Synchronous bidecadal periodic changes of oxygen, phosphate and temperature between the Japan Sea deep water and the North Pacific intermediate water

Abstract

From time series of dissolved oxygen (O 2 ), phosphate (PO 4 ) and water temperature (T) during the last forty years in the Japan Sea Deep Water and the North Pacific Intermediate Water, we found that O 2 , PO 4 and T show a clear bidecadal oscillations of about 18 years superimposed on the linear trends of decrease of 0.47 μmol‐O 2 kg −1 yr −1 and increase of 0.003 μmol‐PO 4 kg −1 yr −1 and 0.005°C yr −1 in both two oceanic areas. The changes of O 2 , PO 4 and T in the two oceanic areas were synchronized despite the water formation systems of each area being independent. Both the linear trends and the oscillations of O 2 , PO 4 and T in the two oceanic areas also showed a strong correlation with the anomaly of the sea surface level pressure in the North Pacific that possibly affects the change of surface oceanic condition.