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Precipitation‐Induced Reduction in Surface Ocean pCO 2 : Observations From the Eastern Tropical Pacific Ocean
Author(s) -
Ho David T.,
Schanze Julian J.
Publication year - 2020
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl088252
Subject(s) - seawater , sink (geography) , salinity , oceanography , environmental science , precipitation , outgassing , atmospheric sciences , pacific ocean , climatology , geology , chemistry , meteorology , physics , cartography , organic chemistry , geography
Determining air‐sea CO 2 fluxes using pCO 2 disequilibrium requires knowing the gas transfer velocity and air‐sea pCO 2 difference. Most pCO 2 measurements are made from ships, whose uncontaminated seawater intakes are located at >5‐m depth to prevent ingestion of air. However, there could be bias in determinations of CO 2 fluxes if there is disagreement between pCO 2 measurements at the surface and 5 m. Seawater measurements made at the near surface and 5 m in the eastern Equatorial Pacific Ocean show that precipitation can dilute surface seawater salinity and lower the pCO 2 and dissolved inorganic carbon and raise pH of the same water, and that these changes in ocean chemistry are largely missed by measurements at 5 m. This finding implies that estimates of ocean CO 2 uptake might be underestimated, since rain will lower surface ocean pCO 2 in both source and sink regions and, hence, increase uptake in sink regions and decrease outgassing in source regions.