Characterisation of methane variability and trends from near-infrared solar spectra over Hefei, China

Tian, Yuan; Sun, Youwen; Liu, Cheng; Wang, Wei; Shan, Changgong; Xu, Xiangde; Hu, Qihou

doi:10.1016/j.atmosenv.2017.11.001

Cited by 26 publications

(26 citation statements)

References 25 publications

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“…The ground-based FTS instrument, located west of Hefei (117.17 • E, 31.9 • N), is a candidate station for the Network for Detection of Atmospheric Composition Change (NDACC, http://www.ndacc.org/, last access: 8 May 2019). The global NDACC can perform simultaneous retrieval of mixing ratio profiles for trace gases, such as O 3 , CO, CH 4 , NO 2 , and HCHO, using FTS (Kurylo, 1991;Notholt et al, 1995;Vigouroux et al, 2009), and the retrieval results have been widely used for atmospheric chemistry research and the validation of satellite observations (Yuan et al, 2015;Tian et al, 2018;Sun et al, 2018). The observation system consists of a high-resolution Fourier transform spectrometer (IFS 125HR), a solar tracker (Tracker-A solar 547), and a weather station (ZENO-3200).…”

Section: Fts Tropospheric Hcho Column Measurementmentioning

confidence: 99%

Primary and secondary sources of ambient formaldehyde in the Yangtze River Delta based on Ozone Mapping and Profiler Suite (OMPS) observations

Liu

et al. 2019

Atmos. Chem. Phys.

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Formaldehyde (HCHO) in the ambient air not only causes cancer but is also an ideal indicator of volatile organic compounds (VOCs), which are major precursors of ozone (O 3 ) and secondary organic aerosol (SOA) near the surface. It is meaningful to differentiate between the direct emission and the secondary formation of HCHO for HCHO pollution control and sensitivity studies of O 3 production. However, understanding of the sources of HCHO is still poor in China, due to the scarcity of field measurements (both spatially and temporally). In this study, tropospheric HCHO vertical column densities (VCDs) in the Yangtze River Delta (YRD), East China, where HCHO pollution is serious, were retrieved from the Ozone Mapping and Profiler Suite (OMPS) onboard the Suomi National Polar-orbiting Partnership (Suomi-NPP) satellite from 2014 to 2017; these retrievals showed good agreement with the tropospheric HCHO columns measured using ground-based high-resolution Fourier transform infrared spectrometry (FTS) with a correlation coefficient (R) of 0.78. Based on these results, the cancer risk was estimated both nationwide and in the YRD region. It was calculated that at least 7840 people in the YRD region would develop cancer in their lives due to outdoor HCHO exposure, which comprised 23.4 % of total national cancer risk. Furthermore, the contributions of primary and secondary sources were apportioned, in addition to primary and secondary tracers from surface observations. Overall, the HCHO from secondary formation contributed most to ambient HCHO and can be regarded as the indicator of VOC reactivity in Hangzhou and in urban areas of Nanjing and Shanghai from 2015 to 2017, due to the strong correlation between total HCHO and secondary HCHO. At industrial sites in Nanjing, primary emissions more strongly influenced ambient HCHO concentrations in 2015 and showed an obvious decreasing trend. Seasonally, HCHO from secondary formation reached a maximum in summer and a minimum in winter. In the spring, summer, and autumn, secondary formation had a significant effect on the variation of ambient HCHO in urban regions of Nanjing, Hangzhou, and Shanghai, whereas in the winter the contribution from secondary formation became less significant. A more thorough understanding of the variation of the primary and secondary contributions of ambient HCHO is needed to develop a better knowledge regarding the role Published by Copernicus Publications on behalf of the European Geosciences Union. 6718 W. Su et al.: Primary and secondary sources of ambient formaldehyde in the Yangtze River Delta of HCHO in atmospheric chemistry and to formulate effective control measures to decrease HCHO pollution and the associated cancer risk.

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Section: Fts Tropospheric Hcho Column Measurementmentioning

confidence: 99%

Primary and secondary sources of ambient formaldehyde in the Yangtze River Delta based on Ozone Mapping and Profiler Suite (OMPS) observations

Liu

et al. 2019

Atmos. Chem. Phys.

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“…In the absence of such information, the formaldehyde (HCHO) concentration can be used as a proxy for VOC reactivity because it is a short-lived oxidation product of many VOCs and is positively correlated with peroxy radicals (Schroeder et al, 2017). Sillman (1995a) and Tonnesen and Dennis (2000) found that in situ measurements of the ratio of HCHO (a marker of VOCs) to NO 2 (a marker of NO x ) could be used to diagnose local photochemical regimes. Over polluted areas, both HCHO and tropospheric NO 2 have vertical distributions that are heavily weighted toward the lower troposphere, indicating that tropospheric-column measurements of these gases are fairly representative of near-surface conditions.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2018

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Abstract. The seasonal evolution of O3 and its photochemical production regime in a polluted region of eastern China between 2014 and 2017 has been investigated using observations. We used tropospheric ozone (O3), carbon monoxide (CO), and formaldehyde (HCHO, a marker of VOCs (volatile organic compounds)) partial columns derived from high-resolution Fourier transform spectrometry (FTS); tropospheric nitrogen dioxide (NO2, a marker of NOx (nitrogen oxides)) partial column deduced from the Ozone Monitoring Instrument (OMI); surface meteorological data; and a back trajectory cluster analysis technique. A broad O3 maximum during both spring and summer (MAM/JJA) is observed; the day-to-day variations in MAM/JJA are generally larger than those in autumn and winter (SON/DJF). Tropospheric O3 columns in June are 1.55×1018 molecules cm−2 (56 DU (Dobson units)), and in December they are 1.05×1018 molecules cm−2 (39 DU). Tropospheric O3 columns in June were ∼50 % higher than those in December. Compared with the SON/DJF season, the observed tropospheric O3 levels in MAM/JJA are more influenced by the transport of air masses from densely populated and industrialized areas, and the high O3 level and variability in MAM/JJA is determined by the photochemical O3 production. The tropospheric-column HCHO∕NO2 ratio is used as a proxy to investigate the photochemical O3 production rate (PO3). The results show that the PO3 is mainly nitrogen oxide (NOx) limited in MAM/JJA, while it is mainly VOC or mixed VOC–NOx limited in SON/DJF. Statistics show that NOx-limited, mixed VOC–NOx-limited, and VOC-limited PO3 accounts for 60.1 %, 28.7 %, and 11 % of days, respectively. Considering most of PO3 is NOx limited or mixed VOC–NOx limited, reductions in NOx would reduce O3 pollution in eastern China.

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“…In this paper, we investigate the potential of ground-based FTS to accurately and precisely determine temporal variability of atmospheric CO 2 and CO at our measurement site in Hefei, China, and assess the ability of our observations to validate satellite data. Methane was also retrieved from the solar spectra and these results will be the subject of a separate publication (Tian et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Investigating the performance of a greenhouse gas observatory in Hefei, China

et al. 2017

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Abstract. A ground-based high-resolution Fourier transform spectrometer (FTS) station has been established in Hefei, China to remotely measure CO 2 , CO and other greenhouse gases based on near-infrared solar absorption spectra. Total column measurements of atmospheric CO 2 and CO were successfully obtained from July 2014 to April 2016. The spectra collected with an InSb detector in the first year were compared with those collected by an InGaAs detector from July 2015, demonstrating that InGaAs spectra have better signal-to-noise ratios and rms of spectral fitting residuals relative to InSb spectra. Consequently, the measurement precision of the retrieved XCO 2 and XCO for InGaAs spectra is superior to InSb spectra, with about 0.04 and 0.09 % for XCO 2 , and 1.07 and 2.00 % for XCO within clear-sky days respectively. Daily and monthly averages of columnaveraged dry air mole fraction of CO 2 show a clear seasonal cycle, while the daily and monthly averages of XCO displayed no seasonal variation. Also, we analysed the relationship of the anomalies of XCO and XCO 2 , found that the correlations are only observable for individual days, and the data under different prevailing wind conditions during the observations displayed weak correlation. The observations based on the high-resolution FTS were also compared with the temporally coinciding measurements taken with a low-resolution solar FTS instrument, the EM27/SUN. Ratioing the daily averaged XCO 2 of EM27 and FTS gives an overall calibration factor of 0.996 ± 0.001. We also compared ground-based observations from the Tsukuba TCCON station with our observations, the results showing that the variation in phase and seasonal amplitude of XCO 2 are similar to our results, but the variation of XCO in Tsukuba is quite different from our data in Hefei. To further evaluate our retrieved data, we made use of satellite measurements. The direct comparison of our observations with the Greenhouse Gases Observing Satellite (GOSAT) data shows good agreement of daily median XCO 2 , with a bias of −0.52 ppm and standard deviation of 1.63 ppm. The correlation coefficient (R 2 ) is 0.79 for daily median XCO 2 between our FTS and GOSAT observations. Daily median Orbiting Carbon Observatory 2 (OCO-2) data produce a positive bias of 0.81 ppm and standard deviation of 1.73 ppm relative to our ground-based data. Our daily median XCO 2 also show strong correlation with OCO-2 data, with correlation coefficient (R 2 ) of 0.83. Although there were a limited number of data during the observations due to instrument downtime and adverse weather, the results confirm the suitability of the observatory for ground-based long-term measurements of greenhouse gases with high precision and

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Characterisation of methane variability and trends from near-infrared solar spectra over Hefei, China

Cited by 26 publications

References 25 publications

Primary and secondary sources of ambient formaldehyde in the Yangtze River Delta based on Ozone Mapping and Profiler Suite (OMPS) observations

Primary and secondary sources of ambient formaldehyde in the Yangtze River Delta based on Ozone Mapping and Profiler Suite (OMPS) observations

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

Investigating the performance of a greenhouse gas observatory in Hefei, China

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