Satellite oceanography has opened new opportunities in the description of spatial-temporary variability of fronts in a wide range of scales. There is an attempt to formalize frontal zone and frontal section ideas in the ocean with the purpose of their allocation depending on the satellite measurements. The frontal zone is represented as a flow convergence zone, and the maximal flow convergence line in this zone is accepted as frontal division or front. The dynamic fronts are picked out on the data of satellite altimetry information, the thermal fronts are picked out on the sea surface satellite data. The examples of similar estimations for the Sea of Japan are given in this article.