We are grateful for Prof. Dean Roemmich and Dr. Nicholus Schneider for their helpful discussions and kind encouragement. We wish to express our sincere thanks to the members of the Physical Oceanography Group at Tohoku University for their help. Dr. Eitarou Oka kindly provided the quality-controlled Argo float data. Comments from two anonymous reviewers and the editor, Prof. Lynne Talley, greatly helped us to improve the presentation. The first author (HS) was supported by the 21st Century COE program “Advanced Science and Technology Center for Dynamic Earth” (E-ASTEC) at Tohoku University. The second author (TS) was partially supported by funds from the Japanese Society for Promotion of Science [Grants-in-Aid for Scientific Research (B) 13440138, 16340135, and 21340133 and (C) 22540455]; from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan, for the “Western Pacific Air-Sea Interaction Study” (W-PASS; Grants 19030004 and 21014004); and from the Agriculture, Forestry and Fisheries Research Council (AFFRC), Japan, which sponsored the Studies on Prediction and Application of Fish Species Alteration (SUPRFISH) project.
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