Divergence Damping Change Motivation

• Noisy analysis increments in NDAS

• Relatively frequent update every 3 hours

  • We want even more frequent not less

• Insufficient time for model to adjust

• Lack of Digital Filter Initialization in NDAS

  • DFI not easy to include quickly in WRF

• External mode gravity waves most likely ramification of the imbalance

  • Therefore, increase their damping during assimilation