[en] We analyzed seasonality and interannual variability of tropospheric hydrogen cyanide (HCN) columns in densely populated eastern China for the first time. The results were derived from solar absorption spectra recorded with a ground-based high-spectral-resolution Fourier transform infrared (FTIR) spectrometer in Hefei (31°54′ N, 117°10′ E) between 2015 and 2018. The tropospheric HCN columns over Hefei, China, showed significant seasonal variations with three monthly mean peaks throughout the year. The magnitude of the tropospheric HCN column peaked in May, September, and December. The tropospheric HCN column reached a maximum monthly mean of (9.8±0.78)E15 molecules cm−2 in May and a minimum monthly mean of (7.16±0.75)E15 molecules cm−2 in November. In most cases, the tropospheric HCN columns in Hefei (32°N) are higher than the FTIR observations in Ny-Ålesund (79°N), Kiruna (68°N), Bremen (53°N), Jungfraujoch (47°N), Toronto (44°N), Rikubetsu (43°N), Izana (28°N), Mauna Loa (20°N), La Reunion Maido (21°S), Lauder (45°S), and Arrival Heights (78°S) that are affiliated with the Network for Detection of Atmospheric Composition Change (NDACC). Enhancements of tropospheric HCN column were observed between September 2015 and July 2016 compared to the same period of measurements in other years. The magnitude of the enhancement ranges from 5 % to 46 % with an average of 22 %. Enhancement of tropospheric HCN (ΔHCN) is correlated with the concurrent enhancement of tropospheric CO (ΔCO), indicating that enhancements of tropospheric CO and HCN were due to the same sources. The GEOS-Chem tagged CO simulation, the global fire maps, and the potential source contribution function (PSCF) values calculated using back trajectories revealed that the seasonal maxima in May are largely due to the influence of biomass burning in Southeast Asia (SEAS) (41±13.1 %), Europe and boreal Asia (EUBA) (21±9.3 %), and Africa (AF) (22±4.7 %). The seasonal maxima in September are largely due to the influence of biomass burnings in EUBA (38±11.3 %), AF (26±6.7 %), SEAS (14±3.3 %), and North America (NA) (13.8±8.4 %). For the seasonal maxima in December, dominant contributions are from AF (36±7.1 %), EUBA (21±5.2 %), and NA (18.7±5.2 %). The tropospheric HCN enhancement between September 2015 and July 2016 at Hefei (32°N) was attributed to an elevated influence of biomass burnings in SEAS, EUBA, and Oceania (OCE) in this period. In particular, an elevated number of fires in OCE in the second half of 2015 dominated the tropospheric HCN enhancement between September and December 2015. An elevated number of fires in SEAS in the first half of 2016 dominated the tropospheric HCN enhancement between January and July 2016.
Research center :
Sphères - SPHERES
Disciplines :
Earth sciences & physical geography
Author, co-author :
Sun, Y.
Liu, C.
Zhang, L.
Palm, M.
Notholt, J.
Yin, H.
Vigouroux, C.
Lutsch, E.
Wang, W.
Shan, C.
Blumenstock, T.
Nagahama, T.
Morino, I.
Mahieu, Emmanuel ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Groupe infra-rouge de phys. atmosph. et solaire (GIRPAS)
F.R.S.-FNRS - Fonds de la Recherche Scientifique [BE] Bundesamt für Meteorologie und Klimatologie MeteoSchweiz [CH] BELSPO - Politique scientifique fédérale [BE]
Akagi, S. K., Yokelson, R. J., Wiedinmyer, C., Alvarado, M. J., Reid, J. S., Karl, T., Crounse, J. D., and Wennberg, P. O.: Emission factors for open and domestic biomass burning for use in atmospheric models, Atmos. Chem. Phys., 11, 4039-4072, https://doi.org/10.5194/acp-11-4039-2011, 2011.
Akagi, S. K., Craven, J. S., Taylor, J.W., McMeeking, G. R., Yokelson, R. J., Burling, I. R., Urbanski, S. P.,Wold, C. E., Seinfeld, J. H., Coe, H., Alvarado, M. J., andWeise, D. R.: Evolution of trace gases and particles emitted by a chaparral fire in California, Atmos. Chem. Phys., 12, 1397-1421, https://doi.org/10.5194/acp-12-1397-2012, 2012.
Andreae, M. O. and Merlet, P.: Emission of trace gases and aerosols from biomass burning, Global Biogeochem. Cy., 15, 955-966, https://doi.org/10.1029/2000gb001382, 2001.
Ashbaugh, L. L., Malm, W. C., and Sadeh, W. Z.: A residence time probability analysis of sulfur concentrations at Grand Canyon National Park, Atmos. Environ., 19, 1263-1270, 1985.
Bange, H. W. and Williams, J.: New Directions: Acetonitrile in atmospheric and biogeochemical cycles, Atmos. Environ., 34, 4959-4960, https://doi.org/10.1016/s1352-2310(00)00364-2, 2000.
Barret, B., De Mazière, M., and Mahieu, E.: Ground-based FTIR measurements of CO from the Jungfraujoch: characterisation and comparison with in situ surface and MOPITT data, Atmos. Chem. Phys., 3, 2217-2223, https://doi.org/10.5194/acp-3-2217-2003, 2003.
Bertschi, I., Yokelson, R. J., Ward, D. E., Babbitt, R. E., Susott, R. A., Goode, J. G., and Hao, W. M.: Trace gas and particle emissions from fires in large diameter and belowground biomass fuels, J. Geophys. Res.-Atmos., 108, 8472, https://doi.org/10.1029/2002jd002100, 2003.
Bey, I., Jacob, D. J., Yantosca, R. M., Logan, J. A., Field, B. D., Fiore, A. M., Li, Q., Liu, H. Y., Mickley, L. J., and Schultz, M. G.: Global modeling of tropospheric chemistry with assimilated meteorology: Model description and evaluation, J. Geophys. Res., 106, 23073-23095, https://doi.org/10.1029/2001jd000807, 2001.
Chan, K. L.: Biomass burning sources and their contributions to the local air quality in Hong Kong, Sci. Total Environ., 596, 212-221, https://doi.org/10.1016/j.scitotenv.2017.04.091, 2017.
Chan, K. L.,Wiegner, M.,Wenig, M., and Poehler, D.: Observations of tropospheric aerosols and NO2 in Hong Kong over 5 years using ground based MAX-DOAS, Sci. Total Environ., 619, 1545-1556, https://doi.org/10.1016/j.scitotenv.2017.10.153, 2018.
De Mazière, M., Thompson, A. M., Kurylo, M. J., Wild, J. D., Bernhard, G., Blumenstock, T., Braathen, G. O., Hannigan, J. W., Lambert, J.-C., Leblanc, T., McGee, T. J., Nedoluha, G., Petropavlovskikh, I., Seckmeyer, G., Simon, P. C., Steinbrecht, W., and Strahan, S. E.: The Network for the Detection of Atmospheric Composition Change (NDACC): history, status and perspectives, Atmos. Chem. Phys., 18, 4935-4964, https://doi.org/10.5194/acp-18-4935-2018, 2018.
Di Giuseppe, F., Rémy, S., Pappenberger, F., andWetterhall, F.: Using the Fire Weather Index (FWI) to improve the estimation of fire emissions from fire radiative power (FRP) observations, Atmos. Chem. Phys., 18, 5359-5370, https://doi.org/10.5194/acp-18-5359-2018, 2018.
Dimitriou, K. and Kassomenos, P.: Three year study of tropospheric ozone with back trajectories at a metropolitan and a medium scale urban area in Greece, Sci. Total Environ., 502, 493-501, 2015.
Fisher, J. A., Murray, L. T., Jones, D. B. A., and Deutscher, N. M.: Improved method for linear carbon monoxide simulation and source attribution in atmospheric chemistry models illustrated using GEOS-Chem v9, Geosci. Model Dev., 10, 4129-4144, https://doi.org/10.5194/gmd-10-4129-2017, 2017.
Guenther, A. B., Jiang, X., Heald, C. L., Sakulyanontvittaya, T., Duhl, T., Emmons, L. K., and Wang, X.: The Model of Emissions of Gases and Aerosols from Nature version 2.1 (MEGAN2.1): an extended and updated framework for modeling biogenic emissions, Geosci. Model Dev., 5, 1471-1492, https://doi.org/10.5194/gmd-5-1471-2012, 2012.
Hase, F.: Improved instrumental line shape monitoring for the ground-based, high-resolution FTIR spectrometers of the Network for the Detection of Atmospheric Composition Change, Atmos. Meas. Tech., 5, 603-610, https://doi.org/10.5194/amt-5-603-2012, 2012.
Hase, F., Hannigan, J. W., Coffey, M. T., Goldman, A., Höpfner, M., Jones, N. B., Rinsland, C. P., and Wood, S. W.: Intercomparison of retrieval codes used for the analysis of high-resolution, ground-based FTIR measurements, J. Quant. Spectrosc. Ra., 87, 25-52, 2004.
Hoesly, R. M., Smith, S. J., Feng, L., Klimont, Z., Janssens-Maenhout, G., Pitkanen, T., Seibert, J. J., Vu, L., Andres, R. J., Bolt, R. M., Bond, T. C., Dawidowski, L., Kholod, N., Kurokawa, J.-I., Li, M., Liu, L., Lu, Z., Moura, M. C. P., O'Rourke, P. R., and Zhang, Q.: Historical (1750-2014) anthropogenic emissions of reactive gases and aerosols from the Community Emissions Data System (CEDS), Geosci. Model Dev., 11, 369-408, https://doi.org/10.5194/gmd-11-369-2018, 2018.
Holtslag, A. A. M. and Boville, B. A.: Local Versus Nonlocal Boundary-Layer Diffusion in a Global Climate Model, J. Climate, 6, 1825-1842, https://doi.org/10.1175/1520-0442(1993)006-1825:LVNBLD-2.0.CO;2, 1993.
Holzinger, R., Warneke, C., Hansel, A., Jordan, A., Lindinger, W., Scharffe, D. H., Schade, G., and Crutzen, P. J.: Biomass burning as a source of formaldehyde, acetaldehyde, methanol, acetone, acetonitrile, and hydrogen cyanide, Geophys. Res. Lett., 26, 1161-1164, https://doi.org/10.1029/1999gl900156, 1999.
Kaiser, A., Scheifinger, H., Spangl,W.,Weiss, A., Gilge, S., Fricke, W., Ries, L., Cemas, D., and Jesenovec, B.: Transport of nitrogen oxides, carbon monoxide and ozone to the alpine global atmosphere watch stations Jungfraujoch (Switzerland), Zugspitze and Hohenpeißenberg (Germany), Sonnblick (Austria) and Mt.Krvavec (Slovenia), Atmos. Environ., 41, 9273-9287, 2007.
Kaiser, J. W., Heil, A., Andreae, M. O., Benedetti, A., Chubarova, N., Jones, L., Morcrette, J.-J., Razinger, M., Schultz, M. G., Suttie, M., and van der Werf, G. R.: Biomass burning emissions estimated with a global fire assimilation system based on observed fire radiative power, Biogeosciences, 9, 527-554, https://doi.org/10.5194/bg-9-527-2012, 2012.
Li, M., Zhang, Q., Kurokawa, J.-I., Woo, J.-H., He, K., Lu, Z., Ohara, T., Song, Y., Streets, D. G., Carmichael, G. R., Cheng, Y., Hong, C., Huo, H., Jiang, X., Kang, S., Liu, F., Su, H., and Zheng, B.: MIX: a mosaic Asian anthropogenic emission inventory under the international collaboration framework of the MICS-Asia and HTAP, Atmos. Chem. Phys., 17, 935-963, https://doi.org/10.5194/acp-17-935-2017, 2017.
Li, Q., Palmer, P. I., Pumphrey, H. C., Bernath, P., and Mahieu, E.: What drives the observed variability of HCN in the troposphere and lower stratosphere?, Atmos. Chem. Phys., 9, 8531-8543, https://doi.org/10.5194/acp-9-8531-2009, 2009.
Li, Q. B., Jacob, D. J., Bey, I., Yantosca, R. M., Zhao, Y. J., Kondo, Y., and Notholt, J.: Atmospheric hydrogen cyanide (HCN): Biomass burning source, ocean sink?, Geophys. Res. Lett., 27, 357-360, https://doi.org/10.1029/1999gl010935, 2000.
Li, Q. B., Jacob, D. J., Yantosca, R. M., Heald, C. L., Singh, H. B., Koike, M., Zhao, Y. J., Sachse, G. W., and Streets, D. G.: A global three-dimensional model analysis of the atmospheric budgets of HCN and CH3CN: Constraints from aircraft and ground measurements, J. Geophys. Res.-Atmos., 108, 8827, https://doi.org/10.1029/2002jd003075, 2003.
Liu, H., Jacob, D., J., Bey, I., Yantosca, R., M., and Duncan, B., N.: Transport pathways for asian pollution outflow over the pacific: interannual and seasonal variations, J. Geophys. Res., 108, 8786, https://doi.org/10.1029/2002JD003102, 2003.
Liu, Y., Cobb, K. M., Song, H. M., Li, Q., Li, C. Y., Nakatsuka, T., An, Z. S., Zhou, W. J., Cai, Q. F., Li, J. B., Leavitt, S. W., Sun, C. F., Mei, R. C., Shen, C. C., Chan, M. H., Sun, J. Y., Yan, L. B., Lei, Y., Ma, Y. Y., Li, X. X., Chen, D. L., and Linderholm, H.W.: Recent enhancement of central Pacific El Nino variability relative to last eight centuries, Nat. Commun., 8, 15386, https://doi.org/10.1038/ncomms15386, 2017.
Lobert, J. M., Scharffe, D. H., Hao, W. M., and Crutzen, P. J.: Importance of biomass burning in the atmospheric budgets of nitrogen-containing gases, Nature, 346, 552-554, https://doi.org/10.1038/346552a0, 1990.
Lupu, A., Kaminski, J. W., Neary, L., McConnell, J. C., Toyota, K., Rinsland, C. P., Bernath, P. F., Walker, K. A., Boone, C. D., Nagahama, Y., and Suzuki, K.: Hydrogen cyanide in the upper troposphere: GEM-AQ simulation and comparison with ACE-FTS observations, Atmos. Chem. Phys., 9, 4301-4313, https://doi.org/10.5194/acp-9-4301-2009, 2009.
Lutsch, E., Dammers, E., Conway, S., and Strong, K.: Longrange transport of NH3, CO, HCN, and C2H6 from the 2014 Canadian Wildfires, Geophys. Res. Lett., 43, 8286-8297, https://doi.org/10.1002/2016gl070114, 2016.
Lutsch, E., Strong, K., Jones, D. B. A., Blumenstock, T., Conway, S., Fisher, J. A., Hannigan, J. W., Hase, F., Kasai, Y., Mahieu, E., Makarova, M., Morino, I., Nagahama, T., Notholt, J., Ortega, I., Palm, M., Poberovskii, A. V., Sussmann, R., and Warneke, T.: Detection and Attribution of Wildfire Pollution in the Arctic and Northern Mid-latitudes using a Network of FTIR Spectrometers and GEOS-Chem, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2019-881, in review, 2019.
Mahieu, E., Zander, R., Delbouille, L., Demoulin, P., Roland, G., and Servais, C.: Observed trends in total vertical column abundances of atmospheric gases from IR solar spectra recorded at the Jungfraujoch, J. Atmos. Chem., 28, 227-243, https://doi.org/10.1023/a:1005854926740, 1997.
Nagahama, Y. and Suzuki, K.: The influence of forest fires on CO, HCN, C2H6, and C2H2 over northern Japan measured by infrared solar spectroscopy, Atmos. Environ., 41, 9570-9579, https://doi.org/10.1016/j.atmosenv.2007.08.043, 2007.
Notholt, J., Toon, G. C., Rinsland, C. P., Pougatchev, N. S., Jones, N. B., Connor, B. J., Weller, R., Gautrois, M., and Schrems, O.: Latitudinal variations of trace gas concentrations in the free troposphere measured by solar absorption spectroscopy during a ship cruise, J. Geophys. Res.-Atmos., 105, 1337-1349, https://doi.org/10.1029/1999jd900940, 2000.
Polissar, A., Hopke, P., Paatero, P., Kaufmann, Y., Hall, D., Bodhaine, B., Dutton, E., and Harris, J.: The aerosol at Barrow, Alaska: long-term trends and source locations, Atmos. Environ., 33, 2441-2458, 1999.
Rémy, S., Veira, A., Paugam, R., Sofiev, M., Kaiser, J.W., Marenco, F., Burton, S. P., Benedetti, A., Engelen, R. J., Ferrare, R., and Hair, J. W.: Two global data sets of daily fire emission injection heights since 2003, Atmos. Chem. Phys., 17, 2921-2942, https://doi.org/10.5194/acp-17-2921-2017, 2017.
Rinsland, C. P., Jones, N. B., Connor, B. J., Wood, S. W., Goldman, A., Stephen, T. M., Murcray, F. J., Chiou, L. S., Zander, R., and Mahieu, E.: Multiyear infrared solar spectroscopic measurements of HCN, CO, C2H6, and C2H2 tropospheric columns above Lauder, New Zealand (45-S latitude), J. Geophys. Res.-Atmos., 107, 4185, https://doi.org/10.1029/2001jd001150, 2002.
Rinsland, C. P., Dufour, G., Boone, C. D., Bernath, P. F., Chiou, L., Coheur, P. F., Turquety, S., and Clerbaux, C.: Satellite boreal measurements over Alaska and Canada during June-July 2004: Simultaneous measurements of upper tropospheric CO, C2H6, HCN, CH3Cl, CH4, C2H2, CH3OH, HCOOH, OCS, and SF6 mixing ratios, Global Biogeochem. Cy., 21, Gb3008, https://doi.org/10.1029/2006gb002795, 2007.
Rodgers, C. D.: Inverse Methods for Atmospheric Sounding: Theory and Practice, Singapore, 2000.
Rodgers, C. D. and Connor, B. J.: Intercomparison of remote sounding instruments, J. Geophys. Res.-Atmos., 108, 4116, https://doi.org/10.1029/2002JD002299, 2003.
Rothman, L. S., Gordon, I. E., Barbe, A., Benner, D. C., Bernath, P. E., Birk, M., Boudon, V., Brown, L. R., Campargue, A., Champion, J. P., Chance, K., Coudert, L. H., Dana, V., Devi, V. M., Fally, S., Flaud, J. M., Gamache, R. R., Goldman, A., Jacquemart, D., Kleiner, I., Lacome, N., Lafferty, W. J., Mandin, J. Y., Massie, S. T., Mikhailenko, S. N., Miller, C. E., Moazzen-Ahmadi, N., Naumenko, O. V., Nikitin, A. V., Orphal, J., Perevalov, V. I., Perrin, A., Predoi-Cross, A., Rinsland, C. P., Rotger, M., Simeckova, M., Smith, M. A. H., Sung, K., Tashkun, S. A., Tennyson, J., Toth, R. A., Vandaele, A. C., and Vander Auwera, J.: The HITRAN 2008 molecular spectroscopic database, J. Quant. Spectrosc. Ra., 110, 533-572, https://doi.org/10.1016/j.jqsrt.2009.02.013, 2009.
Schaefer, H., Smale, D., Nichol, S. E., Bromley, T. M., Brailsford, G.W., Martin, R. J., Moss, R., Englund Michel, S., and White, J. W. C.: Limited impact of El Niño-Southern Oscillation on variability and growth rate of atmospheric methane, Biogeosciences, 15, 6371-6386, https://doi.org/10.5194/bg-15-6371-2018, 2018.
Sun, Y., Liu, C., Palm, M., Vigouroux, C., Notholt, J., Hu, Q., Jones, N., Wang, W., Su, W., Zhang, W., Shan, C., Tian, Y., Xu, X., De Mazière, M., Zhou, M., and Liu, J.: Ozone seasonal evolution and photochemical production regime in the polluted troposphere in eastern China derived from high-resolution Fourier transform spectrometry (FTS) observations, Atmos. Chem. Phys., 18, 14569-14583, https://doi.org/10.5194/acp-18-14569-2018, 2018.
Sun, Y., Palm, M., Liu, C., Hase, F., Griffith, D., Weinzierl, C., Petri, C., Wang, W., and Notholt, J.: The influence of instrumental line shape degradation on NDACC gas retrievals: total column and profile, Atmos. Meas. Tech., 11, 2879-2896, https://doi.org/10.5194/amt-11-2879-2018, 2018.
Tang, G., Wang, Y., Li, X., Ji, D., Hsu, S., and Gao, X.: Spatialtemporal variations in surface ozone in Northern China as observed during 2009-2010 and possible implications for future air quality control strategies, Atmos. Chem. Phys., 12, 2757-2776, https://doi.org/10.5194/acp-12-2757-2012, 2012.
Tian, Y., Sun, Y., Liu, C., Wang, W., Shan, C., Xu, X., and Hu, Q.: Characterisation of methane variability and trends from nearinfrared solar spectra over Hefei, China, Atmos. Environ., 173, 198-209, https://doi.org/10.1016/j.atmosenv.2017.11.001, 2017.
Viatte, C., Strong, K., Walker, K. A., and Drummond, J. R.: Five years of CO, HCN, C2H6, C2H2, CH3OH, HCOOH and H2CO total columns measured in the Canadian high Arctic, Atmos. Meas. Tech., 7, 1547-1570, https://doi.org/10.5194/amt-7-1547-2014, 2014.
Viatte, C., Strong, K., Hannigan, J., Nussbaumer, E., Emmons, L. K., Conway, S., Paton-Walsh, C., Hartley, J., Benmergui, J., and Lin, J.: Identifying fire plumes in the Arctic with tropospheric FTIR measurements and transport models, Atmos. Chem. Phys., 15, 2227-2246, https://doi.org/10.5194/acp-15-2227-2015, 2015.
Vigouroux, C., Stavrakou, T., Whaley, C., Dils, B., Duflot, V., Hermans, C., Kumps, N., Metzger, J.-M., Scolas, F., Vanhaelewyn, G., Müller, J.-F., Jones, D. B. A., Li, Q., and De Mazière, M.: FTIR time-series of biomass burning products (HCN, C2H6, C2H2, CH3OH, and HCOOH) at Reunion Island (21-S, 55-E) and comparisons with model data, Atmos. Chem. Phys., 12, 10367-10385, https://doi.org/10.5194/acp-12-10367-2012, 2012.
Wang, T., Xue, L. K., Brimblecombe, P., Lam, Y. F., Li, L., and Zhang, L.: Ozone pollution in China: A review of concentrations, meteorological influences, chemical precursors, and effects, Sci. Total Environ., 575, 1582-1596, https://doi.org/10.1016/j.scitotenv.2016.10.081, 2017.
Xiaoyan, W., Huixiang, W., and Shaoli, W.: Ambient formaldehyde and its contributing factor to ozone and OH radical in a rural area, Atmos. Environ., 44, 2074-2078, https://doi.org/10.1016/j.atmosenv.2010.03.023, 2010.
Xing, C., Liu, C.,Wang, S., Chan, K. L., Gao, Y., Huang, X., Su,W., Zhang, C., Dong, Y., Fan, G., Zhang, T., Chen, Z., Hu, Q., Su, H., Xie, Z., and Liu, J.: Observations of the vertical distributions of summertime atmospheric pollutants and the corresponding ozone production in Shanghai, China, Atmos. Chem. Phys., 17, 14275-14289, https://doi.org/10.5194/acp-17-14275-2017, 2017.
Yevich, R. and Logan, J. A.: An assessment of biofuel use and burning of agricultural waste in the developing world, Global Biogeochem. Cy., 17, 1095, https://doi.org/10.1029/2002GB001952, 2003.
Yin, X., Kang, S., de Foy, B., Cong, Z., Luo, J., Zhang, L., Ma, Y., Zhang, G., Rupakheti, D., and Zhang, Q.: Surface ozone at Nam Co in the inland Tibetan Plateau: variation, synthesis comparison and regional representativeness, Atmos. Chem. Phys., 17, 11293-11311, https://doi.org/10.5194/acp-17-11293-2017, 2017.
Yokelson, R. J., Susott, R., Ward, D. E., Reardon, J., and Griffith, D. W. T.: Emissions from smoldering combustion of biomass measured by open-path Fourier transform infrared spectroscopy, J. Geophys. Res.-Atmos., 102, 18865-18877, https://doi.org/10.1029/97jd00852, 1997.
York, D., Evensen, N. M., Martinez, M. L., and Delgado, J. D.: Unified equations for the slope, intercept, and standard errors of the best straight line, Am. J. Phys., 72, 367-375, https://doi.org/10.1119/1.1632486, 2004.
Zeng, G.,Wood, S.W., Morgenstern, O., Jones, N. B., Robinson, J., and Smale, D.: Trends and variations in CO, C2H6, and HCN in the Southern Hemisphere point to the declining anthropogenic emissions of CO and C2H6, Atmos. Chem. Phys., 12, 7543-7555, https://doi.org/10.5194/acp-12-7543-2012, 2012.
Zhang, C., Liu, C., Hu, Q., Cai, Z., Su, W., Xia, C., Zhu, Y., Wang, S., and Liu, J.: Satellite UV-Vis spectroscopy: implications for air quality trends and their driving forces in China during 2005-2017, Light: Sci. Appl., 8, 100, https://doi.org/10.1038/s41377-019-0210-6, 2019.
Zhao, Y., Kondo, Y., Murcray, F. J., Liu, X., Koike, M., Irie, H., Strong, K., Suzuki, K., Sera, M., and Ikegami, Y.: Seasonal variations of HCN over northern Japan measured by ground-based infrared solar spectroscopy, Geophys. Res. Lett., 27, 2085-2088, https://doi.org/10.1029/1999gl011218, 2000.
Zhao, Y., Strong, K., Kondo, Y., Koike, M., Matsumi, Y., Irie, H., Rinsland, C. P., Jones, N. B., Suzuki, K., Nakajima, H., Nakane, H., and Murata, I.: Spectroscopic measurements of tropospheric CO, C2H6, C2H2, and HCN in northern Japan, J. Geophys. Res.-Atmos., 107, 4343, https://doi.org/10.1029/2001jd000748, 2002.
