Flow structure and transport in the Yucatan Channel

Abstract

The direct ocean current observations across the Yucatan Channel collected during the Canek program allow the best description to date of the exchange between the Caribbean Sea and the Gulf of Mexico. A net transport of 23.8 ± 1 Sv (1 Sv = 106m3s−1; 95% confidence interval) flowed through the Yucatan Channel from the Caribbean Sea into the Gulf of Mexico, during the period between September 1999 and June 2000. This is about 20 percent less than the 30 Sv accepted as the nominal transport of the Florida Current, and less also than the 28 Sv assumed for Yucatan in closing the transport budgets for Caribbean passages. The discrepancy may be an imbalance due to fluctuations in the transports through other passages of the system, especially the Old Bahama and Northwest Providence Channels, which remain poorly known. Our data corroborate the principal features of the flow through the Yucatan Channel: The northerly surface Yucatan Current and its southerly Under‐current off Mexico, and the southerly surface Cuban Counter‐current near Cuba; but previously unobserved mean currents are found to exist at depth, especially on the eastern side of the channel. Fluctuations seen in the deep flows are related to volume anomalies over the Gulf of Mexico. A transport through the Yucatan Channel smaller than previously thought has significant implications for the dynamics of the Gulf of Mexico and its modeling, since this transport is the principal forcing of its circulation. The circulation budgets in the Western Subtropical Atlantic should be revised considering these new results.

Analysis of flow variability in the Yucatan Channel

“…[21] The mean total transport in Yucatan Channel for the period of measurements is 24 ± 1 Sv with a standard deviation of 3.5 Sv (1 Sv = 10 6 m 3 s À1 ) [Sheinbaum et al, 2002], with a maximum in September and a minimum in November, but transport variability is very large in the channel. To compare transport and energy fluctuations in the channel, we computed a ''transport efficiency'' index, as defined by Johns and Schott [1987],…”

“…Details about transport estimates and their comparison with other passages in the system are given by Sheinbaum et al [2002].…”

“…[8] This study is part of the CANEK Project [Sheinbaum et al, 2002], whose main objective was to measure the exchange through the Yucatan Channel and characterize its magnitude and variability throughout the water column. This project was initiated in December 1996, completed in June 2001, and included various shipboard acoustic Doppler current profiler (ADCP) measurements, hydrography-velocity surveys using a package containing a CTD (conductivity-temperature-depth measurement instrument) and a Lowered-ADCP (LADCP) profiler, and current-meter moorings.…”

Loop Current, Rings and Related Circulation in the Gulf of Mexico: A Review of Numerical Models and Future Challenges

“…It originates at the Yucatan Channel (where it is called the Yucatan Current) through which approximately 23~27 Sv ( Sv = 0 6 m 3 s -) transport passes with a large min-max range of 4~36 Sv [Johns et al 2002;Sheinbaum et al, 2002;Candela et al, 2003]. The Yucatan/Loop Current is a western boundary current with peak speeds of .5 to .8 m s -on the western side of the channel near the surface (Pillsbury,[887] based on direct current measurements, plotted in Figure 5 of Gordon [967]; Nowlin [972] based on GEK; Schlitz [973] and Carder et al [977] based on hydrography; and Ochoa et al [200] and Sheinbaum et al [2002] based on ADCPs and hydrography). In the Loop (inside the Gulf) intense speeds reach .7 m s -in in situ measurements [Forristal et al,992].…”

An integrated ocean circulation, wave, atmosphere, and marine ecosystem prediction system for the South Atlantic Bight and Gulf of Mexico

“…The Loop Current originates at the Yucatan Channel, through which approximately 23∼27 Sv (1 Sv = 10 6 m 3 /s) transport passes (Johns et al 2002;Sheinbaum et al 2002). The Loop episodically sheds warm-core rings (Vukovich et al 1979) at intervals of approximately 3-18 months (Sturges & Leben 2000).…”