Model output, satellite data, and in situ observations are used to investigate the conditions that gave rise to an extreme wind event at the Australian Casey Station (66.27°S, 110.53°E) on the coast of East Antarctica. The event took place over the period March 20–22, 1992, and resulted in Casey Station's highest ever wind gust for March (66.9 m s−1, 130 knots) and 10 m mean winds of near 50 m s−1. The event occurred when a deep low was located just north of the coast and there was high surface pressure inland. The rapid deepening of the low took place within a strong baroclinic zone lying north-south between a cold trough and a ridge bringing very warm air southward. A conceptual model is proposed for the very strong winds experienced at Casey Station. Key elements of the model are (1) a synoptic-scale high-low pressure couplet, providing a strengthening pressure gradient; (2) entrainment of radiatively cooled air by the supercritical synoptic gradient, leading to downslope flow; (3) the acceleration of the wind down the lee slope of Law Dome, occurring primarily in response to a topographically induced, long-period, vertically propagating gravity wave; and (4) sources of negative buoyancy, including prestorm radiatively cooled air and, later in the storm, maritime air cooled by heat flux to the ice surface. The topographically induced gravity wave increases the horizontal temperature difference, thus increasing the negative buoyancy of the surface airflow.
If you can't find a tool you're looking for, please click the link at the top of the page to "Go to old article view". Alternatively, view our Knowledge Base articles for additional help. Your feedback is important to us, so please let us know if you have comments or ideas for improvement.