RAQMS Study of Bromine Catalyzed Tropospheric Ozone Loss in the Arctic,

Spring, 2008

Murali Natarajan, Jay Al-Saadi, Brad Pierce,Todd Schaack, Alan Lenzen, John Worden, Anne Thompson, Bill Simpson, Deanna Donohoue,

and Samuel Oltmans

TES Science Team Meeting, Boulder, CO., February 23-25,2009

Background

• Observations of ozone depletion events in the polar boundary layer during springtime have been reported since late 1980’s.

• These events are most likely caused by catalytic destruction involving reactive bromine

• Ground based observations have shown elevated Bromine near surface.

• Satellite observations by GOME, GOME2, OMI, and SCIAMACHY experiments also indicate enhanced BrO column.

• Tropospheric halogen chemistry is among the main themes of the field campaigns during Spring, 2008 (ARCTAS & ARCPAC)

Model Description• Global scale meteorological and chemical modeling

system.• Meteorological forecast by hybrid model developed

at the University of Wisconsin.• Unified stratosphere/troposphere chemistry module

developed at NASA LaRC.• Surface emissions of natural and anthropogenic NOx,

CO, and NMHC species. Updated fire emission data.• GOCART formulation for global aerosol prediction.• Photolysis rates calculated by Fast-JX.• Assimilation of OMI total ozone, MLS stratospheric

ozone, and MODIS aerosol.• Parameterized Bromine release from sea salt and sea

ice surface.

R Mean Bias (%) RMS Diff. (%) Raw Data 0.43 -18.0 66.3 3-day Avg. 0.62 -18.2 44.1 6-day Avg. 0.73 -17.0 34.0

(MAX-DOAS data provided by Bill Simpson and Deanna Donohoue)

RAQMS O3 April 15, 2008, 06Z

Seasalt Seasalt + Seaice Difference

RAQMS O3 at Barrow, Mar - May, 2008

ARCIONS O3 at Barrow, AK, April,2008

(Data provided by Sam Oltmans and Anne Thompson)

(60m Analysis)

(CMDL Data provided by Sam Oltmans)

Canadian Arctic (180E-0E, 60-90N)RAQMS (without TES Observation Operator)

Canadian Arctic (180E-0E, 60-90N)RAQMS (with TES Observation Operator)

Canadian Arctic (180E-0E, 60-90N)

Canadian Arctic (180E-0E, 60-90N)RAQMS (with TES Observation Operator) vs TES

RAQMS highRAQMS Low

RAQMS (with TES Observation Operator) vs TES

Low biases south of 70N cancel high biases north of 70N when TES observation operator is applied

Summary Statistics: RAQMS vs ARCIONS

Arctic (Lat 60N-70N), April, 2008

Summary Statistics: RAQMS vs ARCIONS

Arctic (Lat > 70N), April, 2008

Summary of Arctic Analysis• RAQMS BrO is lower than MAX_DOAS observations during

March, 2008. The agreement with the data is better in April.

• RAQMS shows a 20 - 30% low bias with TES near the tropopause. Raqms is ~40% lower than ARCIONS in 200-300 mb region for 60N - 90N. This implies that TES is within 10% of ARCIONS near the tropopause for lat > 60N.

• South of 70N and below 400mb, RAQMS is about 5% lower than TES and about 10 - 20% lower than ARCIONS. This indirect validation implies that TES is 5 - 15% lower than ARCIONS for Lat < 70N.

• North of 70N, indirect validation shows that TES is ~10% lower than RAQMS, and ARCIONS is ~10 - 20% higher than RAQMS. This implies that TES is lower than ARCIONS by ~ 20 - 30% for Lat > 70N.

• While the comparison of the lowest model level ozone with observed surface ozone time series is good, the model does not show the extreme decreases seen in the data. Mixing up out of the boundary layer probably leads to higher bromine influence in the model Arctic lower troposphere.