Examination of trends in hourly surface pressure in Canada during 1953–2003

Hourly values of surface pressure recorded at 90 stations across Canada during 1953–2003 were examined. For each station, a linear trend was fitted to the data and a statistical t‐test determined whether the trend was significant at the 5% level. Most of the stations located above 60°N latitude reported a statistically significant decrease in winter pressure averaging −5.8 hPa over the 50 year period which is likely a manifestation of the Arctic oscillation (AO). This winter pressure decrease is slightly larger than that found in other studies that determined sea level pressure trends during 1948–1998 using reanalyzed datasets. The present work found fewer and weaker statistically significant trends for the northern stations during the other seasons. Very few stations in southern Canada had significant trends in any season. The data were also examined for possible inhomogeneities, but none that affected the aforementioned conclusions were found. Copyright © 2005 Royal Meteorological Society