Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 14, 5781-5792, 2014
https://doi.org/10.5194/acp-14-5781-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
11 Jun 2014
Convective transport of very short lived bromocarbons to the stratosphere
Q. Liang1,2, E. Atlas3, D. Blake4, M. Dorf5,*, K. Pfeilsticker5, and S. Schauffler6 1NASA Goddard Space Flight Center, Atmospheric Chemistry and Dynamics, Greenbelt, MD, USA
2Universities Space Research Association, GESTAR, Columbia, MD, USA
3University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149, USA
4University of California, 570 Rowland Hall, Irvine, CA 92697, USA
5Institut für Umweltphysik, University of Heidelberg, Heidelberg, Germany
6Earth Observing Laboratory, NCAR, Boulder, CO, USA
*now at: Max-Planck-Institut für Chemie, Mainz, Germany
Abstract. We use the NASA Goddard Earth Observing System (GEOS) Chemistry Climate Model (GEOSCCM) to quantify the contribution of the two most important brominated very short lived substances (VSLSs), bromoform (CHBr3) and dibromomethane (CH2Br2), to stratospheric bromine and its sensitivity to convection strength. Model simulations suggest that the most active transport of VSLSs from the marine boundary layer through the tropopause occurs over the tropical Indian Ocean, the tropical western Pacific, and off the Pacific coast of Mexico. Together, convective lofting of CHBr3 and CH2Br2 and their degradation products supplies ~8 ppt total bromine to the base of the tropical tropopause layer (TTL, ~150 hPa), similar to the amount of VSLS organic bromine available in the marine boundary layer (~7.8–8.4 ppt) in the active convective lofting regions mentioned above. Of the total ~8 ppt VSLS bromine that enters the base of the TTL at ~150 hPa, half is in the form of organic source gases and half in the form of inorganic product gases. Only a small portion (<10%) of the VSLS-originated bromine is removed via wet scavenging in the TTL before reaching the lower stratosphere. On average, globally, CHBr3 and CH2Br2 together contribute ~7.7 pptv to the present-day inorganic bromine in the stratosphere. However, varying model deep-convection strength between maximum (strongest) and minimum (weakest) convection conditions can introduce a ~2.6 pptv uncertainty in the contribution of VSLSs to inorganic bromine in the stratosphere (BryVSLS). Contrary to conventional wisdom, the minimum convection condition leads to a larger BryVSLS as the reduced scavenging in soluble product gases, and thus a significant increase in product gas injection (2–3 ppt), greatly exceeds the relatively minor decrease in source gas injection (a few 10ths ppt).

Citation: Liang, Q., Atlas, E., Blake, D., Dorf, M., Pfeilsticker, K., and Schauffler, S.: Convective transport of very short lived bromocarbons to the stratosphere, Atmos. Chem. Phys., 14, 5781-5792, https://doi.org/10.5194/acp-14-5781-2014, 2014.
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