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Validation of CH 4 surface emission using forward chemistrytransport model P. K. Patra, X. Xiong, C. Barnet, E. J. Dlugokencky, U. Karin, K. Tsuboi, D. Worthy 18 th International Emission Inventory Conference “Comprehensive Inventories – Leveraging Technology and Resources” Baltimore, USA; 1416 April 2009 Acknowledgements: T. Nakazawa, T. Saino, JAMSTEC for funding Research Institute for Global Change, JAMSTEC Yokohama, Japan

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Validation of CH4 surface emission using forward chemistry‐transport model

P. K. Patra, X. Xiong, C. Barnet, E. J. Dlugokencky, 

U. Karin, K. Tsuboi, D. Worthy

18th International Emission Inventory Conference “Comprehensive Inventories – Leveraging Technology and Resources”

Baltimore, USA; 14‐16 April 2009

Acknowledgements: T. Nakazawa, T. Saino, JAMSTEC for funding

Research Institute for Global Change, JAMSTECYokohama, Japan

Introduction

Emission Inventory(EI) for MCF, CH4,

CO2, SF6…

Site-basedobservation

Process-based model

Remote-sensing products

ChemistryTransport

Model (CTM)

Atmospheric Observations

(site & satellite)

Transport ProcessesMeteorology

Radicals (OH, Cl)

Validation of Transport (SF6)

Validation of OH (CH3CCl3 - MCF)

Model-ObservationComparison of CH4

Multiple Tracers is key for Forward modeling and Validation research

Space‐Time scales

Hour Day Month Year

Loca

l R

egio

nal

Hem

isph

eric

Int

er-H

em

PBL

Synoptic/Frontal

Hadley Cell,ITCZ & SPCZMonsoon

Inter-hemisphericExchange

Connectin

g proce

sses

, e.g., M

eteoro

log

Atmospheric Observables, e.g., Concentration

Inpu

t par

amet

er, e

.g.,

Emis

sion

Inve

ntor

y

y

ACTM transport validation: inter‐hemispheric exchange time (τex)

Patra et al., ACP, 2009

En = NH emissionEs = SH emissionCn = NH concentrationCs = SH concentration

ACTM framework for CH4 simulation (Patra et al., JMSJ, in acceptance)

• CCSR/NIES/FRCGC AGCM‐based CTM (ACTM) run at resolution T42 L67 (top 90km)

• NCEP‐2 reanalysis meteorology (U,V,T nudged)

• Hadley Center Sea‐Surface Temperature & Sea‐Ice Cover

• CH4 chemistry (Sander et al., JPL Pub. 06‐2, 2006) as:

• All the radicals are taken from CHASER/STRAT (Sudo et al., Takigawa et al.) models at monthly (or hourly) intervals

CH4+O1D Products (KO1D =1.5×10–10)

CH4+OH CH3 + H2O (KOH= 2.45×10–12 exp(-1775/T)CH4+Cl CH3 + HCl (KCl=7.3×10–12 exp(-1280/T)CH4+hυ Products (wavelength dependent; not considered here)

Validation of CHASER+STRAT OH using MCF

The comparison for the recent times raises a couple of questions:1.Is MCF emission decreasing since 2000 or so. If yes, at what rate and what is present day emission magnitude2.Is the OH production in CHASER is higher than the real values? If so, at which latitudes, longitudes or heights

Surface flux types and annual budget of CH4

Mikaloff Fletcher et al., GBC, 2004

Range Estim.Reported by IPCC [2001]

92‐237

25‐10080‐11520‐2023‐5575‐109

35‐7310‐155‐10500‐600

450‐51040‐4610‐30

Patra et al., JMSJ, 2009, in acceptance

CH4 emission, sinks, and 

concentration

CH4 lifetime and budgets

Instantaneous CH4 Lifetime = 1/[KOH∙OH + KO1D∙O1D + KCl∙Cl]

(useful for understanding the dominance of dynamics vs. chemistry on variability)

Atmospheric Lifetime = burden/loss(Prather et al., IPCC, 2001)

CH4 L. T. = 4999 Tg/580 Tg yr‐1 = 8.62 years

Estimates Atmospheric Lifetime

References

IPCC TAR 8.4 Prather et al.

IPCC FAR (prescribed)

8.67±1.32(m#26)8.45±0.38 (m#12)

Stevenson et al., JGR, 2006

This work (full model)

8.62 Patra et al., JMSJ, 2009

CH4 Measurement Sites – can we track emissions?(~50 used here; >100s are in operation in 2007)

Contributing Institutes: 1. NOAA/ESRL, 2. FEA, Germany, 3. JMA, Japan, 4. EC, Canada, 5. NIWA

CH4 Latitudinal gradients: seasonal and longitudinal variations

1700

1750

1800

1850

1900

1950ACTM: JANACTM: APRACTM: JULACTM: OCT

1700

1750

1800

1850

1900

1950

CH

4 mix

ing

ratio

[pp

b]

ESRL: JANESRL: APRESRL: JULESRL: OCT

90S 60S 30S 0 30N 60N 90N1700

1750

1800

1850

1900

1950

90S 60S 30S 0 30N 60N 90N

a. East Pacific b. America

c. Atlantic d. Ind./Europe

e. Australia-Asia f. West Pacific

TD

F

EIC

SMO C

HR

ML

O MID TH

D

CB

A BR

W

RPB

KE

YB

MW

NW

RW

SA

AL

T

LE

F

TD

F

ASC

IZO

MH

D

STM

ZE

P

SYO

CR

Z

SEY M

KN H

UN

SCH Z

GT

SYO

SPO

CG

O

CFA

BK

T

WL

G

UU

M

AR

H BH

D

GM

I

MN

MY

ON

TA

P

RY

O

SHM

SPO

SPO

SPO

SPO

SPO

FRD

Seasonal cycle in the extra tropics/high latitudes is

controlled by chemical loss and surface em

ission

CH4 Seasonal Cycles in the tropics – produced by chemical loss and dynamics (monsoon)

Preliminary comparison with AIRS/Aqua satellite retrievals

AIRSACTM‐E1ACTM‐E2

80οE‐ 110οE, 20οN ‐35οN; 250‐350 mb

AIRS Precision : ~20 ppb  AIRS – ACTM = 20 ppb

Source: NOAA/N

ESDIS/STA

R

E1 : 80 Tg‐CH4 Rice emisE2 : 40 Tg‐CH4 Rice emis

CH4 Synoptic variations – arising from synoptic meteorology and concentration gradients

0

20

40

60OBSACTM

-20

0

20

40

-40

0

40

80

CH

4 Syn

optic

var

iatio

n [p

pb]

-200

-100

0

100

200

-80

0

80

160

J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D-40

0

40

80

(a) CGO

(c) YON

(e) NGL

(f) BRW

(d) AMY

(b) MLO

2002 | 2003 | 2004

GSN

CD

L

AM

Y

BR

W

TH

D

AL

T

FRD

ZSF

RY

O

NG

L

SMO

DE

U

MN

M

YO

N`

ML

O

CO

I

RPB

ZG

T

SCH

MH

D

IZO

CG

O

HA

T

0

0.2

0.4

0.6

0.8

Cor

rela

tion

(r)

2002-2005DJFMAMJJASON

0

0.5

1

1.5

2

NSD

(un

itles

s)

(a)

(b)

Measure of

Synopticpeakshape /phase

Measure of

Synoptic peakheight

(σobs/σmod)Ideal~1.0

CH4 diurnal cycles:caused by local emission 

and PBL cycle

Obs.      Mod.

0

50

100

150Daily Obs

Daily ACTM

Monthly Obs.

Monthly ACTM

0

50

100

150

CH

4 Diu

rnal

am

plitu

de [

ppb]

2002 2003 20040

200

400

600

(a) FRD

(b) SCH

(c) AMY

0 24 0 24 0 24 0 24 0 24 UTC

Mon

thly

-mea

n di

urna

l CH

4 cy

cle

(ppb

)

Conclusions

• ACTM CH4 simulations have been optimized for a combinations of fluxes, radicals and transport– Examining seasonal cycles of IHGs at a ‘set’ of stations helped to prepare flux‐

types combinations– Very low (~5ppb) CH4 longitudinal gradients between CRZ/CGO/EIC can be 

tracked– Seasonal cycle, synoptic variability and diurnal cycle; all needed to be checked 

for testing bottom‐up fluxes

• The ACTM‐AIRS comparison in the upper troposphere region reveal– A reversal of CH4 seasonal cycle at about 400‐300 mb height– Role of CH4 transport by Asian monsoon during high surface emission period

• Both transport and chemistry components in ACTM have been validated independently using two different chemical tracers, SF6 and MCF, respectively

Outlook• Reduction in radical (e.g., OH) uncertainty by independent 

methodology– Can the MCF emission be available at more confidence?           

e.g., global/country total emission inventory for the users?

– Time dependent gridded distribution of emissions

• Updating chemical (e.g., CH4) emission distribution and strength– A concerted effort?, e.g., EDGAR gives annual mean emission due to 

rice cultivation

– IAVs in wetland or other natural emissions? Validation strategy

• Increased use of remote sensing data for long‐lived gases– Some issues persist with the product quality; more validation and 

comparison would help probing the causes

– More dedicated satellite sensors, e.g., GOSAT, new‐OCO?