What proportion of the North Pacific Current finds its way into the Gulf of Alaska?

This paper builds on methods previously developed to show how the absolute geostrophic circulation of the Gulf of Alaska can be observed. A time series of maps of the monthly circulation patterns in the Gulf allows us to determine how much water is carried from the North Pacific Current and thence into either the Gulf of Alaska or the California Current System. This is of interest because of previous suggestions that fluctuations in the Alaska Current and the California Current might be anti-correlated. I will show that roughly 60% of the water arriving off the west coast of the Americas in the North Pacific Current eventually flows into the Gulf of Alaska, the remaining 40% flowing into the California gyre. Fluctuations in the North Pacific Current do occur, but the dominant response is a simultaneous strengthening of both the Alaska and California Currents. A significantly smaller fraction of variance in the North Pacific Current flow results in a change in the fraction of water supplied to either gyre.