Influence of the Brewer-Dobson Circulation on the Middle/Upper Tropospheric O3

Yi-Der Lin1, Mao-Chang Liang1, Jean-Francois Lamarque 2, Peter Hess 2, 3, Jonathan H. Jiang4, and Yuk L. Yung5

1 Research Center for Environmental Changes, Academia Sinica, Taiwan; 2 National Center for Atmospheric Research, USA; 3 Biological and Environmental Engineering, Cornell University,

USA; 4 Jet Propulsion Laboratory, California Institute of Technology, USA; 5 Division of Geological and Planetary Sciences, California Institute of Technology, USA

Abstract

Lower Stratosphere

--------Observations-------- ---------------------Models---------------------

Middle Troposphere

• TES is used in the mid-upper troposphere to compare with models. • Anomalous enrichments are simulated in the MOZART-2-NCEP during winter/spring seasons at mid-high latitudes. • Between models, STE ozone fluxes vary by a factor of four (340-1440 Tg/yr; Wild O., 2007).

O3

ppbv

O3

ppbv

• The phase of seasonal cycle between models and observations is good in the lower stratosphere.• A few-month lag is observed at mid-troposphere in the spring/summer seasons.

MLS TES MOZART-2-NCEP MOZART-2-MACCM3 CAM

MOZART-2 using reanalysis data of NCEP

MOZART-2-NCEP without surface emission and lightning

• MOZART-2-NCEP without surface emissions of NOx and mechanism of lightning is simulated (center picture).• Lightning is an important source of NOx or O3 at low latitudes.• In MOZART-2-NCEP, the total contribution of lightning is ~5 Tg/yr.

Percentage difference of the above results (~contribution from surface emissions and lightning)

TES maximum

Lat

itud

eL

atit

ude

Lat

itud

e

References:Horowitz, L. W., et al. (2003), A global simulation of tropospheric ozone and related tracers: Description and evaluation of MOZART, version2, J. Geophys. Res., 108(D24), 4784, doi:10.1029/2002JD002853.

Logan, Jennifer A. (1999), An analysis of ozonesonde data for the troposphere: Recommendations for testing 3-D models and development of a gridded climatology for tropospheric ozone, J. Geophys. Res.,

104(D13), 16,115-16,149.Shia, R.L., M. C. Liang, C. Miller, and Yuk L. Yung (2006), CO2 in the upper troposphere: Influence of stratosphere-troposphere exchange, Geophys. Res. Lett., 33, L14814, doi:10.1029/2006GL026141.

Wild O. (2007), Modelling the global tropospheric ozone budget: exploring the variability in current models, Atmos. Chem. Phys., 7, 2,643-2,660.

Worden, H. M., et al. (2007), Comparisons of Tropospheric Emission Spectrometer (TES) ozone profiles to ozonesondes: Methods and initial results, J. Geophys. Res., 112, D03309, doi:10.1029/2006JD007258.

Wu, Shiliang, et al., (2007), Why are there large differences between models in global budgets of tropospheric ozone?, J. Geophys. Res., 112, D05302, doi:10.1029/2006JD007801.

• TES and MLS data are used to study tropospheric ozone from the middle troposphere to the lower stratosphere.• In both hemispheres, MOZART-2-NCEP overestimates the tropospheric ozone at mid-high latitudes during winter and spring seasons. The over predicted ozone is likely the consequence of the STE that is too strong in the NCEP1 meteorological winds.• At ~450hPa, a time lag of a few months between the model and observation is observed, further verifying that the STE across the tropopause is too strong.

• MLS data is used to validate the models in the stratosphere.• The upper boundary of models is set at ~ 1hPa.• The agreement between models and data is good.

Figure 1

Figure 2

Figure 3

Figure 4

Seasonal Cycle Influence of Stratosphere-Troposphere Exchange

Summary

x 100%

O3

ppbv

O3

ppbv

Middle and upper tropospheric ozone is affected by the downwelling transport of air from the stratosphere, where most of ozone is produced. We use the data obtained by Earth Observing System (EOS) Tropospheric Emission Spectrometer (TES) and Microwave Limb Sounder (MLS) to study the ozone distribution from the middle troposphere to the lower stratosphere. Comparisons with model results are made. An off-line chemical transport model (MOZART-2) driven by the NCEP1 and MACCM3 circulations and the on-line model CAM-CHEM, a newly developed model at NCAR, are used to simulate the distribution of ozone from the surface to ~5 mbar. We find that the phase of the seasonal

cycle of the modeled O3 in the mid-troposphere is off by ~1-2 months compared with that

of the observed O3, while the phase between models and observations is good in the lower

stratosphere. This suggests a gap of our understanding of the cross tropopause transport in the current model. The TES total column ozone agrees well with the MOD (TOMS/SBUV Merged Ozone Data) to be within ~5%, but the retrieved vertical profiles of ozone can be differed by as much as 20% from ozone sondes (Worden et al., 2007). The MOZART-2 model driven by NCEP tends to overestimate the abundance of mid-tropospheric ozone at mid-high latitudes compared with TES ozone, suggesting that the STE is too strong in the NCEP.

Figure 1

Figure 2

Jan. Apr.

Jul. Oct.

Jan. Apr.

Jul. Oct.

MLS @ 68 hPa

MOZART-2-MACCM3

@ 66 hPa

MOZART2-NCEP

@ 68 hPa

CAM-CHEM @ 70 hPa

TES @ 450 hPa

MOZART-2-MACCM3

@ 433 hPa

MOZART2-NCEP

@ 435 hPa

CAM-CHEM @ 433 hPa