The association between the BWA index and winter surface temperature variability over eastern Canada and west Greenland

Shabbar, Amir; Higuchi, Kaz; Skinner, W.; Knox, John L.

doi:10.1002/(sici)1097-0088(199709)17:11<1195::aid-joc190>3.3.co;2-l

Cited by 13 publications

(29 citation statements)

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“…This should incorporate not only refinement of the weighting technique used here, but also a formal statistical analysis of the type undertaken by Widmann and Schar (1997) to separate the frequency and intensity aspects of Swiss rainfall trends, along with use of the regional teleconnection approach (e.g. Shabbar et al, 1997) to separate local and regional effects. This will allow more explicit identification of the causes of variation, and thus linking with other aspects of global climate change.…”

Section: Discussionmentioning

confidence: 99%

Temporal trends in United States dew point temperatures

Robinson

2000

Int. J. Climatol.

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In this study, hourly data for the 1951–1990 period for 178 stations in the coterminous United States were used to establish temporal trends in dew point temperature. Although the data had been quality controlled previously (Robinson, 1998. Monthly variations of dew point temperatures in the coterminous United States. International Journal of Climatology 18: 1539–1556), comparisons of values between nearby stations suggested that instrumental changes, combined with locational changes, may have modified the results by as much as 1°C during the 40‐year period. Nevertheless, seasonally averaged results indicated an increase over much of the area, of slightly over 1°C/100 years in spring and autumn, slightly less than this in summer. Winter displayed a drying of over 1°C/100 years. When only the 1961–1990 period was considered, the patterns were similar and trends increased by approximately 1–2°C/100 years, except in autumn, which displayed a slight drying. Analyses for specific stations indicated periods of both increasing and decreasing Td, the change between them varying with observation hour. No single change point was common over a wide area, although January commonly indicated maximum values early in the period in the east and west, and much later in the north‐central portion. Rates of increase were generally higher in daytime than at night, especially in summer. Investigation of the inter‐decadal differences in dew point, as a function of wind conditions, indicated that changes during calm conditions were commonly similar in magnitude to that of the overall average changes, suggesting an important role for the local hydrologic cycle in driving changes. Other inter‐decadal changes could be attributed to the changes in the frequency and moisture content of invading air‐streams. This was particularly clear for the changes in north–south flow in the interior. Copyright © 2000 Royal Meteorological Society

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Section: Discussionmentioning

confidence: 99%

Temporal trends in United States dew point temperatures

Robinson

2000

Int. J. Climatol.

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“…This is consistent with previous studies in eastern Canada. Shabbar et al [1997b] identified a detectable cooling in winter surface temperature data from 12 stations in coastal eastern Canada and western Greenland since 1970 that was linked to an enhancement of the negative phase of the NAO index and of the positive phase of the PNA. Perreault et al [2000] used a Bayesian method to identify a change point in annual reservoir inflows for the Outaouais basin in eastern Canada.…”

Section: Streamflow and Climatic Patternsmentioning

confidence: 99%

Wavelet analysis of variability in annual Canadian streamflows

Coulibaly

Burn

2004

Water Resources Research

208

149

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Wavelet analysis is used to identify and describe variability in annual Canadian streamflows and to gain insights into the dynamical link between the streamflows and the dominant modes of climate variability in the Northern Hemisphere. Results from applying continuous wavelet transform to mean annual streamflows from 79 rivers selected from the Canadian Reference Hydrometric Basin Network (RHBN) reveal striking climate‐related features before the 1950s and after the 1970s. The span of available observations, 1911–1999, allows for depicting variance for periods up to 12 years. Scale‐averaged wavelet power spectra are used to simultaneously assess the interannual and spatial variability in 79 annual streamflow time series. The most striking feature, in the 2–3 year band and in the 3–6 year band (the 6–12 year band is dominated by white noise (since 1950) and is not considered further) is a net distinction between the timing and intensity of the interannual variability in western, central, and eastern streamflows, which is shown to be linked to the regional climatology. It is found that for the 2–3 year band, the Canadian streamflows are depicted mainly by the Pacific North America (PNA) during 1950–1999, and the Northern Hemisphere Annular Mode (NAM) only prior to 1950, and the North Atlantic Oscillation (NAO) after 1970. Similarly, in the 3–6 year band, the streamflows are depicted mostly by the NAO, the sea surface temperature anomalies over the Niño‐3 region (ENSO3) and the PNA during the period 1950–1999, and the NAM prior to 1950. Furthermore, strong local correlations between teleconnection patterns and western, central, and eastern streamflows are also revealed in both the 2–3 and 3–6 year bands with striking changes around 1950 and 1970. The correlation analysis in the 2–3 year and 3–6 year bands revealed the presence of two change points in the west and east streamflows occurring around 1950 and 1970.

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“…However, there has also been considerable spatial and temporal variability (e.g. significant decreases in winter temperature over northeastern Canada since 1970) (Shabbar et al, 1997b). Recent enhanced greenhouse gas general circulation model (GCM) projections indicate further warming over high latitude regions such as northern Canada, as well as, increased temperature variability (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Hurrell (1996) found that the NAO, ENSO, and the NPO collectively explained a significant portion of Northern Hemisphere winter temperature variability with the NAO accounting for the majority of interannual variance. Specifically for Canada, Shabbar et al (1997b) determined that from 1946 to 1995, winter temperature over the northeast was significantly related to the Baffin Island -West Atlantic (BWA) index (which reflects variability in the western structure of the NAO). In particular, a positive (negative) NAO-type pattern was associated with negative (positive) temperature anomalies over this region.…”

Section: Introductionmentioning

confidence: 99%

Impacts of low frequency variability modes on Canadian winter temperature

Bonsal

Shabbar

Higuchi

2001

Intl Journal of Climatology

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125

126

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The impacts of El Niñ o-Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), and the North Atlantic Oscillation (NAO) on winter (January-February-March) temperature variability over Canada are analysed for the period 1900-1995. Through linear regression, regional characteristics in the interannual temperature variability explained by these oscillations are firstly identified. Modulation of El Niñ o and La Niñ a winter temperature responses by various combinations of the PDO and NAO is then investigated via composite analysis. Results show the NAO as the dominant low frequency variability mode affecting winter temperature, however, the effects are mainly confined to north-eastern regions of the country. The ENSO and PDO influences are somewhat weaker and occur over western and central Canada. It is determined that the associated winter PDO pattern has a significant modulating effect on ENSO related temperature responses. Impacts are stronger and more spatially coherent during El Niñ o episodes when positive PDO winters are associated with strong positive temperature anomalies over most of Canada, neutral PDO with weaker anomalies (positive in the west and negative in the east), and negative PDO with strong negative anomalies over western Canada. Analysis also suggests that La Niñ a and negative PDO combinations are associated with negative temperature anomalies, especially in the far west. Over eastern regions of Canada, El Niñ o (La Niñ a) events modulate the typical positive (negative) NAO temperature responses by generally making them warmer (colder). All observed relationships are explained by variations in associated mid-tropospheric circulation over the north Pacific (i.e. Aleutian low region), and western and central North America. Results from this investigation aid in the understanding of relationships between low frequency oscillations and winter temperature variability over Canada. They also suggest the possibility of improved winter temperature forecasts based on conditions in the tropical and north Pacific, and the north Atlantic.

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The association between the BWA index and winter surface temperature variability over eastern Canada and west Greenland

Cited by 13 publications

References 0 publications

Temporal trends in United States dew point temperatures

Temporal trends in United States dew point temperatures

Wavelet analysis of variability in annual Canadian streamflows

Impacts of low frequency variability modes on Canadian winter temperature

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