13th Conference on Applied Climatology and the 10th Conference on Aviation, Range, and Aerospace Meteorology

Wednesday, 15 May 2002: 11:30 AM
A climatological assessment of major 20th century drought in southern Ontario, Canada
Joan M. Klaassen, MSC, Downsview, ON, Canada
Poster PDF (214.6 kB)
A drought study was initiated in 1999 by Meteorological Service of Canada-Ontario Region in response to the concern over the severity of the 1998 and 1999 drought conditions in southern Ontario. Water budget model results and precipitation indices were used to compare 1997-1999 moisture conditions over southern Ontario to historical moisture conditions over the region in the 20th century. The analyses concluded that drought conditions in 1998 and 1999 had indeed rivalled those of even the driest years during the 1930s or 1960s. The results also determined that it is difficult to find specific and consistent predictors in seasonal precipitation and temperatures as predictors for significant drought years.

The drought study also offered some interesting analogues with recent climatic conditions. In particular, it was shown that extreme or heavy rainfall events can often occur in some of the driest years and that a sequence of dry years can often be interrupted by an abnormally wet summer (e.g. 1937, 2000) before drought conditions return the following year (e.g. 1938, 2001). The work also revealed that serious summer drought conditions can often follow winters of heavy, and in some cases, record-breaking snowfall (e.g. 1930, 1999).

Finally, the study concluded that drought conditions aren’t consistently or necessarily linked to atmosphere-ocean circulations such as El Niño, La Niña and the North Atlantic Oscillation.

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