Analysis: NOAA Erase ‘Anomalously Cold Winters’
NOAA Erase “Anomalously Cold Winters”
We looked at this NYT article earlier today. It focussed on this paper by Marlene Kretschmer:
Over the last decades, the stratospheric polar vortex has shifted towards more frequent weak states which can explain Eurasian cooling trends in boreal winter in the era of Arctic amplification.
The extra-tropical stratosphere in boreal winter is characterized by a strong circumpolar westerly jet, confining the coldest temperatures at high latitudes. The jet, referred to as the stratospheric polar vortex, is predominantly zonal and centered around the pole; however, it does exhibit large variability in wind speed and location. Previous studies showed that a weak stratospheric polar vortex can lead to cold-air outbreaks in the mid-latitudes but the exact relationships and mechanisms are unclear. Particularly, it is unclear whether stratospheric variability has contributed to the observed anomalous cooling trends in mid-latitude Eurasia. Using hierarchical clustering, we show that over the last 37 years, the frequency of weak vortex states in mid to late winter (January and February) has increased which were accompanied by subsequent cold extremes in mid-latitude Eurasia. For this region 60% of the observed cooling in the era of Arctic amplification, i.e. since 1990, can be explained by the increased frequency of weak stratospheric polar vortex states, a number which increases to almost 80% when El Niño/Southern Oscillation (ENSO) variability is included as well.
The paper makes this specific comment:
But what do NOAA say about recent winters in the Northeastern United States?
The winters of 2013/14 a,d 2014/15 were a bit colder than average, but there have been many more winters in the last century, which were much colder.
The claim about “anomalously” cold winters simply does not hold water.
All of which brings us back to the massive temperature adjustments made by NOAA. Has Kretschmer been making up data to suit her case?
Or are NOAA’s adjustments wrong, and recent winters really have been anomalously cold?
Of course, looking at the winter season average as a whole might cover up unusual warmth and cold.
When she introduced her work on the subject in 2014, Jennifer Francis specifically referred to the severe cold snap that affected the Northeast in January and February 2014, using it as an example.
The cold weather began on Jan 2nd, and lasted into April.
Yet again NOAA show absolutely nothing unusual going on in either of those months..