Seasonal variation of moisture transport in polar regions and the relation with annular modes
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Climatological seasonal variations of moisture transport and the interannual variations associated with the annular modes in the Arctic and Antarctic regions are investigated using 15-year ECMWF reanalysis data. Over the Arctic, there are strong moisture inflows from the Atlantic and Pacific in all seasons. Over the Antarctic, a strong moisture inflow exists around the Antarctic Peninsula in all seasons and another strong inflow exists over the Bellingshausen Sea and the Amundsen Sea in austral autumn and winter. Transient moisture flux is dominant over stationary flux and transient flux variation mainly controls the seasonal variation of precipitation minus evaporation(P-E) in both regions. The seasonal variations of P-E show a summer maximum in the Arctic and a winter maximum in the Antarctic. It is mainly governed by the seasonal variation of precipitable water variation in the Arctic and transient eddy activity in the Antarctic. The zonal mean poleward and eastward moisture fluxes in high latitudes are positively correlated with annular modes in both regions. Positive polarity of the Arctic Oscillation is associated with enhanced moisture inflow from the Atlantic, while positive polarity of the Antarctic Oscillation is associated with enhanced moisture inflow west of the Antarctic Peninsula.
PMG 18, 30-53, 2004
National Institute of Polar Research