Influence of Lateral Boundary Conditions on Regional Extended-Range Simulations of the MJO

Lateral boundary conditions used in regional extended-range simulations are often analyses from a global data assimilation system as global extended-range forecasts are often not available. However, it is useful to examine the impact of this constraint as this technique would not be possible for real-time forecasts. Using Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPSŪ), we have conducted regional extended-range simulations by using lateral boundary conditions from either global analyses or global extended-range forecasts. Global extended-range atmospheric forecasts from Navy Global Environmental Model (NAVGEM) are produced using persistent SST, analyzed SST, and SST by coupled to global Hybrid Coordinate Ocean Model (HYCOM). The lengths of the extended-range simulations are one-month and the time period is November 2011 during DYNAMO. The simulations are evaluated in terms of their ability to simulate the Madden-Julian Oscillation (MJO) since it is an important source of predictability on intraseasonal timescales. Results from all simulations show relatively insensitive to the lateral boundary conditions, indicating that the local interaction between the large-scale circulation and convective activity may be important for the MJO initiation through atmospheric energy buildup, air-sea interaction and other processes.