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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 Meeting7 January 2009

This presentation builds on the ARCTAS/ARCPAC BrO Workshopheld 3 Oct 2008 in Lanham, Maryland, convened to address the “BrO Puzzle”

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GOME satellite measurements of column BrO: • BrO enhancements >10 × 1013 cm2 over Arctic ice shelf during spring

• BrO column of ~5 1013 cm2 observed at NH mid-latitudes year round

BrO column of ~5 1013 cm2 requires either: a) supply of 6 to 8 ppt of Bry 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

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Flight 4: 080404 (Fairbanks to Thule)

Thule

Thule

× OMI Overpass

× OMI Overpass

GREEN: Br2

RED: BrOBLACK: Soluble Br

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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

Thule

× OMI Overpass

× OMI Overpass

GREEN: Br2

RED: BrOBLACK: Soluble Br

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Flight 5: 080405 (Thule to Fairbanks)

Hudson Bay

Hudson Bay

Thule

Thule

NEW Flight Report: Descended to 500 ft over Hudson Bay in search of high BrO and low O3, as predicted by OMI, GOME-2, and models. These conditions not encountered: O3 was moderately high (30 ppb) and the in situ instrument failed to detect significant BrO concentrations.

↓ DC8 O3

DC8 Alt→

DC8 Br2

OMI Column(1013 mol/cm2) ↓

T. Kurosu, K. Chance, T. Beck, G. Huey, A. Weinheimer

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Flight 6: 080408 (Fairbanks to Thule to Iqaluit) Flight Report: Exploratory BL run north of Alert found O3 < 0.5 ppb (Major ODE) with significant levels of soluble Br and Br2, 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 O3 was depleted, but no BrO was detected.

Iqaluit

Iqaluit

× DC8 ODE

× DC8 ODE

↓O3

Alt→

Br2OMI Column (1013 mol/cm2) ↓

T. Kurosu, K. Chance, T. Beck, G. Huey, A. Weinheimer

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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 O3 & OMI BrO.

Iqaluit

Iqaluit

GREEN: Br2

RED: BrOBLACK: Soluble Br

OMI Column (1013 mol/cm2)

↓

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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 O3/Br chemistry were not striking.

Barrow

BarrowGREEN: Br2

RED: BrOBLACK: Soluble Br

OMI Column (1013 mol/cm2)

↓

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Flight 9: 080416 (Fairbanks Local)

× DC8 Major ODEs×

× DC8 Major ODEs×

GREEN: Br2

RED: BrOBLACK: 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 Br2 detected at ~2 ppt levels and soluble bromide also observed.

OMI Column (1013 mol/cm2)

↓ O3

Alt →

Br2 →

BrO→

T. Kurosu, K. Chance, T. Beck, G. Huey, A. Weinheimer

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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 Br2 observed at lowest levels of O3.

DC8 Major ODEs× ×

DC8 Major ODEs× ×GREEN: Br2

RED: BrOBLACK: Soluble Br

OMI Column(1013 mol/cm2)

↓O3

← Alt

Br2 →

BrO

T. Kurosu, K. Chance, T. Beck, G. Huey, A. Weinheimer

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Column Contribution: 080416

× DC8 Major ODEs×

× DC8 Major ODEs×

← BrO

OMI Column(1013 mol/cm2)

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Column Contribution: 080417

DC8 Major ODEs× ×

DC8 Major ODEs× ×

← BrO

OMI Column(1013 mol/cm2)

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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

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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 5×1013 mol/cm2

Note: this much stratospheric BrO requires 6 to 8 ppt of VSL Bry

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Model Estimates of BrO

Please contact me at rjs@atmos.umd.edu if you’d like a copyof this portion of the talk.

Thanks!

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BrO Columns and Surface O3, Barrow, Alaska

×

×

Tropospheric BrO from MAX-DOAS

W. Simpson, D. Donohoue, D. Carlson & T. Kurosu, K. Chance & S. Oltmans

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Association between OMI and GOME-2 BrO “hotspots” and elevated BrO / depleted O3 in BL during ARCTAS much less than we had expected

Remarkably good agreement between Barrow tropospheric column BrO and OMI column BrO minus 5×1013 mol/cm2

5×1013 mol/cm2 of BrO can exist in the stratosphere if the 6 to 8 ppt of Bry

from very short lived (VSL) source gases crosses the tropopause

Tropospheric column BrO from DC-8 on 080416 and 080417 is 1.6 to 5.3×1013 mol/cm2 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 O3 & model estimates of stratospheric column BrO, provided there is a very large contribution to stratospheric Bry

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

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Follow up research, focused on ARC IONS:

1) Relate regions of stratospheric air at high pressure (defined by O3 > ~100 ppb) to satellite BrO hotspots (like the analysis here of the reln between total column O3 and satellite BrO)

2) Compare sonde O3 to calc O3 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 Bry

Incorporation of ground based BrO measurements critical, but especiallyuseful 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 (CHBr3, CH2Br2, etc) versushalogens from melting sea ice (frost flowers, leeds, etc) is a profoundlyimportant research endeavor