Mehr Blizzards in Nordamerika während solarer Schwächephasen

Im Januar 2017 erschien im Journal of Applied Meteorology and Climatology eine Arbeit von Jill Coleman und Robert Schwartz, in der sie die sogenannten Blizzards in den USA untersuchten. Blizzards sind starke Schneestürme im Zusammenhang mit einem kräftigen Kälteeinbruch.

An Updated Blizzard Climatology of the Contiguous United States (1959–2014): An Examination of Spatiotemporal Trends
Blizzards are extreme winter storms that are defined by strong winds and falling or blowing snow that significantly reduces visibility for an extended period of time. For the conterminous United States, blizzard occurrence by county was compiled from Storm Data for 55 winter seasons from 1959/60 to 2013/14. Spatiotemporal patterns were examined for blizzard seasons (September–August) at annual, decadal, and monthly frequencies. Linear regression and spectral analysis were used to detect any blizzard cycles or trends. Societal impacts such as fatalities, injuries, property damage, and federal disaster declarations were also tallied. Data revealed 713 blizzards over the 55 years, with a mean of 13 events per season. Seasonal blizzard frequency ranged from one blizzard in 1980/81 to 32 blizzards in 2007/08. The average area per blizzard was 83 474 km2, or approximately the size of South Carolina. Blizzard probabilities ranged from 1.8% to 76.4%, with a distinct blizzard zone in North Dakota, western Minnesota, and northern South Dakota. Every month except July, August, and September has reported blizzards with a peak occurrence in December and January. Federal disaster declarations resulting from blizzards totaled 57, with more than one-half of them occurring in the twenty-first century. Storm Data attributed 711 fatalities during the 55-yr study period, with an average of one individual per event; 2044 injuries were reported, with a mean of nearly three per blizzard. Property damage totaled approximately $9.11 billion in unadjusted dollars, with an approximate mean of $12.6 million per storm.

Aus dem Abstract wird man leider nicht so richtig schlau. Und das Paper selber ist hinter einer Bezahlschranke verborgen. Die Daily Mail hatte aber offenbar Zugang zur Arbeit und berichtete interessante Details, die in der Kurzfassung leider keinen Platz fanden:

The number of blizzards has DOUBLED in the past 20 years: Scientists blame global warming and sunspots for rise in storms

–From 1960-94, the US had an average of nine blizzards per year
–But since 1995, the annual average has risen to 19, recent study found
–More blizzards are forming outside normal season of October to March
–One explanation is the use of better methods to record severe storms 

[…] Coleman claims sunspot cycles may also be to blame, with blizzards increasing in periods when sunspot activity has diminished. […] ‚Sunspot-minimum periods tend to coincide with more frequent polar outbreaks in the Northern Hemisphere that could increase the likelihood for blizzard occurrence,‘ Coleman told ABC News. ‚However, sunspot activity is only a small component in explaining the frequency of blizzard occurrence.‘