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| Titel |
Probing the tropical tropopause layer for organic and inorganic bromine |
| VerfasserIn |
Bodo Werner, Klaus Pfeilsticker, Elliot Atlas, Ross Cheung, Martyn Chipperfield, Fedele Colosimo, Tim Deutschmann, Jim Elkins, David Fahey, Wu Feng, James Festa, Ru-Shan Gao, Ryan Hossaini, Maria Navarro, Rasmus Raecke, Lisa Scalone, Max Spolaor, Troy Thornberry, Catalina Tsai, Jochen Stutz |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250123375
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| Publikation (Nr.) |
 EGU/EGU2016-2612.pdf |
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| Zusammenfassung |
| Bromine chemistry impacts the levels of ozone in the upper troposphere and the stratosphere.
An accurate quantitative understanding of the sources, sinks, and chemical transformation of
bromine species is thus important to understand the photochemistry and budget of bromine in
the tropical upper troposphere, tropopause layer and lowermost stratosphere (UT/TTL/LS).
These regions are also known to serve as a gateway for delivery of ozone depleting
gases to the stratosphere. CH3Br, halons, short-lived organic bromine precursors
(VSLS), such as CHBr3, CH2Br2, and possibly inorganic product gases have been
identified as the main bromine gases delivered to the stratosphere. However, many
important details of the transport and delivery of VSLS and inorganic bromine
compounds through the TTL are still uncertain. Moreover, a number of chemical
processes, including the transformation of the source gases and cycling of inorganic
bromine species at low ambient temperature and on ice particles are also poorly
understood.
The presentation reports measurements of CH4, O3, NO2, and BrO performed by
different instruments and techniques during the 2013 NASA-ATTREX flights in the TTL and
LS. The interpretation of our measurements is supported by chemical transport model
(SLIMCAT) simulations. SLIMCAT results, in conjunction with extensive radiative transfer
calculations using the Monte Carlo model McArtim, also are used to improve retrieval of O3,
NO2, and BrO concentrations from limb scattered sunlight measurements made with the
Differential Optical Absorption Spectroscopy (DOAS) technique during ATTREX. The
chemical transport model also allows us to attribute observed concentration variations to
transport and to photochemical processes. When properly accounting for the transport-related
concentration variations in methane and ozone, we find that measured BrO mostly agrees
with model simulations. An exception are regions where the contribution of the
short-lived CH2Br2 or the partitioning of BrONO2 plays an important role. The
present observations confirm previous findings on the formation of BrONO2 of our
workgroup.
When the errors and uncertainties in the involved photochemical reaction rates, which are
mostly available for higher temperature than those (>188K) encountered during
the NASA ATTREX mission, are accordingly considered in the calculation of the
bromine partitioning, a total bromine budget (Bry) in the tropical tropopause layer of
20.3 ppt to 22.3 ppt is inferred, depending on the flight, or region, respectively. |
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