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Weather and Climate Dynamics An interactive open-access journal of the European Geosciences Union
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https://doi.org/10.5194/wcd-2020-20
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/wcd-2020-20
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 19 May 2020

Submitted as: research article | 19 May 2020

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This preprint is currently under review for the journal WCD.

Impacts of the North Atlantic Oscillation on Winter Precipitations and Storm Track Variability in Southeast Canada and Northeast US

Julien Chartrand and Francesco Salvatore Rocco Pausata Julien Chartrand and Francesco Salvatore Rocco Pausata
  • Centre ESCER, Department of Earth and Atmospheric Sciences, University of Quebec in Montreal, Montreal, QC, Canada

Abstract. The North Atlantic Oscillation (NAO) affects atmospheric variability from eastern North America to Europe. Although the link between the NAO and winter precipitations in the eastern North America have been the focus of previous work, only few studies have hitherto provided clear physical explanations on these relationships. In this study we revisit and extend the analysis of the effect of the NAO on winter precipitations over a large domain covering southeast Canada and the northeastern United States. Furthermore, here we use the recent ERA5 reanalysis dataset (1979–2018), which currently has the highest available horizontal resolution for a global reanalysis (0.25°), to track extratropical cyclones to delve into the physical processes behind the relationship between NAO and precipitation, snowfall, snowfall-to-precipitation ratio (S/P), and snow cover depth anomalies in the region. In particular, our results show that positive NAO phases are associated with less snowfall over a wide region covering Nova Scotia, New England and the Mid-Atlantic of the United States relative to negative NAO phases. Henceforth, a significant negative correlation is also seen between S/P and the NAO over this region. This is due to a decrease (increase) in cyclogenesis of coastal storms near the United States east coast during positive (negative) NAO phases, as well as a northward (southward) displacement of the mean storm track over North America.

Julien Chartrand and Francesco Salvatore Rocco Pausata

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Julien Chartrand and Francesco Salvatore Rocco Pausata

Julien Chartrand and Francesco Salvatore Rocco Pausata

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Short summary
This study explores the relationship between the North Atlantic Oscillation and the winter climate of eastern North America using reanalysis data. Results show that negative phases are linked with an increase of frequency of winter storms developing on the east coast of the United States, resulting in much heavier snowfall over the eastern United States. On the contrary, an increase of cyclone activity over southeastern Canada results in heavier precipitation and snowfall during positive phases.
This study explores the relationship between the North Atlantic Oscillation and the winter...
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