A wind-partitioning analysis of the role of evaporation and horizontal moisture advection in the onset and evolution of the MJO

The role of evaporation and moisture advection in the onset and evolution of the MJO is investigated using a wind partitioning technique applied to the ERA-Interim dataset (1979-2011) within the tropical region. This technique separates the wind field into its irrotational, non-divergent and background components using free-space Green functions. We compare the relative contribution of each component to the advection of moisture within the boundary layer and free troposphere during MJO events. The wavenumber-frequency characteristics of each component are also explored and compared with surface fluxes. These results are then analyzed within the context of radiosonde launches from the ARM Madden-Julian Oscillation [MJO] Investigation Experiment (AMIE) and Dynamics of the Madden-Julian Oscillation (DYNAMO).