1. 1 Reconciling satellite and in-situ measurements of BrO Ross Salawitch*, Tim Canty*, Jennifer Leffel, Thomas Kurosu, Kelly Chance, Trevor Beck, Xiong Liu, Qing Liang, Jose Rodriguez, Arlindo da Silva, Joanna Joiner, Greg Huey, Jin Liao, Robert Stickel, David Tanner, Jack Dibb, Andrew Weinheimer, Frank Flocke, David Knapp, Denise Montzka, Yuhang Wang, Sungyeon Choi, Jin Liao, James Crawford, Gao Chen, William Simpson, Deanna Donohoue, Dan Carlson, Francois Hendrick, Michel van Roozendael, Kim Strong, Christine Adams, Karin Kreher, Andy Neumann, Justin Parrella, Daniel Jacob *Now at University of Maryland, College Park 2009 ARC IONS Data Workshop Meeting 7 January 2009 This presentation builds on the ARCTAS/ARCPAC BrO Workshop held 3 Oct 2008 in Lanham, Maryland, convened to address the “BrO Puzzle”

2. 2 GOME satellite measurements of column BrO: BrO enhancements >10 × 10 13 cm 2 over Arctic ice shelf during spring BrO column of ~5  10 13 cm 2 observed at NH mid-latitudes year round BrO column of ~5  10 13 cm 2 requires either: a) supply of 6 to 8 ppt of Br y to stratosphere from Very Short Lived (VSL) organics (if “excess signal” entirely from the stratosphere) or b) presence of ~2 ppt of BrO in troposphere (global, ubiquitous) Enhanced Arctic BrO, Polar Spring Chance, GRL, 1998 Data from April 30 - May 2, 1997

3. 3 Flight 4: 080404 (Fairbanks to Thule) Thule × OMI Overpass × GREEN: Br 2 RED: BrO BLACK: Soluble Br 

4. 4 Flight 4: 080404 (Fairbanks to Thule) Flight Report: Primary objective was timed spiral under OMI in a BrO hotspot (68º 18’ N, 100º 30’ W) Hallway conversation : surprised to not observe elevated BrO or depleted ozone Thule × OMI Overpass × GREEN: Br 2 RED: BrO BLACK: Soluble Br 

5. 5 Flight 5: 080405 (Thule to Fairbanks) Hudson Bay Thule NEW Flight Report: Descended to 500 ft over Hudson Bay in search of high BrO and low O 3, as predicted by OMI, GOME-2, and models. These conditions not encountered: O 3 was moderately high (30 ppb) and the in situ instrument failed to detect significant BrO concentrations. ↓ DC8 O 3 DC8 Alt→ DC8 Br 2 OMI Column (10 13 mol/cm 2 ) ↓ T. Kurosu, K. Chance, T. Beck, G. Huey, A. Weinheimer

6. 6 Flight 6: 080408 (Fairbanks to Thule to Iqaluit) Flight Report: Exploratory BL run north of Alert found O 3 < 0.5 ppb (Major ODE) with significant levels of soluble Br  and Br 2, but very low levels of BrO. Flew length of Frobisher Bay in the BL, just prior to landing, in a satellite BrO “hotspot”. Not clear if O 3 was depleted, but no BrO was detected. Iqaluit × DC8 ODE × ↓O3↓O3 Alt→ Br 2 OMI Column (10 13 mol/cm 2 ) ↓ T. Kurosu, K. Chance, T. Beck, G. Huey, A. Weinheimer

7. 7 Flight 7: 080409 (Iqaluit to Fairbanks) Flight Report: Successful missed approach at Barrow to sample air ~15 m from ground, with hope of detecting high BrO as suggested by OMI. Ozone was moderately high (35-40 ppb) and no BrO was detected. In general, there appears to be little relation between low O 3 & OMI BrO. Iqaluit GREEN: Br 2 RED: BrO BLACK: Soluble Br  OMI Column (10 13 mol/cm 2 ) ↓

8. 8 Flight 8: 080412 (Fairbanks Local) Flight Report: Objective included MBL sampling in a BrO hotspot over Bering Strait reported by OMI & GOME-2 as well as a missed approach over Barrow. Saw weak indications of ODE/Br chemistry at northern most point. Over Barrow, indicators of O 3 /Br chemistry were not striking. Barrow GREEN: Br 2 RED: BrO BLACK: Soluble Br  OMI Column (10 13 mol/cm 2 ) ↓

9. 9 Flight 9: 080416 (Fairbanks Local) × DC8 Major ODEs × × × GREEN: Br 2 RED: BrO BLACK: Soluble Br  Flight Report: Objectives: Asian biomass burning and Arctic haze, two CALIPSO tracks, and ozone depletion in BL. Both ozone depletion and Br chemistry evident: BrO and Br 2 detected at ~2 ppt levels and soluble bromide also observed. OMI Column (10 13 mol/cm 2 ) ↓ O 3 Alt → Br 2 → BrO→ T. Kurosu, K. Chance, T. Beck, G. Huey, A. Weinheimer

10. 10 Flight 10: 080417 (Fairbanks Local) Flight Report: Final flight out of Fairbanks. Mission scientists decided to turn at 88.5N, but pilots wanted to continue to pole, so flew to 90N before heading to Barrow. All five BL legs of this flight encountered ozone depletion, with BrO in partially depleted air masses and Br 2 observed at lowest levels of O 3. DC8 Major ODEs ×× × × GREEN: Br 2 RED: BrO BLACK: Soluble Br  OMI Column (10 13 mol/cm 2 ) ↓O3↓O3 ← Alt Br 2 → BrO T. Kurosu, K. Chance, T. Beck, G. Huey, A. Weinheimer

11. 11 Column Contribution: 080416 × DC8 Major ODEs × × × ← BrO OMI Column (10 13 mol/cm 2 )

12. 12 Column Contribution: 080417 DC8 Major ODEs ×× × × ← BrO OMI Column (10 13 mol/cm 2 )

13. 13 OMI Total Column BrO vs Barrow, Alaska Tropospheric Column BrO × × Tropospheric BrO from MAX-DOAS W. Simpson, D. Donohoue, D. Carlson & T. Kurosu, K. Chance 71.3°N, 156.8°W

14. 14 OMI Total Column BrO vs Barrow, Alaska Tropospheric Column BrO × × W. Simpson, D. Donohoue, D. Carlson & T. Kurosu, K. Chance Remarkably good agreement between ground-based tropospheric BrO and the OMI anomaly with respect to 5×10 13 mol/cm 2 Note: this much stratospheric BrO requires 6 to 8 ppt of VSL Br y

15. 15 Model Estimates of BrO Please contact me at rjs@atmos.umd.edu if you’d like a copyrjs@atmos.umd.edu of this portion of the talk. Thanks!

16. 16 BrO Columns and Surface O 3, Barrow, Alaska × × Tropospheric BrO from MAX-DOAS W. Simpson, D. Donohoue, D. Carlson & T. Kurosu, K. Chance & S. Oltmans

17. 17  Association between OMI and GOME-2 BrO “hotspots” and elevated BrO / depleted O 3 in BL during ARCTAS much less than we had expected  Remarkably good agreement between Barrow tropospheric column BrO and OMI column BrO minus 5×10 13 mol/cm 2  5×10 13 mol/cm 2 of BrO can exist in the stratosphere if the 6 to 8 ppt of Br y from very short lived (VSL) source gases crosses the tropopause  Tropospheric column BrO from DC-8 on 080416 and 080417 is 1.6 to 5.3×10 13 mol/cm 2 or ~16% to 50% of column BrO seen by OMI  BrO hotspots seen by OMI and GOME-2 in early April 2008 exhibit spatial patterns very similar to total column O 3 & model estimates of stratospheric column BrO, provided there is a very large contribution to stratospheric Br y from VSL source species  Note: the idea that the stratosphere might be responsible for the satellite hot spots was first suggested by Brad Pierce! There is no doubt that ODEs are real and are caused by bromine released at the surface during polar spring … nonetheless, perhaps we have been overestimating the geographic extent of these events by associating all satellite “hotspots” with enhancements of boundary layer BrO If this idea is correct, then proper interpretation of satellite BrO hotspots requires accurate, 3D model estimates of stratospheric column BrO

18. 18 Follow up research, focused on ARC IONS: 1) Relate regions of stratospheric air at high pressure (defined by O 3 > ~100 ppb) to satellite BrO hotspots (like the analysis here of the reln between total column O 3 and satellite BrO) 2) Compare sonde O 3 to calc O 3 to better assess model transport 3) Compare sonde-defined ODEs to difference between satellite BrO and models of BrO above the tropopause, for various values of VSL Br y Incorporation of ground based BrO measurements critical, but especially useful if ground based meas can be converted into a Vertical Column Density Long standing problem: if ODEs are really confined to lowest few 100 m, and presumably highly elevated BrO is similarly confined to these altitudes, then how are the satellite BrO “hotspots” affected by clouds? Understanding the contribution from various altitudes to satellite BrO, and relative influence of VSL source gases (CHBr 3, CH 2 Br 2, etc) versus halogens from melting sea ice (frost flowers, leeds, etc) is a profoundly important research endeavor