BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Tropical fingerprints on the polar mesosphere - Dr R E Hibbins\, B
 ritish Antarctic Survey
DTSTART:20071121T140000Z
DTEND:20071121T150000Z
UID:TALK9235@talks.cam.ac.uk
CONTACT:Tracy Moffat-Griffin
DESCRIPTION:An analysis of 11 years of horizontal wind data derived from m
 eteor wind observations from a SuperDARN radar at Halley\, Antarctica show
 s clear evidence of a quasi-biennial modulation of the high latitude south
 ern hemisphere semidiurnal tide in the upper mesosphere. The tide is enhan
 ced when the equatorial stratospheric QBO above 10 hPa is in the westerly 
 phase. This enhancement is greatest in the summer time when the S=1 non-mi
 grating component is known to dominate the semidiurnal wind field at high 
 latitudes\, and is coincident with an enhancement of the summertime planet
 ary wave activity in the upper mesosphere. These results strongly support 
 the hypothesis that the S=1 component of the semidiurnal tide observed at 
 high latitudes is due to a non-linear interaction between the migrating S=
 2 semidiurnal tide and quasi-stationary S=1 planetary waves\, the propogat
 ion of which is dependent on the critical level filtering driven by the eq
 uatorial QBO.\n
LOCATION:British Antarctic Survey\, Room 330B
END:VEVENT
END:VCALENDAR