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

Abstract

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. O 3 , HNO 3 , HCl, HF, ClONO 2 , CH 4 , CO, N 2 O, C 2 H 6 , 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 O 3 , HNO 3 , HCl, HF, and ClONO 2 changed by 1.9, 0.7, 4, 3, and 23 %, respectively, while the columns of tropospheric gases CH 4 , CO, N 2 O, C 2 H 6 , 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 ClONO 2 and other NDACC gases within 10 and 1 %, respectively, the maximum positive ME degradations for O 3 , HNO 3 , HCl, HF, ClONO 2 , CO, C 2 H 6 , and HCN should be less than 6, 15, 5, 5, 5, 5, 9, and 13 %, respectively; the maximum negative ME degradations for O 3 , HCl, and HF should be less than 6, 12, and 12 %, respectively; the influence of ILS degradation on CH 4 and N 2 O can be regarded as being negligible.

Fourier transform infrared time series of tropospheric HCN in eastern China: seasonality, interannual variability, and source attribution

“…With the rapid economic growth in China over the past 3 decades, anthropogenic emissions have increased dramatically, raising concerns about worsening air quality in China (Tang et al, 2012;Chan, 2017;Xing et al, 2017;. These emissions are from automobile exhaust, industrial processes, and biomass burning.…”

“…S1 in the Supplement), but the relative contribution of biomass burning, automobile exhaust, and industrial processes is seldom mentioned in the literature (Tang et al, 2012;Chan, 2017;Wang et al, 2017;Sun et al, 2018a;Xing et al, 2017). This is because both industrial emissions and biomass burning are major sources of the trace gases (e.g., carbon monoxide (CO), formaldehyde (HCHO), and carbon dioxide (CO 2 )) that were used to evaluate regional emissions in the literature, and it is hard to quantify their relative contribution under the complex pollution conditions in China (Chan et al, 2018;Tang et al, 2012;Wang et al, 2017;Xiaoyan et al, 2010;Xing et al, 2017). It has been proven that HCN is an unambiguous tracer of biomass burning emission due to its inactive chemical feature and long lifetime (Rinsland et al, 2002;Zhao et al, 2002).…”

Ozone seasonal evolution and photochemical production regime in the polluted troposphere in eastern China derived from high-resolution Fourier transform spectrometry (FTS) observations

“…With the rapid increase in fossil fuel consumption in China over the past 3 decades, the emission of chemical precursors of O 3 (NO x and VOCs) has increased dramatically, surpassing that of North America and Europe and raising concerns about worsening O 3 pollution in China (Tang et al, 2012;Xing et al, 2017). Tropospheric O 3 was already included in the new air quality standard as a routine monitoring component (http://www.mep.gov.cn; last access: 23 May 2018), where the limit for the maximum daily 8 h average (MDA8) O 3 in urban and industrial areas is 160 µg m −3 (∼ 75 ppbv at 273 K, 101.3 kPa).…”

FTIR time series of tropospheric HCN in eastern China: seasonality, interannual variability and source attribution

“…The onset of the anthropogenic contribution begins in July with a maximum in December. In contrast to the anthropogenic influence, the onset of the oxidation contribution begins in January with a maximum in July, as a result of maximum NMVOC emissions in Summer (Sun et al, 2018b). For biomass burning contribution, two onsets were observed.…”

“…Ground based high-resolution Fourier Transform Spectroscopy (FTIR) measurements of trace gases made by Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences (AIOFM-CAS) at Hefei (117°10′E, 31°54′N, 30 m a.s.l. (above sea level)) is one of few multiyear time series of trace gases on Asian continent (Sun et al, 2018a;Sun et al, 2018b). These measurements are crucial to understanding global warming, regional pollution, and long term transport.…”