Abstract
This study examines the role of the mean state in the propagation of the
Madden-Julian Oscillation (MJO) over the Maritime Continent (MC). We use
an ensemble of simulations made with a single model - the Community
Earth System Model version 2 (CESM2) – to assess the effect of the mean
state that is unaffected by that of model components such as
parameterization schemes. Results show that one ensemble member with an
exceptionally stronger MJO propagation also exhibits a much steeper
background meridional moisture gradient (MMG) over the southern MC
region than the other ensemble members. The simulated mean state affects
MJO via its impacts on moisture dynamics - a column water vapor budget
reveals a greater advection of mean moisture by MJO wind in the southern
MC is responsible for the anomalous MJO activity.