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The future of Antarctica's surface winds simulated by a high‐resolution global climate model: 2. Drivers of 21st century changes
Author(s) -
Bintanja R.,
Severijns C.,
Haarsma R.,
Hazeleger W.
Publication year - 2014
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2013jd020848
Subject(s) - climatology , climate model , climate simulation , meteorology , climate change , high resolution , environmental science , geography , physical geography , atmospheric sciences , geology , oceanography , remote sensing
Antarctica's katabatic winds are among the strongest near‐surface winds on Earth, and among the most consistent ones. As these winds are primarily due to the strong surface cooling, greenhouse warming of the surface may act to reduce the strength of these winds as well as their consistency. Here we use the atmospheric component of the global climate model EC‐Earth in prescribed sea surface temperature (SST) simulations of the present day (2002–2006) and future (2094–2098) climates, using two model resolutions: (1) T159L62 (~100 km, 62 vertical levels), and (2) T799L91 (~20 km, 91 vertical levels) to investigate changes in Antarctica's surface winds and the reasons thereof. Circumpolar westerlies over the Southern Ocean strengthen and shift poleward because of the deepening of the circumpolar trough and the associated increase in Southern Annular Mode (SAM), especially in high resolution, causing weaker coastal easterlies. Generally, surface wind speeds over the Antarctica mainland exhibit a small decrease. According to the simulations, the temperature deficit (or inversion strength) and associated katabatic forcing exhibit only minor changes over the continent. Changes in the surface winds over Antarctica's slopes can thus be attributed mainly to changes in the synoptic forcing (large‐scale pressure gradient). Hence, with modeled 21st century changes in the katabatic forcing being small, changes in zonal and meridional surface winds in and around Antarctica are largely decoupled from those over the Southern Ocean and are governed by changes in synoptic forcing and large‐scale pressure gradients. As a result, these changes are largely independent on model resolution.