The Sensitivity of U.S. Surface Ozone Formation to NO
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The Sensitivity of U.S. Surface Ozone Formation to NO x and VOCs as Viewed from Space: the Ozone Monitoring Instrument (OMI). Bryan Duncan 1 , Yasuko Yoshida 1 , Jennifer Olson 2 , Sandy Sillman 3 , Christian Retscher 1 , Ken Pickering 1 , Randall Martin 4 , Ed Celarier 1 , Jim Crawford 2

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Bryan duncan 1 yasuko yoshida 1 jennifer olson 2

The Sensitivity of U.S. Surface Ozone Formation to NOx and VOCs as Viewed from Space: the Ozone Monitoring Instrument (OMI)

Bryan Duncan1, Yasuko Yoshida1, Jennifer Olson2,

Sandy Sillman3, Christian Retscher1, Ken Pickering1, Randall Martin4, Ed Celarier1, Jim Crawford2

1NASA Goddard Space Flight Center

2NASA Langley Research Center

3University of Michigan

4Dalhousie University

October 20, 2009, CMAS meeting, North Carolina


Bryan duncan 1 yasuko yoshida 1 jennifer olson 2

SO2

NO2

O3

CO

HCHO

OMI

NO2

OMI

HCHO

Main Ingredient in Smog

NOx + VOCs→Ozone

h

Which reactant is the limiting reagent that controls ozone production?

Ozone has little vertical variation.


Bryan duncan 1 yasuko yoshida 1 jennifer olson 2

OMI HCHO/NO2: Air Quality Indicator*

*Based on Sillman [1995]

Martin et al. [2004]

hv

NOx + VOCs → Ozone

• If HCHO/NO2 is low then one must reduce anthropogenic VOCs to lower ozone.

•If HCHO/NO2 is highthen one must reduce NOx to lower ozone.

NOTE: HCHO/NO2 gives info on the sensitivity of instantaneous ozone production, not the ozone concentration!


Bryan duncan 1 yasuko yoshida 1 jennifer olson 2

OMI HCHO/NO2 : August 2006

Lots of Isoprene =

NOx controls

Low VOCs =

VOC controls

VOC controls O3 prod.

NOx controls O3 production

VOC – limited regime

NOx – limited regime

Transition is “fuzzy”: ~1.2-2.2!


Bryan duncan 1 yasuko yoshida 1 jennifer olson 2

OMI HCHO/NO2 : August 2006

Southwest US

Northeast US

Toronto

Las Vegas

Boston

Central

Valley

Phoenix

NYC

San

Francisco

Philly

DC

LA

Richmond

VOC controls O3 prod.

NOx controls O3 production

OMI captures gradient from downtown to suburbs to rural areas!


Bryan duncan 1 yasuko yoshida 1 jennifer olson 2

Minimum & Maximum Ratios of 9 Summer Months

Min Ratio

Max Ratio


Bryan duncan 1 yasuko yoshida 1 jennifer olson 2

Variability Associated with NOx Emissions

The ratio is increasing as NOx emissions decrease. Therefore, ozone formation is becoming more NOx-limited.


Bryan duncan 1 yasuko yoshida 1 jennifer olson 2

June-August OMI NO2: 2007-2005

Wildfires in

2007

Point sources 10% lower in 2007 due to NOx Budget Trading Program of EPA.

Automobile emissions decreased due to Tier 2 Vehicle and Gasoline Sulfur Program.


Bryan duncan 1 yasuko yoshida 1 jennifer olson 2

Variability Associated with Isoprene

Isoprene emissions and, subsequently, HCHO increase with temperature.

Therefore, HCHO/NO2 should increase with temperature.

We know that high O3 events increase with temperature.

Therefore, ozone formation should be more NOx-limited during high ozone events.

But, NOx emissions decreasing!


Bryan duncan 1 yasuko yoshida 1 jennifer olson 2

Conclusions

  • The OMI ratio appears to be a credible air quality indicator and is consistent with in situ observations.

  • Ozone production became more NOx-limited over the U.S. from 2005-2007 because of substantial NOx emission reductions.

  • Ozone production should be more NOx-limited during heat waves in regions with high biogenic emissions.

  • The fine horizontal resolution allows us to see the gradient in the ratio from urban to suburban to rural areas.

  • Currently analyzing CMAQ output. Stay tuned!


Bryan duncan 1 yasuko yoshida 1 jennifer olson 2

Extra Slides


Bryan duncan 1 yasuko yoshida 1 jennifer olson 2

CMAQ Tropospheric Column : HCHO/NO2

4x4 km2 horizontal resolution

July 1st – 4th mean in 2007 at 1-2 pm

Provided by Yongtao Hu, Georgia Tech


Bryan duncan 1 yasuko yoshida 1 jennifer olson 2

Instantaneous Ozone Production Rate (x107 molec/cm3-s) vs HCHO/NO2

(for NO2 columns > 2.5x1015 molec/cm2)

Transition: HCHO/NO2 ~1.2-2.2

Assume Transition= 1

CMAQ

NASA Langley box model output. (Provided by Jennifer Olson)

Transition: HCHO/NO2 1.4-2.6

CMAQ


Bryan duncan 1 yasuko yoshida 1 jennifer olson 2

How do tropospheric and PBL columns (x1015 molec/cm2) compare?

1:1

CMAQ 4 km2 horizontal resolution

over Southern California. (Provided by Yongtao Hu,

Georgia Tech)


Bryan duncan 1 yasuko yoshida 1 jennifer olson 2

How does the Instantaneous O3 Production Rate vary with the PBL column (x1015 molec/cm2), [HCHO], and [NO2]?

CMAQ 4 km2 horizontal resolution

over Southern California. (Provided by Yongtao Hu,

Georgia Tech)

NASA Langley box model output. (Provided by Jennifer Olson)


Bryan duncan 1 yasuko yoshida 1 jennifer olson 2

Above Normal Rainfall

Serious Drought

Historic Drought

OMI HCHO as Proxy for Variability of

Isoprene Emissions

Major player in AQ!

~22% Variation


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