Investigation of the Relationship Between the Yucatan Channel Transport and the Loop Current Area in a Multidecadal Numerical Simulation

Abstract

A hypothesis by Maul (1977), stating the rate of change of loop current (LC) volume is related to deep Yucatan Channel (YC) transport, is tested with a continuous 54-year simulation of the Gulf of Mexico (GoM) using a regional 1/25° resolution Hybrid Coordinate Ocean Model (HYCOM) configuration. The hypothesis states that the imbalance of transport between the upper YC and the Florida Straits controls the rate of change of the LC volume and that the imbalance is compensated by transport through the deep YC. Bunge et al. (2002) found a strong relationship between the deep YC transport and the LC area using 7.5 months of data from a mooring array in the YC, but the observational record length was relatively short compared to the time scale of LC variability. The 54-year HYCOM simulation provides a much longer and spatially complete data set to study the LC variability. Results show that the time evolution of the LC between two shedding events can be viewed as a combination of relatively high-frequency fluctuations superimposed on a low-frequency trend. The high-frequency variability of the LC area time derivative and the deep YC transport are related. The low-frequency variability is examined by comparing the LC area time series with time-integrated transport in the deep YC, and statistically similar trends are identified, supporting the Maul (1977) theory.

Nonlocal impacts of the Loop Current on cross‐slope near‐bottom flow in the northeastern Gulf of Mexico

“…[] show that this model realistically represents the stochastic Loop Current cycle and eddy propagation pathways, and Nedbor‐Gross et al . [] show that the simulation represents Loop Current variability in a manner consistent with past theoretical and observational studies [ Maul , ; Bunge et al ., ]. Further details of this simulation can also be found in these two papers.…”

Impact of upstream variability on the Loop Current dynamics in numerical simulations of the Gulf of Mexico

“…The zonal displacement of the maximum velocity is quite strong in the upper 1000 m, especially close to the western boundary, with a higher transport in the upper layer (Table 3). In the center of the current, meridional velocity anomalies are negative throughout the complete water column during expansion, which generates in the lower layer an outward flow (Table 3) as extensively discussed by different authors (Maul, 1977;Bunge et al, 2002;Ezer et al, 2003;Lee & Mellor, 2003;Chang & Oey, 2011;Nedbor-Gross et al, 2014). This is true for both ClimBc and VarBC (see summary in Table 3).…”

“…In addition, variability in the LC generates topographic Rossby waves (Oey, 2008;Hamilton, 2009) and is correlated with deep water exchanges through the YC. An increase in volume of the LC when it expends is compensated by a the deep outflow in the YC and vice-versa after a shedding event (Maul, 1977;Bunge et al, 2002;Ezer et al, 2003;Lee & Mellor, 2003;Chang & Oey, 2011;Nedbor-Gross et al, 2014). The LC and associated LCEs have been the subject of numerous studies, starting with in-situ observations (Leipper, 1970;Behringer et al, 1977;Maul, 1977) and, with the advent of satellites, synoptic views of surface fields such as temperature (e.g., Maul, 1975) and sea surface height (SSH) (e.g., Leben, 2005).…”

Upper-Ocean Processes Controlling the Near-Surface Temperature in the Western Gulf of Mexico from a Multidecadal Numerical Simulation

“…The present study uses a 54-year ocean simulation with the 1/25 GOM HYCOM [30][31][32][33] presented in [27]. Model output fields are available at https://www.hycom.org/data/ goml0pt04/expt-02pt2 (accessed on 17 March 2022).…”

“…Model output fields are available at https://www.hycom.org/data/ goml0pt04/expt-02pt2 (accessed on 17 March 2022). The 54-year GOM HYCOM experiment was validated in [27] and analyzed in several other studies [28][29][30]. The model realistically reproduces LC variability and LCE statistics, and accurately simulates upper ocean and deep ocean dynamics [29].…”