TY - JOUR A1 - Hossaini, Ryan A1 - Patra, Prabir K. A1 - Leeson, Amber A. A1 - Krysztofiak, Gisèle A1 - Abraham, N. Luke A1 - Andrews, Steve J. A1 - Archibald, Alexander Thomas A1 - Aschmann, Jan A1 - Atlas, Elliot L. A1 - Belikov, Dmitry A. A1 - Bönisch, Harald A1 - Butler, Robyn A1 - Carpenter, Lucy J. A1 - Dhomse, Sandip A1 - Dorf, Marcel A1 - Engel, Andreas A1 - Feng, Liang A1 - Feng, Wuhu A1 - Fuhlbrügge, Steffen A1 - Griffiths, Paul T. A1 - Harris, Neil R. P. A1 - Hommel, René A1 - Keber, Timo A1 - Krüger, Kirstin A1 - Lennartz, Sinikka T. A1 - Maksyutov, Shamil A1 - Mantle, Hannah A1 - Mills, Graham A1 - Miller, Benjamin R. A1 - Montzka, Stephen A. A1 - Moore, Fred A1 - Navarro, Maria A. A1 - Oram, David A1 - Palmer, Paul I. A1 - Pfeilsticker, Klaus A1 - Pyle, John A. A1 - Quack, Birgit A1 - Robinson, Andrew D. A1 - Saikawa, Eri A1 - Saiz-Lopez, Alfonso A1 - Sala, Stephan A1 - Sinnhuber, Björn-Martin A1 - Taguchi, Shoichi A1 - Tegtmeier, Susann A1 - Lidster, Richard Terence A1 - Wilson, Chris A1 - Ziska, Franziska T1 - 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 T2 - Atmospheric chemistry and physics. Discussions N2 - The first concerted multi-model intercomparison of halogenated very short-lived substances (VSLS) has been performed, within the framework of the ongoing Atmospheric Tracer Transport Model Intercomparison Project (TransCom). Eleven global models or model variants participated, simulating the major natural bromine VSLS, bromoform (CHBr3) and dibromomethane (CH2Br2), over a 20-year period (1993-2012). The overarching goal of TransCom-VSLS was to provide a reconciled model estimate of the stratospheric source gas injection (SGI) of bromine from these gases, to constrain the current measurement-derived range, and to investigate inter-model differences due to emissions and transport processes. Models ran with standardised idealised chemistry, to isolate differences due to transport, and we investigated the sensitivity of results to a range of VSLS emission inventories. Models were tested in their ability to reproduce the observed seasonal and spatial distribution of VSLS at the surface, using measurements from NOAA’s long-term global monitoring network, and in the tropical troposphere, using recent aircraft measurements - including high altitude observations from the NASA Global Hawk platform. The models generally capture the seasonal cycle of surface CHBr3 and CH2Br2 well, with a strong model measurement correlation (r ≥0.7) and a low sensitivity to the choice of emission inventory, at most sites. In a given model, the absolute model-measurement agreement is highly sensitive to the choice of emissions and inter-model differences are also apparent, even when using the same inventory, highlighting the challenges faced in evaluating such inventories at the global scale. Across the ensemble, most consistency is found within the tropics where most of the models (8 out of 11) achieve optimal agreement to surface CHBr3 observations using the lowest of the three CHBr3 emission inventories tested (similarly, 8 out of 11 models for CH2Br2). In general, the models are able to reproduce well observations of CHBr3 and CH2Br2 obtained in the tropical tropopause layer (TTL) at various locations throughout the Pacific. Zonal variability in VSLS loading in the TTL is generally consistent among models, with CHBr3 (and to a lesser extent CH2Br2) most elevated over the tropical West Pacific during boreal winter. The models also indicate the Asian Monsoon during boreal summer to be an important pathway for VSLS reaching the stratosphere, though the strength of this signal varies considerably among models. We derive an ensemble climatological mean estimate of the stratospheric bromine SGI from CHBr3 and CH2Br2 of 2.0 (1.2-2.5) ppt, ∼57% larger than the best estimate from the most re- cent World Meteorological Organization (WMO) Ozone Assessment Report. We find no evidence for a long-term, transport-driven trend in the stratospheric SGI of bromine over the simulation period. However, transport-driven inter-annual variability in the annual mean bromine SGI is of the order of a ±5%, with SGI exhibiting a strong positive correlation with ENSO in the East Pacific Y1 - 2016 UR - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/41963 UR - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-419639 UR - http://www.atmos-chem-phys.net/16/9163/2016 SN - 1680-7375 SN - 1680-7367 N1 - © Author(s) 2016. CC-BY 3.0 License. VL - 16 SP - 1 EP - 49 PB - European Geosciences Union CY - Katlenburg-Lindau ER -