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Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 12, issue 18
Biogeosciences, 12, 5495-5514, 2015
https://doi.org/10.5194/bg-12-5495-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Biogeosciences, 12, 5495-5514, 2015
https://doi.org/10.5194/bg-12-5495-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 24 Sep 2015

Research article | 24 Sep 2015

Air–sea CO2 fluxes in the East China Sea based on multiple-year underway observations

X.-H. Guo1, W.-D. Zhai1,2, M.-H. Dai1, C. Zhang1, Y. Bai3, Y. Xu1, Q. Li1, and G.-Z. Wang1 X.-H. Guo et al.
  • 1State Key Laboratory of Marine Environmental Science, Xiamen University, 361102 Xiamen, China
  • 2National Environmental Monitoring Center, 116023 Dalian, China
  • 3State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, State Oceanic Administration, 310012 Hangzhou, China

Abstract. This study reports the most comprehensive data set thus far of surface seawater pCO2 (partial pressure of CO2) and the associated air–sea CO2 fluxes in a major ocean margin, the East China Sea (ECS), based on 24 surveys conducted in 2006 to 2011. We showed highly dynamic spatial variability in sea surface pCO2 in the ECS except in winter, when it ranged across a narrow band of 330 to 360 μatm. We categorized the ECS into five different domains featuring with different physics and biogeochemistry to better characterize the seasonality of the pCO2 dynamics and to better constrain the CO2 flux. The five domains are (I) the outer Changjiang estuary and Changjiang plume, (II) the Zhejiang–Fujian coast, (III) the northern ECS shelf, (IV) the middle ECS shelf, and (V) the southern ECS shelf. In spring and summer, pCO2 off the Changjiang estuary was as low as < 100 μatm, while it was up to > 400 μatm in autumn. pCO2 along the Zhejiang–Fujian coast was low in spring, summer and winter (300 to 350 μatm) but was relatively high in autumn (> 350 μatm). On the northern ECS shelf, pCO2 in summer and autumn was > 340 μatm in most areas, higher than in winter and spring. On the middle and southern ECS shelf, pCO2 in summer ranged from 380 to 400 μatm, which was higher than in other seasons (< 350 μatm). The area-weighted CO2 flux on the entire ECS shelf was −10.0 ± 2.0 in winter, −11.7 ± 3.6 in spring, −3.5 ± 4.6 in summer and −2.3 ± 3.1 mmol m−2 d−1 in autumn. It is important to note that the standard deviations in these flux ranges mostly reflect the spatial variation in pCO2 rather than the bulk uncertainty. Nevertheless, on an annual basis, the average CO2 influx into the entire ECS shelf was 6.9 ± 4.0 mmol m−2 d−1, about twice the global average in ocean margins.

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We report the most comprehensive data set of surface seawater pCO2 and air-sea CO2 fluxes in the East China Sea (ECS) based on 24 surveys conducted in 2006-2011. We categorized the ECS into five different domains characterized by different physics and biogeochemistry to better characterize the seasonality of the pCO2 dynamics and to better constrain the CO2 flux. The annual average CO2 influx into the entire ECS shelf was 6.9+/-4.0 mmol m-2 d-1, about twice the global average in an ocean margin.
We report the most comprehensive data set of surface seawater pCO2 and air-sea CO2 fluxes in the...
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