Heidy Plata1, Ezinne Achinivu1, Szu-Ting Chou1, Sheryl Ehrman1, Dale Allen

2, Kenneth Pickering2♦, Thomas Pierce3, James Gleason 3

1Department of Chemical and Biomolecular Engineering2Department of Atmospheric and Oceanic Science

University of Maryland, College Park, Maryland♦Laboratory for Atmospheres, NASA Goddard Space Flight Center

3 Atmospheric Modeling and Analysis Division, NERL, US EPA, Research Triangle Park, North Carolina

Towards improved emissions inventories of soil NOx via model/satellite measurement

intercomparisons

UNIVERSITY OF MARYLAND

Outline

Current Problem Objectives Brief introduction to BEIS3 and satellite products

• Biogenic Emissions Inventory System• OMI-standard and OMI-DOMINO tropospheric

NO2 products Effect of precipitation on NO emissions Approach Discussion and Future Work

Current Problem

NOx contributes

Sources of NOx

Sources of Nitrogen Oxides

Biogenic

Anthropogenic

Modeling NOx emissions from biogenic sources poses a challenge as the frequency and magnitude of their emissions are uncertain.

Point Combustion Sources/Power Plants

Motor Vehicles

Lightning

Soil

Objectives

Develop a better understanding of soil based sources of nitrogen oxides

Evaluate whether satellite observations of NO2 can be used to improve emissions estimates for soil derived NOx

Use this understanding and satellite observations to improve model estimates of NOx emissions in BEIS3, which is the biogenic emission module used in CMAQ

Details about BEIS3

Soil NO emissions in BEIS3 are a function of:

• Land use and temperature

• Precipitation: Emissions can increase by up to a factor of 12 with heavy rain.

• Fertilizer: It doesn’t vary with region. Emissions are constant for first month of growing season (April) and then decrease

• Canopy: the canopy adjustment factor is 1 for the first 30 days of

the growing season then goes down linearly until it is 0.5 and then remains constant.  

Details about BEIS3

Land use (crop) and temperature

Details about Ozone Monitoring Instrument (OMI) Tropospheric NO2 column

OMIOMI

NASA Standard Product

NASA Standard Product

KNMI DOMINO Product

KNMI DOMINO Product

Start with same slant column densities fromspectral fit of OMI observed radiances

Estimate stratospheric NO2 column using data from areas without significant tropospheric pollution. Interpolate globally using a wave-2pattern.

Use stratospheric Column NO2 from TM4 global chemical transport model.

AMF assumes annual mean vertical profiles from GEOS-Chem global model

AMF assumes daily vertical profiles from TM4 model

Effect of precipitation on NO emissions

If dry soil is wetted, a large burst, or pulse occurs and then decays rapidly over a period of time following the wetting event.

Wetting Drying

Nutrient Accumulation

NO

Effect of precipitation on NO emissions

<0.1 cm/day no pulse

0.1<rain<0.5 sprinkle (3 day pulse)

0.5<rain<1.5 shower (1-week pulse)

1.5<rain heavy rain (2 week pulse)

0

2

4

6

8

10

12

14

0 2 4 6 8 10 12 14 16

days following precipitation event

pre

cip

itati

on c

orr

ecti

on f

acto

r sprinkle

shower

heavy rains

Approach

Choose dates with likely

NOx soil emissions due to precipitation

Remove days with lightning or days

with aerosol index>1

Spring 2005(April6-May15)

Select regions in which Biogenic emissions are substantial compared to anthropogenic

North and South Dakota

Missouri and Arkansas

Approach

Evaluate response of BEIS3 emissions

and CMAQ tropospheric NO2

columns to precipitation events

Choose dates with likely

NOx soil emissions due to precipitation

Remove days with lightning or days

with aerosol index>1

Spring 2005(April6-May15)

Select regions in which Biogenic emissions are substantial compared to anthropogenic

Evaluate response of CMAQ

tropospheric NO2 columns using OMI-retrieved

columns

Time

Episode of April 11

Biog

enic(mol/s

)

Episode of April 11

Time

cm

/day

101

5 mo

lecules /cm2

Episode of April 11

Episode of April 12

Pre

cipi

tatio

n (

cm

/day

)

Biog

enic(mol/s

)

Time

Pre

cip

itatio

n (

cm

/da

y )

and

CM

AQ

(10^

15 m

olec

ules

/cm

^2)

Biog

enic(mol/s

)

Episode of April 12

Time

cm

/day

101

5 mo

lecules /cm2

Episode of April 12

Time

Episode of May 9

Biog

enic(mol/s

)

Time

Episode of May 9

Biog

enic(mol/s

)

Pre

cip

itatio

n (

cm

/da

y )

and

CM

AQ

(1015

mol

ecul

es /

cm2 )

Time

Episode of May 9

101

5 mo

lecules /cm2

cm

/day

Discussion

Analysis is hampered by lack of OMI data on days during and sometimes following rainfall events due to clouds.

For cases in which CMAQ tropospheric NO2 columns show the clearest response to increases in biogenic emissions:

• CMAQ high-bias relative to OMI increases after precipitation events implying that the sensitivity of BEIS3 soil emissions to precipitation events is overestimated at least for these cases

Firm conclusions must await analysis of additional cases.

Can additional cases be found in regions where the magnitudes of anthropogenic and biogenic emissions are comparable?

Episode of May 08

Biog

enic(mol/s)

Pre

cipi

tatio

n (

cm

/day

)

Biog

enic(mol/s)

Pre

cip

itatio

n (

cm

/da

y )

and

CM

AQ

(10^

15 m

olec

ules

/cm

^2)

Time

Episode of May 08

101

5 mo

lecules /cm2

cm

/day

Time

Episode of May 08

101

5 mo

lecules /cm2

cm

/day

Time

Discussion

For regions with a greater fraction of anthropogenic emissions, NO2 pulses reflected in BEIS3 output but response of CMAQ tropospheric NO2 columns is controlled by other factors

Suggests utility of our approach limited to rural regions

Future Work

Continue focus on Northern Great Plains and Upper Midwest Region

Expand analysis to include spring 2006 precipitation events

Re-run analysis with reprocessed OMI data Refine screening algorithms

Future Work

Refine method used to determine if tropospheric NO2 column response to changes in biogenic emissions is more than expected from normal day-to-day variations

Use satellite-derived adjustments to improve BEIS-3 emissions

Consider modifying BEIS3 to better resolve the magnitude and duration of soil NOx pulses associated with precipitation

Acknowledgments

Financial Support: NASA Applied Sciences Air Quality Decision Support System Program.