Boundary layer characteristics of the Wilkes ice cap

• Main Author: Bromwich, David, MSc
• Format: Master Thesis
• Language: English
• Published: University of Melbourne 1976
• Subjects: Boundary layer (Meteorology) Ice caps > Antarctica > Wilkes Land; Wilkes Land (Antarctica) > Climate; Antarctic; East Antarctica; Maudheim; Midwinter; Sastrugi; The Antarctic; Wilkes Land; Antarc*; Antarctica; Ice cap; Ice Shelf
• Online Access: http://hdl.handle.net/11343/340985

Typescript (photocopy) Thesis (MSc) -- University of Melbourne, Faculty of Science, 1976 Includes bibliographical references (leaves 112-115) This pilot study presents and analyses 27 coarse profiles of wind and temperature measured in the boundary layer (between the surface and roughly 150 m.) over the Wilkes ice cap, East Antarctica between August and October 1970. The revealed temperature structure enables improved barometric altimetry on the ice cap; while the profiles have implications in the study of intermediate scale katabatic flows. The kytoon- and kite-borne sensor system operated successfully in surface winds between 2 and 8 m/sec. Temperature was measured directly; wind speed and height were derived from the tether characteristics. Wind direction was monitored by the azimuth of the sensor package. This system is inappropriate to investigate the wide range of katabatic conditions - one possibility is a dropsonde released from a small rocket. Sastrugi directions reveal a surface layer wind field over the ice cap that is independent of the Antarctic Continent. The surface wind is persistent in speed and direction and has a magnitude which is more than twice the synoptic value. Monthly averages show a diurnal temperature variation between September and March, but no accompanying wind speed oscillation. However, a run of observations during a cloudless period showed definite daily cycles - the maximum wind speed coincided with minimum temperature and the smallest cross-slope wind direction. The mean surface inversion strength (6 hours from local noon) varied from 11*C in midwinter to 1*C in midsummer. As the synoptic scale wind speed increases, the inversion strength decreases. It is also strongly influenced by the low and middle level cloud amount. Measured wind and temperature profiles display the same properties as those found for the surface layer over the Maudheim ice shelf (Liljequist, 1957). Some wind profiles exhibit the logarithmic behaviour reported by Budd (1966). Synoptic forcing does ...