Articles | Volume 8, issue 3
Atmos. Meas. Tech., 8, 1575–1591, 2015
Atmos. Meas. Tech., 8, 1575–1591, 2015

Research article 26 Mar 2015

Research article | 26 Mar 2015

Towards validation of ammonia (NH3) measurements from the IASI satellite

M. Van Damme1,2, L. Clarisse1, E. Dammers2, X. Liu3, J. B. Nowak4,5,*, C. Clerbaux1,6, C. R. Flechard7, C. Galy-Lacaux8, W. Xu3, J. A. Neuman4,5, Y. S. Tang9, M. A. Sutton9, J. W. Erisman2,10, and P. F. Coheur1 M. Van Damme et al.
  • 1Spectroscopie de l'atmosphère, Chimie Quantique et Photophysique, Université Libre de Bruxelles, Brussels, Belgium
  • 2Cluster Earth and Climate, Department of Earth Sciences, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
  • 3College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China
  • 4Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado, USA
  • 5Chemical Sciences Division, Earth System Research Laboratory, NOAA, Boulder, Colorado, USA
  • 6UPMC; Université Versailles St. Quentin; CNRS/INSU, LATMOS-IPSL, Paris, France
  • 7INRA, Agrocampus Ouest, UMR 1069 SAS, Rennes, France
  • 8Laboratoire d'Aérologie, UMR 5560, Université Paul-Sabatier (UPS) and CNRS, Toulouse, France
  • 9Centre for Ecology and Hydrology, Edinburgh Research Station, Bush Estate, Penicuik, Midlothian EH26 0QB, UK
  • 10Louis Bolk Institute, Driebergen, the Netherlands
  • *now at: Aerodyne Research, Inc., Billerica, MA, USA

Abstract. 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 NH3 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-NH3 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 NH3 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-NH3 columns are discussed. Perspectives and guidelines for future validation work on NH3 satellite observations are presented.

Short summary
In this study, comprehensive ground-based data sets (Europe, China, Africa and United States) are used to evaluate NH3 measurements from IASI. Global yearly and regional monthly comparisons show fair agreement, while hourly measurements are used to investigate the limitations of direct comparisons. In addition, dense airborne measurements are explored and show the highest correlation coefficients in this study. Finally, the urgent need for independent NH3 column measurements is discussed.