Possible teleconnections between North Pacific sea surface temperatures and extended dry spells and droughts on the Canadian Praries
Date
1991
Authors
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ORCID
Type
Degree Level
Masters
Abstract
This thesis examines the possible teleconnections
between North Pacific sea surface temperatures and synoptic
extended dry spells and droughts on the Canadian Prairies.
Dry spells are a natural occurrence on the Canadian Prairies.
It is also a well known fact that extended dry spells often
lead to droughts. The major synoptic cause of extended dry
spells and droughts on the Canadian Prairies includes the
presence of a quasi-stationary mid-tropospheric ridge over
the area. What causes this ridge to become quasi-stationary
is not certain. Some previous studies have shown that sea
surface temperature anomalies over the North Pacific Ocean
may be a significant factor in affecting upper atmospheric
long wave patterns and abnormal weather conditions over North
America.
The main objective of this study is to determine if
there is a significant statistical relationship between
anomalous North Pacific sea surface temperatures and the
occurrence of extended dry spells and droughts on the
Canadian Prairies during the agricultural growing season (May
- August) for the period 1948-1988. Individual extended dry
spells are identified and then ranked in terms of their
severity. Results show a significant correlation between
these extended dry spells and a positive sea surface temperature anomaly gradient located in the east central
North Pacific. This gradient consists of a region of
anomalously cold water located in the east-central North
Pacific in the area bounded by 30°N to 40°N latitude and
165°W to 135°W longitude and a region of anomalously warm
water found along the west coast of North America bounded by
the coordinates 45°N to 55°N latitude and 130°W to 125°W
longitude. A probability model shows that the longer this
gradient persists, the greater the probability of a major
extended dry spell. A conceptual model is also constructed
and shows a distinctive pattern in sea surface temperature
anomalies and 50 kPa anomalies associated with the major
extended dry spells.
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Degree
Master of Science (M.Sc.)
Department
Geography
Program
Geography