open access

https://hdl.handle.net/2115/47344

Decreasing pH trend estimated from 25-yr time series of carbonate parameters in the western North Pacific

英語

2010-11

Blackwell Publishing

Tellus B

62(5)

649-659

We estimated long-term trends of ocean acidification in surface waters in latitudinal zones from 3°N to 33°N along the repeat hydrographic line at 137°E in the western North Pacific Ocean. Estimates were based on the observational records of oceanic CO2 partial pressure and related surface properties over the last two decades. The computed pH time series both for 25 years in winter (late January to early February) and for 21 years in summer (June to July) exhibited significant decreasing trends in the extensive subtropical to equatorial zones, with interannual variations that were larger in summer. The calculated rates of pH decrease ranged from 0.0015 to 0.0021 yr^[-1] (average, 0.0018 ± 0.0002 yr^[-1]) in winter and from 0.0008 to 0.0019 yr^[-1] (average, 0.0013 ± 0.0005 yr^[-1]) in summer. The thermodynamic effects of rising sea surface temperature (SST) accounted for up to 44% (average, 15%) of the trend of pH decrease in the subtropical region in winter, whereas a trend of decreasing SST slowed the pH decrease in the northern subtropical region (around 25°N) in summer. We used the results from recent trends to evaluate future possible thermodynamic changes in the upper ocean carbonate system.

学術雑誌論文

Accepted Manuscript

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