INTERANNUAL VARIATIONS IN ANTARCTIC PRECIPITATION RELATED TO EL NINO SOUTHERN OSCILLATION

摘要

The accurate estimation of Antarctic precipitation variability is an essential component in understanding global sea level fluctuations; direct measurement techniques, however, are replete with practical difficulties. In this study, net precipitation (precipitation minus sublimation) for the Antarctic continent is computed for 1980-1994 using operational numerical analyses obtained from the ECMWF (European Centre for Medium-Range Weather Forecasts). The resulting estimations reveal a strong interannual variability for the Antarctic continent, implying a +/-1.2 - 1.5 mm yr(-1) maximum range in the Antarctic eustatic change contribution. In particular, variability for the South Pacific sector (120 degrees W-180 degrees W) is shown to be correlated with the El Nino-Southern Oscillation (ENSO) phenomenon for 1980-1990. The relation becomes anticorrelated after 1990, associated with a strong East Antarctic ridging pattern that coincides with the start of the prolonged series of warm events of the early 1990s. This result is relevant to other studies relating ENSO variability to high southern latitudes, and a more elaborate picture of this teleconnection pattern is presented. Comparisons of sea level pressure values using available ship observations show good agreement and offer a confirmation of the analyses in this data-sparse region. Additionally, a comparison of results with values obtained from the precipitation fields of the NCEP/NCAR (NCEP: National Centers for Environmental Prediction; NCAR: National Center for Atmospheric Research) reanalysis project are discussed. [References: 67]