Trend detection in satellite observations of formaldehyde tropospheric columns

Being an intermediate product in the oxidation of a large number of non-methane volatile organic compounds (NMVOCs), formaldehyde (H2CO) is a useful indicator of biogenic, pyrogenic and anthropogenic hydrocarbon emissions. We present the first trend study performed on H2CO satellite columns, retrieved from the GOME and SCIAMACHY instruments between 1997 and 2009. A linear model with a seasonal component is used to fit the time series of monthly averaged columns. The error and statistical significance of the inferred trends are estimated. The study focuses on Asia but results are also provided for large cities worldwide. Statistically significant positive trends of formaldehyde columns are observed over northeastern China (4% yr(-1)) and India (1.6% yr(-1)), related to strong increases in anthropogenic NMVOC emissions, whereas negative trends of about -3% yr(-1) are observed over Tokyo as well as over cities of the northeast U.S. urban corridor as a result of effective pollution regulation measures. Citation: De Smedt, I., T. Stavrakou, J.-F. Muller, R. J. van der A, and M. Van Roozendael (2010), Trend detection in satellite observations of formaldehyde tropospheric columns, Geophys. Res. Lett., 37, L18808, doi: 10.1029/2010GL044245.