The Pacific North Equatorial Countercurrent (NECC) is a major upper-ocean zonal flow of the wind-driven circulation in the tropical Pacific, flowing eastward across the Pacific Ocean basin between 2°N and 10°N. The NECC transport is about 10-30 Sv eastward out of the warm pool region to the relatively cold eastern Pacific on average. It plays important roles in the volume and heat budget of the warm pool and in shaping the tropical Pacific climate.