Autumn synoptic conditions and rainfall in the subarctic Canadian Shield of the Northwest Territories, Canada
✍ Scribed by Christopher Spence; Jara Rausch
- Publisher
- John Wiley and Sons
- Year
- 2005
- Tongue
- English
- Weight
- 792 KB
- Volume
- 25
- Category
- Article
- ISSN
- 0899-8418
- DOI
- 10.1002/joc.1185
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✦ Synopsis
Autumn precipitation is important to the annual water budget and spring streamflow magnitude in the subarctic Canadian Shield portion of the Mackenzie Basin in northwestern Canada. The objective of this study is to improve understanding of the synoptic mechanisms generating this autumn precipitation by investigating a wet (1998) and a dry (1999) autumn over a portion of this region north of Great Slave Lake. Seven synoptic map patterns were identified using a hybrid manual-revised Kirchhofer correlation methodology. Cyclones were found to be the most important map pattern providing autumn rainfall. These cyclones tend to occur 2 to 3 days following the presence of a low in the Gulf of Alaska near the Aleutian Islands. The results of this study corroborate past research that shows Pacific atmospheric moisture transported inland provides the source for much of the cyclonic rainfall in the Mackenzie Basin. Aleutian lows, which encourage this transportation, were as common in 1998 as in 1999, but the mechanisms necessary to transfer moisture to the North Great Slave region were more entrenched in 1998 than in 1999. Winds along storm tracks through the region were weaker and more dispersed in 1999. In addition, conditions for cyclogenesis in the region were less favourable in 1999.