Atmospheric water-vapour transport to Antarctica inferred from radiosonde data

Data from 16 radiosonde stations are used to study the transport of water vapour in the antarctic atmosphere. Total column moisture (TCM), winds and moisture flux measurements are presented, together with an analysis of their reliability. Annual TCM values are similar—about 4 kg m−2—at all stations around the coast of East Antarctica but are much smaller on the East Antarctic Plateau. Over a period of 6 years the interannual variation (standard deviation) of the TCM is about 10% of the mean value. At the coastal stations moisture fluxes reflect the predominantly zonal easterly flow in the lower troposphere, and their meridional components are generally small. As a result of interannual variations in the strength of the atmospheric circulation, and to a lesser extent in the TCM, interannual variability of the fluxes is high, suggesting that there may be large interannual variability in the precipitation over Antarctica. From the data a water-vapour budged for East Antarctica is computed. The annual accumulation rate obtained agrees surprisingly well with glaciological estimates. However, the uncertainties are considerable as a result of measurement errors and the representativity of the stations available. The conclusion is that the data are more suitable for evaluating the regional performance of circulation models from which systematic budget estimates may be derived.

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