# Presentation: 827548

## Mid-Latitude and Polar Ozone: Sensitivity to Bromine

**R. J. Salawitch**** ****1****, D. K. Weisenstein**** ****2****, L. J. Kovalenko**** ****1**** T. Canty****1****, **
**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@jpl.nasa.gov**

**Notes:**
Thank everyone by first name and move on!

## Bromine Budget

- Wamsley et al., JGR, 1998

## 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

**Notes:**
Best Fit: Wamsley: plus 4.2 ppt    AER: plus 6.9 ppt

## Bromine Budget

- Salawitch et al., GRL, in press

**Notes:**
Best Fit: Wamsley: plus 4.2 ppt    AER: plus 6.9 ppt

## 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

- BrOx=BrO+BrCl

**Notes:**
Measurements of BrO in tropics from SAOZ and column BrO from GOME consistent with these results.  Only counter example are in situ observations of BrO of Avallone et al., 1995.

## Sensitivity of Ozone Trends to Kinetics

-  18% reduction in computed ozone depletion using 2002 kinetics
-  Most models underestimate observed ozone trends

- AER model (JPL 2000)
- & column data same as
- Fig 4-33, WMO [2003]

- Salawitch et al., GRL, in press

**Notes:**
Get through this fast, or else skip !!!

## Sensitivity of Ozone Trends to Bromine

- Enhanced Bromine:
-        increase in computed ozone depletion
-        better agreement with observation

**Br****y****TROP**** = 8 ppt model**
**accounts for ~94%**
**of observed O****3**** depletion**
**in the N.H.**

- Salawitch et al., GRL, in press

**Notes:**
Explain that the tabular numbers are area between the zero line and the model/data, divided by the length of the record (1980 to end 2000)
SH more complicated: results shown in our paper.

## Polar Ozone Loss - SOLVE

## Polar Ozone Loss - SOLVE

-  • Photochemical model run along 10-day back
-    trajectories, originating from the ER-2 flight track
-  • ER-2 observations of ClO*x* 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

## 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

**Notes:**
15% increase due to CLOOCL cross section

## Polar Ozone Loss - SOLVE

- Canty et al., JGR, 2005

- Account for all of observed ozone loss

**Notes:**
20% increase due to BrOx

## Polar Ozone Loss - PAVE

- Thanks to Armin Kleinböhl
- and colleagues for ASUR data

**Notes:**
Comment that ClONO2 is needed to close Cly budget!

## 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

**Notes:**
Anthropogenic sources of C2H4Br2: anti-knock agent in leaded auto fuel & aviation fuel
Rasmussen & Khalil: observations suggest C2H4Br2 associated with pollution; Atlas et al. 1992 : observations suggest C2H4Br2 biogenic

## Follow On Research Issues

**      ** **Better definition of Br****y****TROP ****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 O****3**** trends of Br****y****TROP**** (SLIMCAT)**
-        **Polar ozone loss**
**	****Measured and modeled polar O****3**** loss from Aura**
**	****Validation of MLS ClO**
**	****Aura Cl****y**** budget : HIRDLS ClONO****2**** important!  ACE ClONO****2**** !!**
**	****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**
**	****Climate****–****chemistry interactions ********  sensitivity of Br****y****TROP**** to El Ni****ñ****o,               **
**                                                                            ****changing ocean T , or nutrient supply**
**                    **** **

**Notes:**
Emphasize climate-chemistry interaction is a long-term research efforts that will involve modeling & observations from “top down” as well as “bottom up” --> ocean color related to stratospheric ozone

## Extra Material To Follow

## Bromine Budget

-        				  _Br content (ppt)_	_Lifetime_	(yr)       _Source_
-      CHBr3	             Bromoform		        0 to 30	  0.03 to 0.1           N, A
-      CHBr2Cl         Dibromochloromethane      < 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

- 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

**Notes:**
Anthropogenic source of CHBr3 is from water chlorination.

## Bromoform

- Sturges et al., 27, 2081, 2002

- WAS measurements of CHBr3, collected
- over the Azores, France, and Kiruna

**Notes:**
Anthropogenic source of CHBr3 is from water chlorination.
Lifetime for CHBr3 loss: 36 days for photolysis, 100 days for reaction with OH.  Photolysis leads to elimination of Br atom, and formation of a formyl halide radicals.  Degradation products: HBrC(O) & Br2C(O)