Investigating Tropical Tropospheric O
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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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Ray nassar jennifer logan lee murray lin zhang inna megretskaia harvard university

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


El ni o southern oscillation enso

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


Ozone during the 1997 el ni o

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


Modeling o 3 during the 1997 el ni o

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


Tropospheric emission spectrometer tes

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


Changes to o 3 and co during the 2006 el ni o

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?


Tes geos chem lt co october 2006

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


Tes geos chem lt o 3 october 2006

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


2006 2005 co differences

2006–2005 CO Differences

GEOS-Chem

TES Observations

October

November

December


Biomass burning impact on co

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


2006 2005 o 3 differences

2006–2005 O3 Differences

GEOS-Chem

GFEDv2 2005 & 2006

GEOS-Chem

GFEDv2 2005 both years

TES Observations

October

November

December


Evolution of indonesian co plume

Evolution of Indonesian CO plume

ppb


Ray nassar jennifer logan lee murray lin zhang inna megretskaia harvard university

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)


Ray nassar jennifer logan lee murray lin zhang inna megretskaia harvard university

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


Updated 2006 lower trop timeseries

Updated 2006 Lower Trop Timeseries

GFEDv2

November GFEDv2 emissions increased 3x to account for smoldering peat fires


Geos chem lightning imaging sensor lis

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


Updated 2006 lower trop timeseries1

Updated 2006 Lower Trop Timeseries

Scaling model lightning to LIS observations improves the O3 timeseries

but

discrepancy remains


Tes geos 4 ut h 2 o comparison with o 3 anomalies

TES & GEOS-4 UT H2O comparison with O3 anomalies


Outgoing longwave radiation olr from noaa and geos 4

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


Summary and conclusions

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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