Decadal variability in the Arctic Ocean shown in hydrochemical data

The recent distribution of Russian hydrochemical data collected from the Arctic Basin provides useful information on ocean interior variabilities. Among various chemical components, silicate is the most valuable for showing the boundary between the silicate‐rich Pacific Water and the opposite Atlantic Water. Here, it is assumed that the silicate distribution receives minor influence from seasonal biological productivity and Siberian Rivers outflow. It shows a clear maximum around 100‐m depth in the Canada Basin. The vertical gradient below 100 m provides information on the vertical motion of the upper boundary of the Atlantic Water at a decadal time scale: i.e., the boundary shifts upward (downward), as realized by the silicate reduction (increase) at a fixed depth, responding to a more intense (weaker) Polar Vortex or the positive (negative) phase of the Arctic Oscillation. This valuable hydrochemical data set has provided a tool for verifying Arctic Ocean models with decadal responses to atmospheric variabilities.