Item

Abstract

It is suggested that internal ocean variability plays a significant role in Florida Current transport variability on interannual time scales. A clear relationship is found between different stages within a ring shedding cycle of the Loop Current in the Gulf of Mexico and minima in the Florida Current transport in mesoscale eddy-permitting ocean model simulations. Available observations are generally in agreement with such a relation but too sparse to give full evidence. Before the Loop Current intrudes far into the Gulf of Mexico a coherent eddy within the Loop Current partly blocks the inflow from the Caribbean Sea through Yucatan Channel leading to a minimum in the Florida Current transport. Such a blocking situation typically occurs over a period of 1-2 months. The irregular blocking leads to interannual variability explaining large parts of the variability of the Florida Current transport in the model simulations, even exceeding atmospheric forcing variability on the considered time scales. Model simulations without ring shedding produce significantly less variability in Florida Current transport. Simulations without interannual variability in the surface forcing show almost as large (or even larger) interannual Florida Current transport changes as without forcing variability. Adding a seasonal cycle can lead to a beat frequency which might be important for the decadal variability.