Long-Term Trends of Carbon Monoxide Total Columnar Amount in Urban Areas and Background Regions: Ground- and Satellite-based Spectroscopic Measurements

Abstract

A comparative study was carried out to explore carbon monoxide total columnar amount (CO TC) in background and polluted atmosphere, including the stations of ZSS (Zvenigorod), ZOTTO (Central Siberia), Peterhof, Beijing, and Moscow, during 1998–2014, on the basis of ground- and satellite-based spectroscopic measurements. Interannual variations of CO TC in different regions of Eurasia were obtained from ground-based spectroscopic observations, combined with satellite data from the sensors MOPITT (2001–14), AIRS (2003–14), and IASI MetOp-A (2010–13). A decreasing trend in CO TC (1998–2014) was found at the urban site of Beijing, where CO TC decreased by 1.14%±0.87% yr−1. Meanwhile, at the Moscow site, CO TC decreased remarkably by 3.73%±0.39% yr−1. In the background regions (ZSS, ZOTTO, Peterhof), the reduction was 0.9%–1.7% yr−1 during the same period. Based on the AIRSv6 satellite data for the period 2003–14, a slight decrease (0.4%–0.6% yr−1) of CO TC was detected over the midlatitudes of Eurasia, while a reduction of 0.9%–1.2% yr−1 was found in Southeast Asia. The degree of correlation between the CO TC derived from satellite products (MOPITTv6 Joint, AIRSv6 and IASI MetOp-A) and ground-based measurements was calculated, revealing significant correlation in unpolluted regions. While in polluted areas, IASI MetOp-A and AIRSv6 data underestimated CO TC by a factor of 1.5–2.8. On average, the correlation coefficient between ground- and satellite-based data increased significantly for cases with PBL heights greater than 500 m.