熱帯季節内振動に対する冬季中高緯度大気の応答特性

Abstract

The influence of Madden-Julian Oscillation (MJO) on the extratropical circulation in the boreal winter (DJF) is statistically investigated using OLR data and JRA-55 reanalysis data during 35 years. We especially focus on response characteristics of atmospheric fields to the amplitude and polarity of MJO in each phase. It is found that the velocity potential field where its composited anomaly for the phase of MJO has statistical significance responds not only linearly to the amplitude but also symmetrically to the polarity. On the other hand, the stream function field has not such linear characteristics to the amplitude and polarity of MJO even though the composite anomaly has statistical significance. We also discuss relationship between the response characteristic of atmospheric anomaly fields to MJO and their formation mechanism based on the vorticity equation.