Azores High

Azores High

Subject: Geography

Extremely dry winter in Western Mediterranean due to expansion of ‘Azores High’

• Azores High is a subtropical high pressure system that extends over the eastern subtropical North Atlantic and western Europe during winter.
• It is associated with anticyclonic winds in the subtropical North Atlantic.
• It is formed by dry air aloft descending the subtropics and coincides with the downward branch of the Hadley Circulation.

Reasons for the expansion of Azores High

• The Azores High expansion is driven by external climate forces and that the only external forcing that produces this signal in the industrial era is atmospheric greenhouse gas concentrations.
• Azores High expansion emerged after 1850 and strengthened in the twentieth century, consistent with anthropogenically driven warming.
• The Azores High has changed dramatically in the past century and that these changes in North Atlantic climate are unprecedented within the past millennium.
• An expanding Azores High agrees with reports of a poleward shift in the North Atlantic storm track and an increase in anticyclone frequency at the Azores High’s poleward edge as well as a positive trend in regional subtropical indicators.