Affiliation:
1. Division of Earth and Climate Sciences Nicholas School of the Environment Duke University Durham NC USA
2. College of Oceanography Hohai University Nanjing China
3. Nicholas School of the Environment Duke University Durham NC USA
4. Department of Civil and Environmental Engineering Duke University Durham NC USA
5. CNRS Univ Brest IRD Ifremer LEMAR Plouzané France
Abstract
AbstractThe global air‐sea CO2 flux (F) impacts and is impacted by a plethora of climate‐related processes operating at multiple time scales. In bulk mass transfer formulations, F is driven by physico‐ and bio‐chemical factors such as the air‐sea partial pressure difference (∆pCO2), gas transfer velocity, sea surface temperature, and salinity–all varying at multiple time scales. To de‐convolve the impact of these factors on variability in F at different time scales, time‐resolved estimates of F were computed using a global data set assembled between 1988 and 2015. The F anomalies were defined as temporal deviations from the 28‐year time‐averaged value. Spectral analysis revealed four dominant timescales of variability in F–subseasonal, seasonal, interannual, and decadal with relative amplitude differences varying across regions. A second‐order Taylor series expansion was then conducted along these four timescales to separate drivers across differing regions. The analysis showed that on subseasonal timescales, wind speed variability explains some 66% of the global F anomaly and is the dominant driver. On seasonal, interannual, and decadal timescales, the ∆pCO2 effect controlled by the ∆pCO2 anomaly, explained much of the F anomaly. On decadal timescales, the F anomaly was almost entirely governed by the ∆pCO2 effect with large contributions from high latitudes. The main drivers across timescales also dominate the regional F anomaly, particularly in the mid‐high latitude regions. Finally, the driver of the ∆pCO2 effect was closely connected with the relative strength of atmospheric pCO2 and the nonthermal component of oceanic pCO2 anomaly associated with dissolved inorganic carbon and alkalinity.
Funder
China Scholarship Council
National Science Foundation
U.S. Department of Energy
Publisher
American Geophysical Union (AGU)
Subject
Paleontology,Atmospheric Science,Soil Science,Water Science and Technology,Ecology,Aquatic Science,Forestry
Cited by
3 articles.
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