Understanding the Influence of Biomass Burning on Tropospheric Ozone through Assimilation of TES data

Jennifer Logan Harvard University

Dylan Jones, Mark ParringtonUniversity of Toronto

Kevin Bowman, Helen Worden, John Worden, Greg OstermanJet Propulsion Laboratory

California Institute of Technology

Impact of Biomass Burning on Tropospheric O3

TES CO, 421 mb: Nov 4-17, 2004 TES O3, 421 mb: Nov 5-17, 2004

GEOS-Chem CO 421 mb: Nov 4-17, 2004 GEOS-Chem O3, 421 mb: Nov 4-17, 2004

Climatological emission inventory in the model underestimates the impact biomass burning on CO and O3 in the southern hemisphere

ppb ppb

Objective: Assess the potential of TES data to improve O3 in the model in a chemical data assimilation framework

Impact of Assimilation on CO and O3 (using a sequential sub-optimal

Kalman filter with TES O3 and CO profile retrievals for Nov. 4-17, 2004)

Change in O3 at 7 km (assim. - without assim.)

24-hr averaged assimilated O3 at 7 km on Nov. 17

(ppb CO)

percent

• Assimilation increases CO throughout the southern hemisphere• Largest increases in O3 (20-50%) are over the Indian Ocean and the

Indonesian/Australian region

(ppb O3)

percent

24-hr averaged assimilated CO at 7 km on Nov. 17

Change in CO at 7 km (assim. - without assim.)

Assimilation of TES O3 for 1 July 2005 - 1 Jan. 2006

Assimilation

Free running model

O3 difference: assimilation - free running model

data gaps

Mean GEOS-Chem O3 at 8 km between 20°S-equator and 180°W-180°E

• In early Sept 2005 the assimilation increases O3 by about 20% in upper troposphere

• During the 2 week data gap in September the analysis reverts to the state of the free running model

Comparison with Ozonesonde Data at La Reunion Island (21°S, 55°E)

12 Oct 2005 17 Oct 2005 28 Oct 2005

2 Nov 2005assimilation

free running model

sonde

• The ozone tropopause in GEOS-Chem is too low in Austral spring 2005 compared to the sonde data

• Assimilation of TES data reduces the bias in the model

Comparison of the O3 Analysis with TES Observations (350 mb)

• During October the assimilation reduces the bias in the model by about a factor of 2

• Despite the reduction in the bias, the residuals for the OmA are still large

Obs minus Forecast

Obs minus Analysis

Comparison of the CO Analysis with TES Observations (350 mb)

• Following the warm-up of the TES optical bench in Dec. 2005, the assimilation significantly reduced the bias in CO in the model

• In contrast to the O3 analysis, the CO OmA residuals are small, reflecting the longer lifetime of CO

Obs minus Forecast

Obs minus AnalysisTES OB warm-up

Assimilation extended through 1 Sept 2006

Latitudinal Dependence of the O3 Analysis Residuals (350 mb)

The assimilation has less impact in summer 2006 because we are propagating the forecast error variance without accounting for forecast error growth by summer 2006 the forecast error is about 15% in the tropics and subtropics, compared to the assumed 50% error in July 2005

Larger OmA residuals in the tropics, reflecting the shorter O3 lifetime and a lower density of TES data

20°S-0°

30°N-60°N

Obs minus Forecast

Obs minus Analysis

Conclusions

•Assimilation of TES O3 data produces a much improved distribution of O3 in the model, which provides greater constraints on model parameters such as the lifetime of NOx a better constraint on the NOx lifetime will result in improved estimates of NOx emissions from lightning and of the export of NOy from continental source regions

•In contrast to the CO analysis, the residuals in the O3 assimilation are large, especially in the tropics, reflecting the shorter lifetime of O3 (and the low density of the TES data) assimilating trace gases that are more chemical active than CO will be a challenge

•A better approach for exploiting the satellite data would be to optimize the model parameters, such as the emissions, using adjoint techniques work is needed to characterize the forecast errors across the range of chemical timescales in the model