A West Florida Shelf ROMS model nested in HYCOM: validation, application and data assimilation

A high-resolution regional model for the West Florida Shelf based on ROMS is nested into the GODAE Atlantic and Global HYCOM models. The benefit of using HYCOM boundary conditions instead of climatology is established by comparing the nested model to altimetry, in situ temperature time series, andADCP and high-frequency (HF) radar currents.
Jointly with the Fish and Wildlife Research Institute, the model is applied to assist in harmful algae bloom forecasts. The model currents are used to estimate the trajectories of water parcels where red tide organisms have been detected. This system has been able to simulate the onset of the 2005 red tide event.
HF Radar Currents are assimilated to improve the shelf circulation. An ensemble simulation of the WFS ROMS model is carried out under different wind forcings in order to estimate the error covariance of the model state vector and the covariance between ocean currents and winds. Radial currents measured by HF Radar antennas near St. Petersburg and Venice, FL, are assimilated using this ensemble-based error covariance. Different assimilation techniques using a time-average ensemble, a filter to reduce surface gravity waves and an extended state vector including wind stress were tested. Results of WFS ROMS model assimilating surface currents show an improvement of the model currents not only at the surface but also at depth.
This model is run daily, to provide forecasts for the next 3.5 days. The model predictions and validations are available at http://ocgweb.marine.usf.edu under "WFS Model Forecasts".