Precipitation‐Induced Reduction in Surface Ocean pCO2: Observations From the Eastern Tropical Pacific Ocean. Issue 15 (6th August 2020)

• Record Type: Journal Article
• Authors: Ho, David T.; Schanze, Julian J.
• Is Part Of: Geophysical research letters. Volume 47:Issue 15(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-08-06
• Subjects: carbon cycling -- biogeochemical cycles, processes, and modeling -- gases; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2020GL088252
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Determining air‐sea CO2 fluxes using pCO2 disequilibrium requires knowing the gas transfer velocity and air‐sea pCO2 difference. Most pCO2 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 CO2 fluxes if there is disagreement between pCO2 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 pCO2 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 CO2 uptake might be underestimated, since rain will lower surface ocean pCO2 in both source and sink regions and, hence, increase uptake in sink regions and decrease outgassing in source regions. Key Points: Simultaneous measurements at the ocean surface and at 5 m show significant differences in pCO2 Rain affects surface ocean pCO2 by mainly by dilution but also by temperature change Rain‐induced changes in pCO2 could significantly bias the determination of global air‐sea CO2 fluxes