2007年3月に生じた成層圏惑星規模波下方伝播イベントの予測可能性

Abstract

In order to reveal the prediction skill as well as the key condition of the downward propagation of stratospheric planetary wave packets observed in early March of 2007, we conduct a series of ensemble reforecast experiments using the Ensemble Prediction System of the Meteorological Research Institute (MRI-EPS). It is found that the downward propagation in high latitudes of the lower stratosphere is predictable from about 8 days in advance. A regression analysis using all ensemble members indicates that the related circulation anomaly before the downward propagation resides within the stratosphere, but not in the troposphere. It is also suggested that the downward propagation is associated with barotropic instability of zonally asymmetric basic flow of the stratosphere.