by Chuck Wiese, Meteorologist, Weatherwise, Inc.
This paper is a critique Francis and Vavrus (2012), hereinafter FV (2012), by atmospheric scientists Jennifer Francis from Rutgers University and Steve Vavrus of the University of Wisconsin. Their paper can be downloaded here:
and an updated version here:
FV (2012) claims a measured decrease in the zonal or west to east wind component due to “arctic amplification” (AA) would increase jet stream meandering, increase the amplitude or “waviness” of the flow, and increase persistent long wave blocking patterns around the northern hemisphere. This, in turn, would increase severe weather, droughts, floods and temperature extremes.
To quote the authors directly:
“Two effects are identified that each contribute to a slower eastward progression of Rossby waves in the upper-level flow: 1) weakened zonal winds, and 2) increased wave amplitude. These effects are particularly evident in autumn and winter consistent with sea-ice loss, but are also apparent in summer, possibly related to earlier snow melt on high-latitude land. Slower progression of upper-level waves would cause associated weather patterns in mid-latitudes to be more persistent, which may lead to an increased probability of extreme weather events that result from prolonged conditions, such as drought, flooding, cold spells, and heat waves.”
To quote the authors again, the effects described above are the result of arctic amplification, a term defined by the authors as:
“Arctic amplification (AA) – the observed enhanced warming in high northern latitudes relative to the northern hemisphere”
This definition seems to fit the claims made by NASA GISS and NOAA that temperature measurements of the arctic are warming at a much greater rate than anywhere else in the northern hemisphere. [Read more…]