U N I V E R S I T Y O F W A S H I N G T O N S C H O O L O F N U R S I N G

Sensitivity of surface O3 to soil NOx emissions over the U.S.

Lyatt JaegléDepartment of Atmospheric Sciences

University of Washington

+ New formulation of HO2 uptake on aerosols Joel Thornton+ H2 and D simulation Heather Price

O3 increase due to soils New HO2 H2 and D

Soil NOx emissions inferred from GOME NO2A posteriori (8.9 TgN/yr) ~70% larger than a priori

A prioriA priori A posterioriA posteriori

Largest soil emissions: seasonally dry tropical ecosystems

(±200%) (±90%)

Jaeglé et al. (2005)+ fertilized cropland ecosystems

What are the implications for surface O3 over N. America? Sensitivity to doubling of soil NOx for dry ecosystems + fertilizer

US: soil NOx increased by 85%Summer (JJA): soils = 0.6 TgN vs. anthropogenic US = 1.4 TgN

1010atoms N cm-2 s-1

High soil: Surface O3Standard: Surface O3

3-7 ppbv increase in O3 over Great Plains+SWIs this consistent with AIRS surface O3 observations?

1-5 pm

Effects on surface O3 over the U.S. (JJA 2001)

High soil - Standardppbv

ppbv

AIRS Observations: O3

1-5 pm ppbv

High soil – AIRS O3Standard – AIRS O3

Comparison to AIRS observations (JJA 2001)

ppbv

Reduced model bias over Great Plains from –3.5 to +0.6 ppbv

Model bias -3.5 ppbv Model bias +0.6 ppbv

1-5 pm 1-5 pm

Standard ModelEnhanced Soil Model

Daily variations in surface O3 Enhanced-Standard O3 (ppbv)

AIRS observationsModel with no soil emissions

Overall, soil emissions increase O3 by 7-8 ppbv + double modeled variance

1-5pm

2001

Heterogeneous uptake of HO2 on aerosols

Thornton, Jaeglé & McNeill (2007)

LatitudeLow HO2 (<0.05) in LTHigh HO2 (>0.1) in cold UT

If dissolved Cu(II) ions present: HO2 > 0.2 [Mozurkewich et al. 1987] Without Cu(II) ions: HO2=f(temp, aerosol radius, pH) [Thornton and Abbatt, 2005]

Surface HO2 Zonal mean HO2

Implement new HO2 = f(temp, r, pH=5) in GEOS-Chem for all aerosols except dust (HO2=0.2)

HO2 <0.005 in Tropics (temp) + industrialized/BB regions (r)

Effects of HO2 uptake on oxidants

New HO2 % change relative to HO2=0

HO2 (%)

-1 to -5%

H2O2 (%)

+1 to 10%

Alti

tude

(km

)A

ltitu

de (k

m)

HO2=0.2

-5 to -25%

+5 to 30%

HO2 (%)

H2O2 (%)

Alti

tude

(km

)A

ltitu

de (k

m)

Tie et al. [2001,2005]Martin et al. [2003]Tang et al. [2003]

HO2>0.1 overestimates effects on oxidants?

HO2 0.5 H2O2

aerosols

What HO2 to use?

Not enough Cu(II) in aerosols for high HO2? IMPROVE [Thornton et al., 2007], NEAQS [Murphy, 2007]

New HO2 consistent with comparisons to obs High in UT [Jaeglé et al., 2000], low in LT over US [Hudman et al., 2007] and over BB regions [Sauvage et al., 2007]

… but inconsistent with HO2>0.1 inferred from HOx obs MBL over Mauna Loa [Cantrell et al.,1996], Cape Grim [Sommariva et al., 2004; Haggerstone et al., 2005], Mace Head [Smith et al., 2006]. Halogen chemistry?

GEOS-Chem: HO2 =0.2 (v4-30, Mar ‘02-Jun ‘06)HO2 =0 (v7-04-06 and higher)

Implement new formulation?

INTEX-AH2O2

HO2 =0.2

+

D(H2): DJF

Photochemical production (162 57‰) + stratospheric transport (34‰)

H2 and D simulation in GEOS-ChemPrice et al., JGR, 2007

H2: SON

Soil sink (55 9 Tg yr-1)

Ocean source (6 3 Tg yr-1)

Observations:H2 -- CMDL ground sites + aircraft, Novelli et al. (1999) D -- cruises from Gerst & Quay (2000), Rice & Quay (2007)

H2 (ppbv)A

ltitu

de (k

m)

H2 profile: Poker Flat, Alaska

Summary

Increased soil NOx emissions consistent with observed surface O3 over Great Plains

New HO2 formulation HO2 >0.1 in UT, but HO2 <0.01 in LT

Simultaneous constraints on H2 and D budget: soil sink, ocean source, and isotopic signatures.

How much copper is there in aerosols?

Cu(II) Solute Mass Fraction

90% of the observations, Cu mass fraction < 3x10-4 50% of the observations, Cu mass fraction < 8x10-5

1E-5 1E-4 1E-30.0

0.2

0.4

0.6

0.8

1.0

IMPROVE Cu fine mode mass fraction1988- 2004

Cum

ulat

ive

freq

uenc

y di

strib

utio

n

Threshold for Cu-catalyzed HOx loss