Dr Ryan Hossaini

NERC Research Fellow

Research Interests

Ryan's research examines long-term changes in the chemistry and composition of Earth’s atmosphere and how such changes may influence climate. This involves the development and application of state-of-the-art numerical models, run on supercomputers, which simulate the past, present and future state of the atmosphere. His recent work has focussed on:

  • Non-Montreal Protocol Ozone-Depleting Substances (ODSs). Despite production of many long-lived ODSs (e.g. CFCs) being controlled by the UN Montreal Protocol and its amendments, ozone depletion remains a persistent environmental issue. Our research examines trends in the atmosphere abundance of so-called Very Short-Lived Substances (VSLS) – a class of ODSs not controlled by the Protocol – whose emissions have been increasing in recent years. Our recent Nature Comms. paper highlighted the increasing threat to stratospheric ozone from anthropogenic VSLS emissions. See also recent Nature review on ozone layer recovery.
  • Ozone Chemistry-Climate Interactions. In the stratosphere ozone prevents damaging levels of UV radiation reaching Earth’s surface. Ozone also absorbs terrestrial IR radiation and is therefore a greenhouse gas. Changes in can ozone exert a significant and complex influence on climate. This research seeks to understand chemical drives of ozone changes, particularly in the climate-relevant upper troposphere/lower stratosphere, and the radiative implications. See recent our recent Nature Geoscience paper on the efficiency of halogenated VSLS at influencing climate through ozone loss in the lower stratosphere.
  • Tropospheric Chlorine Impacts. Chlorine atoms are highly reactive in the troposphere and are therefore a potentially important atmospheric oxidant, influencing the lifetime of greenhouse gases (e.g. methane) and a range of volatile organic compounds. Despite this, the tropospheric abundance of chlorine atoms is very poorly known. Our work seeks to understand processes governing the release and recycling of chlorine in the troposphere and we are building models to simulate and provide insight into such processes.
  • Data-Driven Clustering Methods for Climate Science. This work is supported by the EPSRC to explore the use of clustering in the analysis of large climate model datasets from model intercomparison projects. Clustering can potentially provide powerful insight into such data and may help characterise areas of uncertainty across models.

Detecting recovery of the stratospheric ozone layer
Chipperfield, M.P., Bekki, S., Dhomse, S., Harris, N.R.P., Hassler, B., Hossaini, R., Steinbrecht, W., Thiéblemont, R., Weber, M. 14/09/2017 In: Nature. 549, 7671, p. 211-218. 8 p.
Journal article

The increasing threat to stratospheric ozone from dichloromethane
Hossaini, R., Chipperfield, M.P., Montzka, S.A., Leeson, A.A., Dhomse, S., Pyle, J. 27/06/2017 In: Nature Communications. 8, 9 p.
Journal article

A new Differential Optical Absorption Spectroscopy instrument to study atmospheric chemistry from a high- altitude unmanned aircraft
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., Hintsa, E.J., Elkins, J., Moore, F.L., Daube, B., Pittman, J., Wofsy, S., Pfeilsticker, K. 15/03/2017 In: Atmospheric Measurement Techniques. 10, 3, p. 1017-1042. 26 p.
Journal article

Probing the subtropical lowermost stratosphere and the tropical upper troposphere and tropopause layer for inorganic bromine
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., Fahey, D., Gao, R., Hintsa, E.J., Thornberry, T.D., Moore, F.L., Navarro, M.A., Atlas, E., Daube, B.C., Pittman, J., Wofsy, S., Pfeilsticker, K. 25/01/2017 In: Atmospheric Chemistry and Physics . 17, 2, p. 1161-1186. 26 p.
Journal article

Model sensitivity studies of the decrease in atmospheric carbon tetrachloride
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., Frazer, P.J., Steele, L.P., Happell, J.D., Rhew, R.C., Butler, J., Yvon-Lewis, S., Hall, B., Nance, D., Moore, F., Miller, B.R., Elkins, J.W., Harrison, J.J., Boone, C.D., Atlas, E.L., Mahieu, E. 20/12/2016 In: Atmospheric Chemistry and Physics . 16, 24, p. 15741-15754. 14 p.
Journal article

A global model of tropospheric chlorine chemistry: organic versus inorganic sources and impact on methane oxidation
Hossaini, R., Chipperfield, M.P., Saiz-Lopez, A., Fernandez, R., Monks, S., Feng, W., Brauer, P., von Glasow, R. 16/12/2016 In: Journal of Geophysical Research: Atmospheres. 121, 23, p. 14271-14297. 27 p.
Journal article

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
Hossaini, R., Patra, P.K., Leeson, A.A., Krysztofiak, G., Abraham, N.L., Archibald, A.T., Aschmann, J., Atlas, E.L., Belikov, D.A., Bönisch, H., Carpenter, L.J., Dhomse, S., Dorf, M., Engel, A., 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., Montzka, S.A., Moore, F., Navarro, M.A., Oram, D.E., Pfeilsticker, K., Pyle, J.A., Quack, B., Saikawa, E., Saiz-Lopez, A., Sala, S., Sinnhuber, B., Taguchi, S., Tegtmeier, S., Lidster, R.T., Ziska, F. 26/07/2016 In: Atmospheric Chemistry and Physics . 16, 14, p. 9163-9187. 25 p.
Journal article

On the ambiguous nature of the 11year solar cycle signal in upper stratospheric ozone
Dhomse, S.S., Chipperfield, M.P., Damadeo, R.P., Zawodny, J.M., Ball, W.T., Feng, W., Hossaini, R., Mann, G.W., Haigh, J.D. 16/07/2016 In: Geophysical Research Letters. 43, 13, p. 7241-7249. 9 p.
Journal article

Modelling marine emissions and atmospheric distributions of halocarbons and dimethyl sulfide: the influence of prescribed water concentration vs. prescribed emissions
Lennartz, S.T., Krysztofiak, G., Marandino, C.A., Sinnhuber, B.M., Tegtmeier, S., Ziska, F., Hossaini, R., Krüger, K., Montzka, S.A., Atlas, E., Oram, D.E., Keber, T., Bönisch, H., Quack, B. 22/10/2015 In: Atmospheric Chemistry and Physics . 15, 20, p. 11753-11772. 20 p.
Journal article

Growth in stratospheric chlorine from short-lived chemicals not controlled by the Montreal Protocol
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., Bernath, P.F. 1/07/2015 In: Geophysical Research Letters. 42, 11, p. 4573-4580. 8 p.
Journal article

Reaction between CH3O2 and BrO Radicals: a new source of upper troposphere lower stratosphere hydroxyl radicals
Shallcross, D.E., Leather, K.E., Bacak, A., Xiao, P., Lee, E.P.F., Ng, M., Mok, D.K.W., Dyke, J.M., Hossaini, R., Chipperfield, M.P., Khan, M.A.H., Percival, C.J. 14/05/2015 In: Journal of Physical Chemistry A. 119, 19, p. 4618-4632. 15 p.
Journal article

Revisiting the hemispheric asymmetry in midlatitude ozone changes following the Mount Pinatubo eruption: a 3-D model study
Dhomse, S.S., Chipperfield, M.P., Feng, W., Hossaini, R., Mann, G.W., Santee, M.L. 28/04/2015 In: Geophysical Research Letters. 42, 8, p. 3038-3047. 10 p.
Journal article

Efficiency of short-lived halogens at influencing climate through depletion of stratospheric ozone
Hossaini, R., Chipperfield, M.P., Montzka, S.A., Rap, A., Dhomse, S., Feng, W. 03/2015 In: Nature Geoscience. 8, 3, p. 186-190. 5 p.
Journal article

Recent Northern Hemisphere stratospheric HCl increase due to atmospheric circulation changes
Mahieu, E., Chipperfield, M.P., Notholt, J., Reddmann, T., Anderson, J., Bernath, P.F., Blumenstock, T., Coffey, M.T., Dhomse, S.S., Feng, W., Franco, B., Froidevaux, L., Griffith, D.W.T., Hannigan, J.W., Hase, F., Hossaini, R., Jones, N.B., Morino, I., Murata, I., Nakajima, H., Palm, M., Paton-Walsh, C., Russell, J.M., Schneider, M., Servais, C., Smale, D., Walker, K.A. 6/11/2014 In: Nature. 515, 7525, p. 104-107. 4 p.
Journal article

Constraining the N2O5 UV absorption cross section from spectroscopic trace gas measurements in the tropical mid-stratosphere
Kritten, L., Butz, A., Chipperfield, M.P., Dorf, M., Dhomse, S., Hossaini, R., Oelhaf, H., Prados-Roman, C., Wetzel, G., Pfeilsticker, K. 16/09/2014 In: Atmospheric Chemistry and Physics . 14, 18, p. 9555-9566. 12 p.
Journal article

Update on Ozone-Depleting Substances (ODSs) and Other Gases of Interest to the Montreal Protocol: Chapter 1
Carpenter, L., Reimann, S., Burkholder, J., Clerbaux, C., Hall, B., Hossaini, R., Laube, J., Yvon-Lewis, S. 2014 In: Scientific Assessment of Ozone Depletion: 2014. Geneva, Switzerland : World Meteorological Organization
Chapter (peer-reviewed)

The contribution of oceanic methyl iodide to stratospheric iodine
Tegtmeier, S., Krueger, 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., Ziska, E. 9/12/2013 In: Atmospheric Chemistry and Physics . 13, 23, p. 11869-11886. 18 p.
Journal article

Evaluating global emission inventories of biogenic bromocarbons
Hossaini, R., Mantle, H., Chipperfield, M.P., Montzka, S.A., Hamer, P., Ziska, E., Quack, B., Krueger, K., Tegtmeier, S., Atlas, E., Sala, S., Engel, A., Boenisch, H., Keber, T., Oram, D., Mills, G., Ordonez, C., Saiz-Lopez, A., Warwick, N., Liang, Q., Feng, W., Moore, E., Miller, B.R., Marecal, V., Richards, N.A.D., Dorf, M., Pfeilsticker, K. 6/12/2013 In: Atmospheric Chemistry and Physics . 13, 23, p. 11819-11838. 20 p.
Journal article

Atmospheric test of the J(BrONO2)/k(BrO+NO2) ratio: implications for total stratospheric Br-y and bromine-mediated ozone loss
Kreycy, S., Camy-Peyret, C., Chipperfield, M.P., Dorf, M., Feng, W., Hossaini, R., Kritten, L., Werner, B., Pfeilsticker, K. 2/07/2013 In: Atmospheric Chemistry and Physics . 13, 13, p. 6263-6274. 12 p.
Journal article

Modelling future changes to the stratospheric source gas injection of biogenic bromocarbons
Hossaini, R., Chipperfield, M.P., Dhomse, S., Ordonez, C., Saiz-Lopez, A., Abraham, N.L., Archibald, A., Braesicke, P., Telford, P., Warwick, N., Yang, X., Pyle, J. 28/10/2012 In: Geophysical Research Letters. 39, 20, 4 p.
Journal article

The contribution of natural and anthropogenic very short-lived species to stratospheric bromine
Hossaini, R., Chipperfield, M.P., Feng, W., Breider, T.J., Atlas, E., Montzka, S.A., Miller, B.R., Moore, F., Elkins, J. 5/01/2012 In: Atmospheric Chemistry and Physics . 12, 1, p. 371-380. 10 p.
Journal article

Impact of deep convection and dehydration on bromine loading in the upper troposphere and lower stratosphere
Aschmann, J., Sinnhuber, B., Chipperfield, M.P., Hossaini, R. 22/03/2011 In: Atmospheric Chemistry and Physics . 11, 6, p. 2671-2687. 17 p.
Journal article

Bromoform and dibromomethane in the tropics: a 3-D model study of chemistry and transport
Hossaini, R., Chipperfield, M.P., Monge-Sanz, B.M., Richards, N.A.D., Atlas, E., Blake, D.R. 25/01/2010 In: Atmospheric Chemistry and Physics . 10, 2, p. 719-735. 17 p.
Journal article