Archives par mot-clé : Winds

Mountain glacier melting is linked to shifting westerlies and likely to accelerate

by University of Maine, Dec 13, 2022 in ScienceDaily 

The combination of global atmospheric warming and westerly winds shifting toward the poles will likely speed up the recession of mountain glaciers in both hemispheres, according to a UMaine study.

Mountain glaciers freeze and gain mass when the climate cools, and melt and lose mass when the climate warms. The extent to which the fluctuations in mountain glaciers are reflective of local, regional and even hemispheric climate variations, however, is less clear, which has made it more difficult for scientists to use glacial data to interpret past climate dynamics and make predictions for the future.

A team of researchers from the University of Maine conducted a National Science Foundation-funded study evaluating how atmospheric conditions are reflected in the mass fluctuations of mid-latitude glaciers on opposite sides of the Earth, comparing global temperature and wind changes with glacier snowline elevations (also called “equilibrium-line altitudes”) in the Southern Alps of New Zealand and in the European Alps observed over the course of nearly four decades. Glacier extent is dependent on the height of the snowline in the atmosphere, below which ice melts, which in turn is determined by the temperature of the atmosphere.

The data showed that the fluctuations in glacial snowlines reflected temperature changes over large regions of the atmosphere for the two mountain systems studied — even on hemispheric scales. Moreover, the latitudes of westerly wind belts were found to be important for regulating the proportion of cold versus warm air masses that influence glacier melting and freezing.


by Cap Allon, November 16, 2019 in Electroverse

The GFS and it’s ensembles are forecasting a dramatic reduction in westerly Zonal winds over the North Pole during the latter half of November and throughout December.

Conversely, October and the first half of November brought very strong Zonal winds at 60N, which went hand-in-hand with below-average temperatures at the Pole — Zonal winds in the stratosphere strengthen as the temperature over the North Pole drops:


Following the onset of an SSW event, temperatures at the pole will often climb sharply, and the high altitude winds will have reversed to flow in an eastward direction instead of their usual westward one.

These eastward winds progress down through the atmosphere and weaken the jet stream, often resulting in easterly winds near the surface which usually bring with them a dramatic drop in temperatures across Europe and North America.

Check out what happened to temps over the South Pole in September as an SSW took hold there: