Figure 4.1-4.2. 4.1 Main features of the upwelling-favorable wind conditions off west coast of Vancouver Island during the summer. Northerly North Pacific High (NPH) winds generate a southward surface flow and a consequent offshore Ekman transport inducing upwelling. 4.2 Main features of wind-induced downwelling off the west coast of Vancouver Island during the winter. Southerly Aleutian Low (AL) winds generate a northward drift and a consequent onshore Ekman transport (modified after Thomson, 1981).