Historical Data from Canadian Arctic
Historical Data Utilized in First-hand accounts from 19th century explorers' logs for the Canadian Arctic reflect similar climate conditions as present
Wood, K.R., and J.E. Overland (2003): Accounts from 19th-century Canadian Arctic explorers' logs reflect present climate conditions. Eos Trans. AGU, 84(40), 410, 412, doi: 10.1029/2003EO400003.
by Kevin R. Wood and James E. Overland
Contact: James E. Overland, NOAA/PMEL, James.E.Overland@noaa.gov
This table lists the 44 expeditions that published scientific observations or other material used in the study, and shows which types of data were available. Monthly and daily mean air temperature data and ice thickness data were used to calculate departure from 20th century reference mean values. Descriptive records (including visual records where available) were used to provide qualitative context and to confirm that results derived from instrumental records were consistent with observed phenomena. Sea surface temperatures were not generally used. The daily temperatures from Back 1836-37 were not used because the record was too fragmented around the seasonal transition periods in spring and fall.
It is difficult to provide a precise estimate of instrumental data quality for each expedition. The performance of thermometers was degraded at temperatures approaching the freezing point of mercury (-38.8 C) and therefore the value of extremely low temperature measurements during winter is questionable. In summer, the presence of melting ice and snow constrain air temperature. In addition, the sheltering of thermometers was not standardized in the modern sense. Instruments were generally sheltered in a specially constructed observatory, but Stevenson screens were not in use during the period. For these reasons it is most likely that monthly temperatures in the spring and autumn are more accurate, as are the estimated annual dates of melt and freeze transition calculated from daily temperatures. Melt and freeze transition dates are produced when the 15 day running mean of the daily average temperature crosses -1 C. The date estimate produced is not especially sensitive to small amounts of bias in the daily data.
The quality of the descriptive records is in some respects easier to assess, but their interpretation in terms of climate change may always be problematic. In this study we have focussed on two main issues where the use of descriptive records may be less ambiguous: where and when did expeditions reach certain locations, and were their observations of the environment consistent with the instrumental record.