Effects of Cloud Microphysics and SST on the Initiation and Propagation of the DYNAMO November MJO Event

A series of 30-day hindcast simulations of the MJO events during the dynamics of the MJO (DYNAMO) field campaign are conducted with a global model that utilizes superparameterization (SPCAM). To investigate the impact of cloud microphysics, simulations are performed with single- and double-moment cloud microphysics scheme in the cloud resolving model embedded in each grid box. Two sets of the sea surface temperature (SST) boundary condition – the observed SST in Year 2011 and the climatological SST – are used to examine the role of SST on the simulation of the MJO event.

The results show that the horizontal distribution of precipitation and MJO propagation are varied by different microphysics and also by SST boundary conditions used. The double-moment microphysics scheme tends to yield stronger and more organized convection over the Indian Ocean and the Maritime Continent, resulting in a more pronounced MJO initiation and more coherent MJO propagation. While having a negligible impact on the initiation of the MJO, the SST boundary conditions do affect MJO propagation, with the 2011 SST giving a stronger MJO propagation over the MC area.