Influence of cyclonic perturbations on surface winds around Dumont d'Urville, East Antarctica, using wavelet transform

Wavelet analyses of the surface winds at Dumont d'Urville, an East Antarcti c station, have been performed for the months April, June, September, and D ecember 1993, representing autumn, winter, spring, and summer, respectively . The 3 hourly 10 min averaged meteorological station data have been used. The site is characterized by intense katabatic winds that arrive from the s outheast. During the year 1993 the maximum occurrence of wind was from 160 degrees direction sector. The wavelet transform spectra of horizontal wind show prominent periodicities in the interval between 2 and 20 days. The spe ctral energies in the diurnal scale are comparatively very low even in summ er. A comparison with wavelet spectra of pressure for synoptic scale (2-10 days) confirms the influence of synoptic disturbances that are frequent in coastal regions of the Antarctic continent. The same analysis carried out o n the wind components, parallel and transverse to the main katabatic flow d irection, reveals that these periodicities are mainly due to the katabatic flow behavior. Although the katabatic wind flow is the dominant force chara cterizing the day-to-day weather conditions, the influence of transient cyc lones offshore cannot be ignored; in situations of considerable synoptic ac tivity the intensity and duration of katabatic wind flow are prolonged.