成層圏における惑星規模波反射現象の予測可能性--2014年2月の事例のアンサンブル再予報実験--

Abstract

A series of reforecast experiments using the ensemble prediction system of the Meteorological Research Institute is conducted to reveal the predictability and downward influence of a reflection event of stratospheric planetary waves in February 2014, which recorded the highest level of the downward propagation of the wave activity. The reflection is predictable from at least 7 days in advance. It is found that the skill of forecasts with a prediction period around the predictability limit crucially depends on whether planetary waves are reflected or absorbed in the stratosphere. Composite analyses also reveal that the persistence of the tropospheric wave source in the eastern hemisphere is a key in determining the propagating property of stratospheric planetary waves. When the reflection occurs in association with a weak persistence of the wave source, the subsequent downward propagating wave from the stratosphere enforces anomalous tropospheric circulation in the western hemisphere.