TRAJECTORIES IN THE ANTARCTIC LOWER TROPOSPHERE

The statistics of air mass transport to the Neumayer Antarctic station (8 degrees 22'W, 70 degrees 7'S) are derived from three-dimensional 5 -day backward trajectories on the basis of a numerical weather predict ion model, the Global Model of the German Weather Service, for the per iod April 1993 to March 1996. Trajectory errors are discussed in detai l and errors of individual trajectories may sum up to from a few hundr ed to more than a thousand kilometers during 5 days' traveling time de spite the high quality of the Global Model and trajectory module descr ibed. The most frequent easterly flow at Neumayer consists of advectio n from oceanic and continental regions. During southeasterly flow, mea n trajectories document oceanic air passing coastal continental region s during the 3 days preceding arrival. Air arriving from above the Ant arctic continent south of 75 degrees S usually descends over the margi nal plateau and especially over the slope region. Advection from the c entral plateau regions poleward of 80 degrees S is rare. Marine trajec tories from latitudes north of 60 degrees S mostly start in 0 - 3 km h eight. The modeled transport for the arrival levels at 950 hPa and 850 hPa at Neumayer station document that the frequency of oceanic source regions increases with height. Trajectories for 15 other coastal dest inations show that near-surface easterly winds with a downslope compon ent dominate along the eastern shore of the Weddell Sea. The prevailin g transport from the south at the Filchner Ronne ice shelf arises from deflected barrier winds along the Transantarctic Mountains. At the no rthern tip of the peninsula, westerly winds prevail, and the air usual ly originates from the Bellingshausen Sea. The probability of contact with air masses from ice-free continents is small for all coastal site s.