Seasonal Variability of the California Undercurrent: Statistical Analysis Based on the Trajectories of Floats with Neutral Buoyancy

Abstract

The seasonal variation of the kinetic energy of the California Undercurrent and the eddy field in the region of this current are reconstructed by analyzing the trajectories of floats with neutral buoyancy (RAFOS) launched by the researchers of the Naval Postgraduate School (Monterey, California, USA) for 10 yr (since 1992). These data are processed by using a mathematical approach based on the combination of a procedure of averaging over cells and a special filtration approach with an aim to improve the statistical reliability of numerical calculations. The analysis of the accumulated data shows that the kinetic energy of the California Undercurrent has a well pronounced seasonal variation with two extrema in late spring and early autumn. The intensification of the California Undercurrent in autumn is accompanied by a decrease in its extension in the direction transverse to the coast. The eddy field of the California Undercurrent is especially intense in autumn. At depths of 300–600 m, the annual average kinetic energy of the eddy field increases with the distance from the coast up to about 127°W. Moreover, in this case, the zonal anisotropy of the eddy field increases.