TY - JOUR
T1 - An evaluation of IASI-NH3 with ground-based Fourier transform infrared spectroscopy measurements
AU - Dammers, Enrico
AU - Palm, Mathias
AU - Van Damme, Martin
AU - Vigouroux, Corinne
AU - Smale, Dan
AU - Conway, Stephanie
AU - Toon, Geoffrey C.
AU - Jones, Nicholas
AU - Nussbaumer, Eric
AU - Warneke, Thorsten
AU - Petri, Christof
AU - Clarisse, Lieven
AU - Clerbaux, Cathy
AU - Hermans, Christian
AU - Lutsch, Erik
AU - Strong, Kim
AU - Hannigan, James W.
AU - Nakajima, Hideaki
AU - Morino, Isamu
AU - Herrera, Beatriz
AU - Stremme, Wolfgang
AU - Grutter, Michel
AU - Schaap, Martijn
AU - Kruit, Roy J.Wichink
AU - Notholt, Justus
AU - Coheur, Pierre F.
AU - Erisman, Jan Willem
PY - 2016/8/16
Y1 - 2016/8/16
N2 - Global distributions of atmospheric ammonia (NH3) measured with satellite instruments such as the Infrared Atmospheric Sounding Interferometer (IASI) contain valuable information on NH3 concentrations and variability in regions not yet covered by ground-based instruments. Due to their large spatial coverage and (bi-)daily overpasses, the satellite observations have the potential to increase our knowledge of the distribution of NH3 emissions and associated seasonal cycles. However the observations remain poorly validated, with only a handful of available studies often using only surface measurements without any vertical information. In this study, we present the first validation of the IASI-NH3 product using ground-based Fourier transform infrared spectroscopy (FTIR) observations. Using a recently developed consistent retrieval strategy, NH3 concentration profiles have been retrieved using observations from nine Network for the Detection of Atmospheric Composition Change (NDACC) stations around the world between 2008 and 2015. We demonstrate the importance of strict spatio-temporal collocation criteria for the comparison. Large differences in the regression results are observed for changing intervals of spatial criteria, mostly due to terrain characteristics and the short lifetime of NH3 in the atmosphere. The seasonal variations of both datasets are consistent for most sites. Correlations are found to be high at sites in areas with considerable NH3 levels, whereas correlations are lower at sites with low atmospheric NH3 levels close to the detection limit of the IASI instrument. A combination of the observations from all sites (Nobs Combining double low line 547) give a mean relative difference of ĝ'32.4ĝ€±ĝ€(56.3)ĝ€%, a correlation r of 0.8 with a slope of 0.73. These results give an improved estimate of the IASI-NH3 product performance compared to the previous upper-bound estimates (-50 to +100%).
AB - Global distributions of atmospheric ammonia (NH3) measured with satellite instruments such as the Infrared Atmospheric Sounding Interferometer (IASI) contain valuable information on NH3 concentrations and variability in regions not yet covered by ground-based instruments. Due to their large spatial coverage and (bi-)daily overpasses, the satellite observations have the potential to increase our knowledge of the distribution of NH3 emissions and associated seasonal cycles. However the observations remain poorly validated, with only a handful of available studies often using only surface measurements without any vertical information. In this study, we present the first validation of the IASI-NH3 product using ground-based Fourier transform infrared spectroscopy (FTIR) observations. Using a recently developed consistent retrieval strategy, NH3 concentration profiles have been retrieved using observations from nine Network for the Detection of Atmospheric Composition Change (NDACC) stations around the world between 2008 and 2015. We demonstrate the importance of strict spatio-temporal collocation criteria for the comparison. Large differences in the regression results are observed for changing intervals of spatial criteria, mostly due to terrain characteristics and the short lifetime of NH3 in the atmosphere. The seasonal variations of both datasets are consistent for most sites. Correlations are found to be high at sites in areas with considerable NH3 levels, whereas correlations are lower at sites with low atmospheric NH3 levels close to the detection limit of the IASI instrument. A combination of the observations from all sites (Nobs Combining double low line 547) give a mean relative difference of ĝ'32.4ĝ€±ĝ€(56.3)ĝ€%, a correlation r of 0.8 with a slope of 0.73. These results give an improved estimate of the IASI-NH3 product performance compared to the previous upper-bound estimates (-50 to +100%).
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U2 - 10.5194/acp-16-10351-2016
DO - 10.5194/acp-16-10351-2016
M3 - Article
AN - SCOPUS:84983238976
SN - 1680-7316
VL - 16
SP - 10351
EP - 10368
JO - Atmospheric Chemistry and Physics
JF - Atmospheric Chemistry and Physics
IS - 16
ER -