Across-shelf heat transport off the Atlantic Coast of South Florida

Near-bottom current meter and temperature data, combined withcoastal wind records, describe across-shelf heat transport off the Atlantic coastof South Florida. Data were collected during two 138-day seasonal studies,from early summer to late fall , and from early spring to mid summer. Spectralanalysis of wind stress and near-bottom current meter data indicates thatacross-shelf flow occurs in response to along-shelf wind stress forcing overtime scales on the order of 2-3 days. Also, seasonal scale variations in alongshelfwind stress appear to drive seasonal scale variations in both across-shelfand along-shelf flow . Across-shelf flow is predominantly landward duringboth seasonal studies. This is partly in response to the south-to-north broadeningof the shelf, and partly due to an ageostrophic across-isobath flow in the lowestlayers of a northward moving current. A modified form of perturbation analysiscombines across-shelf current components with unseasonably warm or coolwater, defined by the linear regression line through the temperature observations.Plots of cumulative seaw_ard and landward heat transport describe the acrossshelfmovement of relatively warm or cool water over time scales of days toweeks. Heat transport du'ring the summer-fall study includes a net shorewardmovement of relatively cool water, and a net seaward movement of relativelywarm water. Embedded in this pattern are episodic upwelling events forced bythe Florida Current. During the spring-summer study, the alternation ofrelatively warm and cool water moving either seaward or shoreward results inlittle net heat transport.