02/07/2011

New Detailed Global Climate Record Produced for the 20th Century

Summary

Detailed records of past climate are needed to analyze climate change. However, previous climate records have been coarse in spatial and temporal scales and of limited duration. These limitations have been addressed by an international team of scientists in a project partially supported by DOE. The team has produced a dataset for Earth’s surface and atmosphere, spanning beyond the entire twentieth century (1871-2008), assimilating large-scale surface observations of pressure and prescribing monthly sea surface temperature and sea ice distribution. The scientists used an assimilation method with background ‘first guess’ fields supplied by an ensemble of forecasts from a global numerical weather prediction model. This directly yields a global analysis every six hours as the most likely state of the atmosphere and an uncertainty estimate of that analysis. Analysis of the dataset is already yielding some surprising results. For example, the long-term trends of indices representing the North Atlantic Oscillation, the tropical Pacific Walker Circulation, and the Pacific–North American pattern are weak or non-existent over the full period of record. It is anticipated that the new dataset will be a valuable resource to the climate research community for both model validations and diagnostic studies.

References

Compo, G. P., J. S. Whitaker, P. D. Sardeshmukh, N. Matsui, R. J. Allan, X. Yin, B. E. Gleason, R. S. Vose, G. Rutledge, P. Bessemoulin, S. Brönnimann, M. Brunet, R. I. Crouthamel, A. N. Grant, P. Y. Groisman, P. D. Jones, M. Kruk, A. C. Kruger, G. J. Marshall, M. Maugeri, H. Y. Mok, Ø. Nordli, T. F. Ross, R. M. Trigo, X. L. Wang, S. D. Woodruff, and S. J. Worley. 2011. “The Twentieth-Century Reanalysis Project,” Quarterly Journal of the Royal Meteorological Society 137, 1-28. DOI: 10.1002/qj.776.