Abstract:

Terra Nova Bay (TNB), Antarctica, is one of the confluence zones where strong katabatic winds are intense.
In this paper, data from the high-resolution Antarctic mesoscale prediction system (AMPS) and automatic
weather station (AWS) Manuela on Inexpressible Island in TNB are used to analyze the characteristics
of katabatic winds in these areas. The AMPS shows good capability in simulating wind speed and air temperature
at Inexpressible Island; however, the simulated wind direction is about 30° further westward than
measured. The wind speed at Inexpressible Island increases rapidly from January and it is maintained at a
high level during April–September. Data from the Manuela AWS indicate the strongest winds lag the lowest
temperatures by about 3 h in January, and in winter, the measured wind direction is mostly west-southwest.
Katabatic winds in TNB and the surrounding area are derived from the higher ice sheet to the west, and the
spatial distribution of the wind direction rarely changes with season. The wind speed shows considerable
seasonal variation; winds are generally a breeze during November–January, before increasing during
March–September. In winter, katabatic winds form confluence zones at several glaciers near the coast of
TNB, and Inexpressible Island is affected by katabatic winds from the Reeves Glacier. Boundaries are clear
in the upper, northern, and southern sides of the katabatic winds areas of the Reeves Glacier. Strong katabatic
winds extend from the surface to 650–800 m above ground level (AGL), and the core of the maximum
wind speed is located at about 50–200 m AGL. Strong katabatic winds can be weakened because of the terrain
of Inexpressible Island. The surface potential temperature differs little from the inland plateau to the
coastal area near TNB, indicating a dry adiabatic process within the march of the katabatic winds in these
areas.

Key words: Antarctica, Terra Nova Bay, Inexpressible Island, katabatic winds