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estimates of CO 2 flux are sensitive to the rates of pCO 2 s increase used to constrain the long-term pCO 2 s change for each sub-region.

[1] The Japan Meteorological Agency has acquired dissolved oxygen (DO) concentration data each year since 1967 along the 137 E repeat section in the western North Pacific. In this data set we found significant regional temporal trends of decreasing or increasing DO concentrations on various isopycnal surfaces. DO decreases were particularly significant after the mid-1980s in the subtropical gyre; mean rates of DO change at 20-25 N for 1985-2010 À1 on 27.3 s q in the O 2 minimum Layer (OML). The cause of DO decrease differed among isopycnal surfaces. On density surfaces shallower than 26.0 s q (less than about 400 m), the deepening of isopycnal surfaces and decline of oxygen solubility due to ocean warming have had the greatest influence. In particular, between 25.2 s q and 25.8 s q near the NPSTMW their combined contributions accounted for >50% of the DO decrease. In the NPIW core at roughly 26.8 s q ($700 m), the decline in DO was attributable to the DO decrease in the formation region. In the OML between 27.0 s q and 27.3 s q ($1000 m), the DO decrease likely resulted from an increase in westward transport of low O 2 water due to strengthening of the subtropical gyre. The result of this study shows the importance of the long-term and high-frequency along the 137 E repeat section.Citation: Takatani, Y., D. Sasano, T. Nakano, T. Midorikawa, and M. Ishii (2012), Decrease of dissolved oxygen after the mid1980s in the western North Pacific subtropical gyre along the 137 E repeat section, Global Biogeochem. Cycles, 26, GB2013,

The 137°E repeat hydrographic section of the Japan Meteorological Agency across the western North Pacific was initiated in 1967 as part of the Cooperative Study of the Kuroshio and Adjacent Regions and has been continued biannually in winter and summer. The publicly available data from the section have been widely used to reveal seasonal to decadal variations and long-term changes of currents and water masses, biogeochemical and biological properties, and marine pollutants in relation to climate variability such as the El Niño-Southern Oscillation and the Pacific Decadal Oscillation. In commemoration of the 50th anniversary in 2016, this review summarizes the history and scientific achievements of the 137°E section during 1967-2016. Through the publication of more than 100 papers over this 50-year span, with the frequency and significance of the publication increasing in time, the 137°E section has demonstrated its importance for future investigations of physical-biogeochemical-biological interactions on various spatiotemporal scales, and thereby its utility in enhancing process understanding to aid projections of the impact of future climate change on ocean resources and ecosystems over the twentyfirst century.