Rynda C. Hudman (hudman@berkeley.edu), A.R. Russell, L.C. Valin, R.C. Cohen

Department of Chemistry

U.C. Berkeley

1. Background1. Background

(c)

REFERENCES REFERENCES

This work was supported by NASA (grant NNX08AE566)

INTERANNUAL VARIABILITY IN SOIL NITRIC OXIDE EMISSIONS OVER THE UNITED STATES AS VIEWED FROM SPACE

OMI NO2 Column Aug 4, 2004OZONE MONITORNING INSTRUMENT8

• 2600 km swath width providing daily global coverage

•1:45 pm equatorial overpass time

•14 x 24 km pixel size at nadir

I. Soil NOx Emissions (SNOx)

Nitric oxide (NO) is a highly variable product of microbial activity in soils.

Processes governing SNOx are not well understood, but correlate best

with water-filled pore space, temperature, and N availability, so that

emissions are highly dependent on local temperature, precipitation, as

well as fertilizer management practices1-6. Surface observations of soil

NOx emissions (SNOx) have sparse spatial coverage, so generalizing

these results to regional and global budgets has proven difficult, with

global above-canopy estimates ranging from 4.7 -13 Tg N yr-1.

II. Satellite Observations

Satellite observations of NO2 have advanced such that they can provide

global continuous coverage on fine spatio-temporal scales allowing a

bridge in the gap between previous satellite analysis at regional scales

(100s of km) and process-based observations at meter scales.7

We use tropospheric NO2 column densities from the Ozone Monitoring Instrument (OMI)8, interpreted with a model of SNOx

9, driven by daily soil temperature and precipitation from the North American Regional Reanalysis (NARR) for 2005-200810, to show that satellite observations can detect interannualvariability in SNOx over the United States. This interannualvariability is a function of climate and soil state variables. We then use GEOS-Chem, a chemical transport model, which represents the variability in N emissions to examine implications of this variability for ozone air quality.

III. Model Description

3. 3. InterannualInterannual variability in OMI NOvariability in OMI NO22 & & SSNOxNOx

ACKNOWLEDGEMENTS ACKNOWLEDGEMENTS

4. Soil 4. Soil NOxNOx impact on ozone air quality impact on ozone air quality

CONCLUSIONS CONCLUSIONS

Algorithm9: SNOx = f( T, biome, w/d)

x Pulse (dryspell)

x canopy uptake

Inputs (2005-2008):daily NARR Temp &

Precipitation10

MODIS Landtype

Fertilizer emissions11

Daily SNOx (0.25°x0.25°) for 2005-2008 Mean Yearly Total: 0.62 Tg N/yr (Fert: 0.12 Tg N/yr)

GEOS-Chem12-14 CTM to examine Ozone air quality

Dry, warm conditions ���� anomalously high June 2006 soil

emissions (Largest predicted month to month variability)

SNOx should be visible from

space. Soil column predicted to comprise 15-40% (mean) and 50-75% (std dev) of the tropospheric NO2 column.

OMI NO2 JUNE INTERANNUAL VARIABILITY FOLLOWS SOIL NOx

June mean OMI NO2 tropospheric column concentrations (top) are compared to mean anomaly for OMI NO2, SNOx, and lightning flashes calculated as difference between with June 2005-2008 mean.

Timeseries of soil NO pulsing event over rural South Dakota (43-45N, 98.75 - 96.25W). OMI NO2 (top) for Standard Product (black) and DOMINO Product (grey) are compared with SNOx (top, green) and ppt (bottom, red) for May - July 2006.

Pulsing event reaches 4x1015 molec cm-2, ~ 2 ppbv assuming 1km well mixed BL

Ozone enhancement due to SNOx increases from 3 ���� 5 ppbv in 2006 vs. 2005-2008 mean.

Mean 8-hr maximum June ozone

enhancement from SNOx for 2005 –2008 (top) are compared with 2006 (bottom) simulated using GEOS-Chem.

*SOIL COLUMN = TROPOSPHERIC

COLUMN – NO SOIL COLUMN

•The interannual variability in the OMI NO2 column over much of the

central United States in June is driven by fertilizer application.

•Dry, warm conditions followed by convective precipitation induced

pulsed SNOx over the agricultural Great Plains in June 2006 resulted in a

50% increase in SNOx and a 30% increase in the tropospheric NO2

column relative to June 2005-2008 mean.

• In a case-study of fertilized fields over SE South Dakota, we find an

associated pulsing event reaching up to 4.6x1015 molec cm-2, equivalent

to a surface concentration of 2 ppbv.

•Driving GEOS-Chem with predicted SNOx we find a mean maximum

surface 8-hr ozone enhancement due to SNOx of 5 ppbv in June 2006

compared with 3 ppbv for 2005-2008.

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Springer, pp. 233–255. 7Bertram, T.H. et al. (2005), Geophys. Res. Lett., 32, L24812, doi:10.1029/2005GL024640. 8Boersma, K.F. et al. (2002), OMI Trace Gas Algorithms,

ATBD-OMI-04 2002, (Version 2), 13-2. 9Yienger, J. J. and Levy II, H. (1995), J. Geophys.

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2. Simulated 2. Simulated SSNOxNOx contribution to NOcontribution to NO22 columncolumn

4. Case4. Case--study of fertilizer induced pulsing over South Dakotastudy of fertilizer induced pulsing over South Dakota