Extended Abstract (92K)12.9
Changes in hourly surface relative humidity measurements and instruments in Canada during 1953–2003
Lucie A. Vincent, MSC, Toronto, ON, Canada; and W. A. Van Wijngaarden
Hourly values of relative humidity recorded at 75 stations across Canada were examined. Data were checked for possible discontinuities due to changes in procedures and instruments. Notable changes included a refinement of the psychrometric tables around 1960 and the replacement of the psychrometer by the dewcel in the early 1970s. The latter is shown to have caused a decreasing step in relative humidity at a number of stations. The statistical significance of the step was determined by comparing two regression models using the F-test. This step particularly affects the relative humidity trends for stations experiencing cold temperatures. The impact of the change in instruments on seasonal trends during the period 1953-2003 will be presented.
Session 12, Observed Climate Change: 2 (parallel with Session 13)
Thursday, 13 January 2005, 8:30 AM-12:00 PM
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