Identification of von Karman vortices in the surface winds of Heard Island

Heard Island (73°30′ E, 53°05′ S) is an isolated island in the sub-Antarctic located in a region of strong westerly winds. The dominant topographic feature is a large glaciated volcano, which peaks at 2,745 m in altitude. Only limited meteorological information exists for the island, with incomplete records from a station at Atlas Cove covering the period 1948 to 1954, and from a station at The Spit from 1992 onwards. We present the results of wind observations that were conducted on Dovers Moraine at the eastern end of Heard Island over the 2000/2001 summer, with the aim of characterising local winds at this location on the island. Wind was measured using a Woelfle type mechanical wind recorder. Wind speed was comparable, and on occasions stronger, at this location compared to simultaneous records at the western end of the island. Winds were predominantly from the south-south-west, or north-north-west to north. A number of periods of relatively low wind speed coincided with repeated wind direction patterns, which we associate with the surface signature of von Karman vortices. Results from this study suggest there are significant topographically-generated differences in wind characteristics between the eastern and western ends of the island.