Surface ozone (O3) measurements indicate that extended periods with depleted O3 concentrations can exist during springtime in the boundary layer over the frozen Arctic Ocean. The longest observed ODE lasted for 11 days. 24-hr backward trajectories for this period cover roughly a triangle between the northern coasts of Greenland and Svalbard and the North Pole. The time series of O3 and air temperature exhibited similar features. However, the air temperature remained above 20 °C during one third of the periods with depleted O3 concentrations.