Extreme snow events along the coast of the northeast United States: Potential changes due to global warming

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  • 1 Atmospheric Sciences Research Center, University at Albany, State University of New York, Albany, New York, U.S.A
  • 2 Department of Atmospheric and Oceanic Sciences & Institute of Atmospheric Sciences, Fudan University, Shanghai, China
  • 3 National Science and Technology Center for Disaster Reduction, Taiwan
  • 4 Research Center for Environmental Changes, Academia Sinica, Taiwan
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Abstract

Winter extreme snowstorm events along the coast of the northeast United States incur significant impacts on social and economic activities, and their potential changes under global warming are of great concern. Here, we adopted the pseudo global warming approach to investigate the responses of 93 events identified in our previous observational analysis. The study was conducted by contrasting two sets of WRF simulations for each event: the first set driven by ERA-Interim reanalysis and the second set by ERA data superimposed with mean-climate changes simulated from HiRAM historical (1980–2004) and future (2075–2099; RCP8.5) runs. Results reveal that the warming together with increased moisture tends to decrease the snowfall along the coast but increase the rainfall throughout the region. For example, the number of events having daily snow-water-equivalent larger than 10 mm day-1 at Boston, New York City, Philadelphia and Washington D.C. is decreased by 47, 46, 30 and 33%, respectively. The compensating changes in snowfall and rainfall lead to total precipitation increased in 3 southern cities but decreased in Boston. In addition, the southwestward shift of regional precipitation distribution is in coherence with the enhancement/reduction of upward vertical motion in the south/north and the movement of cyclone centers (westward in 58% of events and southward in 72%). Finally, perhaps more adversely, because of the northward retreat of the 0°C and the expansion of near-freezing zone, the number of events with mixed rain-snow and freezing precipitations in the north (especially the inland area) is increased.

Corresponding author: Wei-Chyung Wang, wcwang@albany.edu

Abstract

Winter extreme snowstorm events along the coast of the northeast United States incur significant impacts on social and economic activities, and their potential changes under global warming are of great concern. Here, we adopted the pseudo global warming approach to investigate the responses of 93 events identified in our previous observational analysis. The study was conducted by contrasting two sets of WRF simulations for each event: the first set driven by ERA-Interim reanalysis and the second set by ERA data superimposed with mean-climate changes simulated from HiRAM historical (1980–2004) and future (2075–2099; RCP8.5) runs. Results reveal that the warming together with increased moisture tends to decrease the snowfall along the coast but increase the rainfall throughout the region. For example, the number of events having daily snow-water-equivalent larger than 10 mm day-1 at Boston, New York City, Philadelphia and Washington D.C. is decreased by 47, 46, 30 and 33%, respectively. The compensating changes in snowfall and rainfall lead to total precipitation increased in 3 southern cities but decreased in Boston. In addition, the southwestward shift of regional precipitation distribution is in coherence with the enhancement/reduction of upward vertical motion in the south/north and the movement of cyclone centers (westward in 58% of events and southward in 72%). Finally, perhaps more adversely, because of the northward retreat of the 0°C and the expansion of near-freezing zone, the number of events with mixed rain-snow and freezing precipitations in the north (especially the inland area) is increased.

Corresponding author: Wei-Chyung Wang, wcwang@albany.edu
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