Ribas-Ribas, Mariana and Battaglia, Gianna and Humphreys, Matthew P. and Wurl, Oliver (2019) Impact of Nonzero Intercept Gas Transfer Velocity Parameterizations on Global and Regional Ocean–Atmosphere CO2 Fluxes. Geosciences, 9 (5). p. 230. ISSN 2076-3263

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Abstract

Carbon dioxide (CO2) fluxes between the ocean and atmosphere (FCO2) are commonly computed from differences between their partial pressures of CO2 (ΔpCO2) and the gas transfer velocity (k). Commonly used wind-based parameterizations for k imply a zero intercept, although in situ field data below 4 m s−1 are scarce. Considering a global average wind speed over the ocean of 6.6 m s−1, a nonzero intercept might have a significant impact on global FCO2. Here, we present a database of 245 in situ measurements of k obtained with the floating chamber technique (Sniffle), 190 of which have wind speeds lower than 4 m s−1. A quadratic parameterization with wind speed and a nonzero intercept resulted in the best fit for k. We further tested FCO2 calculated with a different parameterization with a complementary pCO2 observation-based product. Furthermore, we ran a simulation in a well-tested ocean model of intermediate complexity to test the implications of different gas transfer velocity parameterizations for the natural carbon cycle. The global ocean observation-based analysis suggests that ignoring a nonzero intercept results in an ocean-sink increase of 0.73 Gt C yr−1. This corresponds to a 28% higher uptake of CO2 compared with the flux calculated from a parameterization with a nonzero intercept. The differences in FCO2 were higher in the case of low wind conditions and large ΔpCO2 between the ocean and atmosphere. Such conditions occur frequently in the Tropics.

Item Type:	Article
Additional Information:	Publiziert mit Hilfe des DFG-geförderten Open Access-Publikationsfonds der Carl von Ossietzky Universität Oldenburg.
Uncontrolled Keywords:	gas transfer velocity, low wind speed, carbon dioxide, ocean-atmosphere CO2 flux, carbon cycle
Subjects:	Science and mathematics > Physics Science and mathematics > Earth sciences and geology
Divisions:	Faculty of Mathematics and Science > Institute for Chemistry and Biology of the Marine Environment (ICBM)
Date Deposited:	19 Mar 2020 09:11
Last Modified:	19 Mar 2020 09:11
URI:	https://oops.uni-oldenburg.de/id/eprint/4503
URN:	urn:nbn:de:gbv:715-oops-45845
DOI:	10.3390/geosciences9050230
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