THE RELATIONSHIP BETWEEN VARIATIONS IN THE GULF-OF-MEXICO LOOP CURRENT AND STRAITS OF FLORIDA VOLUME TRANSPORT

Twelve years of monthly mean positions of the northern boundary of the Loop Current in the eastern Gulf of Mexico from satellite and in situ data have been compared with coincident 1977-1988 estimates of volume transport in the Straits of Florida in the subseasonal frequency band 15(-1) to 5(-1) cycles per month. Volume transport estimated from Cub a minus Florida sea level difference in this frequency band accounts f or 69% of the variance in volume transport estimated from the Florida- Grand Bahama Island submarine cable. On average, the Loop Current has a dominant period of 11 months whereas the volume transport is dominat ed by annual spectral energy; little significant coherence squared occ urs between them. The maximum northward penetration of the Loop Curren t occurs on average in winter when the volume transport is a minimum, but this is an artifact of the sampling epoch. This negative relations hip is most pronounced for 1979-1981 when transport is characterized a s unimodal, but for 1984-1985 and 1987 the Loop Current and volume tra nsport are more in phase, bimodal, and transport and position tend to have more semiannual energy. In this subseasonal band, the volume tran sport undergoes a significant change in the phase of its annual cycle after 1985 as compared with 1977-1984. For the twelve years considered in this study, the ensemble correlation between monthly position of t he Loop Current and volume transport is essentially zero.