Variability in moist static energy budget associated with the Madden-Julian Oscillation over the eastern Maritime Continent during CINDY2011/DYNAMO extended observing period

Abstract:

In this study, we examine variability in the moist static energy (MSE) budget over eastern Maritime Continent during the CINDY2011/DYNAMO extended observing period (from October 2011 through March 2012) associated with five convective disturbance events that can be recognized as the Madden-Julian oscillation (MJO). It reveals that the surface fluxes and radiative heating contribute to the maintenance of the amplitude of column-integrated MSE anomaly, and thus to the intensity of the MJO. The vertical and horizontal advection terms contribute to the phase progression and possibly eastward propagation of MJO. The contribution of the vertical advection is mainly due to lower-tropospheric decent after the precipitation and MSE maxima, presumably associated with rain re-evaporation, while that of the horizontal advection is due to so-called dry intrusion.

We also argue impact of several assumptions used in recent idealized models of the MJO on the MSE budget. The assumptions we examined include (1) the column-integrated radiative heating anomaly is taken proportional to the column water vapor, and (2) the anomaly in vertical advection of MSE is taken proportional to that of dry static energy (in other words, the normalized gross moist stability is taken constant). We demonstrate that the assumption 1 tends to speed up the phase progression, while the assumption 2 tends to slow it down.