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Atmospheric Measurement Techniques An interactive open-access journal of the European Geosciences Union
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Volume 11, issue 5 | Copyright
Atmos. Meas. Tech., 11, 2879-2896, 2018
https://doi.org/10.5194/amt-11-2879-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 17 May 2018

Research article | 17 May 2018

The influence of instrumental line shape degradation on NDACC gas retrievals: total column and profile

Youwen Sun1,3,*, Mathias Palm2,*, Cheng Liu3,4,1, Frank Hase5, David Griffith6, Christine Weinzierl2, Christof Petri2, Wei Wang1, and Justus Notholt2 Youwen Sun et al.
  • 1Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
  • 2University of Bremen, Institute of Environmental Physics, P.O. Box 330440, 28334 Bremen, Germany
  • 3Center for Excellence in Urban Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
  • 4University of Science and Technology of China, Hefei, 230026, China
  • 5Karlsruhe Institute of Technology (KIT), Institute for Meteorology and Climate Research (IMK-ASF), Karlsruhe, Germany
  • 6School of Chemistry, University of Wollongong, Northfields Ave, Wollongong, NSW, 2522, Australia
  • *These authors contributed equally to this work.

Abstract. We simulated instrumental line shape (ILS) degradations with respect to typical types of misalignment, and compared their influence on each NDACC (Network for Detection of Atmospheric Composition Change) gas. The sensitivities of the total column, the root mean square (rms) of the fitting residual, the total random uncertainty, the total systematic uncertainty, the total uncertainty, degrees of freedom for signal (DOFs), and the profile with respect to different levels of ILS degradation for all current standard NDACC gases, i.e. O3, HNO3, HCl, HF, ClONO2, CH4, CO, N2O, C2H6, and HCN, were investigated. The influence of an imperfect ILS on NDACC gases' retrieval was assessed, and the consistency under different meteorological conditions and solar zenith angles (SZAs) were examined. The study concluded that the influence of ILS degradation can be approximated by the linear sum of individual modulation efficiency (ME) amplitude influence and phase error (PE) influence. The PE influence is of secondary importance compared with the ME amplitude. Generally, the stratospheric gases are more sensitive to ILS degradation than the tropospheric gases, and the positive ME influence is larger than the negative ME. For a typical ILS degradation (10%), the total columns of stratospheric gases O3, HNO3, HCl, HF, and ClONO2 changed by 1.9, 0.7, 4, 3, and 23%, respectively, while the columns of tropospheric gases CH4, CO, N2O, C2H6, and HCN changed by 0.04, 2.1, 0.2, 1.1, and 0.75%, respectively. In order to suppress the fractional difference in the total column for ClONO2 and other NDACC gases within 10 and 1%, respectively, the maximum positive ME degradations for O3, HNO3, HCl, HF, ClONO2, CO, C2H6, and HCN should be less than 6, 15, 5, 5, 5, 5, 9, and 13%, respectively; the maximum negative ME degradations for O3, HCl, and HF should be less than 6, 12, and 12%, respectively; the influence of ILS degradation on CH4 and N2O can be regarded as being negligible.

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We simulated instrumental line shape (ILS) degradations with respect to typical types of misalignment, and compared their influence on each NDACC gas. The requirements to suppress the ILS-degradation-related biases within a specified accuracy for all NDACC gases were deduced.
We simulated instrumental line shape (ILS) degradations with respect to typical types of...
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