A Comparison of Twin MOM6 and HYCOM Eddy-Resolving Global Ocean Simulations

Alan J Wallcraft1, Eric Chassignet1 and Robert Hallberg2, (1)Florida State University, Center for Ocean-Atmospheric Prediction Studies, Tallahassee, FL, United States, (2)NOAA/Geophysical Fluid Dynamics Laboratory, Princeton, NJ, United States
The HYbrid Coordinate Ocean Model (HYCOM) was the first widely available ocean model to use the Arbitrary Lagrangian Eulerian (ALE) technique in the vertical. ALE allows for any coordinate choice in the vertical and, in HYCOM, the vertical coordinate was chosen to be like z-levels near the surface, terrain-following in shallow water, and isopycnal over most of the deep ocean. HYCOM is the ocean component of the US Navy's and NOAA's global ocean prediction systems, and will be part of the Navy's first Earth System Prediction Capability (ESPC), coupling the atmosphere, ocean, sea ice and waves at high resolution globally for 30+ day forecasts. MOM6, on the other hand, is the most recent ocean numerical model to implement ALE in the vertical, and as a newer implementation, it has several advantages over HYCOM. Our philosophy for ocean prediction is that an ocean model that performs better in free-running simulations will produce better predictions and forecasts when in a data assimilative system. We are therefore evaluating MOM6 as the next generation "HYCOM 3.0" for high resolution global ocean prediction applications. We report on the results of twin 1/12 degree global simulations performed with HYCOM and MOM6 with a configuration similar to the operational HYCOM model, but using only features that are available in both HYCOM and MOM6.