Quantifying CO2 Uptakes Over Oceans Using LIDAR: A Tentative Experiment in Bohai Bay

Oceans are widely regarded as major offsets for anthropogenic carbon emissions, leading to an evident lower measured atmospheric CO2 concentration than expected. It is thus of great significance to develop effective means to monitor CO2 fluxes over oceans globally. In this work, we utilized observations obtained by an airborne CO2-IPDA LIDAR to evaluate the potential of such means in estimating sea-air CO2 flux. During a flight experiment in 2019, we have estimated the CO2 exchange rate, -1.5 0.18 mmol/m(2)/h, between the Bohai Bay and the atmosphere using equilibrium atmospheric boundary layer theory. These findings indicated that the forthcoming space-borne CO2-IPDA LIDAR is capable of identifying CO2 uptakes over oceans qualitatively, which would be a novel means and a basis for monitoring CO2 fluxes over global oceans. Plain Language Summary Oceans are regarded as important offsets to anthropogenic CO2 emissions, delaying an increase in atmospheric CO2 concentration. However, there is a lack of understanding of the intensity, distribution, and variability of marine carbon sinks. China is due to launch a space-borne LIDAR for measuring atmospheric CO2 concentration globally in 2021. In this work, we utilized data collected during a flight test for the forthcoming satellite mission to explore the ability of such a novel means in revealing and estimating CO2 fluxes of oceans quantitatively. Results confirmed an evident CO2 uptake in the Bohai Bay and exhibited a promising prospect for the novel CO2 measuring means. Key Points We detected XCO2 gradient during a flight campaign in China Retrieve XCO2 in the atmosphere boundary layer by cloud slicing method Provide a model to retrieve CO2 flux over ocean by CO2-IPDA system

Automated summary

Oceans are considered significant offsets to anthropogenic CO2 emissions, with a need for effective monitoring of global sea-air CO2 fluxes. This study utilized data from a flight test to explore the potential of a novel means in estimating oceanic CO2 fluxes. The results confirmed CO2 uptake in the Bohai Bay and showed promise for the new CO2 measuring method.