Structure of the katabatic winds at Mizuho Station, East Antarctica

The structure of katabatic wind at Mizuho Station (70°42′S 44°20′E, 2230 m above sea level) in East Antarctica is described using data from radiosondes and a 30‐m tower. This station is characterized by a so‐called “cold katabatic” region. The frequency of occurrence of a single wind direction (in this case, east) is higher at Mizuho than at any other station in Antarctica. Because of this and the strong wind, well‐developed sastrugi can be seen in the vicinity. The characteristics of the temperature inversion during clear sky conditions in winter were a quasi‐isothermal layer from the surface up to 50 m capped by a thermocline of stronger temperature gradient. The maximum wind speed occurred near this height. The height of the top of the boundary layer, where turbulence becomes quite small, can be considered as the height above this thermocline. The d value of the stable boundary layer obtained by using the above height was 0.048–0.19 in the present case. This value is lower than the values obtained on the flat horizontal surface and on a slope of 0.002 m km−1 in the mid‐latitudes. Taking the above height as the top of the katabatic wind, the two‐layer model including the surface friction can explain the observational results well, better than the inversion wind model. This seems to indicate that the surface stress is important in the development of the katabatic wind at Mizuho but that the interfacial stress at the top of the inversion layer is not important in its development.