Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 17, 1161-1186, 2017
http://www.atmos-chem-phys.net/17/1161/2017/
doi:10.5194/acp-17-1161-2017
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
25 Jan 2017
Probing the subtropical lowermost stratosphere and the tropical upper troposphere and tropopause layer for inorganic bromine
Bodo Werner1, Jochen Stutz2, Max Spolaor2, Lisa Scalone1, Rasmus Raecke1, James Festa2, Santo Fedele Colosimo2, Ross Cheung2, Catalina Tsai2, Ryan Hossaini3, Martyn P. Chipperfield4, Giorgio S. Taverna4, Wuhu Feng5, James W. Elkins6, David W. Fahey6, Ru-Shan Gao6, Erik J. Hintsa6,7, Troy D. Thornberry6,7, Free Lee Moore6,7, Maria A. Navarro8, Elliot Atlas8, Bruce C. Daube9, Jasna Pittman9, Steve Wofsy9, and Klaus Pfeilsticker1 1Institute of Environmental Physics, University of Heidelberg, Heidelberg, Germany
2Department of Atmospheric and Oceanic Science, University of California Los Angeles, Los Angeles, California, USA
3Lancaster Environment Centre, University of Lancaster, Lancaster, UK
4Institute for Climate and Atmospheric Science, School of Earth and Environment, University of Leeds, Leeds, UK
5National Centre for Atmospheric Science, School of Earth and Environment, University of Leeds, Leeds, UK
6NOAA Earth System Research Laboratory, Boulder, Colorado, USA
7Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, Colorado, USA
8The Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida, USA
9School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA
Abstract. We report measurements of CH4 (measured in situ by the Harvard University Picarro Cavity Ringdown Spectrometer (HUPCRS) and NOAA Unmanned Aircraft System Chromatograph for Atmospheric Trace Species (UCATS) instruments), O3 (measured in situ by the NOAA dual-beam ultraviolet (UV) photometer), NO2, BrO (remotely detected by spectroscopic UV–visible (UV–vis) limb observations; see the companion paper of Stutz et al., 2016), and of some key brominated source gases in whole-air samples of the Global Hawk Whole Air Sampler (GWAS) instrument within the subtropical lowermost stratosphere (LS) and the tropical upper troposphere (UT) and tropopause layer (TTL). The measurements were performed within the framework of the NASA-ATTREX (National Aeronautics and Space Administration – Airborne Tropical Tropopause Experiment) project from aboard the Global Hawk (GH) during six deployments over the eastern Pacific in early 2013. These measurements are compared with TOMCAT/SLIMCAT (Toulouse Off-line Model of Chemistry And Transport/Single Layer Isentropic Model of Chemistry And Transport) 3-D model simulations, aiming at improvements of our understanding of the bromine budget and photochemistry in the LS, UT, and TTL.

Changes in local O3 (and NO2 and BrO) due to transport processes are separated from photochemical processes in intercomparisons of measured and modeled CH4 and O3. After excellent agreement is achieved among measured and simulated CH4 and O3, measured and modeled [NO2] are found to closely agree with  ≤  15 ppt in the TTL (which is the detection limit) and within a typical range of 70 to 170 ppt in the subtropical LS during the daytime. Measured [BrO] ranges between 3 and 9 ppt in the subtropical LS. In the TTL, [BrO] reaches 0.5 ± 0.5 ppt at the bottom (150 hPa∕355 K∕14 km) and up to about 5 ppt at the top (70 hPa∕425 K∕18.5 km; see Fueglistaler et al., 2009 for the definition of the TTL used), in overall good agreement with the model simulations. Depending on the photochemical regime, the TOMCAT∕SLIMCAT simulations tend to slightly underpredict measured BrO for large BrO concentrations, i.e., in the upper TTL and LS. The measured BrO and modeled BrO ∕ Bryinorg ratio is further used to calculate inorganic bromine, Bryinorg. For the TTL (i.e., when [CH4]  ≥  1790 ppb), [Bryinorg] is found to increase from a mean of 2.63 ± 1.04 ppt for potential temperatures (θ) in the range of 350–360 K to 5.11 ± 1.57 ppt for θ  = 390 − 400 K, whereas in the subtropical LS (i.e., when [CH4]  ≤  1790 ppb), it reaches 7.66 ± 2.95 ppt for θ in the range of 390–400 K. Finally, for the eastern Pacific (170–90° W), the TOMCAT/SLIMCAT simulations indicate a net loss of ozone of −0.3 ppbv day−1 at the base of the TTL (θ  =  355 K) and a net production of +1.8 ppbv day−1 in the upper part (θ  =  383 K).


Citation: 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. W., Fahey, D. W., Gao, R.-S., Hintsa, E. J., Thornberry, T. D., Moore, F. L., Navarro, M. A., Atlas, E., Daube, B. C., Pittman, J., Wofsy, S., and Pfeilsticker, K.: Probing the subtropical lowermost stratosphere and the tropical upper troposphere and tropopause layer for inorganic bromine, Atmos. Chem. Phys., 17, 1161-1186, doi:10.5194/acp-17-1161-2017, 2017.
Publications Copernicus
Short summary
The paper reports on inorganic and organic bromine measured in the tropical tropopause layer (TTL) over the eastern Pacific in early 2013. Bryinorg is found to increase from a mean of 2.63 ± 1.04 ppt for θ in the range of 350–360 K to 5.11 ± 1.57 ppt for θ=390 ± 400 K, whereas in the subtropical lower stratosphere, it reaches 7.66 ± 2.95 ppt for θ in the range of 390–400 K. Within the TTL, total bromine is found to range from 20.3 ppt to 22.3 ppt.
The paper reports on inorganic and organic bromine measured in the tropical tropopause layer...
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