Norris, J. R., 2000: What can cloud observations tell us about climate variability? Space Sci. Rev., 94, 375380.

  • Norris, J. R., 2002: Evidence for globally decreasing subtropical stratocumulus since 1952. Proc. 2002 Fall AGU Meeting, San Franciso, CA, Amer. Geophys. Union, A21D-10. [Available online at http://meteora.ucsd.edu/~jnorris/presentations/AGU2002.pdf.]

    • Search Google Scholar
    • Export Citation
  • Norris, J. R., 2005: Trends in upper-level cloud cover and surface divergence over the tropical Indo-Pacific Ocean between 1952 and 1997. J. Geophys. Res., 110, D21110, doi:10.1029/2005JD006183.

    • Search Google Scholar
    • Export Citation
  • Norris, J. R., and C. B. Leovy, 1994: Interannual variability in stratiform cloudiness and sea surface temperature. J. Climate, 7, 19151925.

    • Search Google Scholar
    • Export Citation
  • Park, S., and C. B. Leovy, 2004: Marine low-cloud anomalies associated with ENSO. J. Climate, 17, 34483469.

  • Press, W. H., S. A. Teukolsky, W. T. Vetterling, and B. P. Flannery, 2002: Numerical Recipes in C: The Art of Scientific Computing. 2nd ed. Cambridge University Press, 994 pp.

    • Search Google Scholar
    • Export Citation
  • Randall, D. A., J. A. Coakley, Jr., C. W. Fairall, A. Kropfli, and D. H. Lenschow, 1984: Outlook for research on subtropical marine stratiform clouds. Bull. Amer. Meteor. Soc., 65, 12901301.

    • Search Google Scholar
    • Export Citation
  • Rayner, N. A., D. E. Parker, E. B. Horton, C. K. Folland, L. V. Alexander, D. P. Rowell, E. C. Kent, and A. Kaplan, 2003: Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century. J. Geophys. Res., 108 (D14), 4407, doi:10.1029/2002JD002670.

    • Search Google Scholar
    • Export Citation
  • Solomon, S., D. Qin, M. Manning, M. Marquis, K. Averyt, M. M. B. Tignor, H. L. Miller Jr., and Z. Chen, Eds., 2007: Climate Change 2007: The Physical Science Basis. Cambridge University Press, 996 pp.

    • Search Google Scholar
    • Export Citation
  • Thorne, P. W., and R. S. Vose, 2010: Reanalysis suitable for long-term trends: Are they really achievable? Bull. Amer. Meteor. Soc., 91, 353361.

    • Search Google Scholar
    • Export Citation
  • Trenberth, K. E., and J. T. Fasullo, 2009: Global warming due to increasing absorbed solar radiation. Geophys. Res. Lett., 36, L07706, doi:10.1029/2009GL037527.

    • Search Google Scholar
    • Export Citation
  • Warren, S. G., and C. J. Hahn, 2002: Cloud climatology. Encyclopedia of Atmospheric Sciences, Oxford University Press, 476–483.

  • Warren, S. G., C. J. Hahn, and J. London, 1985: Simultaneous occurrence of different cloud types. J. Climate Appl. Meteor., 24, 658667.

    • Search Google Scholar
    • Export Citation
  • Warren, S. G., C. J. Hahn, J. London, R. M. Chervin, and R. L. Jenne, 1988: Global distribution of total cloud cover and cloud type amounts over the ocean. NCAR Tech. Note TN-317+STR, 212 pp.

    • Search Google Scholar
    • Export Citation
  • Warren, S. G., R. M. Eastman, and C. J. Hahn, 2007: A survey of changes in cloud cover and cloud types over land from surface observations, 1971–96. J. Climate, 20, 717738.

    • Search Google Scholar
    • Export Citation
  • WMO, 1956: International Cloud Atlas. World Meteorological Organization, 72 plates, 62 pp.

  • WMO, 1974: Manual on codes. Vol. 1. World Meteorological Organization Publication 306, 348 pp.

  • Wood, R., and D. L. Hartmann, 2006: Spatial variability of liquid water path in marine low clouds: The importance of mesoscale cellular convection. J. Climate, 19, 17481764.

    • Search Google Scholar
    • Export Citation
  • Woodruff, S. D., R. J. Slutz, R. L. Jenne, and P. M. Steurer, 1987: A comprehensive ocean atmosphere data set. Bull. Amer. Meteor. Soc., 68, 12391250.

    • Search Google Scholar
    • Export Citation
  • Woodruff, S. D., H. F. Diaz, J. D. Elms, and S. J. Worley, 1998: COADS release 2 data and metadata enhancements for improvements of marine surface flux fields. Phys. Chem. Earth, 23, 517526.

    • Search Google Scholar
    • Export Citation
  • Worley, S. J., S. D. Woodruff, R. W. Reynolds, S. J. Lubker, and N. Lott, 2005: ICOADS Release 2.1 data and products. Int. J. Climatol., 25, 823842.

    • Search Google Scholar
    • Export Citation
  • Wyant, M. C., C. S. Bretherton, H. A. Rand, and D. E. Stevens, 1997: Numerical simulations and a conceptual model of the stratocumulus to trade cumulus transition. J. Atmos. Sci., 54, 169192.

    • Search Google Scholar
    • Export Citation
  • Wylie, D., D. L. Jackson, W. P. Menzel, and J. J. Bates, 2005: Trends in global cloud cover in two decades of HIRS observations. J. Climate, 18, 30213031.

    • Search Google Scholar
    • Export Citation
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