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Atmospheric boundary layer research at Halley, Antarctica Phil S. Anderson Russ Ladkin John C. King British Antarctic Survey Natural Environment Research Council Cambridge, UK j.c.king@bas.ac.uk. Why study the ABL in Antarctica ?. Boundary-layer processes exert strong control over
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Atmospheric boundary layer research at Halley, Antarctica Phil S. Anderson Russ Ladkin John C. King British Antarctic Survey Natural Environment Research Council Cambridge, UK j.c.king@bas.ac.uk
Why study the ABL in Antarctica ? • Boundary-layer processes exert strong controlover • SH high latitude circulation, driving the katabatic • circulation. • Boundary-layer parametrisations currently used in • GCMs may not be appropriate for Antarctic conditions • Antarctica offers some near-ideal sites for SBL studies: • - little or no diurnal variation • - strong stability • - uniform, flat and unobstructed sites • Turbulent transport is a key part of air-snow exchange
Halley Research Station • 75oS, 26oW, 30 m.a.s.l. • Brunt Ice Shelf - flat, uniform, unobstructed • Prevailing easterlies have > 50 km fetch • 3 months of winter darkness • Synoptic and upper-air station (WMO 89022)
History of boundary-layer studies at Halley (1) 1986: Stable Antarctic Boundary Layer Expt. (STABLE) 10-min eddy-correlation fluxes from sonic anemometers at 5, 15, 30m Profiles of mean wind and temperature to 30m Sodar 1991: STABLE-II As STABLE, plus: Microbarograph array Blowing snow measurements
History of boundary-layer studies at Halley (2) 1995 - 2000 FLUX/Polar Snow 10-min eddy correlation fluxes at 4m Limited profile to 10 m Snow surface and snowpack temperatures Solar and terrestrial radiation Sodar Tethersonde profiling 1995 - ? Katabatic wind studies AWS network up continental slope inland from Halley Autonomous doppler sodar deployed 2002
100 km 100 m contours
Planned measurements at Halley, 2002-2005 • Turbulence • Metek sonic anemometers at 4, 15, 30m • Sampling at 40Hz, recorded continuously at 10Hz • 2 additional Meteks at 10m on remote masts • Applied Technologies M100 infrared hygrometer for • fast-response water vapour measurement
Planned measurements at Halley, 2002-2005 • Mean profiles • Vaisala HMP35 (Temperature/humidity) in aspirated • radiation shields at 1, 2, 4, 8, 15 and 30m • RM Young propellor/vane Wind Monitor at 1, 2, 4, 8, • 15 and 30m • Cooled-mirror frost point hygrometer (Michell • Dewmet) for accurate humidity measurement • Record 10-minute means
Planned measurements at Halley, 2002-2005 • Radiation and snow temperature • Global, diffuse and reflected shortwave (Kipp & • Zonen solarimeters, aspirated and heated) • Downwelling and upwelling longwave (Kipp & Zonen • pyrgeometers, aspirated and heated) • Didcot Instruments net radiometer • 2 x Heitronics infrared thermometers for snow • surface temperature • Snow temperature profile to 10m depth • Record 10 minute means
Planned measurements at Halley, 2002-2005 • Other measurements • Microbarograph array • Sodar array • Kite / helikite tethersonde for measuring temperature, • humidity and wind profiles to ~ 500m. Usually used • during limited, intensive campaigns • Routine daily (1200 UTC) launch of Vaisala • radiosonde with GPS windfinding. Sounding to • ~100 hPa. Fine structure data retained. • (contact BAS Meteorological and Ozone Monitoring • Unit for data)
Further information • Bibliography – please take one • Science queries to John King or Phil Anderson • Technical queries on instruments to Russ Ladkin