A type of mode water found in the subtropical gyre in the North Pacific. The NPSTMW thermostad has a core temperature range of 16°–19° C centered at 150°–160° E south of the Kuroshio Extension. The formation area is centered just north of 30° N and west of 155° E. The temperature of the layer decreases eastward. Two processes contribute to the thickness of this mode water:

large winter heat loss due to advection of warm water into the region; and

cold, dry air blowing off the continents, with the tilt of isopycnals in the Kuroshio Extension and recirculation creating a bowl of warm water between the Extension and the recirculation.