Using beryllium-7 to assess cross-tropopause transport in global models

Liu, Hongyu; Considine, David B.; Horowitz, Larry W.; Crawford, James H.; Rodriguez, Jose M.; Strahan, Susan E.; Damon, Megan R.; Steenrod, Stephen D.; Xu, Xiaojing; Kouatchou, Jules; Carouge, Claire; Yantosca, Robert M.

doi:https://doi.org/10.5194/acp-16-4641-2016

Articles | Volume 16, issue 7

Atmos. Chem. Phys., 16, 4641–4659, 2016

https://doi.org/10.5194/acp-16-4641-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Atmos. Chem. Phys., 16, 4641–4659, 2016

https://doi.org/10.5194/acp-16-4641-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 16, issue 7

Research article 14 Apr 2016

Research article | 14 Apr 2016

Using beryllium-7 to assess cross-tropopause transport in global models

Hongyu Liu¹, David B. Considine^2,a, Larry W. Horowitz³, James H. Crawford², Jose M. Rodriguez⁴, Susan E. Strahan^4,5, Megan R. Damon^4,6, Stephen D. Steenrod^4,5, Xiaojing Xu⁷, Jules Kouatchou^4,6, Claire Carouge^8,b, and Robert M. Yantosca⁸ Hongyu Liu et al.

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¹National Institute of Aerospace, Hampton, VA, USA
²NASA Langley Research Center, Hampton, VA, USA
³NOAA Geophysical Fluid and Dynamics Laboratory, Princeton, NJ, USA
⁴NASA Goddard Space Flight Center, Greenbelt, MD, USA
⁵Universities Space Research Association, Columbia, MD, USA
⁶Science Systems and Applications, Inc., Lanham, MD, USA
⁷Science Systems and Applications, Inc., Hampton, VA, USA
⁸John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
^anow at: NASA Headquarters, Washington, D.C., USA
^bnow at: ARC Centre of Excellence for Climate System Science, University of New South Wales, Sydney, Australia

Received: 26 Jul 2015 – Discussion started: 25 Sep 2015 – Revised: 16 Mar 2016 – Accepted: 23 Mar 2016 – Published: 14 Apr 2016

Abstract. We use the Global Modeling Initiative (GMI) modeling framework to assess the utility of cosmogenic beryllium-7 (⁷Be), a natural aerosol tracer, for evaluating cross-tropopause transport in global models. The GMI chemical transport model (CTM) was used to simulate atmospheric ⁷Be distributions using four different meteorological data sets (GEOS1-STRAT DAS, GISS II′ GCM, fvGCM, and GEOS4-DAS), featuring significantly different stratosphere–troposphere exchange (STE) characteristics. The simulations were compared with the upper troposphere and/or lower stratosphere (UT/LS) ⁷Be climatology constructed from ∼  25 years of aircraft and balloon data, as well as climatological records of surface concentrations and deposition fluxes. Comparison of the fraction of surface air of stratospheric origin estimated from the ⁷Be simulations with observationally derived estimates indicates excessive cross-tropopause transport at mid-latitudes in simulations using GEOS1-STRAT and at high latitudes using GISS II′ meteorological data. These simulations also overestimate ⁷Be deposition fluxes at mid-latitudes (GEOS1-STRAT) and at high latitudes (GISS II′), respectively. We show that excessive cross-tropopause transport of ⁷Be corresponds to overestimated stratospheric contribution to tropospheric ozone. Our perspectives on STE in these meteorological fields based on ⁷Be simulations are consistent with previous modeling studies of tropospheric ozone using the same meteorological fields. We conclude that the observational constraints for ⁷Be and observed ⁷Be total deposition fluxes can be used routinely as a first-order assessment of cross-tropopause transport in global models.