Atmospheric column CO₂ measurement from a new automatic ground-based sun photometer in Beijing from 2010 to 2012

Abstract. Carbon dioxide is generally regarded as the most important greenhouse gas affecting global warming. Many researches have been conducted to measure atmospheric CO₂ concentration, analyze CO₂ variation on both seasonal and interannual scales and predict future CO₂ tendencies. Among them, ground-based remote sensing observation of CO₂ is the essential approach to provide validation data for satellite observation owning to its much higher accuracy and column CO₂ measurement capability. Unlike the Fourier Transform Spectrometer, the sun photometer observation system introduced in this paper takes advantages of full-automation, easily portable and mobility to provide a non-supervised automatic field operational CO₂ observation approach. In this study we acquired the CO₂ measurements from 2010 to 2012 in Beijing, translated them to cloud free data, and designed an index related to column CO₂ amount. The diurnal and seasonal variations of atmospheric CO₂ acquired by the system were also analyzed. We compared our observation with the simulation of CarbonTracker model, and good agreements with the model suggested the long-term stability of the system and reasonability of the data processing method. The future work will focus on absolute CO₂ quantity retrieval and accuracy assessment of this observation system.