Surface-pressure change through Loewe's phenomena and katabatic flow jumps: study of two cases in Adelie Land, Antarctica

Abstract

Several Loewe's phenomena, where a sudden transition from shooting to tranquil flow takes place, have been observed. For both cases, as observed at a downstream station close to the coast, the mean wind speed suddenly decreased from about 20 m s-1 to almost zero, while a large pressure increase was recorded (5.7 hPa on 3 December 1985 and 2.1 hPa on 18 December 1985). For both cases it is found that the flow is stratified upwards with a surface well-mixed cold air layer, a very stable capping inversion layer, an overlying unstable layer thickening from upstream to downstream and a stable transition layer to the free atmosphere. This study supports the idea that the pressure change is mainly connected with the strong acceleration of the downslope katabatic layer under the effect of gravity, rather than with the change in depth of the cold air layer. -from Authors