ALBERT

Description: Minor changes to seasonal air temperature and precipitation can have a substantial impact on the availability of water resources within large watersheds. Two such watersheds, the north-flowing Mackenzie and east-flowing Saskatchewan Basins have been identified as highly vulnerable to such changes, and, therefore, selected for study as part of the Climatic Redistribution of western Canadian Water Resources (CROCWR) project. CROCWR aims to evaluate spatial and temporal changes to water resource distribution through the analysis of a suite of hydroclimatic and streamflow variables. As part of this analysis, dominant summer (May-Oct) circulation patterns at 500-hPa for 1950-2011 are identified using the method of Self-Organizing Maps (SOM). Surface climate variables associated with these patterns are then identified, including both daily air temperature and precipitation, and seasonal Standardized Precipitation-Evapotranspiration Index (SPEI) values. Statistical methods are applied to assess the relationships between dominant circulation patterns and the Southern Oscillation Index (SOI) and Pacific Decadal Oscillation (PDO). Results indicate that mid-summer (Jul-Aug) is dominated by a split-flow blocking pattern, resulting in cool (warm), wet (dry) conditions in the southern (northern) portion of the study area. By contrast, the shoulder season (May and Oct) is dominated by a trough of low-pressure over the North Pacific Ocean. The frequency of weak split-flow blocking is higher during positive SOI and negative PDO, while ridging over the western continent is more frequent during negative SOI and positive PDO. Results from this analysis increase our knowledge of processes controlling the distribution of summer water resources in western Canada. This article is protected by copyright. All rights reserved.

Description: The Climatic Redistribution of western Canadian Water Resources (CROCWR) project was designed to identify regions of increased/decreased water availability by evaluating a suite of atmospheric, hydroclimatic, and streamflow variables. This research component focuses on the atmospheric drivers of air temperature and precipitation in the watersheds originating on the leeward slopes of the Rocky Mountains. Dominant winter (Nov-Apr) synoptic-scale mid-tropospheric circulation patterns from 1950-2011 are classified using Self-Organizing Maps (SOM), and frequency distributions for positive/negative phases of the Southern Oscillation Index (SOI), Pacific Decadal Oscillation (PDO), and Arctic Oscillation (AO) are statistically compared. Corresponding high-resolution gridded temperature and precipitation anomalies are calculated for each synoptic type and spatial patterns of above/below average temperature and precipitation and north/south gradients are identified. Gridded six-month values of the Standardized Precipitation-Evapotranspiration Index (SPEI) are also used to categorize winters into regions of high/low snowpack. Results indicate high-pressure ridges over the Pacific Ocean (western North America) and low-pressure troughs over western North America (Pacific Ocean) are associated with anomalously cool (warm), wet (dry) conditions in the study region. Several statistically different synoptic type frequencies were found for positive/negative phases of the SOI, PDO, and AO. Most notably, positive (negative) phases of the SOI and negative (positive) phases of the PDO are associated with a higher (lower) frequency of ridging over the Pacific Ocean (western North America). Through improved knowledge of the relationships between teleconnections, mid-tropospheric circulation, and surface climate, the spatial and temporal distribution of water resources in western Canada is better understood. This article is protected by copyright. All rights reserved.

Description: Minor changes to seasonal air temperature and precipitation can have a substantial impact on the availability of water resources within large watersheds. Two such watersheds, the north-flowing Mackenzie and east-flowing Saskatchewan Basins, have been identified as highly vulnerable to such changes and, therefore, selected for study as part of the Climatic Redistribution of western Canadian Water Resources project. This project aims to evaluate spatial and temporal changes to water resource distribution through the analysis of a suite of hydroclimatic and streamflow variables. As part of this analysis, dominant summer (May-October) circulation patterns at 500hPa for 1950-2011 are identified using the method of self-organizing maps. Surface climate variables associated with these patterns are then identified, including both daily air temperature and precipitation and seasonal Standardized Precipitation Evapotranspiration Index values. Statistical methods are applied to assess the relationships between dominant circulation patterns and the Southern Oscillation Index (SOI) and Pacific Decadal Oscillation (PDO). Results indicate that mid-summer (July-August) is dominated by a split-flow blocking pattern, resulting in cool (warm), wet (dry) conditions in the southern (northern) portion of the study area. By contrast, the shoulder season (May and October) is dominated by a trough of low pressure over the North Pacific Ocean. The frequency of weak split-flow blocking is higher during positive SOI and negative PDO, whereas ridging over the western continent is more frequent during negative SOI and positive PDO. Results from this analysis increase our knowledge of processes, controlling the distribution of summer water resources in western Canada. © 2014 John Wiley & Sons, Ltd.

Description: The Climatic Redistribution of western Canadian Water Resources project was designed to identify regions of increased/decreased water availability by evaluating a suite of atmospheric, hydroclimatic and streamflow variables. This research component focuses on the atmospheric drivers of air temperature and precipitation in the watersheds originating on the leeward slopes of the Rocky Mountains. Dominant winter (November-April) synoptic-scale mid-tropospheric circulation patterns from 1950 to 2011 are classified using self-organizing maps, and frequency distributions for positive/negative phases of the Southern Oscillation Index (SOI), Pacific Decadal Oscillation (PDO) and Arctic Oscillation are statistically compared. Corresponding high-resolution gridded temperature and precipitation anomalies are calculated for each synoptic type, and spatial patterns of above/below-average temperature and precipitation and north/south gradients are identified. Gridded 6-month values of the Standardized Precipitation-Evapotranspiration Index are also used to categorize winters into regions of high/low snowpack. Results indicate high-pressure ridges over the Pacific Ocean (western North America), and low-pressure troughs over western North America (Pacific Ocean) are associated with anomalously cool (warm) and wet (dry) conditions in the study region. Several statistically different synoptic type frequencies were found for positive/negative phases of the SOI, PDO and Arctic Oscillation. Most notably, positive (negative) phases of the SOI and negative (positive) phases of the PDO are associated with a higher (lower) frequency of ridging over the Pacific Ocean (western North America). Through improved knowledge of the relationships between teleconnections, mid-tropospheric circulation and surface climate, the spatial and temporal distribution of water resources in western Canada is better understood. © 2014 John Wiley & Sons, Ltd.