Cooperative Institute for Research in Environmental Sciences

An analysis of near-surface winds, air temperature, and cyclone activity in Terra Nova Bay Antarctica from 1993-2009.

Knuth, S.L. and J.J. Cassano

2011, Journal of Applied Meteorology and Climatology, 50, 662-680

In September 2009, the first unmanned aerial vehicles were flown over Terra Nova Bay, Antarctica to collect information regarding air-sea interactions. Prior to the field season, wind and temperature data from a local automatic weather station (AWS) were collected from 1993-2007 and compared to an August-October 2006-2008 satellite cyclone analysis to place the September 2009 observations into a broader context. AWS wind data revealed a strong tendency toward downslope flow in the region regardless of season, as the majority (55%) of winds were from the west to northwesterly directions. Most winds observed at the site were less than 20 m s-1, but 83% of the stronger winds were associated with downslope flow. Fifteen of 418 strong wind events (greater than 20 m s-1) occurred during the cyclone analysis period, with 100% of those events occurring in the presence of a cyclone in the adjacent Ross Sea. Winter experienced the greatest number of strong wind events (68%), while summer had the lowest (4%). Most temperatures were between -15 and -25ºC, with temperatures strongly influenced by wind fluctuations. The cyclone analysis revealed 64% of systems were comma-shaped, and most cyclones (84%) within the Ross Sea were mesocyclones. A comparison of AWS data for Septembers 1993-2007 and September 2009 showed more strong wind events during 2009, while the cyclone analysis revealed a shift in cyclonic activity eastward. Reanalysis data comparing September 1993-2007 and September 2009 shows an eastward shift in a deeper upper-level trough, indicating September 2009 was an anomalous year.