A preliminary estimate of inertia effects in a bulk model of katabatic wind

Observed sastrugi orientations showed considerable deviation from a bulk theory of katabatic wind in lee sides of troughs in ice sheet undulations of which the wavelength is about 400km on the Mizuho Plateau, East Antarctica. The effect of the inertia term which may account for the deviations but is often neglected in the equation of motion for katabatic wind is estimated with the perturbation method. A sinusoidally undulating slope with ridges and troughs is assumed for the model calculation instead of an infinite flat slope for the inertiafree model. The calculated results, in a typical inversion, suggest that the inertia term is significant if the wavelength of the undulations is smaller than about 200km while the effect of the undulations can be neglected if the wavelength is smaller than about 50km. Observed variability in the wind direction in the lee of the troughs may be accounted for by the effect of the inversion height which enhances the inertia effect

Heart flux in surface snow at Mizuho Station, Antarctica: Monthly values and errors

Investigations are made on the determination of conductive snow heat flux at an Antarctic snow field, Mizuho Station, from the end of February to December 1979 during the first year of POLEX-South. Some preliminary analyses on the heat flux meter outputs raised questions on the data. As an alternative method, numerical differentiation and integration method is used to calculate snow heat flux from snow temperature. Errors accompanying the calculation are investigated, and it revealed that this method gives monthly heat flux with a relative error of about 10%. Snow temperature gradient in the surface layer is consistent with the present estimates. Estimated snow heat flux is compared with the results obtained at other sites in Antarctica

Temperature, wind and atmospheric circulation in East Queen Maud Land, Antarctica

Proxy observations of wind and temperature are carried out in East Queen Maud Land. The atmospheric circulation patterns are further studied by in situ observation of the diurnal wind vector variation and the upper air soundings. It was revealed that the high wind directional constancy at Mizuho Station is derived not only from the katabatic wind but also from the general synoptic pressure patterns. The katabatic wind is weakened when the westerly wind intensifies as part of the 30 to 50 day cycle synoptic pattern changes (T. YASUNARI and S. KODAMA, J. Geophys. Res., 98,13063,1992) of which the cause is still to be solved