The Impact of Including a Wave Model in the Seasonal Forecast System

The Environmental Modeling Center’s (EMC’s) ongoing work to develop the Seasonal Forecast System (SFS) weather model has the potential to greatly improve long range environmental forecasting globally. The SFS is currently at an early stage of development with multiple areas of continuing research. One question facing the EMC is whether a wave model (WAVEWATCH III) should be included within the SFS. The SFS will replace the Climate Forecast System version 2 (CFSv2), which does not utilize a wave model, providing little background on the value of coupling WAVEWATCH III in the SFS. This work compares forecasts from a developmental version of the SFS with and without the wave model. Starting from several historical initial condition dates selected for being winters with a strong El Niño, the SFS is run with 11 members, 90 days into the future. Model ensemble means of sea surface temperatures (SSTs), ocean mixed layer depth, 850 hPa geopotential height, and precipitation are compared with and without waves to assess the value of coupling WAVEWATCH III.