Mid-Latitude and Polar Ozone: Sensitivity to Bromine

1
Mid-Latitude and Polar Ozone Sensitivity to
Bromine
R. J. Salawitch 1, D. K. Weisenstein 2, L. J.
Kovalenko 1 T. Canty1, C. E. Sioris 3, P. O.
Wennberg 4, K. Chance 3, M. K. W. Ko 5, and C. A.
McLinden 6
1Jet Propulsion Laboratory, Caltech, Pasadena
CA 2Atmospheric and Environmental Research, Inc,
Lexington MA 3Harvard-Smithsonian Center for
Astrophysics, Cambridge MA 4California Institute
of Technology, Pasadena CA 5NASA Langley Research
Center, Hampton VA 6Meteorological Service of
Canada, Toronto, Canada
Ross.Salawitch_at_jpl.nasa.gov
2
Bromine Budget
Wamsley et al., JGR, 1998
3
Bromine Budget
Organics CH3Br 9.8 Halons
5.9 CH2Br2 2.2 CH2BrCl 0.2
Total 17.9
Organics CH3Br 9.8 Halons
5.9 Total 15.7
Salawitch et al., GRL, in press
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Bromine Budget
Salawitch et al., GRL, in press
5
Bromine Budget
Evidence for supply of significant amounts of
stratospheric bromine from sources besides CH3Br
halons SCIAMACHY (Sioris et al., in prep)
SAOZ balloons (Pundt et al.,
2002) DOAS balloons (Pfeilsticker et al.,
2000) GOME column (Chance, 1998)
Ground-based column (Sinnhuber et al., 2002
Schofield et al., 2004)
Canty et al., JGR, 2005
BrOxBrOBrCl
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Sensitivity of Ozone Trends to Kinetics
AER model (JPL 2000) column data same as Fig
4-33, WMO 2003
? 18 reduction in computed ozone depletion using
2002 kinetics ? Most models underestimate
observed ozone trends
Salawitch et al., GRL, in press
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Sensitivity of Ozone Trends to Bromine
BryTROP 8 ppt model accounts for 94 of
observed O3 depletion in the N.H.
Enhanced Bromine ? increase in computed
ozone depletion ? better agreement with
observation
Salawitch et al., GRL, in press
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Polar Ozone Loss - SOLVE
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Polar Ozone Loss - SOLVE
Photochemical model run along 10-day back
trajectories, originating from the ER-2 flight
track ER-2 observations of ClOx and O3 used
to initialize model Observed ozone loss
based on time evolution of O3 vs N2O relation
Account for 72 of observed ozone loss
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Polar Ozone Loss - SOLVE
See Stimpfle et al., JGR, 2004 for
discussion of ClOOCl cross section
illustration Burkholder cross section
gives better agreement with measured
ClO/ClOOCl ratio
Account for 83 of observed ozone loss
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Polar Ozone Loss - SOLVE
Canty et al., JGR, 2005
Account for all of observed ozone loss
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Polar Ozone Loss - PAVE
Thanks to Armin Kleinböhl and colleagues for ASUR
data
13
Species Responsible for Enhanced Bromine
Most of these species ? biogenic produced
by marine algae ? very short lived (VSL) in
the troposphere (lifetimes
between 13 and 120 days)
See Quack et al., GRL, 2004
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Follow On Research Issues
? Better definition of BryTROP and effects
on mid-latitude trends Accurate and precise
measurements of BrO in TTL (aircraft or
balloon) Bromine budget from BrO in middle
upper stratosphere (MLS) Measured and modeled
column BrO (OMI) More model
estimates of impact on O3 trends of BryTROP
(SLIMCAT) ? Polar ozone loss Measured and
modeled polar O3 loss from Aura Validation of
MLS ClO Aura Cly budget HIRDLS ClONO2
important! ACE ClONO2 !! BrOx (from BrO) in the
polar vortices ? Species responsible and
mechanism(s) of delivery Measure BrO suite of
organics from boundary layer to tropopause Roles
of heterogeneous chemistry, aerosol
scavenging Climatechemistry interactions ?
sensitivity of BryTROP to El Niño,

changing ocean T , or
nutrient supply
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Extra Material To Follow
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Bromine Budget
Gases considered by Wamsley
Br content (ppt) CH3Br Methyl
bromide 9.8 ? Montzka
2003 CBrClF2 Halon 1211 2.5
? Montzka 2003 CBrF3 Halon 1301 2.0
? Montzka 2003 C2Br2F4 Halon
2402 1.0 ? Montzka
2003 CH2Br2 Dibromomethane 2.2
CH2BrCl Bromochloromethane 0.3

Total 17.8 ppt
Wamsley et al. did not consider Br
content (ppt) Lifetime (yr) Source
CHBr3 Bromoform 0 to 30
0.03 to 0.1 N, A CHBr2Cl
Dibromochloromethane lt 2.0 0.4
N CHBrCl2
Bromodichloromethane 0.6 to 3.8 0.4
N CH2BrCH2Br
1,2-dibromomethane 0 to 35 0.4
A CHBr2F2 Halon 1202
0.088 2.9
A C2H4Br2
Ethylene dibromide perhaps 10
40 A A
Anthropogenic

N Natural
17
Bromoform
Sturges et al., 27, 2081, 2002
WAS measurements of CHBr3, collected over the
Azores, France, and Kiruna