How to achieve local time step in MPAS?

[caoyer]

For variable mesh in MAPS, we need a global time step for all resolutions. For instance, the 3km to 60 km mesh provided by MPAS, the time step will be set to 15s (as recommended by MPAS, config_dt is 5-6 times of resulotion in kilometers) to satisfy the CFL condition for 3km mesh grid, but for 60km mesh grid, time step is 300s. Global time step would cause computational waste. My question is how to achieve a local time step or adaptive time step for MPAS variable mesh? because that will significantly save computational resources for a global simulation.