By using historical climate data to understand current weather patterns the 20CR team, which includes 27 international scientists, are building on the work of their meteorological forebears such as the U.S. Historical Weather Map Series produced by the U.S. Weather Bureau to better understand weather events preceding World War II. However, the 20CR is the first project of its kind to span a full century.
"A preliminary version of this project (20CRv1, Compo et al., 2008) spanned the period 1908 to 1958," said Compo. "In this second and complete version (20CRv2), the global atmospheric fields for 1871 to 2008 have been generated. We hope, as Wexler and Tepper of the US Weather Bureau said in 1947, that this project can 'breathe life into a mass of inert data' while providing an indispensable aid to future research."
The 20CR dataset provides the first long-term estimates of global tropospheric variability, weather maps from the Earth's surface to the level of the jet-stream, and of their time-varying quality, from 1871 to the present at 6- hourly temporal and 2 spatial resolutions.
"The new dataset will allow climate scientists to put current weather extremes in a historical perspective and determine how extremes are changing," said Compo. "Just how extreme is the recent European cold wave, for example, or the blizzard in the US Northeast?"
The 20CR dataset also gives a new insight into the weather events that may have misinformed early-century policy decisions, such as the wet period in central North America that led to overestimates of rainfall and over-allocation of water resources in the Colorado River basin in the years before the US Dust Bowl of the 1930's.
"This reanalysis data
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