Recent changes in the frequency of freezing precipitation in North America and Northern Eurasia

Pavel Ya Groisman,Olga N Bulygina,Olga N Bulygina,Xungang Yin,Eirik Førland,Inger Hanssen-Bauer,Russell S Vose,Sergey K Gulev

doi:10.1088/1748-9326/11/4/045007

Abstract

Freezing rain and freezing drizzle events represent a critical feature of many regions of the world. Even at low intensities, these events often result in natural hazards that cause damage to housing, communication lines, and other man-made infrastructure. These events usually occur near the 0 °C isotherm. In a changing climate, this isotherm will not disappear, but its position in space and time will likely change as will the geography of freezing precipitation. A larger influx of water vapor into the continents from the oceans may also increase the amount and frequency of freezing precipitation events. This paper assesses our current understanding of recent changes in freezing precipitation for the United States, Canada, Norway, and Russia. The research is part of a larger GEWEX Cross-Cut Project addressing ‘cold/shoulder season precipitation near 0 °C’. Using an archive of 874 long-term time series (40 years of data) of synoptic observations for these four countries, we document the climatology of daily freezing rain and freezing drizzle occurrences as well as trends therein. The regions with the highest frequency of freezing rains (from 3 to 8 days per year) reside in the northeastern quadrant of the conterminous United States and adjacent areas of southeastern Canada south of 50 °N and over the south and southwest parts of the Great East European Plain. The frequency of freezing drizzle exceeds the frequency of freezing rain occurrence in all areas. During the past decade, the frequency of freezing rain events somewhat decreased over the southeastern US. In North America north of the Arctic Circle, it increased by about 1 day yr−1. Over Norway, freezing rain occurrences increased substantially, especially in the Norwegian Arctic. In European Russia and western Siberia, the frequency of freezing rain somewhat increased (except the southernmost steppe regions and the Arctic regions) while freezing drizzle frequency decreased over entire Russia.

Highlights

Many regions of the world are subjected to precipitation occurring near 0 °C during the cold and shoulder seasons
An overarching objective is to improve our understanding of future changes in hazardous freezing precipitation events and, when possible, to assess their societal impact
The study employed hourly surface station data from the Integrated Surface Database (ISD; Smith et al 2011). This global archive was supplemented with additional data from the Russian Institute for Hydrometeorological Information (RIHMI-WDC-B) and at the Norwegian Meteorological Institute (MET Norway)

Summary

Introduction

Many regions of the world are subjected to precipitation occurring near 0 °C during the cold and shoulder seasons (hereafter, near 0 °C precipitation) Some of these events occur as freezing rain and freezing drizzle, which are the foci of this study. Freezing rain events may create hazardous traffic conditions and icing on communication lines (Changnon 2003, Changnon and Bigley 2005). They can have major impacts on ecosystems and wildlife (Millward and Kraft 2004, Zhou et al 2011, Stien et al 2012, Stewart et al 2015). Higher latitude areas such as Russia, Fennoscandia, Canada, and the United States are prone, but on occasion, lower latitude regions are affected as well (see Carriere et al 2000, Cortinas et al 2004, Zhou et al 2011)

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Conclusion