<P> In the western region of the North Pacific, the surface of the Subtropical Gyre generally has a "C - shape". The Kuroshio current and Kuroshio Extension roughly from the outside of this "C - shape" where it then turns westwards into recirculation, where it then flows south parallel to the Kuroshio Current . From here the "C - shape" then flows eastward comprising the Subtropical Countercurrent at roughly 20--250N, then finally the "C" wraps back towards the west forming the North Equatorial Current just south of 200N . It is common for subtropical gyres to have this "C - shape" surface flow . The Subtropical Countercurrent is a shallow area of this "C"; at only about 250 dbar under the surface, circulation is a simpler closed, anticyclonic gyre . </P> <P> Narrow east - west frontal zones that cross the Pacific are less than 100 km wide . The Subarctic Frontal Zone or Subarctic Boundary, about 420N, is fixed in the North Pacific Current . The Subarctic Frontal Zone, slightly south of the maximum westerly wind speeds, separates the North Pacific Subpolar Gyre from the Subtropical Gyre . In the central and eastern Pacific at roughly 320N is the Subtropical Frontal Zone . Sometimes referred to as the Subtropical Convergence Zone, this frontal zone serves as the boundary between the west flowing North Equatorial Current from the North Pacific Current . With increasing depth in the North Pacific Subtropical Gyre, it gets smaller in the western region near Japan and it also loses strength . The Subtropical Gyre does not exist below 1500 m below the surface with the exception of the Kuroshio Current and Extension regions . </P> <P> The North Pacific Subtropical Gyre diminishes spatially with increasing depth . Similar to all subtropical gyre systems, the North Pacific Subtropical Gyre shrinks towards its most energetic surface flows, in a northwestern direction between the Kuroshio Current and the Kuroshio Extension . This is drastic shrinkage from the surface to about 200 m below . At the surface, the boundary that separates the westward and eastward flows from south of 200N to about 25--300N at 200 m . The "C - shape" in the western region of the Subtropical Gyre, including the Subtropical Countercurrent, generally does not exist below 200 m . At about 1000--1500 m, the Subtropical Gyre is located entirely in the western region of the North Pacific near the Kuroshio Current and Kuroshio Extension . In the subtropical regions, flow is weak where influences from the Subtropical Gyre are minimal . Differences in steric heights over distances of 1000 km are on the order of 1 cm, rather than the differences of 10 cm within the area of the North Pacific Subtropical Gyre . </P>

Describe the overall pattern of current flow in the northern pacific ocean