An important aspect of NOAA’s core mission is to support and protect American lives and the economy through their operational climate monitoring products and predictions. One avenue to provide subseasonal climate prediction is via multi-model systems that will provideoperational 30-45 day forecasts. However, before an individual model system can be included in the suite, it must be tested to be skillful and demonstrate suitability for real-time prediction at these time scales. Here we propose to use the Navy’s Earth System Model (NESM) to support the North American Multi-Model Ensemble intercomparison of subseasonal forecasts.
NESM is built upon the NAVy Global Environmental Model (NAVGEM) for the atmosphere, the HYbrid Coordinate Ocean Model (HYCOM) for the ocean and the Community Ice CodE (CICE) for the cryosphere. It is unique in that the atmospheric component will be run at relatively fine resolution (T359) compared to many other models used in NMME and the oceanic mesoscale will truly be resolved with its 9 km equatorial horizontal resolution. In the polar latitudes the horizontal resolution for ice is approximately 3.5 km. NESM has been shown to have predictive skill with regard to the Madden-Julian Oscillation and multi-month forecasts of the Arctic sea ice minimum.
During the first part of the proposed project, NESM will be used to provide weekly reforecasts (with 4 ensemble members) for the time period 1999-2015. Initial conditions (ICs) for the atmosphere will be derived from operational versions of the Navy Operational Global Atmospheric Predictions System or NAVGEM. Ocean and ice ICs will be derived from HYCOM/CICE reanalyses that span this time frame and assimilate all available observations. Model diagnostics, especially those related to subseasonal time scales, will be performed to test model capabilities and all model output in the required formats will be forwarded to NCEP. In the second year, atmosphere/ocean/ice ICs will be provides by the operational centers running the systems. A total of four one day lagged ensembles will be completed each week before the Wednesday deadline and model output will be forwarded to NCEP.