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Antarctic local wind dynamics and polynya effects on the Adélie Land coast
Author(s) -
Savijärvi Hannu
Publication year - 2011
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.874
Subject(s) - katabatic wind , sea breeze , geology , mesoscale meteorology , climatology , geostrophic wind , atmospheric sciences , westerlies
Mesoscale winds on the sloping coast of Adélie Land in East Antarctica were studied via idealized clear‐sky integrations with a two‐dimensional model. The calm‐case ( V g = 0) wintertime surface winds were steady katabatic southeasterlies. They were enhanced to a strong downslope low‐level jet (LLJ) during a southerly geostrophic flow but damped during a moderate westerly ‘counter‐katabatic’ flow. A strong westerly flow could overwhelm the katabatic component while a northerly V g induced strong coastal easterlies with an easterly LLJ. On‐slope flow without the katabatic forcing generated a barrier effect. An ice‐free wintertime zone (a coastal polynya) increased the coastal 2 m winds by about 50% (and drag on the ice floes, by 125%) through the induced extra land breeze circulation and unstable stratification. The midsummer morning coastal winds were also katabatic in the morning as the slopes cooled rapidly after midnight. In a prevailing flow these behaved much as in wintertime but were strong only at 0400–0700 hours local time. By 0800–0900 hours local time the snowy slopes were melting in sunshine. With V g = 0 this induced weak anabatic winds up the slope. At the coast a midday ‘sea breeze’‐like circulation was present, insensitive however to the sea state (frozen vs . open) or the coast state (snowy vs . black rock) of the model. These anabatic winds were quite weak and hence easily overwhelmed by any larger‐scale flow, surviving only during a weak westerly flow. The typically easterly V g along the East Antarctica coast induced katabatic‐like surface winds throughout the day, as is commonly observed, despite the midday solar heating. Copyright © 2011 Royal Meteorological Society