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SUMMARY:Tropospheric and stratospheric cloud and dynamics research at the 
 Australian Antarctic Division - Simon Alexander\, Australia Antarctic Divi
 sion\, Hobart\, Australia
DTSTART:20140130T140000Z
DTEND:20140130T150000Z
UID:TALK50526@talks.cam.ac.uk
CONTACT:Victoria Hamilton-Morris
DESCRIPTION:The Davis\, Antarctica (69S\, 78E) atmospheric observatory con
 tains numerous remote sensing instruments\, including a Rayleigh lidar and
  a VHF wind-profiling radar. Ozonesondes and twice-daily radiosondes are a
 lso launched from Davis. In this seminar I will focus on some of the scien
 ce conducted using data which we have collected in the troposphere and str
 atosphere. \n\nLittle is known about Antarctic clouds compared to other re
 gions\, yet they are crucial for a correct understanding of the ice sheet 
 mass balance and surface radiative balance. The incorrect representation o
 f Southern Ocean clouds creates uncertainties in future projections of the
  Antarctic via atmospheric transport processes. Measuring various cloud pr
 operties over seasonal time-scales will provide parameters for climate and
  forecast model evaluation. The poor quality of gravity wave drag paramete
 rizations limits models’ ability to accurately represent stratospheric o
 zone change and its consequences for the weather and climate. Observations
  we are making at Davis seek to improve this aspect of models too\, by\, a
 s a first step\, quantifying and understanding wave sources in the souther
 n high latitudes. \n\nFor the last few years\, a Rayleigh lidar has made c
 ampaign-based observations of upper tropospheric cirrus clouds and polar s
 tratospheric clouds. During spring 2012\, a new polarization system was de
 ployed to Davis\, allowing for the determination of cloud phase. High-reso
 lution observations of polar stratospheric clouds demonstrate the presence
  of high frequency gravity waves throughout the cloud decks: I will discus
 s PSC and tropospheric cloud results from the Davis lidar and the CALIPSO 
 satellite lidar (from the entire Antarctic). I will provide an overview of
  a planned field experiment to quantify key tropospheric cloud and surface
  radiation properties in the Southern Ocean and East Antarctic via the dep
 loyment of several remote-sensing instruments to both Davis and Macquarie 
 Island (54S\, 159E) for a year-long campaign at each location. \n \nThe VH
 F radar at Davis provides wind profiles in the troposphere and is currentl
 y being upgraded to increase the altitude coverage into the lower stratosp
 here. Using these observations and reanalyses data\, I will show both the 
 seasonal cycle of gravity wave activity and a case study of orographic and
  non-orographic gravity waves observed in the troposphere above Davis. Thi
 s case study will demonstrate the interaction of katabatic winds and wind 
 from transient synoptic-scale depressions passing to the north of Davis wi
 th the topography to generate the gravity waves seen above Davis with the 
 radar.\n
LOCATION:British Antarctic Survey\, Room 307
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