Correlation of CO-HCN-C2H2-C2H6: Global Constraints on Combustion Sources

Biomass burning Biofuels

Natural gas/coal

C2H6

~2 mon

CO

Fossil fuel combustion

Auto combustion

C2H2

~2 mon

~2 wks

uptake

HCN

~5 mon

ocean

Yaping XiaoAtmospheric Chemistry Modeling Group

Harvard University

Observed correlation of CO-HCN-C2H2-C2H6

FTIR column measurements Ship cruises

Key questions: What do the correlations imply? Are they consistent with our

current understanding of sources? How can we use them to constrain source terms? What constraints can C2H2-CO correlation provide on OH

concentration?

Model analysis of CO-HCN-C2H2-C2H6 system

Tasks: Improve understanding of global C2H2 budget

Constrain regional OH concentration using C2H2/CO relationship

Improve understanding of HCN oceanic sink with the new column data in Southern Hemisphere

Interpret column and aircraft data in terms of constraining sources using forward model analysis of CO-HCN-C2H2-C2H6 system

C2H2 preliminary emission inventory

total ff bf bb oceanicEDGAR 3.2 4

Gupta et al.[1998] 3.1

Gautrois et al.[2003] 8.8

Blake et al.[1996] 2.1/2.8

Kanikiou et al.[1988] 0.2~1.4

Plass et al.[1992] Very small

Plass-Dulmer et al.[1993] 0.16~0.54

This work 4.2 1.1 1.5 1.6 ?0.53

Asia

Streets et al.[2003] 0.9 1.3

This work 0.25 0.88 0.45

Evaluation of C2H2 with seasonal variationNA bf & Streets in Asia With NA bfPreliminary

Arctic

Europe

NA

Tropical Pacifc

C2H2: Tropical pacific

Pem-TA (Sep)

Pem-TB(Mar)

Constrain sources using C2H2 /CO

Trace-P

China Coast S ChinaCoast SJapan

CO

C2H2

Constrain OH using C2H2 /CO correlation

Trace-P

Pemw-a

HCN: Two different oceanic sink parameterizations

constant seawater conctr. (xyp)uniform saturation ratio (qli)

Lauder Antarctic

The model with constant seawater HCN conctr. improves comparison in SH

Southern Ocean is not a sink for HCN?

HCN CO

AntarcticObsModel

LauderObsModel

CO yield from CH4 oxidation in tagged CO model

Mean yields in austral winter at SH mid and high latitudes are 0.81-0.86, otherwise about 0.95

With modified yield, mean bias in tagged CO at southern high latitudes decreases from 9 to 6 ppb in May-Aug.

C2H6 emission inventory: Streets vs. standard

Standard GEOS-CHEM:

ff scaled from CH4

Streets: Streets ff/bf in Asia, elsewhere increased by 30%

C2H6 (Tg/yr) ff bf bb

Standard 8.4 (2.4)

2.0(1.5)

2.0

Streets10.1(0.8)

2.0(1.5)

CO: SH mid/high latitude problem

Model CO at 45S-90S is overestimated by ~15 ppb in full chem

Mean yields in austral winter at SH mid and high latitudes are 0.81-0.86

With yield update in tagged CO model, bias decreases from 9 to 6 ppb in May-Aug.

How can this be accounted for in full chemistry simulation?

CO yield from CH4

amf v4-33mje v5-07-08

xyp tagged v4-33 OHrvm v4-26 1997