Stratospheric response to Arctic sea ice retreat and associated planetary wave propagation changes
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The stratospheric response to the observed Arctic sea ice retreat is analysed based on European Centre for Medium-Range Weather Forecast (ECMWF) Re-Analysis Interim (ERA-Interim) atmospheric data from 1979-2012. It is shown that changes in August/September sea ice concentration impact on tropospheric and stratospheric geopotential heights in the following winter. During low ice phases a negative tropospheric Arctic Oscillation pattern is found, which is connected to a weakened stratospheric polar vortex and warmer stratospheric temperatures. Furthermore, the analysis reveals enhanced upward EP fluxes due to planetary waves for low ice conditions. Strong stratospheric anomalies in the Atlantic/European region are associated with a weaker polar vortex. Low ice periods are connected with additional tropospheric wave energy excitation in the Pacific/North America region and influence the stratosphere through three-dimensional planetary wave propagation.
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