The Spatial and Temporal Variability of the Polar Front in the Sea of Japan (Polar Front, Eddies, Thermal Gradient).

Abstract

The spatial and temporal variability of the Polar Front in the Sea of Japan is investigated by analyzing both the conventional hydrographic data from the files of NODC and sea surface temperature (SST) data and sea height data derived from satellites. The root mean square variability of the annual mean frontal position, which extends from 38.5(DEGREES)N near the Korean Peninsula to 41.5(DEGREES)N near the Tsugaru Strait, is about 100 to 120 km in the western and central region and is 300 km in the eastern region. The Polar Frontal zone appears to be unstable in summer, suggested by the large amplitude of the frontal wave motion. Small scale eddies (50-100 km) are prevalent in the frontal zone. Entrainment associated with these eddies appears to be important in transferring momentum, heat and salt to the cold water region north of the Polar Front. Both hydrographic and satellite data show the dominance of the seasonal time scale in frontal dynamics. A monthly time scale is found to be of secondary importance. Frontal dynamics on the eastern and western extremities of the Polar Front are suggested to be different.