Inverse Modeling of Asian CO and NOx emissions

Yuxuan WangYuxuan Wang

M.B. McElroy, T. Wang, and P. I. PalmerM.B. McElroy, T. Wang, and P. I. Palmer

22ndnd GEOS-CHEM Users’ Meeting GEOS-CHEM Users’ Meeting

April 5, 2005April 5, 2005

2

Nested grid version of GEOS-CHEM

11 x1 x1

44 x5 x5

v5-07-08

3

TRACE-P Aircraft and Chinese Stations Data

Time frame: Jan – Apr., 2001

Hong Kong

Lin An

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A priori Emissions of CO and NOx

r

Uncertainties: 154% for CO, 27% for NOx

Source: Streets et al. [2003]

5

Model Underestimates Aircraft Observations of CO and NOy

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Model Underestimates Surface Measurements

CO

NOy

Lin An

Hong Kong

Lin An

Hong Kong

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Tagged Tracer Simulation

Assume the model concentration fields are linear combinations of contributions from tagged sources

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Tagged Tracer Simulation

Assume the model concentration fields are linear combinations of contributions from tagged sources

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NOy Chemistry and Deposition Scheme

1. Model has no bias in simulating 1. Model has no bias in simulating contributions of contributions of component NOcomponent NOyy species to total NO species to total NOyy below 6km below 6km

no systematic bias in NOno systematic bias in NOyy chemistry and relative chemistry and relative deposition rate in the model deposition rate in the model

2. Linear relationship between NO2. Linear relationship between NOxx emissions and NO emissions and NOyy concentrations can thus be adopted. concentrations can thus be adopted.

NOx/NOy HNO3/NOy PAN/NOy

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Error specification

RRE method for aircraft observations RRE method for aircraft observations (spatially selected bins) [Palmer et al., 2003](spatially selected bins) [Palmer et al., 2003]RE = (modeled – observed ) / observedRE = (modeled – observed ) / observed mean of RE due to bias in emissions; mean of RE due to bias in emissions;

std. of RE due to total model errorstd. of RE due to total model error Values of RRE for the aircraft data: 20% for Values of RRE for the aircraft data: 20% for

CO and 30% for NOCO and 30% for NOyy

RRE method for station data (temporal RRE method for station data (temporal selected bins) selected bins)

mean of RE due to bias in emissions; std. of mean of RE due to bias in emissions; std. of RE due to total model errorRE due to total model error

)Kx(ySK)SKS(Kxx a1

ΣT11

a1

ΣT

a

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Treatment for the station data

N

tt

kN

tktt

k

xx

xxxx

kN

Nr

1

2

1

)(

))((

1.1. average the observed and simulated concentrations of CO average the observed and simulated concentrations of CO and NOand NOyy every 2 days (~76 data) every 2 days (~76 data)

2.2. Errors: 7% (Feb) ~15% (Apr) for CO and NOErrors: 7% (Feb) ~15% (Apr) for CO and NOyy at Lin An; at Lin An; 14% ~ 7% for CO at HK, 47% ~ 24% for NO14% ~ 7% for CO at HK, 47% ~ 24% for NOyy at HK at HK

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Uncertainties are from ensemble simulations

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?

Uncertainties are from ensemble simulations

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Microbial Sources of NOx and N2O

Nitrification: NHNitrification: NH44++ NO NO22

-- NO NO33--

Denitrification: NODenitrification: NO33-- N N22O O N N22

The weight of the evidence suggests The weight of the evidence suggests that nitrification provides the that nitrification provides the dominant source of Ndominant source of N22O. O.

NH2OH

N2O, NO

O2 O2

N2O, NO

Low levels of O2 Aerobic denitr.

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Survey of Field and Laboratory Studies

Yield of NYield of N22O and NO increases with O and NO increases with

decreasing levels of Odecreasing levels of O22

So does the NO / NSo does the NO / N22O ratio O ratio

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N Processed through the Agriculture/Animal/Human Food Chain

0

50

100

150

200

250

Tg

N/y

r

Global China India US EU Russia

animal wastes

human wastes

chemical fertilizer

226

Data from FAO

4832 22 22

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N Processed through the Agriculture/Animal/Human Food Chain

226 TgN/yr * 2% = 4.4 TgN-N2O /yr

NOx/N2O = 3 or 6% yield for NOx

0

50

100

150

200

250

Tg

N/y

r

Global China India US EU Russia

animal wastes

human wastes

chemical fertilizer

Central China: 30% of Chinese N 0.9 TgN-NOx/yr

226

4832 22 22

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Biological and combustion sources of NOx

0

5

10

15

20

25

30

35

Global China India US EU Russia

Tg

N-N

Ox/

yr

biological NOx sources

fossil fuel sources

Biomass burning sources are excluded

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Future Work

1.1. Reconcile our results with previous top-Reconcile our results with previous top-down estimates of NOdown estimates of NOxx emissions (e.g., emissions (e.g.,

GOME NOGOME NO22 column) column)

2.2. Seasonality of biological sources Seasonality of biological sources (relative abundance of NO(relative abundance of NO22

-- and O and O22) )

3.3. Impact of biological sources of NOImpact of biological sources of NOxx on on

ozone and OHozone and OH

4.4. 3-D modeling of N3-D modeling of N22O O