Air temperature changes in the Canadian Arctic from the early instrumental period to modern times

Abstract

This article presents a detailed account of air temperature (using four thermal parameters: mean daily air temperature (MDAT), maximum daily temperature (TMAX), minimum daily temperature (TMIN), and diurnal temperature range (DTR)) in the Canadian Arctic from 1819 to 1859. As source data, the authors have used hourly, two-hourly, four-hourly, or six-hourly temperature measurements carried out during exploratory (land or marine) expeditions sent mainly by the Royal Navy to find the Northwest Passage and later also during a lost expedition under the command of Sir John Franklin. Standard climate analyses (using monthly means) and more detailed and precise analyses based on daily data showing a wide spectrum of temperature regimes were conducted. The latter analysis examined the frequency of occurrence of MDAT in particular intervals, day-to-day variability of MDAT, annual courses of MDAT and DTR, and the frequency of occurrence of different kinds of characteristic days (e.g. very warm, warm, severe cold, very cold). All studied aspects of historical temperature changes in the Canadian Arctic from 1819 to 1859 were compared with present-day (1961–1990) values. All the results obtained suggest that in the nineteenth century a moderate cooling occurred in the Canadian Arctic. The average annual temperature during the study period was only about 0.3 °C lower in comparison with the present-day value. The most typical features in the annual courses of air temperature in the study period were very cold winter months (December to February, 1.0–2.5 °C below today’s norm) and warm springs (March to May, 0.2–2.6 °C above today’s norm). The majority of mean monthly and daily temperatures lie within one SD from the modern mean.