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Ray Nassar, Jennifer Logan, Lee Murray, Lin Zhang, Inna Megretskaia Harvard University

Investigating Tropical Tropospheric O 3 and CO during the 2006 El Niño using TES observations and GEOS-Chem. Ray Nassar, Jennifer Logan, Lee Murray, Lin Zhang, Inna Megretskaia Harvard University COSPAR, Montreal, 2008 July 13-19. El Niño Southern Oscillation (ENSO).

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Ray Nassar, Jennifer Logan, Lee Murray, Lin Zhang, Inna Megretskaia Harvard University

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  1. Investigating Tropical Tropospheric O3 and CO during the 2006 El Niño using TES observations and GEOS-Chem Ray Nassar, Jennifer Logan, Lee Murray, Lin Zhang, Inna Megretskaia Harvard University COSPAR, Montreal, 2008 July 13-19

  2. El Niño Southern Oscillation (ENSO) Oceanic-Atmospheric phenomenon warm phase – El Niño cold phase – La Niña SST anomalies and changes in ocean circulation induce changes in atmospheric convection, precipitation and chemical composition … also Indian Ocean Dipole (IOD) both ENSO & IOD influence Indonesian region, but warm phases rarely coincide: 1963, 1972, 1997 and 2006 Niño 3.4 5°N-5°S, 170-120°W http://www.cgd.ucar.edu/cas/ IOD ENSO Saji et al. (1999) Nature

  3. Ozone during the 1997 El Niño 1997 – 1996 Anomalies “Asymmetric Dipole Anomalies” TOMS Tropospheric Column Ozone (TCO) residual MLS H2O at 215 hPa NOAA Outgoing Longwave Radiation (OLR) O3 H2O OLR http://ggweather.com/enso/nino_regions.gif Chandra et al. (1998) GRL

  4. Modeling O3 during the 1997 El Niño Hauglustaine, Brasseur & Levine (1999) GRL MOZART model Sudo & Takahashi (2001) GRL CHASER model Trop Column Ozone from TOMS using Convective Cloud Differential technique Chandra et al. (2002) JGR GEOS-Chem model TCO using CCD, TOMS TOMS Aerosol Index for biomass burning -> Biomass Burning component -> Meteorology/Dynamics/Convection component Duncan et al. (2003) JGR GEOS-Chem, focus on biomass burning and lightning Observations Model Chandra et al. (2002) JGR

  5. Tropospheric Emission Spectrometer (TES) High resolution Fourier Transform Spectrometer (FTS) on Aura, measures nadir IR emission, launched 2004 July 15, ~705 km sun-sync orbit GEOS-ChemTropospheric Chemical Transport Model

  6. Changes to O3 and CO during the 2006 El Niño TES TES has well-characterized O3 with ~2 DOFS in the troposphere and simultaneous coincident CO as proxy for biomass burning Logan et al. (2008) GRL 1) Does GEOS-Chem properly simulate CO and O3 distributions during the El Niño? 2) How do biomass burning, lightning and transport contribute to enhanced tropospheric CO and O3? 3) How can the model simulations be improved?

  7. TES & GEOS-Chem LT CO: October 2006 2ºx2.5º resolution • TES v02 CO cloud and data quality flag filtered • Constant TES prior based on 30ºS-30ºN July mean • Horizontal 2ºx2.5º, Vertical average of 6 TES levels LT (825-511 hPa) • Differences exceed TES CO biases of ±10%, Luo et al. (2007) JGR

  8. TES & GEOS-Chem LT O3: October 2006 2ºx2.5º resolution • TES v02 O3 cloud, data quality and emission layer flag filtered • Constant TES prior based on 30ºS-30ºN July mean • Horizontal 2ºx2.5º, Vertical average of 6 TES levels LT (825-511 hPa) • Differences exceed TES O3 biases of 3-10 ppb, Nassar et al. (2008) JGR

  9. 2006–2005 CO Differences GEOS-Chem TES Observations October November December

  10. Biomass Burning impact on CO GEOS-Chem GFEDv2 2005 & 2006 GEOS-Chem GFEDv2 2005 both years TES Observations October November December GFEDv2 = Global Fire Emissions Database (version 2) 8-day temporal resolution

  11. 2006–2005 O3 Differences GEOS-Chem GFEDv2 2005 & 2006 GEOS-Chem GFEDv2 2005 both years TES Observations October November December

  12. Evolution of Indonesian CO plume ppb

  13. CO and O3 Lower Troposphere (LT) Timeseries TES TES GEOS-Chem wAK TES corrected GEOS-Chem wAK GFEDv2 Subtracted 6 ppbv from TES O3 to account for bias determined in validation (Nassar et al., 2008 JGR)

  14. Global Fire Emission Database v2 Methodology 1) MODIS fire counts (8-day) for timing and spatial distribution 2) Emission factors for each land type (savanna, tropical forest, temperate forest) and each chemical species

  15. Updated 2006 Lower Trop Timeseries GFEDv2 November GFEDv2 emissions increased 3x to account for smoldering peat fires

  16. GEOS-Chem & Lightning Imaging Sensor (LIS) NOx from lightning reacts with CO or hydrocarbons to form tropospheric O3 LIS Observations 2006-2005 GEOS-Chem 2006 Lightning Flashrate GEOS-Chem 2006-2005 October November December Note: Flashrates below a given absolute threshold were omitted for % differences Hamid et al. (2001) GRL, discuss lightning enhancement over Indonesia during 1997 El Nino

  17. Updated 2006 Lower Trop Timeseries Scaling model lightning to LIS observations improves the O3 timeseries but discrepancy remains

  18. TES & GEOS-4 UT H2O comparison with O3 anomalies

  19. Outgoing Longwave Radiation (OLR) from NOAA and GEOS-4 NOAA Indonesian OLR anomaly OLRYYYY – OLRclimatology From Australian Bureau of Meteorology http://www.bom.gov.au/bmrc/clfor/cfstaff/matw/maproom/index.htm *High OLR = Low Convection NOAA OLR 2006-2005 GEOS-4 OLR 2006-2005 W/m2 W/m2

  20. Summary and Conclusions • GEOS-Chem can simulate the main CO and O3 features of the 2006 El Niño • Biomass burning, lightning and transport are all important contributors to enhanced tropospheric O3 during El Niño • GFEDv2 must account for CO from smoldering fires • GEOS-Chem should move away from climatological approach to lightning • Improvements to GEOS meteorological fields such as H2O and deep convection fields will result in better simulations of atmospheric composition Acknowledgments: Work was funded by a NASA grant to Harvard University

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