School of Earth and Environment

Ryan Hossaini Dr Ryan Hossaini

Visiting Researcher

Telephone number: c/o Martyn Chipperfield
Email address:

Affiliation: Institute for Climate and Atmospheric Science


Ryan's homepage is here.

Ryan is currently a NERC Independent Research Fellow in the Lancaster Environment Centre at Lancaster University. Prior to this he has held fellowship and postdoctoral positions in the Department of Chemistry at the University of York and the Department of Chemistry at the University of Cambridge. He obtained his PhD in atmospheric chemistry modelling from the Institute for Climate and Atmospheric Science (ICAS) at the University of Leeds in 2012.

Ryan's research examines how changes in the chemistry and composition of Earth’s atmosphere influence climate. A focus of his work to date has been on (1.) constraining oceanic missions of climate-relevant marine trace gases (e.g. short-lived halogen compounds), (2.) modelling their chemistry and transport in the troposphere and (3.) quantifying their impact on global ozone, climate and air quality. Ryan currently leads the TransCom-VSLS model intercomparison project, involving a consortium of 12 atmospheric modelling groups, was a co-author on Chapter 1 of the 2014 WMO/UNEP Scientific Assessment of Ozone Depletion, and is a co-author of the upcoming IGAC Tropospheric Ozone Assesment Report.

For some recent research highlights, see papers on (i) the impact of chlorine chemistry on tropospheric methane oxidation, published in JGR, (ii.) the climate-relevance of naturally-occurring very short-lived substances, published in Nature Geoscience, and (iii) growth in atmospheric levels of short-lived ozone-depleting chemicals not controlled by the UN Montreal Protocol, published in GRL.

Research Interests

  • Chemistry of the troposphere and stratosphere
  • Chemistry-climate interactions
  • Biosphere-atmosphere-climate feedbacks
  • Marine emissions of ozone-depleting compounds
  • Halogen chemistry & impact on atmospheric oxidation
  • Air Quality


  • Chipperfield, M. P., Bekki, S., Dhomse, S., Harris, N. R. P., Hassler, B., Hossaini, R., Steinbrecht, W., and Weber, M.: Detecting recovery of the stratospheric ozone layer, Nature, 549, 211-218, doi:10.1038/nature23681, 2017.

  • Hossaini, R., Chipperfield, M. P., Montzka, S. A., Leeson, A. A., Dhomse, S., and Pyle, J. A.: The increasing threat to stratospheric ozone from dichloromethane, Nature Communications, 15962, doi:10.1038/ncomms15962, 2017.

  • Werner, B., Stutz, J., Spolaor, M., Scalone, L., Raecke, R., Festa, J., Colosimo, S. F., Cheung, R., Tsai, C., Hossaini, R., Chipperfield, M. P., Taverna, G. S., Feng, W., Elkins, J. W., Fahey, D. W., Gao, R.-S., Hintsa, E. J., Thornberry, T. D., Moore, F. L., Navarro, M. A., Atlas, E., Daube, B. C., Pittman, J., Wofsy, S., and Pfeilsticker, K.: Probing the subtropical lowermost stratosphere and the tropical upper troposphere and tropopause layer for inorganic bromine, Atmos. Chem. Phys., 17, 1161-1186, doi:10.5194/acp-17-1161-2017, 2017.

  • Stutz, J., Werner, B., Spolaor, M., Scalone, L., Festa, J., Tsai, C., Cheung, R., Colosimo, S. F., Tricoli, U., Raecke, R., Hossaini, R., Chipperfield, M. P., Feng, W., Gao, R.-S., Hintsa, E. J., Elkins, J. W., Moore, F. L., Daube, B., Pittman, J., Wofsy, S., and Pfeilsticker, K.: A new differential optical absorption spectroscopy instrument to study atmospheric chemistry from a high-altitude unmanned aircraft, Atmos. Meas. Tech. Discuss., doi:10.5194/amt-2016-251, 2016.

  • Hossaini, R., Chipperfield, M. P., Saiz-Lopez, A., Fernandez, R., Monks, S., Feng, W., Brauer, P., and von Glasow, R.: A global model of tropospheric chlorine chemistry: organic versus inorganic sources and impact on methane oxidation, J. Geophys. Res. Atmos., 121, doi:10.1002/2016JD025756, 2016.

  • Chipperfield, M. P., Liang, Q., Rigby, M., Hossaini, R., Montzka, S. A., Dhomse, S., Feng, W., Prinn, R. G., Weiss, R. F., Harth, C. M., Salameh, P. K., Mühle, J., O’Doherty, S., Young, D., Simmonds, P. G., Krummel, P .B., Fraser, P. J., Steele, L. P., Happell, Rhew, R. C., Butler, J., Yvon-Lewis, S., Hall, B., Harrison, J. J., and Mahieu, E.: Model sensitivity studies of the decrease in atmospheric carbon tetrachloride, Atmos. Chem. Phys., 16, 15741-15754, doi:10.5194/acp-16-15741-2016, 2016.

  • Hossaini, R., Patra, P. K., Leeson, A. A., Krysztofiak, G., Abraham, N. L., Andrews, S. J., Archibald, A. T., Aschmann, J., Atlas, E. L., Belikov, D. A., Bönisch, H., Butler, R., Carpenter, L. J., Dhomse, S., Dorf, M., Engel, A., Feng, L., Feng, W., Fuhlbrügge, S., Griffiths, P. T., Harris, N. R. P., Hommel, R., Keber, T., Krüger, K., Lennartz, S. T., Maksyutov, S., Mantle, H., Mills, G. P., Miller, B., Montzka, S. A., Moore, F., Navarro, M. A., Oram, D. E., Palmer, P. I., Pfeilsticker, K., Pyle, J. A., Quack, B., Robinson, A. D., Saikawa, E., Saiz-Lopez, A., Sala, S., Sinnhuber, B.-M., Taguchi, S., Tegtmeier, S., Lidster, R. T., Wilson, C., and Ziska, F.: A multi-model intercomparison of halogenated very short-lived substances (TransCom-VSLS): linking oceanic emissions and tropospheric transport for a reconciled estimate of the stratospheric source gas injection of bromine, Atmos. Chem. Phys., 16, 9163-9187, doi:10.5194/acp-16-9163-2016, 2016.

  • Dhomse, S., Chipperfield, M. P., Damadeo, R. P., Zawodny, J. M., Ball, W., Feng, W., Hossaini, R., Mann, G. W., Haigh, J. D.: On the ambiguous nature of the 11-year solar cycle signal profile in stratospheric ozone, Geophys. Res. Lett., 43, 7241-7249, doi:10.1002/2016GL069958, 2016.

  • Lennartz, S. T., Kryzstofiak-Tong, G., Marandino, C. A., Sinnhuber, B.-M., Tegtmeier, S., Ziska, F., Krüger, K., Hossaini, R., Montzka, S. A., Atlas, E., Oram, D., Keber, T., Bönisch, H., and Quack, B.: Modelling marine emissions and atmospheric distributions of halocarbons and dimethyl sulfide: the influence of prescribed water concentration vs. prescribed emissions, Atmos. Chem. Phys., 15, 11753-11772, doi:10.5194/acp-15-11753-2015, 2015.

  • Hossaini, R., Chipperfield, M. P., Saiz-Lopez, A., Harrison, J. J., von Glasow, R., Sommariva, R., Atlas, E., Navarro, M., Montzka, S. A., Feng, W., Dhomse, S., Harth, C., Mühle, J., Lunder, C., O'Doherty, S., Young, D., Reimann, S., Vollmer, M. K., Krummel, P. B., and Bernath, P. F.: Growth in stratospheric chlorine from short-lived chemicals not controlled by the Montreal Protocol, Geophys. Res. Lett., doi:10.1002/2015GL063783, 2015.

  • Shallcross, D., Leather, K., Bacak, A., Xiao, P., Lee, E., Ng, M., Mok, D., Dyke, J., Hossaini, R., Chipperfield, M. P., Khan, A., and Percival, C.: The reaction between CH3O2 and BrO radicals: a new source of upper troposphere-lower stratosphere hydroxyl radicals, J. Phys. Chem. A., doi:10.1021/jp5108203, 2015.

  • Dhomse, S., Chipperfield, M. P., Feng, W., Hossaini, R., Mann, G., and Santee, M.: Revisiting the hemispheric aysmmetry in mid-latitude ozone changes following the Mount Pinatubo eruption: a 3-D model study, Geophys. Res. Lett,. doi:10.1002/2015GL063052, 2015.

  • Hossaini, R., Chipperfield, M. P., Montzka, S. A., Rap, A., Dhomse, S., and Feng, W.: Efficiency of short-lived halogens at influencing climate through depletion of stratospheric ozone, Nature Geosci., 8, 186-190, doi:10.1038/ngeo2363, 2015.

  • Mahieu, E., Chipperfield, M. P., Notholt, J., Reddmann, T., Anderson, J., Bernath, P. F., Blumenstock, T., Coffey, M. T., Dhomse, S., Feng, W., Franco, B., Froidevaux, L., Griffith, D. W. T., Hannigan, J., Hase, F., Hossaini, R., Jones, N. B., Morino, I., Murata, I., Nakajima, H., Palm, M., Paton-Walsh, C., Russell III, J. M., Schneider, M., Servais, C., Smale, D., and Walker, K.A.: Recent Northern Hemisphere stratospheric HCl increase due to atmospheric circulation changes, Nature, 515, 104-107, doi:10.1038/nature13857, 2014.

  • Carpenter, L. J., Reimann, S., Burkholder, J. B., Clerbaux, C., Hall, B. D., Hossaini, R., Laube, J. C., Yvon-Lewis, S. A.: Update on Ozone-Depleting Substances (ODSs) and Other Gases of Interest to the Montreal Protocol, Chapter 1 in Scientific Assessment of Ozone Depletion: 2014, Global Ozone Research and Monitoring Project, Report No. 55, World Meteorological Organization, Geneva, Switzerland, 2014.

  • Kritten, L., Butz, A., Chipperfield, M. P., Dorf, M., Dhomse, S., Hossaini, R., Oelhaf, H., Prados-Roman, C., Wetzel, G., and Pfeilsticker, K.: Constraining the N2O5 absorption cross-section from spectroscopic measurements in the tropical mid-stratosphere, Atmos. Chem. Phys., 14, 9555-9566, doi:10.5194/acp-14-9555-2014, 2014.

  • Hamer, P. D., Marecal, V., Hossaini, R., Pirre, M., Warwick, N., Chipperfield, M. P., Samah, A. A., Harris, N., Robinson, A., Quack, B., Engel, A., Krüger, K., Atlas, E., Subramaniam, K., Oram, D., Leedham, E., Mills, G., Pfeilsticker, K., Sala, S., Keber, T., Bönisch, H., Peng, L. K., Nadzir, M. S. M., Lim, P. T., Mujahid, A., Anton, A., Schlager, H., Catoire, V., Krysztofiak, G., and Dorf, M.: Modelling the chemistry and transport of bromoform within a sea breeze driven convective system during the SHIVA campaign, Atmos. Chem. Phys. Discuss., 13, 20611-20676, doi:10.5194/acpd-13-20611-2013, 2013.

  • Hossaini, R., Mantle, M., Chipperfield, M. P., Montzka, S. A., Hamer, P., Ziska, F., Quack, B., Krüger, K., Tegtmeier, S., Atlas, E., Sala, S., Engel, A., Bönisch, H., Keber, T., Oram, D., Mills, G., Ordonez, C., Saiz-Lopez, A., Warwick, N., Liang, Q., Feng, W., Moore, F., Miller, B. R., Marecal, V., Richards, N. A. D., Dorf, M., and Pfeilsticker, K.: Evaluating global emission inventories of biogenic bromocarbons, Atmos. Chem. Phys. 13, 11819-11838, doi:10.5194/acp-13-11819-2013, 2013.

  • Tegtmeier, S., Krüger, K., Quack, B., Atlas, E., Blake, D. R., Boenisch, H., Engel, A., Hepach, H., Hossaini, R., Navarro, M. A., Raimund, S., Sala, S., Shi, Q., and Ziska, F.: The contribution of oceanic methyl iodide to stratospheric iodine, Atmos. Chem. Phys., 13, 11869-11886, doi:10.5194/acp-13-11869-2013, 2013.

  • Kreycy, S., Camy-Peyret, C., Chipperfield, M. P., Dorf, M., Feng, W., Hossaini, R., Kritten, L., Werner, B., and Pfeilsticker, K.: Atmospheric test of the J(BrONO2)/k(BrO+NO2) ratio: implications for total stratospheric Bry and bromine-mediated ozone loss, Atmos. Chem. Phys., 13, 6263-6274, doi:10.5194/acp-13-6263-2013, 2013.

  • Hossaini, R., Chipperfield, M. P., Dhomse, S., Ordonez, C., Saiz-Lopez, A., Abraham, N. L., Archibalid, A., Braesicke, P., Telford, P., Warwick, N. J., Yang, X., and Pyle, J.: Modelling future changes to the stratospheric source gas injection of biogenic bromocarbons, Geophys. Res. Lett., 39, L20813, doi:10.1029/2012GL053401, 2012.

  • Hossaini, R., Chipperfield, M. P., Feng, W., Breider, T. J., Atlas, E., Montzka, S. A., Miller, B. R., Moore, F., and Elkins, J.: The contribution of natural and anthropogenic very short-lived species to stratospheric bromine, Atmos. Chem. Phys., 12, 371-380, doi:10.5194/acp-12-371-2012, 2012.

  • Aschmann, J., Sinnhuber, B.-M., Chipperfield, M. P., and Hossaini, R.: Impact of deep convection and dehydration on bromine loading in the upper troposphere and lower stratosphere, Atmos. Chem. Phys., 11, 2671-2687, doi:10.5194/acp-11-2671-2011, 2011.

  • Hossaini, R., Chipperfield, M. P., Monge-Sanz, B. M., Richards, N. A. D., Atlas, E., and Blake, D. R.: Bromoform and dibromomethane in the tropics: a 3-D model study of chemistry and transport, Atmos. Chem. Phys., 10, 719-735, doi:10.5194/acp-10-719-2010, 2010.