Influence of the diurnal behaviour of pressure on wind speed in East Antarctica

The analysis of data obtained in 1994 from AWSs Dome C and D-80 and at meteorological station of Dumont d’Urville (Eastern Antarctica) shows the existence of a remarkable half-day component in the surface pressure time series during the whole year while the one-day periodicity is absent. The half-day periodicity at individual sites produces the same component in the quasi-meridional gradient of pressure between different pairs of stations. This quasi-meridional gradient seems to be one of the mechanisms determining the diurnal behaviour of the wind regime, especially during the winter when the diurnal variation of the buoyancy difference is weak. The analysis of the wind speed average diurnal cycle for different seasons shows that its behaviour in winter differs from that one during summer and interseasons. In winter the maximum is observed between 1500 h and 1700 h LT when the pressure gradient is maximum. During the summer the maximum is reached between 2300 h and 0300 h LT when the difference in the buoyancy between different stations is greater. These phenomena should be taken into account in modeling the wind regime over Antarctica. The presence of observed half-day periodicity suggests to suppose the influence of the moon as a possible forcing, through a process similar to high and low tide phenomena in the sea.