Effects of Mechanical and Thermal Forcing on the 2007-08 Madden-Julian Oscillation (MJO07-08) System during the Splitting Stage Over the New Guinea Highlands (Part III)

In this study (Part III), effects of the mechanical and thermal forcing on the 2007-08 Madden-Julian Oscillation (MJO07-08) system during the splitting stage over the New Guinea Highlands (NGH) are investigated. During the splitting stage of MJO07-08 convective system following the blocking stage highlights the relatively stronger role played by thermal forcing associated with the NGH, owing to the interaction between land/sea breeze and the basic flow. Moreover, the mechanical forcing influences the amount of rainfall along NGH as the weakened mesoscale convective system (MCS) and incoming flow associated with MJO07-08 interact with the complex terrain of NGH. This study also explores how the common ingredients and major mechanisms for heavy rainfall, as identified in the previous studies, are affected during the splitting of the MCS around NGH. In short, this research provides in-depth insights into the roles of mechanical and thermal forcing on the rainfall modification and propagation of MJO07-08 over the NGH. By employing the Weather and Research Forecasting (WRF) model, the research uncovers the significance of these factors influencing orographic blocking, flow regimes, and the NGH modification of the MJO07-08 rainfall.