Monday, 10 February 2003
Observed high latitude temperature change in North America(Formerly paper 4.9)
The observed warming in global surface temperatures has occurred in two phases, the period from 1900-1940 and from 1976-2001, with a period of little or no trend in between. The high latitudes of the Northern Hemisphere have experienced very strong warming during the latter period, with the former Soviet Union (fSU) and Canada exhibiting trends as strong as 1C/Decade for the 1976-2000 period. However, questions remain regarding the nature of this warming. These questions include the role of maximum vs. minimum temperature trends, and the seasonal, and daily distribution of temperature changes. Recent results for the fSU (Easterling et al. 2002) indicate that updated trends in maximum and minimum temperatures (1950-1999) show a continuation of previously documented trends with minimum temperatures rising faster than maximum temperatures resulting in a decrease in the diurnal temperature range (dtr) for most parts of the country. Examining changes in the distribution of daily temperatures indicates for the for winter and spring, when the trends in max/min/dtr are greatest, the greatest warming for both maximum and minimum temperatures is generally in the coldest days for each season. Here we extend this analysis to the higher latitudes of North America, including both Canada and Alaska.
Easterling, D.R., B. Gleason, D. Weurtz, R. Vose, and P. Groisman 2002: Characteristics of Recent Temperature Change in the former Soviet Union. manuscript in preparation for submission to J. Geophys. Research.