backyard view

IPCC / NGGIP, Expert Meeting
Emission Estimation of Aerosols Relevant to Climate Change
2-4 May 2005, Geneva

Climate Forcing through Atmospheric Chemistry►indirect effects on greenhouse gases► secondary organic aerosols
Michael J. Prather
Earth System Science Dept
University of California at Irvine

IPCC TAR, 2001

IPCC TAR, 2001 - impacted by reactive chemistry & aerosols

IPCC / NGGIP, Expert Meeting
Emission Estimation of Aerosols Relevant to Climate Change
2-4 May 2005, Geneva"Reactive" Atmospheric Chemistry► Greenhouse Agents►emission of reactive trace gas (NOx, CO, VOC)
►fast atmospheric chemistry (O3, OH, HO2, RO2, ...)
►produce tropospheric O3, perturb global CH4►emission of reactive trace gas (VOC like terpenes, toluene,...)►fast atmospheric chemistry (O3, OH, HO2, RO2, ...)
►produce secondary organic aerosols (SOA)►emission of reactive trace gas (NOx, CO, VOC)
►fast atmospheric chemistry (O3, OH, HO2, RO2, ...)

►produce tropospheric O3, perturb global CH4►emission of reactive trace gas (VOC like terpenes, toluene,...)►fast atmospheric chemistry (O3, OH, HO2, RO2, ...)

►produce secondary organic aerosols (SOA)

IPCC / NGGIP, Expert Meeting
Emission Estimation of Aerosols Relevant to Climate Change
2-4 May 2005, Geneva

Climate Forcing through Atmospheric Chemistry►indirect effects on greenhouse gases► secondary organic aerosols

Reactive chemistry and the greenhouse gases ?
CH4HFC

COCH4VOC

OH
O3

HO2
NO

CO, VOC, NOX (=NO+NO2), & CH4 control
Tropospheric Chemistry (OH, HO2)
which is the sink for CH4 & HFCs; the source for O3

CH4 feedback on its lifetime
+40%

CH4OH

CH4O3Isaksen & Hov, 1987
Prather, 1994
IPCC SAR (multi-model assessment), 1995

CH4 self-feedback, 2001

CO becomes an indirect greenhouse gas

COOH

CH4O3long-term
CH4 increase

3D CTM: add CO- tropical bio-burn- NH industrial

short-term
O3 increaseCO indirectClouds & Aerosols impact photochemistry by changing
photolytic rates (J-values)

water cloudBian H., M. J. Prather, and T. Takemura,
Tropospheric aerosol impacts on trace gas budgets through photolysis,J. Geophys. Res. 108 (D8), 4242, doi:10.1029/2002JD002743, 2003.
Aerosols affect the global budgets of O3, OH, and CH4 in part through their alteration ofphotolysis rates and in part through their direct chemical interactions with gases (i.e.,‘‘heterogeneous chemistry’’). ... Globally averaged, the impact of aerosols on
photolysis alone is to increase tropospheric O3 by 0.63 Dobson units andincrease tropospheric CH4 by 130 ppb (via tropospheric OH decreases of 8%).
These greenhouse gas increases lead to an aerosol indirect effect (counting bothnatural and anthropogenic aerosols) of +0.08 W/m2. ... The predominant impact is dueto the aerosols over land; aerosols over the ocean contribute less than a third to
globally integrated changes.

Martin R. V., D. J. Jacob, R. M. Yantosca, M. Chin, and P. Ginoux,
Global and regional decreases in tropospheric oxidants from photochemical
effects of aerosols, J. Geophys. Res., 108 (D3), 4097, 2003.
We evaluate the sensitivity of tropospheric OH, O3, and O3 precursors tophotochemical effects of aerosols not usually included in global models: (1) aerosol
scattering and absorption of ultraviolet radiation (via Fast-J), and (2) reactive uptake ofHO2, NO2, and NO3. ... Aerosols decrease the O3ÆO(1D) photolysis frequency by 520% at the surface throughout the Northern Hemisphere (largely due to mineral dust)
and by a factor of 2 in biomass burning regions (largely due to black carbon). Aerosol
uptake of HO2 ... Annual mean OH concentrations decrease by 9% globally and by
5-35% in the boundary layer over the Northern Hemisphere. Simulated CO
increases by 5-15 ppbv in the remote Northern Hemisphere, improving agreementwith observations. Simulated boundary-layer O3 decreases by 15-45 ppbv over India
during the biomass burning season in March, and by 5-9 ppbv over northern Europe inAugust, again improving comparison with observations. We find that particulate matter
controls would increase surface O3 over Europe and other industrial regions.

butstudies focus on total aerosol(primarily dust)
not on anthropogenic aerosols

NOx identified as an indirect greenhouse gas

NOXO3OHCH4O3NOx proposed as indirect greenhouse gas(Shine, Derwent, et al, 1st IPCC Assessment Report)

Rejected as too far ahead of its time
(1992 IPCC Interim Report)
Post SAR, explicit in IPCC Aviation Assessment, NOx is indirect
greenhouse gas.

NOXO3OH
regional

CH4O3(Wild, Prather, Akimoto, 2001)

globalshort-term O3 increase
regional heating
long-term CH4 decrease
global coolingImpact of NOx is strongly depends on location(Wild, Prather, Akimoto, 2001)

0.5 Tg-N of NOx:tropical, high-altitude emissions have greatest impact
increased trop-O3 warming Æ
decreased CH4 cooling ÆNOx (and O3 prod.)
is highly regional
Global Inventory of Nitrogen
Oxide Emissions Constrainedby Space-based (GOME)
Observations of NO2 Columns,R.V. Martin et al.,
JGR, 2003.

future NOx increases are projected to be highly regional
Geographic shift in NOx emissions

Look at regional and global O3 from a single day’semissions over Shanghai in March 2001
March 12: Sunny, high pressure = Cook-then-mix

March 16: Heavily overcast = Mix-then-cook
Regional production different,
Global production similar, butEvolution quite different.

NOx production of Air Quality O3 vs. Greenhouse O3• Added O3 burden from a single day's emissions:– over Region (3-day integral: air quality)– over Globe (1-month integral: climate)• Global impact smaller when AQ ozone impact large– Tokyo has greater climate impact than Shanghai

Likewise,
SOA yield from VOC precursors depends on location.

TAR / SRES for reactive chemistry & aerosols:a grim picture for O3
What is suspect ?

non-SRES futuresnon-SRES futures

The “Current Legislation” (CLE) scenario reflects the current perspectivesof individual countries on future economic development and takes theanticipated effects of presently decided emission control legislation in theindividual countries into account.
The “Maximum technically Feasible Reduction” (MFR) scenario considers
emission reductions offered by full implementation of the presently
available emission control technologies, while maintaining the projectedlevels of anthropogenic activities.
Whereas the resulting projections of methane emissions lie within therange suggested by other greenhouse gas projections, the recent pollution
control legislation of many Asian countries, requiring introduction ofcatalytic converters for vehicles, leads to significantly lower growth inemissions of the air pollutants NOx, NMVOC and CO than in SRES.
These new scenarios form the core the new IPCC AR4 atmosphericchemistry studies (Stevenson and Dentener, ACCENTworkshop, Jan2005, Oslo).

NOX emissions◄SRES A2
◄SRES B2
◄CLE

◄MFR

CO emissions◄SRES A2
◄SRES B2
◄CLE
◄MFR

IPCC / NGGIP, Expert Meeting
Emission Estimation of Aerosols Relevant to Climate Change
2-4 May 2005, Geneva

Climate Forcing through Atmospheric Chemistry►indirect effects on greenhouse gases► secondary organic aerosolsbackyard view

backyard view

backyard view

inventory issues !!

backyard view

backyard view

backyard view

backyard view► secondary organic aerosols
complications► secondary organic aerosols
a reviewIPCC / NGGIP, Expert Meeting
Emission Estimation of Aerosols Relevant to Climate Change
2-4 May 2005, Geneva

Climate Forcing through Atmospheric Chemistry►indirect effects on greenhouse gases► secondary organic aerosols
Michael J. Prather
Earth System Science Dept
University of California at Irvine

backyard SOA