Detection and propagation of the Madden-Julian Oscillation in the equatorial stratosphere

The possibility of vertical propagation of the Madden-Julian Oscillation (MJO) signal into the stratosphere is examined using 22 years of Lanczos filtered wind and temperature field ERA-40 reanalysis data. The analysis is based on the first three leading empirical orthogonal functions (EOFs) modes of each field and their associated Time Coefficients (Principal Components). In conjunction with the EOFs, time-lagged correlations calculated from the Time Coefficients allowed for the estimation of propagation velocities for the MJO signal in both the wind and temperature fields.;Based on calculations of propagation velocities and comparisons to MJO observations and theory, Kelvin waves and possibly fast gravity waves associated with the MJO and its convective envelope were found to exist in the stratospheric wind field and possibly the temperature field at pressure heights generally up through 20mb or 30mb, and even up to 10mb for the second leading mode of the wind field. In addition, results of this study suggest the possible existence of MJO-associated westward propagating Rossby waves in the temperature field up through a pressure height of 30mb. This finding suggests that in addition to Kelvin and fast gravity waves, Rossby waves also play a significant role in propagating the MJO signal upward into the stratosphere.