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In this study, we map and describe both surface and subsurface pH distributions in the global ocean based on the recently released Global Ocean Data Analysis Project Version 2 (GLODAPv2) database, and discuss their mechanisms. Gridded surface ocean pH ranges between 7.77 and 8.35 globally, with an area-averaged surface pH of 8.08. Surface pH is mainly controlled by water temperature and the ratio of total alkalinity and dissolved inorganic carbon. Vertically, pH is highest in the surface mixed layer, but unlike calcium carbonate saturation state, minimum pH is often found in mid-water depths ranging from 200 to 2000 m. Subsurface pH shows large differences among the major ocean basins. Aerobic respiration within the global thermohaline circulation plays a major role in shaping out the subsurface pH distribution. In addition, subsurface pH is also controlled by temperature, and pressure. Decreasing temperature with depth increases pH, and increasing pressure lowers pH, so that at about 6000 meters, these two effects cancel out each other. Multi-Linear regression equations between pH and temperature, salinity and dissolved oxygen are derived from the subsurface data at 160 nodes covering the entire Indian, Pacific and Atlantic Oceans to provide monthly pH climatologies for the subsurface ocean.


Jiang, L., University of Maryland, USA,

Feely, R. A., NOAA Pacific Marine Environmental Laboratory, USA,

Lauvset, S. K., University of Bergen, Norway,

Carter, B., NOAA Pacific Marine Environmental Laboratory, USA,

olsen, A., University of Bergen, Norway,


Oral presentation

Session #:056
Date: 03/01/2017
Time: 10:15
Location: 305 A/B

Presentation is given by student: No