Spurious internal wave generation during data assimilation in eddy resolving ocean model simulations

Keshav Raja, Research Faculty at FSU, and other NOPP GIW team members have a new paper in revision at Ocean Modelling!

Data assimilation combines observations with ocean models to improve ocean state predictions beyond the capabilities of observations or models alone, but it can introduce problems like initialization shocks leading to spurious internal waves. These spurious waves disrupt the model energetics and must be controlled for accurate representation of high-frequency, small-scale ocean dynamics in assimilative model simulations. To solve this, the US Navy’s ocean forecast system uses the Incremental Analysis Update (IAU) method, dispersing the data-derived corrections over a defined time window (3 hours in the operational system). In this paper, we analyze a global HYCOM-NCODA simulation and show that initialization shocks and spurious waves persist despite the 3-hour IAU period. We propose extending the IAU period to longer than the local inertial period as a practical solution to reduce spurious internal waves.

Download the paper here: http://dx.doi.org/10.13140/RG.2.2.36179.76322

If you want to see Keshav’s colloqium about this work, watch this: