Limited availability of ammonia (NH3) observations is currently a barrier for effective monitoring of the nitrogen cycle. It prevents a full understanding of the atmospheric processes in which this trace gas is involved and therefore impedes determining its related budgets. Since the end of 2007, the Infrared Atmospheric Sounding Interferometer (IASI) satellite has been observing NH<inf>3</inf> from space at a high spatio-temporal resolution. This valuable data set, already used by models, still needs validation. We present here a first attempt to validate IASI-NH<inf>3</inf> measurements using existing independent ground-based and airborne data sets. The yearly distributions reveal similar patterns between ground-based and space-borne observations and highlight the scarcity of local NH<inf>3</inf> measurements as well as their spatial heterogeneity and lack of representativity. By comparison with monthly resolved data sets in Europe, China and Africa, we show that IASI-NH3 observations are in fair agreement, but they are characterized by a smaller variation in concentrations. The use of hourly and airborne data sets to compare with IASI individual observations allows investigations of the impact of averaging as well as the representativity of independent observations for the satellite footprint. The importance of considering the latter and the added value of densely located airborne measurements at various altitudes to validate IASI-NH<inf>3</inf> columns are discussed. Perspectives and guidelines for future validation work on NH<inf>3</inf> satellite observations are presented.
van Damme, M., Clarisse, L., Dammers, E., Liu, X., Nowak, J., Clerbaux, C., ... Coheur, P. F. (2015). Towards validation of ammonia (NH3) measurements from the IASI satellite. Atmospheric Measurement Techniques. https://doi.org/10.5194/amt-8-1575-2015