Short- and long-term relationships between the Yucatan Channel transport and the Loop Current System

This work uses twin 22-year free-running simulations of the Gulf of Mexico hydrodynamics performed with the HYCOM, one considering only ocean dynamics and the other incorporating atmospheric forcing, to study the behavior of the Yucatan Channel transport (YCT), the Loop Current (LC), the Loop Current Eddies (LCEs), their relationships, and the atmospheric forcing effect on them in short (daily) and long (monthly) time scales. A more comprehensive description of the LC intrusion and LCE separations was obtained by considering the upper eastern or western YCT (whose magnitudes are determined by the longitudinal displacements of the Yucatan Current's core), a perspective not evident when considering the upper total YCT; specifically, the eastern YCT provides the most meaningful description of the studied processes. Atmospheric forcing mainly affects the extended stage of the LC by creating a higher dispersion in the YCT and LC circulation values in comparison when considering only ocean dynamics. For the long-term analysis, standardized indexes that integrate the daily values of the eastern YCT and LC circulation in time were used; their temporal propagation and persistence (the changes of their characteristics from short to long time scales) were studied. Intrinsic ocean dynamics produces a persistent YCT and LC intrusion behavior and consistent LCE separation patterns from daily to 5-month scales. The atmospheric forcing effects are more emphasized on the LC intrusion and LCE separations than on the YCT: the YCT persistence is maintained but not that of the LC intrusion. An increased occurrence of LCE separations with low or moderate LC intrusion is expected due to climate change. Using the standardized indexes of the LC metrics to construct a predictive model of the LC intrusion and LCE separations using only current and past LC information is proposed for future research.