Halogen Chemistry at NCAR D. Kinnison, J.Orlando, J-F Lamarque, S. Schaffler, G. Brasseur, R....

Halogen Chemistry at NCARD. Kinnison, J.Orlando, J-F Lamarque, S. Schaffler, G. Brasseur, R. Garcia, et al…

NCAR

Alfonso Saiz-Lopez and S. SanderJPL

11 February 2008.

[email protected]

Outline• Modeling Tools…

• Updated Chemistry.

• UTLS Studies…• Ozone Trends (stratosphere; CCMVal)

• Dynamics and Transport Evaluations of CCMs in UTLS

• Support START08 and UTLS initiative

• Polar Troposphere…• Ozone Loss (from Bromine Explosions)

• Support OASIS 2009

• Importance of Iodine chemistry (ARCTAS)

+

NCAR Community Climate System Model

Atmosphere CAM3

(WACCM3)

Ocean Sea Ice

Land

Used in decadal and

longer simulations

NCAR Community Climate System Model

Atmosphere CAM3

(WACCM3)

GEOS-5 Met. Fields (U, V, T, etc…).

Advantage:• Allows direct comparisons with observations.

• Have fields from 2004-present day (Aura)

Process oriented evaluati

on:

SPARC CCMVal

Middle Atmosphere Mechanism (57 species; 148 Gas-phase; 17 Heterogeneous; 47 Photolytic)

Long-lived Species: (19-species) Misc: CO2, CO, CH4, H2O, N2O, H2, O2

CFCs: CCl4, CFC-11, CFC-12, CFC-113 HCFCs: HCFC-22 Chlorocarbons: CH3Cl, CH3CCl3, Bromocarbons: CH3Br Halons: H-1211, H-1301 Constant Species: M, N2

Short-lived Species: (38-species) OX: O3, O, O(1D)NOX: N, N (2D), NO, NO2, NO3, N2O5, HNO3, HO2NO2

ClOX: Cl, ClO, Cl2O2, OClO, HOCl, HCl, ClONO2, Cl2BrOX: Br, BrO, HOBr, HBr, BrCl, BrONO2

HOX: H, OH, HO2, H2O2

HC Species: CH2O, CH3O2, CH3OOHIons: N+, N2

+, NO+, O+, O2+

Radiatively Active

Whole Atmosphere Mechanism(115 species; 287 Gas-phase; 17 Heterogeneous; 72 photolytic)

Additional Surface Source Gases (14 additional) … NHMCs: CH3OH,

C2H6, C2H4, C2H5OH, CH3CHOC3H8, C3H6, CH3COCH3 (Acetone)C4H8 (BIGENE), C4H8O (MEK)C5H8 (Isoprene), C5H12 (BIGALK)C7H8 (Toluene) C10H16 (Terpenes)

Radicals: Approx. 44 additional species

Total ~140 species

Next: Additional Organic Bromine (~ 7 species) Organic Iodine Species (~ 8 species)

Additional IOX and BrOX radicals (~10 species)

Total Inorganic Bromine Loading

Taken from Chapter 2, VSLS, WMO, 2006

Ozone Trends

Taken from Chapter 2, VSLS, WMO, 2006

CCMVal 2008/09

•WACCM3 will be used to investigate the impact of enhanced BrOy on model derived ozone trends.

Organic Halogens with varying lifetimes can also tell us about transport pathways in the atmosphere and how well models represent these pathways.

Very Short-lived Substances (VSLS)

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

•SG = Organic VSL Source Gas

•PG = VSL Product gas

•XyVSLS = inorganic halogens from organic SG degradation.

TC4, Whole Air Sampler, Schauffler, Atlas, et al., AGU, 2007

15x10 3

10

5

3210B rom oform (pm ol/m ol)

< > 20151050La titude

Flt 0808

00 1 2 3

5

10

15

km

Bromoform

pptv

15 x103

1 0

5

30252015T ota l O rga nic B ro m in e (pm ol/m o l)

< > 20151050La titu de

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5

15

15

20 25 30pptv

10

km

• Convection lofting VSLS into the TTL.

• Influencing the total inorganic bromine abundance.

• Transported to ExTL?

Org. BrOy

Good Profile Data!

http://utls.tiimes.ucar.edu/science/start08.html

Field experiment: Stratosphere-Troposphere Analyses of Regional Transport (START-08)- Spring 2008.

Goal: Study the transport characteristics of the ExUTLS region. START08 will take advantage of the capabilities of HIAPER and set the stage for more complex and comprehensive field studies of UTLS chemistry and microphysics.

START 2008

Modeling: WACCM3 will be used. Chemical characterization of the UTLS will be evaluated. Transport and mixing processes will be examined.

Halogenated Very Short-lived Substances (VSLS) currently being added the WA3 UTLS mechanism

Source Gas FormulaLocal

Lifetime (days)

Main Loss processes WAS

Bromochloromethane CH2BrCl 150 OH

Trichloromethane (chloroform)

CHCl3 150 OH

Methylene chloride CH2Cl2 140 OH

Dibromomethane CH2Br2 120 OH

Bromodichloromethane CHBrCl2 78 OH, hv

Dibromochloromethane CHBr2Cl 69 hv, OH

Tribromomethane (bromoform)

CHBr3 26 hv

VSL Organic Bromine Species

Ocean

sea ice, ~1-2m thick

Cl- Br-

O3

BrO- H+HOBr Br-

Br2 snowpack

Br2

hυ2Br

O3

BrO

BrOHO2

HOBr

Hg

HgBr Br HgBr2

HgOHgBr

HO2

HOHgBr

“bromine explosion”

BrX?

Hg?

O3?

Potential ACD Contribution:

OH, HO2, RO2, VOC/OVOC, CH2O H2SO4, aerosol properties, radiation

Fast O3, NOx/NOy, PANModels (1-D, 3-D)

Courtesy of J. Orlando

OASIS Program(Ocean/Atmosphere/Sea Ice/Snowpack)

“OASIS program was created to coordinate efforts aimed at determining the importance of OASIS chemical, physical and biological exchange processes on tropospheric chemistry, the cryosphere, and the marine environment”.

• To address these issues, NCAR ACD is planning to participate in a field campaign under the OASIS umbrella for Spring 2009; at Barrow, AK and the Navy Ice Camp located NE of Barrow.

• The deployment will consist of measurements of key chemical species active in the Arctic boundary layer:

• HOx, NOx/NOY, BrOx, O3, halocarbons, organics, and aerosols

• Learn more about the oxidative capacity of the Arctic Troposphere and how bromine explosions impact depletion of Hg from the atmosphere.http://oasishome.net/

Modeling support for OASIS A connection will be initiated between the OASIS

measurement community and the global modeling community at NCAR to examine the impact of of OASIS exchange processes on air quality. Parameterizations of the emissions of halogens and NOx will be

incorporated into CAM-CHEM for studies of regional- and hemispheric-scale air quality impacts.

We will also conduct climate impacts using CCSM (with chemistry). A major initial focus will be on changing sea ice characteristics, and in

particular, first year sea ice which has been shown to correlate with halogen activation.

More first year sea ice in the future might mean more ozone depletion.

Trends in Sea Ice Extent, IPCC WG1, 2007. Multi-model simulated anomalies.

How important are iodine species in affecting ozone loss in the polar lower troposphere?

ACD Collaboration with Alfonso Saiz-Lopez and Stan Sander (JPL).

Observations from Space: Saiz-Lopez et al., GRL, 34, 2007

IO and BrO similar in Antarctica

From Saiz-Lopez et al., Boundary Layer Halogen in Coastal Antarctica, Science, 2007.

•Bromine oxide comes from bromine ions found in sea ice.

•Iodine oxide most likely comes from marine organisms such as phytoplankton and algae, which concentrate the iodide ions that are eventually released in the atmosphere.

Phytoplankton (under Antarctic sea ice)

From A. Saiz-Lopez

IO has not been observed in the Arctic?!

Source Gas FormulaLocal

Lifetime (days)

Main Loss processes WAS

Methyl iodide CH3I 7 hv

Trifluoroiodomethane CF3I 4 hv ?

Ethyl iodide C2H5I 4 hv ?

2-Iodopropane i-C3H7I 1.2 hv ?

1-Iodopropane n-C3H7I 0.5 hv ?

Chloroiodomethane CH2ClI 0.1 hv ?

Bromoiodomethane CH2BrI 0.04 hv ?

Diiodomethane CH2I2 0.003 hv ?

VSL Iodine Species

Halogenated Very Short-lived Substances (VSLS) currently being added the CAM-CHEM, WA3 UTLS mechanism

Summary•Implementing organic halogen species in CAM-CHEM / WACCM3.• Approximately 140 species total.

•Examine the impact of enhance BrOy on model derived ozone trends.• Connected with ongoing WACCM3 CCMVal activities.

•Use VSL organic halogens to understand transport pathways in the UTLS region and evaluate model representation of these pathways.• Support the START08 field mission. Use specified Met version of CAM-CHEM/WACCM3.

•Model Halogen activation in polar troposphere. Support both OASIS 2009 (and ARCTAS) field campaigns. • Investigate both air quality and climate change issues.

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Halogen Chemistry at NCAR D. Kinnison, J.Orlando, J-F Lamarque, S. Schaffler, G. Brasseur, R....

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