9:00 AM - 10:30 AM
[AAS07-P08] Examination of a method to detect nitrogen oxides originated from lightning by the combined use of ground-based and satellite remote sensing-From observations at Chiba and Fukue
Keywords:Lightning NOx, ground-based and satellite remote sensing
In recent years, there has been a growing concern about climate change and air pollution. Nitrogen oxides (NOx), recently also known as one of the Short Lived Climate Forcers (SLCFs), are not only an air pollutant but also a precursor of photochemical oxidants such as ozone, affecting human health, agricultural products, and climate. With this importance, the dominant source of NOx in the middle and upper troposphere is NOx originated from lightning (Lightning NOx; LNOx). It has been estimated that the amount of LNOx released into the atmosphere accounts for 10% of the total amount of global NOx emissions and it is the largest source of natural sources. However, the observation data for the evaluation of LNOx is limited. To overcome this problem, this study attempted to examine a method for detecting LNOx by combining ground-based remote sensing observation MAX-DOAS (Multi-Axis Differential Optical Absorption Spectroscopy) and satellite observation TROPOMI (TROPOspheric Monitoring Instrument). We focused on the data obtained at the Chiba and Fukue sites during the summer of 2021. The Chiba site is an area with high anthropogenic NOx emissions in the lower troposphere, while the Fukue site is an area with low anthropogenic NOx emissions.
At the Chiba site, the correlation analysis of NO2 column concentration data from both observations showed that the tropospheric NO2 column concentration of TROPOMI was higher than that of MAX-DOAS on July 31 and August 7, and was approximately twice as high as that of MAX-DOAS. This is thought to reflect the increase in NO2 in the middle and upper troposphere because MAX-DOAS observation is less sensitive to the middle and upper troposphere. To confirm this, we used data from LIghtning DEtection Network system (LIDEN) and backward trajectory analysis. We found that on both days, an air mass passed through the place where lightning occurred within one day before the observation. Therefore, it was found that the identified increase in NO2 column concentration may be affected by LNOx. At the Fukue site, the tropospheric NO2 column concentration of TROPOMI was higher than that of MAX-DOAS on all days. Therefore, it was difficult to distinguish between the day affected by LNOx and other days. To investigate the cause of this problem, by using LIDEN and backward trajectory analysis, we extracted the days that was potentially affected by LNOx. However, no significant differences in NO2 concentrations were found between the extracted days and other days. The NO2 concentrations at the Fukue site were lower than those at the Chiba site, suggesting that even if the Fukue site was affected by LNOx, it was not as strongly affected by LNOx as the Chiba site.
At the Chiba site, the correlation analysis of NO2 column concentration data from both observations showed that the tropospheric NO2 column concentration of TROPOMI was higher than that of MAX-DOAS on July 31 and August 7, and was approximately twice as high as that of MAX-DOAS. This is thought to reflect the increase in NO2 in the middle and upper troposphere because MAX-DOAS observation is less sensitive to the middle and upper troposphere. To confirm this, we used data from LIghtning DEtection Network system (LIDEN) and backward trajectory analysis. We found that on both days, an air mass passed through the place where lightning occurred within one day before the observation. Therefore, it was found that the identified increase in NO2 column concentration may be affected by LNOx. At the Fukue site, the tropospheric NO2 column concentration of TROPOMI was higher than that of MAX-DOAS on all days. Therefore, it was difficult to distinguish between the day affected by LNOx and other days. To investigate the cause of this problem, by using LIDEN and backward trajectory analysis, we extracted the days that was potentially affected by LNOx. However, no significant differences in NO2 concentrations were found between the extracted days and other days. The NO2 concentrations at the Fukue site were lower than those at the Chiba site, suggesting that even if the Fukue site was affected by LNOx, it was not as strongly affected by LNOx as the Chiba site.