“We find that the most prominent annual mean surface and tropospheric warming in the Arctic since 1979 has occurred in northeastern Canada and Greenland,” the authors wrote. “In this region, much of the year-to-year temperature variability is associated with the leading mode of large-scale circulation variability in the North Atlantic, namely, the North Atlantic Oscillation.”
But the researchers show that the increased warming is from a “negative trend in the North Atlantic Oscillation” is in response to “anomalous Rossby wave-train activity originating in the tropical Pacific.”
Wallace told CTV News that the increased warming in parts of the Arctic is due to unusually heavy rainfall in the South Pacific, which cause atmospheric turbulence around the globe.
“It induces what we call a planetary scale wave train,” Wallace said. “We can see exactly those kind of waves — like ship wakes — if we have the air flowing over an island and if we look down we can see in the cloud patterns exactly those kinds of wakes.”
The “wakes” Wallace talks about create waves throughout the atmosphere that warm the air by compressing it slightly. This in turn causes sea ice to melt in the Arctic.
“Think of Canada as downstream in that wake,” said Wallace. “If it happens to be in a ridge of that wave train, that translates into it being warmer than normal. That warmth comes from the prevalence of sinking motion in the atmosphere — it warms it by compressing it.”
An alternate take on Arctic climate variation.