Wednesday, 25 January 2017: 11:45 AM
605 (Washington State Convention Center )
Warm stratospheric events in polar winters are separated by duration and strength of the polar night jet oscillation (PJO). 9 strong PJOs and 7 no-PJO events have been identified for the ERA-Interim period of 1979-2013. With a composite analysis it is demonstrated that strong PJOs show a significant stronger downward propagating signal for the evolution of NAM and for the zonal mean zonal wind anomaly due to differential planetary wave absorption in the higher stratosphere. There, the reestablishment of the polar vortex with stronger westerlies for strong PJOs after wind reversal is mainly caused by radiative cooling and reduced upward transport of angular momentum by planetary waves. For these strong PJO cases, the mean polar total ozone anomaly is enhanced, the NAO in upper troposphere is weakened, and the mean polar surface pressure is also stronger in comparison to warm events with no-PJO which indicate an enhanced stratosphere-troposphere coupling regime.
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