Adverse results of the economic crisis: A study on the emergence of enhanced formaldehyde (HCHO) levels seen from satellites over Greek urban sites

In order to study the years of the outbreak of the financial crisis in Greece, we use a continuous eight-year record (2008–2015) of formaldehyde, HCHO, columns retrieved from the GOME-2/MetOp-A and GOME-2/MetOp-B satellite instruments over two urban Greek regions, Thessaloniki and Athens. A statistical linear regression analysis that was applied to the GOME-2/MetOp-A HCHO time series over both cities revealed positive annual changes. On seasonal basis, the wintertime HCHO change per annum was found to be 7.43 ± 2.26% and 6.13 ± 2.12% over Thessaloniki and Athens, respectively. A corresponding seasonal time series analysis was also applied to tropospheric nitrogen dioxide, NO ₂ , levels. The tropospheric NO ₂ winter change per annum is shown to be negative, at −3.0 ± 0.13% and −3.94 ± 0.14% over Thessaloniki and Athens, respectively. The satellite HCHO and NO ₂ observations levels are comparable to collocated ground-based MAX-DOAS measurements. Furthermore, the Comprehensive Air Quality Model with extensions chemical transport model, CAMx CTM, as well as the driving emission inventory in CAMx are used for further investigation of the seasonality of the HCHO concentrations and emissions. The CTM model analysis of the annual HCHO cycle and the winter season anti-correlation between HCHO total columns and surface temperature, mostly over Thessaloniki (R = –0.3), point to the fact that the winter HCHO enhancements, likely connected with enhanced anthropogenic activities, are not being captured by the model. The results of this study indicate a possible enhanced anthropogenic activity during the winter season that was strengthened through the investigation on the origins of the wintertime increase in HCHO columns since the beginning of the economic crisis in the country.