Time-Varying Biases in U.S. Total Cloud Cover Data

Melissa Free NOAA/Air Resources Laboratory, College Park, Maryland

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Bomin Sun NOAA/NESDIS/Center for Satellite Applications and Research, Camp Springs, and I.M. Systems Group, Rockville, Maryland

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Abstract

This paper presents evidence of significant discontinuities in U.S. cloud cover data from the Integrated Surface Database (ISD) and its predecessor datasets. While long-term U.S. cloud records have some well-known homogeneity problems related to the introduction of the Automated Surface Observing System (ASOS) in the 1990s, the change to the international standard reporting format [aviation routine weather report (METAR)] in the United States in July 1996 introduces an additional inhomogeneity at many of the stations where humans still make or supplement cloud observations. This change is associated with an upward shift in total cloud of 0.1%–10%, statistically significant at 95 of 172 stations. The shift occurs at both National Weather Service and military weather stations, producing a mean increase in total cloud of 2%–3%. This suggests that the positive trends in U.S. cloud cover reported by other researchers for recent time periods may be exaggerated, a conclusion that is supported by comparisons with precipitation and diurnal temperature range data.

Additional discontinuities exist at other times in the frequency distributions of fractional cloud cover at the majority of stations, many of which may be explained by changes in the sources and types of data included in ISD. Some of these result in noticeable changes in monthly-mean total cloud. The current U.S. cloud cover database needs thorough homogeneity testing and adjustment before it can be used with confidence for trend assessment or satellite product validation.

Corresponding author address: Melissa Free, NOAA/Air Resources Laboratory, R/ARL, NCWCP, 5830 University Research Court, College Park, MD 20740. E-mail: melissa.free@noaa.gov

Abstract

This paper presents evidence of significant discontinuities in U.S. cloud cover data from the Integrated Surface Database (ISD) and its predecessor datasets. While long-term U.S. cloud records have some well-known homogeneity problems related to the introduction of the Automated Surface Observing System (ASOS) in the 1990s, the change to the international standard reporting format [aviation routine weather report (METAR)] in the United States in July 1996 introduces an additional inhomogeneity at many of the stations where humans still make or supplement cloud observations. This change is associated with an upward shift in total cloud of 0.1%–10%, statistically significant at 95 of 172 stations. The shift occurs at both National Weather Service and military weather stations, producing a mean increase in total cloud of 2%–3%. This suggests that the positive trends in U.S. cloud cover reported by other researchers for recent time periods may be exaggerated, a conclusion that is supported by comparisons with precipitation and diurnal temperature range data.

Additional discontinuities exist at other times in the frequency distributions of fractional cloud cover at the majority of stations, many of which may be explained by changes in the sources and types of data included in ISD. Some of these result in noticeable changes in monthly-mean total cloud. The current U.S. cloud cover database needs thorough homogeneity testing and adjustment before it can be used with confidence for trend assessment or satellite product validation.

Corresponding author address: Melissa Free, NOAA/Air Resources Laboratory, R/ARL, NCWCP, 5830 University Research Court, College Park, MD 20740. E-mail: melissa.free@noaa.gov
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  • Campbell, G., 2004: View angle dependence of cloudiness and the trend in ISCCP cloudiness. Preprints, 13th Conf. on Satellite Meteorology and Oceanography, Norfolk, VA, Amer. Meteor. Soc., P6.7. [Available online at https://ams.confex.com/ams/13SATMET/techprogram/paper_79041.htm.]

  • Dai, A., Del Genio A. D. , and Fung I. Y. , 1997: Clouds, precipitation and temperature range. Nature, 386, 665666.

  • Dai, A., Karl T. R. , Sun B. , and Trenberth K. E. , 2006: Recent trends in cloudiness over the United States: A tale of monitoring inadequacies. Bull. Amer. Meteor. Soc., 87, 597606.

    • Search Google Scholar
    • Export Citation
  • Evan, A. T., Heidinger A. K. , and Vimont D. J. , 2007: Arguments against a physical long-term trend in global ISCCP cloud amounts. Geophys. Res. Lett., 34, L04701, doi:10.1029/2006GL028083.

    • Search Google Scholar
    • Export Citation
  • FAA, 2001: Surface weather observations. Order 7900.5B, Department of Transportation, Federal Aviation Administration, 267 pp. [Available online at http://www.faa.gov/air_traffic/publications/at_orders/media/SWO.pdf.]

  • Jacobowitz, H., Stowe L. L. , Ohring G. , Heidinger A. , Knapp K. , and Nalli N. R. , 2003: The Advanced Very High Resolution Radiometer Pathfinder Atmosphere (PATMOS) climate dataset. Bull. Amer. Meteor. Soc., 84, 785793.

    • Search Google Scholar
    • Export Citation
  • Karl, T. R., and Steurer P. M. , 1990: Increased cloudiness in the United States during the first half of the twentieth century: Fact or fiction? Geophys. Res. Lett., 17, 19251928.

    • Search Google Scholar
    • Export Citation
  • Lawrimore, J. H., Menne M. J. , Gleason B. E. , Williams C. N. , Wuertz D. B. , Vose R. S. , and Rennie J. , 2011: An overview of the Global Historical Climatology Network monthly mean temperature dataset, version 3. J. Geophys. Res., 116, D19121, doi:10.1029/2011JD016187.

    • Search Google Scholar
    • Export Citation
  • Long, C. N., Dutton E. G. , Augustine J. A. , Wiscombe W. , Wild M. , McFarlane S. A. , and Flynn C. J. , 2009: Significant decadal brightening of downwelling shortwave in the continental United States. J. Geophys. Res., 114, D00D06, doi:10.1029/2008JD011263.

    • Search Google Scholar
    • Export Citation
  • Lott, N., Baldwin R. , and Jones P. , 2001: The FCC Integrated Surface Hourly database: A new resource of global climate data. National Climatic Data Center Tech. Rep. 2001-01, 42 pp.

  • Lott, N., Vose R. S. , Del Greco S. A. , Ross T. F. , Worley S. , and Comeaux J. L. , 2008: The Integrated Surface Database: Partnerships and progress. Preprints, 24th Conf. on Interactive Information Processing Systems, New Orleans, LA, Amer. Meteor. Soc., 3B.5. [Available online at https://ams.confex.com/ams/88Annual/techprogram/paper_131387.htm.]

  • NCDC, 2003: Data documentation for data set 9956 (DSI-9956): DATSAV3 global surface hourly data. National Climatic Data Center, 52 pp. [Available online at ftp://ftp.ncdc.noaa.gov/pub/data/documentlibrary/tddoc/td9956.pdf.]

  • NCDC, 2005: Data documentation for data set 3280 (DSI-3280): Surface airways hourly. National Climatic Data Center, 30 pp. [Available online at ftp://ftp.ncdc.noaa.gov/pub/data/documentlibrary/tddoc/td3280.pdf.]

  • NCDC, 2011: Data documentation for Integrated Surface Data. Federal Climate Complex, National Climatic Data Center, 130 pp. [Available online at ftp://ftp.ncdc.noaa.gov/pub/data/noaa/ish-format-document.pdf.]

  • NOAA, 1988: Surface synoptic codes. Federal Meteorological Handbook 2, FCM-H2-1988, Office of the Federal Coordinator for Meteorology, 131 pp. [Available online at http://www.ofcm.gov/fmh2/fmh2.htm.]

  • NWS, 1994: Surface observations. Observing Handbook No. 7, U.S. Department of Commerce, 215 pp.

  • Pachauri, R. K., and Reisinger A. , Eds., 2007: Climate Change 2007: Synthesis Report. Cambridge University Press, 104 pp.

  • Reeves, J., Chen J. , Wang X. L. , Lund R. , and Lu Q. , 2007: A review and comparison of changepoint detection techniques for climate data. J. Appl. Meteor. Climatol., 46, 900915.

    • Search Google Scholar
    • Export Citation
  • Smith, A., Lott N. , and Vose R. , 2011: The Integrated Surface Database: Recent developments and partnerships. Bull. Amer. Meteor. Soc., 92, 705708.

    • Search Google Scholar
    • Export Citation
  • Steurer, P. M., and Bodosky M. , 2000: Surface airways hourly (TD-3280) and airways solar radiation (TD-3281). National Climatic Data Center, 50 pp.

  • Sun, B., and Groisman P. Ya. , 2004: Variations in low cloud cover over the United States during the second half of the twentieth century. J. Climate, 17, 18831888.

    • Search Google Scholar
    • Export Citation
  • Sun, B., Groisman P. Ya. , and Mokhov I. I. , 2001: Recent changes in cloud-type frequency and inferred increases in convection over the United States and the former USSR. J. Climate, 14, 18641880.

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

    • Search Google Scholar
    • Export Citation
  • U.S. Air Force, 2009: Surface weather observations. U.S. Air Force Manual 15-111, 138 pp.

  • Wang, W.-C., Zhang Q.-Y. , Easterling D. R. , and Karl T. R. , 1993: Beijing cloudiness since 1875. J. Climate, 6, 19211927.

  • Warren, S. G., London J. , and Hahn C. J. , 1991: Cloud hole over the United States? Bull. Amer. Meteor. Soc., 72, 237238.

  • Warren, S. G., Eastman R. , and Hahn C. , 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
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