Abstract
Modeled and observed empirical orthogonal functions of currents in the Yucatan Channel, Gulf of Mexico
Modeled and observed empirical orthogonal functions of currents in the Yucatan Channel, Gulf of Mexico
Lie-Yauw Oey
Program in Atmospheric and Oceanic Sciences, Princeton University, Princeton, New Jersey, USA
Tal Ezer
Program in Atmospheric and Oceanic Sciences, Princeton University, Princeton, New Jersey, USA
Wilton Sturges
Department of Oceanography, Florida State University, Tallahassee, Florida, USA
Candela et al. [2003]
have reported empirical orthogonal function (EOF) analyses based on 23-month current-meter and acoustic Doppler current profiler
measurements in the Yucatan Channel. Those authors noted the difference between EOFs obtained from observations and their
z-level models and EOFs calculated by
Ezer et al. [2003]
from the results of a terrain-following model. Here a new analysis is reported that explains this difference, and that also
suggests the importance of shelf-edge meander mode of the core Loop Current in the channel. We show that the terrain-following
model gives EOFs with characteristics similar to those observed when data from the upper slope and shelf in the western portion
of the model channel are omitted. Modes 1 and 2 have tripole and dipole structures with energies (35%, 26%), respectively,
of total energy, and correlate with “slow” vacillation of the core-current for periods >50 days. Exclusion of upper-slope
and shelf data eliminates a short-period and energetic component inherent in Ezer et al.'s original mode 1 EOF. This mode
correlates with frontal meanders of the core current over the shelf edge in the western portion of the channel. The short-period
mode may be missing or underestimated in observational and z-level models' analyses, since there were only a few moorings over the upper slope and shelf, and z-level models have step-like topography with generally lower resolution in shallower seas.
Received 24
February
2004;
accepted 23
June
2004;
published 14
August
2004.
Citation: Oey, L.-Y., T. Ezer, and W. Sturges
(2004),
Modeled and observed empirical orthogonal functions of currents in the Yucatan Channel, Gulf of Mexico,
J. Geophys. Res.,
109,
C08011,
doi:10.1029/2004JC002345.