3-DIMENSIONAL PERSPECTIVES OF THE FLORIDA CURRENT - TRANSPORT, POTENTIAL VORTICITY, AND RELATED DYNAMICAL PROPERTIES

The Florida Current flows through the Straits of Florida, which starts as a zonal channel and turns to become a meridional channel. The spat ial structure of the Florida Current and its transport, potential vort icity, and related dynamical properties are investigated using a three -dimensional, baroclinic, primitive equation model with a mesoscale-ad mitting (5.6 km) horizontal resolution and 25 vertical (sigma: terrain -following) levels. At 83 degrees W, the Florida Current fills only a portion of the channel; however, due to the interaction with the shoal ing bottom topography (from a maximum depth of over 2000 m at 83 degre es W to less than 800 m at 27 degrees N) and the narrowing Straits of Florida (from a maximum width of about 170 km at 83 degrees W to about 110 km at 27 degrees N), the Florida Current fills the entire channel at 27 degrees N, and the potential vorticity distribution is altered. The specified transport of 28.6 Sverdrup (1 Sv = 10(6) m(3) s(-1)) fr om the Loop Current at the western boundary and the inflow from the Ol d Bahama Channel of 1.9 Sv converge into the meridional channel. With an additional inflow of 1.2 Sv from the Northwest Providence Channel, the simulated total transport of 31.8 Sv at 27 degrees N is comparable to the STAGS (Subtropical Atlantic Climate Studies) mean transport of 31.7 Sv. Both vertically and laterally integrated subsectional transp orts are examined at transects 83 degrees W, 82 degrees W, 81 degrees W, 25 degrees N, 26 degrees N, and 27 degrees N. The potential vortici ty increases (decreases) on the cyclonic (anticyclonic) side of the Fl orida Current at 27 degrees N compared to 83 degrees W. The downstream variation of static stability, relative vorticity, and Froude number is also examined. While the vertical shear is strong only on the north ern side at 83 degrees W, it is comparable on the both western and eas tern sides downstream at 27 degrees N, reaching to the bottom of the m eridional channel. Large values of the Froude number exist only in the upper 300 m of the zonal channel. but they reach to the bottom of the meridional channel. (C) 1997 Elsevier Science B.V.