Mar 13, 2013

Exploring links between Arctic amplification and mid-latitude weather

Screen, James A., Simmonds, Ian
Geophysical Research Letters
  • Examines observed changes (1979–2011) in atmospheric planetary-wave amplitude over northern mid-latitudes, which have been proposed as a possible mechanism linking Arctic amplification and mid-latitude weather extremes
  • Uses two distinct but equally-valid definitions of planetary-wave amplitude, termed meridional amplitude, a measure of north-south meandering, and zonal amplitude, a measure of the intensity of atmospheric ridges and troughs at 45°N
  • Holds that statistically significant changes in either metric are limited to few seasons, wavelengths, and longitudinal sectors
  • Identifies in the summer, however, significant increases in meridional amplitude over Europe, but significant decreases in zonal amplitude hemispherically, and also individually over Europe and Asia
  • Argues that possible connections between Arctic amplification and planetary waves, and implications of these, are sensitive to how waves are conceptualized
  • States that the contrasting meridional and zonal amplitude trends have different and complex possible implications for midlatitude weather, and we encourage further work to better understand these