The two major wind systems driving the waters of the Pacific ocean are the westerlies which lie about 40-50° lat in both hemispheres (the roaring forties) and the trade winds from the east which dominate in the region between
20°N and 20°S. These give momentum directly to the west wind drift (flow to the east) in high latitudes and to the equatorial currents which flow to the west. Climate in the South West Pacific region varies due to superimposed effects of El Niño and  seasonal variations.