Sea surface pCO2 dynamics in the East China Sea and its controlling processes based on buoy time series observations
Yaohua Luo 1, Zhirong Zhang 1, Xianghui Guo 1,2, *
1. College of Ocean and Earth Sciences, Xiamen University, China
2. State Key Laboratory of Marine Environmental Science (Xiamen University)
The sea surface partial pressure of carbon dioxide (pCO2) is quite dynamic in coastal oceans. In this study we examined the seasonal variability of sea surface pCO2 and its controlling processes at a buoy site in the East China Sea (122.8°E, 31°N). The seasonal average pCO2 was 351 ± 68 μatm, 357 ± 138 μatm, 474 ± 80 μatm, and 382 ± 15 μatm respectively from spring to winter, and was overall undersaturated with respect to atmosphere on a yearly basis. Sea surface pCO2 ranged from 68 to 806 μatm over the whole year and exhibited remarkably large variability in summer. The amplitude of daily averaged pCO2 ranged from 327 to 529 μatm from May to September, while it was only 36 to 87 μatm from October to April. The controls of sea surface pCO2 variability differ seasonally. In cold months from November to March, horizontal mixing between multiple end-members control the monthly pCO2 variations. In warm months from May to September, biological activity was the predominant factor in controlling monthly pCO2 variations. For the transition months, April and October, mixing, moderate biological uptake and temperature effects influenced the monthly pCO2 variations together.
Keywords: pCO2 dynamics, East China Sea, time-series observations
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