Comparison between the Droughts of the 1930s and the 1980s in the Southern Prairies of Canada

Abstract

Abstract The drought decades of the 1930s and 1980s in the southern prairies of Canada were compared using Palmer’s drought severity index (PDSI). Nine of the 11 yr from 1929 to 1939 inclusive were drought years compared to 6 of 11 from 1979 to 1989. The longest runs were 4 yr for the 1930s and three for the 1980s. Although the territorial size under mild to extreme drought was 16% larger in the 1930s than in the 1980s, the area impacted by extreme drought was 10% more during the 1980s. In the 1930s, PDSI averaged −1.39 in dry years compared to −1.33 in the 1980s; the most severe drought (average PDSI −3.18) occurred in the 1980s. Recovery in the 1980s averaged 1.20 PDSI units yr−1 compared to 1.02 units in the 1930s. Spatially, the pattern of drought intensity was patchy in the 1930s but zoned in the 1980s. A southwest–northeast-running “moist plume” coupled with regular storm activity point to one possible cause of drought in the 1930s, namely, a southerly displacement of the Alberta storm track from it...