The Tampa Bay Coastal Ocean Model Performance for Hurricane Irma

摘要

The Tampa Bay response to Hurricane Irma in September 2017 is analyzed using a combination of in situ observations and numerical model simulations. The observations include winds and water levels from in situ recording stations. The model simulations are by the Tampa Bay Coastal Ocean Model (TBCOM), which downscales from the continental shelf to the estuary by nesting the unstructured grid, Finite-Volume, primitive equation Community Ocean Model (FVCOM) in the West Florida Coastal Ocean Model, which in turn downscales from the deep ocean across the continental shelf by nesting FVCOM in the Gulf of Mexico Hybrid Coordinate Ocean Model. Both the observations and the model simulations show a rapid negative storm surge (a setdown of sea level) followed by a positive surge associated with the change of wind direction. The initial forecast underestimates the magnitude of the negative surge. After adjusting for the difference between the winds actually observed compared with the original forecast winds, the hindcast sea level simulation very closely matches the observations. These findings imply that a massive exchange of water occurred between Tampa Bay and the adjacent continental shelf as the hurricane passed by the region. A large portion of the bay water was flushed out to the south, to be replaced by new waters advected in from the along the coast to the north.