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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 113, D05115, doi:10.1029/2006JD008091, 2008

Global changes in extreme daily temperature since 1950

S. J. Brown

Met Office Hadley Centre for Climate Change, Exeter, UK


J. Caesar

Met Office Hadley Centre for Climate Change, Exeter, UK


C. A. T. Ferro

School of Engineering, Computing and Mathematics, University of Exeter, Exeter, UK


Abstract

Extreme value analysis of observed daily temperature anomalies from a new quasi-global data set indicates that extreme daily maximum and minimum temperatures (>98.5 or <1.5 percentile) have warmed for most regions since 1950. Changes in extreme anomalous daily temperatures are determined by fitting extreme value distributions with time-varying parameters. Changes in the distribution of anomaly exceedances above a high threshold are found to be statistically significant at the 10% level for most land areas when compared with a time-invariant distribution and with the unforced natural variability produced by a coupled climate model. The largest positive trends in the location parameter of the extreme distribution are found in Canada and Eurasia where daily maximum temperatures have typically warmed by 1 to 3°C since 1950. The total area exhibiting positive trends is significantly greater than can be attributed to unforced natural variability. For most regions, positive trend magnitudes are larger and cover a greater area for daily minimum temperatures than for maximum temperatures. The comparatively small areas of cooling are found to be consistent with unforced natural climate variability. The North Atlantic Oscillation (NAO) is found to have a significant influence on extreme winter daily temperatures for many areas, with a negative NAO of one standard deviation reducing expected extreme winter daily temperatures by ∼2°C over Eurasia but increasing temperatures over northeastern North America.

Received 2 October 2006; accepted 7 December 2007; published 13 March 2008.

Keywords: extreme; temperature; climate.

Index Terms: 3305 Atmospheric Processes: Climate change and variability (1616, 1635, 3309, 4215, 4513); 3309 Atmospheric Processes: Climatology (1616, 1620, 3305, 4215, 8408); 3322 Atmospheric Processes: Land/atmosphere interactions (1218, 1631, 1843); 3394 Atmospheric Processes: Instruments and techniques.

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Citation: Brown, S. J., J. Caesar, and C. A. T. Ferro (2008), Global changes in extreme daily temperature since 1950, J. Geophys. Res., 113, D05115, doi:10.1029/2006JD008091.