Moist entropy and the simulation of convection processes in Madden Julian Oscillation

Moist processes in multiple high and intermediate resolution regional and global model simulations of the two Madden Julian Oscillation episodes observed during the 2011 AMIE/DYNAMO/CINDY campaign are examined. The fidelity of the simulated MJO convection is found to be sensitive to the relationship between gross moist stability (GMS) and saturation fraction. In comparison to observations, simulations with low or negative GMS at low saturation fraction simulate the eastward propagation of MJO convection better than those that precipitate and export moist entropy too early. The association of long-wave radiative heating variability with saturation fraction is found to be the main source of moist entropy variability in the observed and simulated episodes of MJO.