The relationship between Canadian Prairie dry and wet months and circulation anomalies in the mid‐troposphere

Knox, John L.; Lawford, R. G.

doi:10.1080/07055900.1990.9649374

Cited by 39 publications

(40 citation statements)

References 16 publications

(14 reference statements)

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“…These persistent upper-level ridges over the boreal forest are teleconnected (spatially and temporally correlated) to upper-level troughs in the North Pacific and eastern North America. This teleconnection is called the Pacific North America pattern (Rogers 1981;Wallace and Gutzler 1981;Knox and Lawford 1990;Johnson and Wowchuk 1993). Similar patterns have been described in the southwestern United States as a result of ENSOs (Swetnam and Betancourt 1990).…”

Section: Boreal Forest Wildfires Forest Fragmentation and Loggingsupporting

confidence: 55%

Compounded Perturbations Yield Ecological Surprises

1998

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All species have evolved in the presence of disturbance, and thus are in a sense matched to the recurrence pattern of the perturbations. Consequently, disturbances within the typical range, even at the extreme of that range as defined by large, infrequent disturbances (LIDs), usually result in little long-term change to the system's fundamental character. We argue that more serious ecological consequences result from compounded perturbations within the normative recovery time of the community in question. We consider both physically based disturbance (for example, storm, volcanic eruption, and forest fire) and biologically based disturbance of populations, such as overharvesting, invasion, and disease, and their interactions. Dispersal capability and measures of generation time or age to first reproduction of the species of interest seem to be the important metrics for scaling the size and frequency of disturbances among different types of ecosystems. We develop six scenarios that describe communities that have been subjected to multiple perturbations, either simultaneously or at a rate faster than the rate of recovery, and appear to have entered new domains or ''ecological surprises.'' In some cases, three or more disturbances seem to have been required to initiate the changed state. We argue that in a world of ever-more-pervasive anthropogenic impacts on natural communities coupled with the increasing certainty of global change, compounded perturbations and ecological surprises will become more common. Understanding these ecological synergisms will be basic to environmental management decisions of the 21st century.

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Section: Boreal Forest Wildfires Forest Fragmentation and Loggingsupporting

confidence: 55%

Compounded Perturbations Yield Ecological Surprises

1998

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“…The PDO climate pattern was described by Zhang et al (1997) and Mantua et al (1997). Many authors have reported strong relationships between the Pacific climate features and climate, hydrology and ecology (Knox and Lawford, 1990;Francis and Hare, 1994;Francis et al, 1998;Bonsal and Lawford, 1999;Hare et al, 1999;Overland et al, 1999;Dettinger and Diaz, 2000;Bond and Harrison, 2000;Brito-Castillo et al, 2003;Pavia et al, 2006). The PDO index as developed by Hare (1996) and Zhang (1996), and used by Mantua et al (1997), is the leading principal component (PC) from an un-rotated empirical orthogonal function analysis (EOFA) of monthly "residual" sea surface temperature anomalies, poleward of 20°N for the 1900-1993 period of record.…”

Section: The Pacific Decadal Oscillation: a Primermentioning

confidence: 99%

Pacific Decadal Oscillation and the Hydroclimatology of Western Canada—Review and Prospects

Whitfield¹,

Moore²,

Fleming³

et al. 2010

Canadian Water Resources Journal

110

127

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Abstract:The Pacific Decadal Oscillation (PDO) is a large-scale climate system feature that influences the surface climate and hydrology of western North America. In this paper, we review the literature describing the PDO and demonstrate its effects on temperature, precipitation, snowfall, glacier mass balance, and streamflow with a focus on western Canada, and particularly British Columbia. We review how the PDO index was developed and discuss other North Pacific climate patterns that resemble the PDO. The impacts of PDO on glacier mass balance and streamflow from retrospective studies are also reviewed and illustrated with specific examples from BC. We assess the current state of knowledge regarding the PDO and provide a critical assessment of its use in hydroclimatology. This information should provide insight on the sensitivity of projects to climatic variability.

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“…This SST pattern is consistent with the PDO-related inter-decadal mode of variability highlighted by Zhang et al (1997). While examining spring and summer wet and dry periods over the Prairies, Knox and Lawford (1990) found that the Northern Hemisphere circulation modes related to the PNA and NAO played a prominent role. They suggested that high-latitude blocking over the North Atlantic (associated with the NAO) and North Pacific often related to wet springs, whereas blocking over western Canada associated with an amplification of the western Canadian ridge (positive PNA) led to dry summer months.…”

Section: Large-scale Circulation and Low-flow Related Climatementioning

confidence: 99%

“…It has been determined that the main teleconnections affecting Canadian climate include El Niño/Southern Oscillation (ENSO) (e.g., Shabbar and Khandekar, 1996;Shabbar et al, 1997), the Pacific Decadal Oscillation (PDO) (e.g., Bonsal et al, 2001), the Pacific North American (PNA) pattern (e.g., Knox and Lawford, 1990), and the North Atlantic Oscillation (NAO) (e.g., Bonsal et al, 2001) and closely related Arctic Oscillation (AO) (Cohen and Barlow, 2005) or Northern Annular Node (NAM) (Thompson and Wallace, 1998). The strongest links occur during the cold season and are generally less robust during summer.…”

Section: Introductionmentioning

confidence: 99%

Impacts of Large-Scale Circulation Variability on Low Streamflows over Canada: A Review

Bonsal¹,

Shabbar²

2008

Canadian Water Resources Journal

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Low streamflows constitute an important component of hydro-climatic extremes. This is particularly true for Canada where reduced flows can affect several economic and environmental activities ranging from less hydro-electric production and increased freshwater transportation costs, to reduced water quality and ecological habitat destruction. This paper reviews past research regarding the impacts of large-scale circulation patterns on streamflow variability (including low flows) over Canada.

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The relationship between Canadian Prairie dry and wet months and circulation anomalies in the mid‐troposphere

Abstract: We identify Dry and Wet months for the Canadian Prairies during the 40-year period 1946-1985

Cited by 39 publications

References 16 publications

Compounded Perturbations Yield Ecological Surprises

Compounded Perturbations Yield Ecological Surprises

Pacific Decadal Oscillation and the Hydroclimatology of Western Canada—Review and Prospects

Impacts of Large-Scale Circulation Variability on Low Streamflows over Canada: A Review

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