Evidence linking Arctic amplification to extreme weather in mid‐latitudes

Abstract

Arctic amplification (AA) – the observed enhanced warming in high northern latitudes relative to the northern hemisphere – is evident in lower‐tropospheric temperatures and in 1000‐to‐500 hPa thicknesses. Daily fields of 500 hPa heights from the National Centers for Environmental Prediction Reanalysis are analyzed over N. America and the N. Atlantic to assess changes in north‐south (Rossby) wave characteristics associated with AA and the relaxation of poleward thickness gradients. 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.

Links between central Greenland stable isotopes, blocking and extreme climate variability over Europe at decadal to multidecadal time scales

“…Cohen et al 2014). Such a polar jet structure is consistent with more persistent weather patterns (Francis and Vavrus 2012). Furthermore, Arctic warming causes the thickness of atmospheric layers to increase more to the north, such that the peaks of atmospheric ridges may elongate northward, and thus, increase the north-south amplitude of the flow (Francis and Vavrus 2012) and therefore more extreme mid-latitude climate.…”

Effects of Arctic geoengineering on precipitation in the tropical monsoon regions

“…In the troposphere, however, there is an increase in the equator to pole temperature gradient (because of the residual warming in the tropics) during summertime corresponding to an accelerated jet stream ( Fig. 10c-f), which could possibly reduce the number of weather extremes in the mid-latitudes (Francis and Vavrus 2012). The anomaly in zonal winds relative to the CTL case is the least in the GLOBAL case (Fig.…”

Reanalysis comparisons of upper tropospheric–lower stratospheric jets and multiple tropopauses

“…Variations in the UTLS jets influence influence surface weather patterns (e.g., see reviews by Lucas et al, 2014;Harnik et al, 2016) such as rainfall changes (e.g., Price et al, 1998;Raible et al, 2004;Karnauskas and Ummenhofer, 2014;Huang et al, 2015;Xie et al, 2015;Delworth and Zeng, 2014;Bai et al, 2016), destructive wind storms (e.g., Pinto et al, 2009Pinto et al, , 2014Gómara et al, 2014;Messori and Caballero, 2015), and extreme temperature events (e.g., Francis and Vavrus, 2012;Harnik et al, 2016). Moreover, transport processes that alter the extent and consequences of extratropical stratosphere-troposphere exchange (STE) are closely linked to the tropopause and jets, which are themselves sensitive to climate change and ozone depletion (e.g., Seidel and Randel, 2006;Lorenz and DeWeaver, 2007;Polvani et al, 2011;WMO, 2011;Hudson, 2012;Grise et al, 2013;Waugh et al, 2015).…”