Retrieval of ammonia from ground-based FTIR solar spectra

We present a retrieval method for ammonia (NH<sub>3</sub>) total columns from ground-based Fourier transform infrared (FTIR) observations. Observations from Bremen (53.10° N, 8.85° E), Lauder (45.04° S, 169.68° E), Réunion (20.9° S, 55.50° E) and Jungfraujoch (46.55° N, 7.98° E) were use...

Full description

Bibliographic Details
Main Authors: E. Dammers, C. Vigouroux, M. Palm, E. Mahieu, T. Warneke, D. Smale, B. Langerock, B. Franco, M. Van Damme, M. Schaap, J. Notholt, J. W. Erisman
Format: Article
Language:English
Published: Copernicus Publications 2015-11-01
Series:Atmospheric Chemistry and Physics
Online Access:http://www.atmos-chem-phys.net/15/12789/2015/acp-15-12789-2015.pdf
Description
Summary:We present a retrieval method for ammonia (NH<sub>3</sub>) total columns from ground-based Fourier transform infrared (FTIR) observations. Observations from Bremen (53.10° N, 8.85° E), Lauder (45.04° S, 169.68° E), Réunion (20.9° S, 55.50° E) and Jungfraujoch (46.55° N, 7.98° E) were used to illustrate the capabilities of the method. NH<sub>3</sub> mean total columns ranging 3 orders of magnitude were obtained, with higher values at Bremen (mean of 13.47 &times; 10<sup>15</sup> molecules cm<sup>−2</sup>) and lower values at Jungfraujoch (mean of 0.18 &times; 10<sup>15</sup> molecules cm<sup>&minus;2</sup>). In conditions with high surface concentrations of ammonia, as in Bremen, it is possible to retrieve information on the vertical gradient, as two layers can be distinguished. The retrieval there is most sensitive to ammonia in the planetary boundary layer, where the trace gas concentration is highest. For conditions with low concentrations, only the total column can be retrieved. Combining the systematic and random errors we have a mean total error of 26 % for all spectra measured at Bremen (number of spectra (<I>N</I>) = 554), 30 % for all spectra from Lauder (<I>N</I> = 2412), 25 % for spectra from Réunion (<I>N</I> = 1262) and 34 % for spectra measured at Jungfraujoch (<I>N</I> = 2702). The error is dominated by the systematic uncertainties in the spectroscopy parameters. Station-specific seasonal cycles were found to be consistent with known seasonal cycles of the dominant ammonia sources in the station surroundings. The developed retrieval methodology from FTIR instruments provides a new way of obtaining highly time-resolved measurements of ammonia burdens. FTIR-NH<sub>3</sub> observations will be useful for understanding the dynamics of ammonia concentrations in the atmosphere and for satellite and model validation. It will also provide additional information to constrain the global ammonia budget.
ISSN:1680-7316
1680-7324