Coastal winds in south Florida

Thirteen-month records for the period of April 1994-April 1995 from eight ( out of nine) Coastal-Marine Automatic Network (C-MAN) stations in south Flo rida are analyzed statistically to study alongshore variability of observed atmospheric variables. The surface variables largely are statistically hom ogeneous and coherent along the Straits of Florida. The maximum correlation for hourly wind components between adjacent stations (separated alongshore by 30-117 km) ranges from 0.9 to 0.75, respectively. However, there is a l ack of coverage in the cross-shore direction; hence, a redistribution of C- MAN stations in the cross-shore direction should be considered to provide b etter spatial coverage of surface atmospheric variables in the south Florid a region. Surface winds from the National Centers for Environmental Prediction (NCEP) 80-km grid, eta (Eta) Model analysis for the same period are compared stat istically with observations from an air-sea interaction buoy and a C-MAN st ation in the south Florida coastal region. The eta winds represent the low- frequency winds (periods between 3 days and 3 weeks) fairly well (e.g., the coherence exceeds 0.8 and the phase difference is less than 15 degrees) bu t generally are weaker in magnitude than are the observed winds. The differ ence can be up to 2 m s(-1) for the monthly mean and 1 m s(-1) for the seas onal mean. The histogram of the eta winds in winter has a single large peak instead of multiple peaks as occur in those of the observed winds. Southwa rd bias in the eta winds exists in summer. The eta Model simulates well the how patterns of a tropical cyclone and an extratropical cyclone on the regional scale but lacks local spatial variabi lity. As demonstrated. local spatial variability can be represented better by a blend of model and observed winds than by either the model-based or ob served local surface winds alone. These issues need to be reexamined periodically with upgraded versions of N CEP's operational models.