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SUMMARY:Inclusion of mountain wave-induced cooling for the formation of po
 lar stratospheric clouds over the Antarctic Peninsula in a chemistry clima
 te model - Dr Andrew Orr (British Antarctic Survey)
DTSTART:20140618T131500Z
DTEND:20140618T141500Z
UID:TALK52884@talks.cam.ac.uk
CONTACT:Dr Scott Hosking
DESCRIPTION:An important source of polar stratospheric clouds (PSCs)\, whi
 ch play a crucial role in controlling polar startospheric ozone depletion\
 , is from the temperature fluctuations induced by mountain waves.  However
 \, this formation mechanism is usually missing in chemistry-climate models
  because these temperature fluctuations are neither resolved nor parameter
 ised.  Here\, we investigate the representation of stratospheric mountain 
 wave-induced temperature fluctuations by the UK Met Office Unified Model (
 UM) at high and low spatial resolution against Atmospheric Infrared Sounde
 r satellite observations over the Antarctic Peninsula.  At a high horizont
 al resolution (4 km) the mesoscale configuration of the UM correctly simul
 ates the magnitude\, timing\, and location of the measured temperature flu
 ctuations.  By comparison\, at a low horizontal resolution (2.5° × 3.75
 °) the climate configuration fails to resolve such disturbances.  However
 \, it is demonstrated that the temperature fluctuations computed by a moun
 tain wave parameterisation scheme inserted into the climate configuration 
 (which computes the temperature fluctuations due to unresolved mountain wa
 ves) are in excellent agreement with the mesoscale configuration responses
 .  The parameterisation was subsequently used to compute the local mountai
 n wave-induced cooling phases in the chemistry-climate configuration of th
 e UM.  This increased stratospheric cooling was passed to the PSC scheme o
 f the chemistry-climate model\, and caused a 30-50% increase in PSC surfac
 e area density over the Antarctic Peninsula compared to a 30-year control 
 simulation.
LOCATION:British Antarctic Survey\, Room 307
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