BioGEOCHEMICAL CYCLESBioGEOCHEMICAL CYCLES

• Most abundant elements: oxygen (in solid earth!), iron (core), silicon (mantle), hydrogen (oceans), nitrogen, carbon, sulfur…

• The elemental composition of the Earth has remained essentially unchanged over its 4.5 Gyr history

– Extraterrestrial inputs (e.g., from meteorites, cometary material) have been relatively unimportant

– Escape to space has been restricted by gravity

• Biogeochemical cycling of these elements between the different reservoirs of the Earth system determines the composition of the Earth’s atmosphere and oceans, and the evolution of life

THE EARTH: ASSEMBLAGE OF ATOMS OF THE 92 NATURAL ELEMENTSTHE EARTH: ASSEMBLAGE OF ATOMS OF THE 92 NATURAL ELEMENTS

BIOGEOCHEMICAL CYCLING OF ELEMENTS:BIOGEOCHEMICAL CYCLING OF ELEMENTS:examples of major processesexamples of major processes

Physical exchange, redox chemistry, biochemistry are involved

Surfacereservoirs

HISTORY OF EARTH’S ATMOSPHEREHISTORY OF EARTH’S ATMOSPHERE

Outgassing

N2

CO2

H2Ooceans form

CO2

dissolves

Life forms in oceans

Onset ofphotosynthesis

O2 O2 reaches current levels; life invades continents

4.5 GyB.P

4 GyB.P.

3.5 GyB.P.

0.4 GyB.P. present

COMPARING THE ATMOSPHERES COMPARING THE ATMOSPHERES OF EARTH, VENUS, AND MARSOF EARTH, VENUS, AND MARS

3x10-41x10-23x10-3H2O (atm, mol/mol)

1.3x10-30.216.9x10-5O2 (mol/mol)

0.007

0.64

1

5.98

91

4.87

Surface pressure (atm)

Mass (1024 kg)

2.7x10-20.783.4x10-2N2 (mol/mol)

0.953x10-40.96CO2 (mol/mol)

340064006100Radius (km)

MarsEarth Venus

H2O (total, bars) 0.3 400 2 x 10 -6

Source: EARLY EARTH Oxygen for heavy-metal fans: Lyons TW, Reinhard CTNATURE Volume: 461 Issue: 7261 Pages: 179-181 SEP 10 2009

0.1x10-9Carbonyl Sulfide (COS)

3.0x10-9Chlorofluorocarbons

0.03x10-6 to 0.3x10-6Carbon Monoxide (CO)

0.32x10-6Nitrous Oxide (N2O)

0.55x10-6Hydrogen (H2)

1.1x10-6Krypton (Kr)

1.7x10-6Methane (CH4)

5.2x10-6Helium (He)

0.02x10-6 to 10x10 –6Ozone (O3) ¶

18.2x10-6Neon (Ne)

Carbon Dioxide (CO2)

0.0093Argon (Ar)

0.04 to < 5x10-3; 4x10-6 -stratWater (H2O)

0.21Oxygen (O2)

0.78Nitrogen (N2)

Mole fractionGasAtmospheric Atmospheric Composition Composition

(average)(average)

1 ppm= 1x101 ppm= 1x10-6-6

red = increased by red = increased by human activityhuman activity

¶ Ozone has increased in the troposphere, but decreased in the stratosphere.

NOAA Greenhouse Gas records

OXIDATION STATES OF NITROGENOXIDATION STATES OF NITROGENN has 5 electrons in valence shell N has 5 electrons in valence shell 9 oxidation states from –3 to +59 oxidation states from –3 to +5

HNO3

Nitric acid

NO3-

Nitrate

+5

NO2

Nitrogen dioxide

+4

HONO

Nitrous acid

NO2-

Nitrite

NO

Nitric oxide

N2O

Nitrous

oxide

N2NH3

Ammonia

NH4+

Ammonium

R1N(R2)R3

Organic N

+3+2+10-3

Decreasing oxidation number (reduction reactions)

Increasing oxidation number (oxidation reactions)

Nitrogen: Nitrogen is a major component of the atmosphere, but an essential nutrient in short supply to living organisms. Why is "fixed" nitrogen in short supply? Why does it stay

in the atmosphere at all?

free radical free radical

THE THE NITROGEN CYCLENITROGEN CYCLE: MAJOR PROCESSES: MAJOR PROCESSES

ATMOSPHEREN2 NO

HNO3

NH3/NH4+ NO3

-

orgN

BIOSPHERE

LITHOSPHERE

combustionlightning

oxidation

deposition

assimilation

decay

nitrification

denitri-ficationbiofixation

burial weathering

free radical

"fixed" or "odd" N is less stable globally=> N2

Oceanic Nitrogen Processes

Org N

NH4+ NH2OH NO2

- NO3-

N2H4 N2

NO

N2O

N2

-3 -2 -1 0 1 2 3 5

-3 -2 -1 0 1 2 3 5

??

ox state

“There are lies, there are big lies, and then there are…box models.”

• Box models are usually considered linear models. Nature isn’t linear.

It matters how you choose to divide up the problem into boxes.

*

*

***************************************************************************************************

time

C1

or

C2

0 2 4 6 8 10

0.0

0.00

20.

004

0.00

60.

008

0.01

0Box 1 of 2

Box 2 of 2

Box 1

Box 2

kk

Only Box 2

Only Box 1

Box 2 only

k=1; M1=1, M2=10; Co = .01 (M1o)

C1=Co/M1+2{M2 exp(-k(M1+2/(M1M2)t) +M1 } C2=CoM1 /M1+2{1 - exp(-k(M1+2/(M1M2)t ) }

Box 1

Box 2

kk

BOX MODEL OF THE NITROGEN CYCLEBOX MODEL OF THE NITROGEN CYCLE

Inventories in Tg NFlows in Tg N yr-1

NN22O: LOW-YIELD PRODUCT OF BACTERIAL O: LOW-YIELD PRODUCT OF BACTERIAL

NITRIFICATION AND DENITRIFICATIONNITRIFICATION AND DENITRIFICATIONImportant as

• source of NOx radicals in stratosphere• greenhouse gas

IPCC[2001]

NH4

++3/2O2 NO2

+ H2O + 2 H+

NO3

+ Org-C N2 + …

N2O

Constraints on N2O budget changes since pre-industrial time from new firn air

and ice core isotope measurements

S. Bernard, T. R¨ockmann, J. Kaiser, J.-M. Barnola, H. Fischer, T. Blunier, and J. Chappellaz, Atmos. Chem. Phys., 6, 493–503, 2006

time

1980 1985 1990 1995 2000 2005

300

305

310

315

320

N2O (ppb)mean annual increase 0.74 ppb/yr

N2O versus depth in the Greenland Ice sheet.

N2O in the atmosphere

PRESENT-DAY GLOBAL BUDGET OF ATMOSPHERIC N2O

SOURCES (Tg N yr-1) 18 (7 – 37)

Natural 10 (5 – 16)

Ocean 3 (1 - 5)

Tropical soils 4 (3 – 6)

Temperate soils 2 (1 – 4)

Anthropogenic 8 (2 – 21)

Agricultural soils 4 (1 – 15)

Livestock 2 (1 – 3)

Industrial 1 (1 – 2)

SINK (Tg N yr-1)

Photolysis and oxidation in stratosphere

12 (9 – 16)

ACCUMULATION (Tg N yr-1) 4 (3 – 5)

Although a closed budget can be constructed, uncertainties in sources are large! (N2O atm mass = 5.13 1018 kg x 3.1 10-7 x28/29 = 1535 Tg )

IPCC[2001]

Inventories in Tg NFlows in Tg N yr-1

BOX MODEL OF THE NBOX MODEL OF THE N22O CYCLEO CYCLE

36 8

1.53 103 N2O

FAST OXYGEN CYCLE: ATMOSPHERE-BIOSPHEREFAST OXYGEN CYCLE: ATMOSPHERE-BIOSPHERE

• Source of O2: photosynthesis

nCO2 + nH2O -> (CH2O)n + nO2

• Sink: respiration/decay

(CH2O)n + nO2 -> nCO2 + nH2O

O2

CO2

orgC

orgClitter

Photosynthesisless respiration

decay

O2 lifetime: 5000 years

……however, abundance of organic carbon in however, abundance of organic carbon in biosphere/soil/ocean reservoirs is too small to control biosphere/soil/ocean reservoirs is too small to control

atmospheric Oatmospheric O2 2 levels levels

SLOW OXYGEN CYCLE: ATMOSPHERE-LITHOSPHERESLOW OXYGEN CYCLE: ATMOSPHERE-LITHOSPHERE

O2CO2

Compressionsubduction

Uplift

CONTINENTOCEAN

FeS2orgC

weatheringFe2O3

H2SO4

runoff

O2CO2

Photosynthesisdecay

orgC

burial

SEDIMENTS

microbesFeS2orgC

CO2orgC: 1x107 Pg CFeS2: 5x106 Pg S

O2: 1.2x106 Pg OO2 lifetime: 3 million years

(C106H124O36) (NH3)16 (H3PO4) + 150 O2 => 106 CO2 + 16 HNO3 + H3PO4 + 78 H2O + energy

Dissolved NO3

-

mole/kg

Dis

solv

ed O

2 m

ole/

kg

The cycle of organic/inorganic C, solubility of O2 in seawater, and onset of denitrification, limit the amount of nitrate in the deep ocean

The heavier temperature lines 160,000 BP to present reflect more data points, not necessarily greater variability.

Source: Climate and Atmospheric History of the past 420,000 years from the Vostok Ice Core, Antarctica , by Petit J.R., Jouzel J., Raynaud D., Barkov N.I., Barnola J.M., Basile I., Bender M., Chappellaz J., Davis J. Delaygue G., Delmotte M. Kotlyakov V.M., Legrand M., Lipenkov V.M., Lorius C., Pépin L., Ritz C., Saltzman E., Stievenard M., Nature, 3 June 1999.

Antarctic Ice Core Data

CO2 varies over geologic time, within the range 190 – 280 ppm for the last 420,000 years. The variations correlate with climate: cold low CO2 . Is CO2 driving climate or vice versa?

Antarctic ice cores compared with modern data for COAntarctic ice cores compared with modern data for CO22

0.0

0.2

0.4

0.6

0.8

CO

2 A

irbor

ne F

rac

1960 1970 1980 1990 2000

CO

2 A

irbor

ne F

ract

ion

60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 00 02

Year-to-year change in CO2 (ppm)

(SPO+MLO)/2

Starting year

RECENT GROWTH IN ATMOSPHERIC CORECENT GROWTH IN ATMOSPHERIC CO2 2

CONCENTRATIONSCONCENTRATIONS

The average annual increase did not change much between 1970 and 2000, despite significant increases in fossil fuel emissions.

1 ppm = 2.1 x 109 tons of C (in CO2)

Average rate of increase per year, 1.5 ppm = 3.25 x 109 tons/yr—little change (some variations) since 1975.

01

23

Airborne fraction, CO2 (ppm)

Arrows indicate El Nino events

Notice:• atmospheric increase is ~50% of fossil fuel emissions• significant interannual variability

GLOBAL PREINDUSTRIAL CARBON CYCLEGLOBAL PREINDUSTRIAL CARBON CYCLE

The carbon cycle can be viewed as a set of "reservoirs" or compartments, each characterizing a form of C (e.g. trees; rocks containing calcium carbonate [limestone]).

The cycle of C globally is then represented as a set of transfer rates between compartments.

The total amount of carbon in the atmosphere + ocean + rocks that exchange with the atmosphere/ocean is fixed by very long-term geophysical processes.

Human intervention may be regarded as manipulation of the rates of transfer between important reservoirs.

Inventories in Pg C

Flows in Pg C a-1

Carbon Cycle on Land•Photosynthesis:

CO2 + H2O + light => "H2CO" + O2

•Respiration:

"H2CO" + O2 => CO2 + H2O + energy

Very little organic matter is stored, on average.

Carbon Cycle in the ocean•Dissolution/evasion

CO2(g) + H2O + CO3(aq) = 2 HCO3

¯

Global CO2 cycle

6.3 - 7.3Total

1-2Deforestation

5.3Fossil Fuel+ cement

Global CO2 budget (PgC yr-1 ) 1980 – 1990 1990 –2000

Sources

1-2"Missing Sink"

6.3 - 7.3Total

2.1Ocean uptake

3.2Atmospheric accumulation

Sinks

2.1 Pg C = 1 ppm atmospheric CO2 [source: Cias et al., Science 269, 1098, (1995)]

6.5

.5-1

7-7.5

3.2

1.5-2

1.8-2.8

7-7.5

EVIDENCE FOR LAND UPTAKE EVIDENCE FOR LAND UPTAKE OF COOF CO22 FROM TRENDS IN O FROM TRENDS IN O22,,

1990-20001990-2000

Composition of Sea WaterComposition of Sea Water

"alkalinity" defines Σ' Zi [i] : response of H+ and OH- to addition of CO2

Charge balance in the ocean:[HCO3

-] + 2[CO32-] = [Na+] + [K+] + 2[Mg2+] + 2[Ca2+] - [Cl-] – 2[SO4

2-] – [Br-] The alkalinity [Alk] ≈ [HCO3

-] + 2[CO32-] = 2.3x10-3M

AlkalinityAlkalinity

• [alk] = Σi Z+[i+] - Σi Z-[i-] = [HCO3-] + 2 [CO3

=]

• [alk] is a re-arrangement of the charge balance equation. It cannot change when adding or removing an uncharged species like CO2.

• [alk] = 2 x 10-3 M -- only 1 in 1000 of total ions!

UPTAKE OF COUPTAKE OF CO22 BY THE OCEANS BY THE OCEANS

CO2(g)

CO2.H2O

CO2.H2O HCO3

- + H+

HCO3- CO3

2- + H+

KH = 3x10-2 M atm-1

K1 = 9x10-7 M

K2 = 7x10-10 M pK 1

Ocean pH = 8.2

pK 2

CO2.H2O HCO3

- CO32-

OCEAN

ATMOSPHERE

LIMIT ON OCEAN UPTAKE OF COLIMIT ON OCEAN UPTAKE OF CO22::

CONSERVATION OF ALKALINITYCONSERVATION OF ALKALINITY Equilibrium calculation for [Alk] = 2.3x10-3 M

pCO2 , ppm100 200 300 400 500

8.6

8.4

8.2

2

3

41.4

1.6

1.8

1.9

2.0

2.1

Ocean pH

[CO32-],

10-4 M

[HCO3-],

10-3M

[CO2.H2O]+[HCO3

-]

+[CO32-], 10-3M

Charge balance in the ocean:[HCO3

-] + 2[CO32-] = [Na+] + [K+] + 2[Mg2+] +

2[Ca2+] - [Cl-] – 2[SO42-] – [Br-]

The alkalinity [Alk] ≈ [HCO3

-] + 2[CO32-] =

2.3x10-3M is the excess base relative to the CO2-H2O system

It is conserved upon addition of CO2

uptake of CO2 is limited by the existing supply of CO3

2-:

Increasing Alk requires dissolution of sediments:…which takes place over a time scale of thousands of years

CO2(g) + CO32 + H2O 2HCO3

-

Ca2+ + CO32-CaCO3

NCO2atm=PCO2 NA = Natm

NCO2aq= PCO2

KH Voc (1 + K1/[H+] + K1 K2 / [H+]2 )

| | |

[CO2 aq] [HCO3

− ] [CO3

= ]

1 : 140 : 16

CO2H2O HCO3

- + H

+ K1 = [ HCO3

- ][ H+ ] / [ CO2H2O ]

HCO3

- H

+ + CO3

= K2 = [ CO3

= ][ H+ ] / [HCO3- ]

[ HCO3- ] = ( K1 /[ H+ ] ) [ CO2H2O ] ; [CO3

= ] = ( K2K1 /[ H+ ]2 ) [ CO2H2O ]

EQUILIBRIUM PARTITIONING OF COEQUILIBRIUM PARTITIONING OF CO22

BETWEEN ATMOSPHERE AND GLOBAL OCEANBETWEEN ATMOSPHERE AND GLOBAL OCEAN

Equilibrium for present-day ocean:

only 3% of total inorganic carbon is currently in the atmosphere

But CO2(g) [H+] F … positive feedback to increasing CO2

Pose problem differently: how does a CO2 addition dN partition between the atmosphere and ocean at equilibrium?

28% of added CO2 remains in atmosphere!

2

2 2 H 1 1 22

( ) 10.03

( ) ( )1 1

N [H ] [H ]

CO

CO CO oc

a

N gF

N g N aq V PK K K K

2

H 1 22 22+

( ) 10.28

( ) ( ) 1H

CO

ocCO CO

a

dN gf

V PK K KdN g dN aq

N

(buffer factor) (buffer factor) Sundquist et al. 1979Sundquist et al. 1979

FURTHER LIMITATION OF COFURTHER LIMITATION OF CO2 2 UPTAKE: UPTAKE:

SLOW OCEAN TURNOVER (~ 200 years)SLOW OCEAN TURNOVER (~ 200 years)

Inventories in 1015 m3 waterFlows in 1015 m3 yr-1

Uptake by oceanic mixed layer only (VOC= 3.6x1016 m3) would give f = 0.94 (94% of added CO2 remains in atmosphere)

compare to ~300 moles CO3=

Observed uptake of fossil fuel CO2 by the oceans

1950

1960

1970

1980

1990

Year

History of consumption of fossil fuels.

Emissions have increased by more than 2X since 1970. There rise in the last 5 years has been really dramatic.

But there has not been a corresponding rise in the annual increment of CO2.

In 1970 ~75% of the emitted CO2 stayed in the atmosphere, but only ~40% in 2000.

3800

6500

Global Fuel UseGlobal Fuel Use

7800 in 2005!

8200 in 2007!

2007

1

09 m

etr

ic t

on

s o

f C

/ yr

0

.5

1.

1

.5

(source: CDIAC –Trends –updated)

US fossil fuel use

The US is the largest consumer of fossil fuels. Per capita use is very high, ~5 tons C per person per year. This rate has not changed much in 50 years.

US per capita fossil fuel use

Metric tons C per person

US and World Per Capita Fossil Fuel Use since 1950

Why don't we see a big upswing due to the emergence of economies in China and India ?

China is projected to exceed US emissions in 2009.

NET UPTAKE OF CONET UPTAKE OF CO22 BY TERRESTRIAL BIOSPHERE BY TERRESTRIAL BIOSPHERE

(1.4 Pg C yr(1.4 Pg C yr-1-1 in the 1990s; IPCC [2001]) in the 1990s; IPCC [2001])is a small residual of large atm-bio exchangeis a small residual of large atm-bio exchange

• Gross primary production (GPP):

GPP = CO2 uptake by photosynthesis = 120 PgC yr-1

• Net primary production (NPP):

NPP = GPP – “autotrophic” respiration by green plants = 60 PgC yr-1

• Net ecosystem production (NEP):

NEP = NPP – “heterotrophic” respiration by decomposers = 10 PgC yr-1

• Net biome production (NBP)

NBP = NEP – fires/erosion/harvesting = 1.4 PgC yr-1

Atmospheric CO2 observations show that the net uptake is at northern midlatitudes but cannot resolve American vs. Eurasian contributions

CO2 + H2O "H2CO" + O2 Photosynthesis and Respiration

CYCLING OF CARBON WITH TERRESTRIAL BIOSPHERECYCLING OF CARBON WITH TERRESTRIAL BIOSPHERE

Inventories in PgCFlows in PgC yr-1

Relatively small reservoirs Short time scales net uptake from reforestation is transitory...unless resources are managed to preserve

organic matter

Carbon-Climate FuturesCarbon-Climate Futures

Carbon Flux: Ocean to Air

-10-8-6-4-202468

10

1850 1900 1950 2000 2050 2100

Pg

C/y

r

Cox et al (2000)

Friedlingstein et al (2001)

Carbon Flux: Land to Air

-10-8-6-4-202468

10

1850 1900 1950 2000 2050 2100

Pg

C/y

r

Atmospheric CO2

200300400500600700800900

1000

1850 1900 1950 2000 2050 2100

pp

m

1850 1900 1950 2000 2050 210013

14

15

16

17

18

19

20

Global Mean Temperature

Ce

lsiu

s

Vegetation matters! Different models project dramatically different futures using different ecosystem models.

~ 2º Kin 2100

Coupled simulations of climate and the carbon cycle

PROJECTIONS OF FUTURE COPROJECTIONS OF FUTURE CO2 2 CONCENTRATIONSCONCENTRATIONS

[IPCC, 2001][IPCC, 2001]

PROJECTED FUTURE TRENDS IN COPROJECTED FUTURE TRENDS IN CO22 UPTAKE UPTAKE

BY OCEANS AND TERRESTRIAL BIOSPHEREBY OCEANS AND TERRESTRIAL BIOSPHERE

IPCC [2001]

C4MIP:coupled climate-biosphere model comparison

(used in IPCC 2007)

US and World Per Capita Fossil Fuel Use since 1950

Japan and Europe…

HIPPO completed the 1st of 5 global surveys in January, 2009

Ne

t E

xc

ha

ng

e (m

ol

CO

2/m

2/s

)

Time (days)3471 3471.5 3472 3472.5 3473

--

-

2001

NEE

R

GEE

-30

-

20

-

10

0

YR

R,

(-1)

*GE

E M

gC/h

a/yr

1992 1996 2000 2004

1012

1416

18

R- GEE

1998

uptake

emission

A

B

C

NE

E M

gC/h

a/yr

1992 1996 2000 2004

-5-4

-3-2

-10

NEEHarvard Forest

1998

A. Eleven years of hourly data for Net Ecosystem Exchange. B. Two days of hourly data. C. 13 years of respiration (R), GEE, and D. 13 years of NEENEE annual sums.

D

Harvard Forest, Petersham, MA. A "typical" New England forest…an artifact!

YR

R,

(-1)

*GE

E M

gC/h

a/yr

1992 1996 2000 2004

1012

1416

18

R- GEE

1998

AG

WB

MgC

/ha

1994 1996 1998 2000 2002 2004

102

106

110

93-798 99 00 01 02 03 04

0.0

0.5

1.0

1.5

AG

WI M

gC

/ha

/yr

Year

GE

E 1

200-

1500

1992 1996 2000 2004

-28

-26

-24

-22

More Efficient

1998

uptake

emission

“LUE”1200-1500

Live Biomass

NE

E M

gC/h

a/yr

1992 1996 2000 2004

-5-4

-3-2

-10

NEEHarvard Forest

1998

Long-term changes at Harvard Forest

NH

% o

f lan

d ar

ea in

fore

sts

20

4

0

6

0

8

0

1

00

Year

1700 1800 1900 2000

MA

Fitzjarrald et al., 2001

A legacy: land use change in New England

-5

-4

-3

-2

-1

0 NEE = -1.28 - 0.146 x (yr-1990); R2 = 0.337

Year

1992 1994 1996 1998 2000 2002 2004

10

12

14

16

-1 x GEE

Resp

GEE = 11.1 + 0.363 x (yr-1990); R2 = 0.732

R = 9.82 + 0.217 x (yr-1990); R2 = 0.626

NEE

(Mg-

Cha-1

yr-1)

Mg-

C ha

-1yr

-1

0

20

40

60

80

100

120

Abo

vegr

ound

woo

dy b

iom

ass

(MgC

ha-1)

93 94 95 96 97 98 99 00 01 02 03 04 05

oak

other spp

Year

Rates for growth and for carbon uptake are accelerating in this 80-year-old New England Forest…why is that? Will that continue? How big do North American trees grow?

Non-CO2 Greenhouse Gases

• CH4 – dominated by fossil emissions over USA and much of Canada

• N2O – mostly agricultural emissions

• CO – a mix of combustion and hydrocarbon sources

Atmospheric Methane (CHAtmospheric Methane (CH44))

SOURCES OF ATMOSPHERIC METHANE

ANIMALS90

LANDFILLS50

GAS60

COAL40RICE

85

TERMITES25

WETLANDS180

BIOMASSBURNING20

GLOBAL METHANESOURCES (Tg CH4 yr-1)

Year

600

800

700

Scenarios

A1BA1TA1F1A2B1B2IS92a

900

Variations of CH4 Concentration (ppbv) Over the Past 1000 years

[Etheridge et al., 1998]

Year20001000

800

IPCCIPCC [2001] Projections of Future [2001] Projections of Future CHCH44 Emissions (Tg CH Emissions (Tg CH44) to 2050) to 2050

1200

1600

1400

1000

1500 2000 2020 2040

Atmospheric CH4: Past Trends, Future Predictions

COBRA-2003§ flight region and footprints

§a CCE ( LBA !) project

LPDM Model: STILTEmissions: EDGAR-2000Met fields: WRF (AER, 35 km, LPDM outputs, Grell-2)

WRF

June 16, 2003 36.72N,96.94W 609 m AGL

1600

170

0 1

800

190

0 2

000

CH4

0 50 100 150 200 250 300

Flask number

WRF/STILT/EDGAR model vs data, with gray and green.

Errors used in fitting are + 38 ppbv for the model, and + 23 ppbv for the measurements

Slope = 0.9

slope = 0.1

EDGAR—2000 confirmed ±10% for CH4 !

This result pertains to urban-industrial sources, which dominate the flight region

N2O Observed vs Model (EDGAR—2000 )

COBRA-2003

Observed N2O (ppbv)

Mo

del

ST

ILT

/ N2O

(p

pb

v)

US sources of N2O are ~2.5x higher than EDGAR Kort et al., 2008

Carbon Monoxide

EPA Inventory 3!

CO, 3!