1. A (preliminary) assessment of the contribution of brominated SGs and PGs to stratospheric Br y based on NASA-ATTREX DOAS O 3, and BrO and AWAS (whole air) data Klaus Pfeilsticker 2, Max Spolaor 1,Catalina Tsai 1, Fedele Colosimo 1, Ross Cheung 1, Tim Deutschmann 2, Marcel Dorf 2, Bodo Werner 2, Rasmus Raecke 1,2, Ugo Tricoli 2, Jochen Stutz 1, Elliot Atlas 3, and Ross Salawitch 4 (1) Department of Atmospheric and Oceanic Science, University of California, Los Angeles, USA (2) Institut für Umweltphysik, University of Heidelberg, Heidelberg, Germany (3) University of Miami, Miami, USA (4) Department of Chemistry and Biochemistry, Department of Atmospheric and Oceanic Sciences, and Earth System Science Interdisciplinary Center, University of Maryland, USA

2. Budget of stratospheric bromine [WMO-2011 with recent updates] [Br y ]= 20.3 ± 3.5 ppt probed in 4.5 yr old air in 2011

3. (courtesy B.-M. Sinnhuber SHIVA WP5) BrO vmr @ 21 km from SCIAMACHY limb observation Ground-based at Harestua/Norway Trend in total stratospherc BrO: Consistency between ground- based, and satellite observations

4. The role of VSLS in stratospheric ozone and climate [Fig. 2.1.3, WMO-2007]  Brominated VSLS are known to contribute 1 – 8 ppt to stratospheric Br y (WMO-2011), but our (IUP-HD) best estimate is 4.1 ± 2.5 ppt (Dorf et al. 2006, and update in WMO-2011). WMO-2007 notation: VSLS: very short lived species (life times < 6 months) SG: source gases (e.g. CFC, HCFC, halons, CH3Br, CH3I, CHBr3, CBr2Cl2, etc.) PG: products gases (e.g. HCl, IO, OIO, BrO, HBr)

5. The ‚big‘ and ‚minor‘ questions related to stratospheric bromine WMO-2011 assessed the contribution of brominated VSLS to stratospheric bromine to 6 (1 – 8) ppt. Comment: All the different assessment of stratospheric Br y were previously based on measurements of Br y (org) and Br y (inorg) in the ‚bulk‘ of the stratosphere Can we do any better with the SGI (source gas injection) and PGI (product gas injection) of brominated species into the stratosphere? Subquestions:  What is the concentration of organic and inorganic Br y at the level of zero radiative heating (LZRH)?  What is the partitioning of Br y (inorg) in the TTL as function of O 3, NO y, VOCs, …?  Is there any processing of Br y (inorg) on aerosol and cloud particles?  In as much is the budget of Br y (org and inorg) in the TTL affected by transport processes, c.f., convective outflow, slow diabatic ascent, wave activity,….?  …..  The NASA-ATTREX GH deployments provide optimal means to simultaneously measure Br y (org) and Br y (inorg) at stratospheric entry level and in the ‚right‘ region, i.e. in the TTL of the tropical Pacific!

6. O 3 and BrO from NASA ATTREX SF2-2013 (Feb. 9/10, 2013)

7. BrO profile from Teresina, Brazil (5.1◦ S, 42.9◦W) in 2005 (Dorf et al., 2008)

8. 8 Daytime: Key obs: CBr y species, BrO, Br*, O 3, HCHO Key sampling strategies: target specific O 3 mixing ratios conduct nighttime flights to target HOBr, BrCl, & Br 2 Caveat: Br y partitioning under low O 3 during daytime is a huge challenge…. (Ross) Br + HCHO is route out of Br-reservoir Inorganic bromine specification in the TTL (from Ross Salawitch) relevant range

9. Total atmospheric bromine Ghost observations during SHIVA Inferred CBr and Bry with Wamsley-relation and MIPAS CFC-11 Bry from SCIAMACHY BrO (Courtesy B.-M. Sinnhuber: SHIVA WP5) TC4 East Pacific (E. Atlas) TTL? ‚Missing‘ CBr y (org) Salawitch et al., GRL, 2010

10. ‚Back on the envolope‘ assessment (± 0.5 ppt) of SGs and PGs Br y in the TTL Altitude (km) O 3 (ppb) from SF2 BrO (ppt) from SF2 (±0.5) ppt BrO/Br and BrO/Br y from Ross (but uncertain) Calc. PG Br y (ppt) SG Br y for all 2013 NASA- ATTREX flights (ppt) Total Br y (ppt) PG Br y plus Br y released from SGs (ppt) BrO/Br and BrO/Br y needed to keep Br y at 19.8 ppt 14.5750.81/0.421.6/1.918.2(±0.3)19.8/20.11.6/1.91/0.5 16.01251.61.5/0.52.4/3.217.420.0/20.62.4/2.72.0/0.66 17.01502.01.9/0.523.0/3.817.320.4/21.12.5/2.84.0/0.8 18.02503.23.2/0.554.2/5.816.520.7/22.33.3/3.616/0.96 red: measured; black: modelled/calculated

11. Summary of findings on the brominated VSLS PGI and SGI 1.In the upper tropical troposphere (TUT), total VSLS bromine ranges between 3.5 ppt (WMO-2010), 3.72 ± 0.6 ppt (SHIVA), 4.2 ± 0.6 ppt (CARIBIC), and 4.0 ± 0.3 ppt (NASA-ATTREX) 2.Simultaneous measurements of stratospheric Br y using the organic and inorganic method revealed  VSLS SGI of 2.6 ± 0.6 ppt at Kiruna (1999), 1.25 ± 0.16 at Teresina (2005), and 2.25 ±0.24 ppt at Teresina (2008)  PGI of 2.1 ± 2.6 ppt at Kiruna (1999), 4.0 ± 2.5 at Teresina (2005), and 2.5 ± 2.6 ppt at Teresina (2008), or  SGI + PGI = 4.75 – 5.25 (± 2.6) ppt 3. The NASA-ATTREX measurements of VSLS SGI and BrO over the Eastern/Central Pacific in 2013 are indicating  VSLS SGI of 4.0 ± 0.3 ppt  PGI injection of 1.6 – 1.9 ppt  SGI + PGI = 5.6 – 5.9 (± 0.7) ppt  What are the numbers for the Western Pacific TTL?

12. Conclusion, and outlook 1.Our BrO measurements together with measured CBr y may provide unprecedented tight information on the delivery of brominated VSLS SGs and PGs into the stratosphere. 2.Preliminary data interpretation fully confirms earlier estimates on the VSLS SGs and PGs injection, however, with a factor of 3.5 smaller uncertainties. Comments: 1.We will need to retrieve more BrO data for a variety of different photochemical condition. 2.Since the measured BrO needs to be photochemically corrected for BrO/Bry, constraining the modelling with actually measured O 3, NO y, VOCs, aerosol surfaces, …. would much improve calculated Br y (inorg) 3.Combining our SGs and PG measurements with transport tracers (N 2 O, CH 4, CFC-11, …) may provide novel insight into the relevant source regions of brominated VSLS, the atmospheric transport and transformation of CBr y and of Br y (inorg). 4.….

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