Climatological distribution of aragonite saturation state in the global oceans

Type Article
Date 2015-10
Language English
Author(s) Jiang Li-Qing1, Feely Richard A.2, Carter Brendan R.3, Greeley Dana J.2, Gledhill Dwight K.4, Arzayus Krisa M.5
Affiliation(s) 1 : Univ Maryland, Cooperat Inst Climate & Satellites, Earth Syst Sci Interdisciplinary Ctr, College Pk, MD 20742 USA.
2 : NOAA, Pacific Marine Environm Lab, Seattle, WA 98115 USA.
3 : Univ Washington, Joint Inst Study Atmosphere & Ocean, Seattle, WA 98195 USA.
4 : NOAA, Ocean Acidificat Program, Silver Spring, MD USA.
5 : NOAA, Natl Ctr Environm Informat, Silver Spring, MD USA.
Source Global Biogeochemical Cycles (0886-6236) (Amer Geophysical Union), 2015-10 , Vol. 29 , N. 10 , P. 1656-1673
DOI 10.1002/2015GB005198
WOS© Times Cited 125
Abstract Aragonite saturation state (Ωarag) in surface and subsurface waters of the global oceans was calculated from up-to-date (through the year of 2012) ocean station dissolved inorganic carbon (DIC) and total alkalinity (TA) data. Surface Ωarag in the open ocean was always supersaturated (Ω > 1), ranging between 1.1 and 4.2. It was above 2.0 (2.0–4.2) between 40°N and 40°S but decreased toward higher latitude to below 1.5 in polar areas. The influences of water temperature on the TA/DIC ratio, combined with the temperature effects on inorganic carbon equilibrium and apparent solubility product (K′sp), explain the latitudinal differences in surface Ωarag. Vertically, Ωarag was highest in the surface mixed layer. Higher hydrostatic pressure, lower water temperature, and more CO2 buildup from biological activity in the absence of air-sea gas exchange helped maintain lower Ωarag in the deep ocean. Below the thermocline, aerobic decomposition of organic matter along the pathway of global thermohaline circulation played an important role in controlling Ωarag distributions. Seasonally, surface Ωarag above 30° latitudes was about 0.06 to 0.55 higher during warmer months than during colder months in the open-ocean waters of both hemispheres. Decadal changes of Ωarag in the Atlantic and Pacific Oceans showed that Ωarag in waters shallower than 100 m depth decreased by 0.10 ± 0.09 (−0.40 ± 0.37% yr−1) on average from the decade spanning 1989–1998 to the decade spanning 1998–2010.
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