Identifying the MJO Skeleton in Observational Data

The MJO skeleton model is a nonlinear oscillator model for the basic planetary, intraseasonal features of the Madden-Julian Oscillation (MJO). As such, it predicts a particular structure of the MJO in terms of its winds, temperature, moisture, and convective activity. The goals of this study are (i) to identify this theoretical structure in observational and reanalysis data, and (ii) to examine and assess its variability. To this end, potential surrogates were examined for the MJO skeleton variables, with particular focus on the lower-tropospheric water vapor, Q, and the convective activity, A. One of the main questions is, To what extent is there agreement between the structure of the theoretical MJO skeleton and the structure of the MJO in nature? Case studies will be presented of well-known MJO (and non-MJO) events, and statistics of MJO skeleton variability are also used to assess these questions.