Search

The coastal region of the Antarctic continent is renowned for the frequent, intense blizzards and associated extreme weather that affect it, creating treacherous conditions that place human activities there in often perilous situations. The understanding and prediction of these events are therefore vital for continued safe operations on the continent. Severe wind events are investigated at two Australian coastal sites, Casey and Mawson. A summer case study at Casey and then the climatology of the events at the two stations are studied using station observations and atmospheric analyses. All events are found to be associated with extratropical cyclones that move close to the stations and lead to strong winds and heavy cloud cover. Most events see the passage of a high pressure ridge over the station ahead of the cyclone that blocks the cyclone, forcing it to move farther south close to the coast, thus intensifying the effect of the cyclone on the coastal weather. The ridge also produces calm, clea...

Strong wind events occurring near Casey (Antarctica) in a long July GCM simulation have been studied to determine the relative roles played by the synoptic situation and the katabatic flow in producing these episodes. It has been found that the events are associated with strong katabatic and strong gradient flow operating together. Both components are found to increase threefold on average for these strong winds, and although the geostrophic flow is the stronger, it rarely produces strong winds without katabatic flow becoming stronger than it is in the mean. The two wind components do not flow in the same direction; indeed, there is some cancellation between them, since katabatic flow acts in a predominant downslope direction, while the geostrophic wind acts across slope. The stronger geostrophic flow is associated with higher-than-average pressures over the continent and the approach of a strong cyclonic system toward the mast and a blocking system downstream. The anomalous synoptic patterns lea...