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New Particle Formation in New Particle Formation in
the Global Atmospherethe Global Atmosphere
Fangqun YuAtmospheric Sciences Research Center, State University of New York at Albany
Zifa WangInstitute of Atmospheric Physics, Chinese Academy of Sciences
Richard TurcoDept. of Atmospheric and Oceanic Sciences, University of California at Los Angeles
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IPCC, 2007
Aerosol second indirect forcing ??
Nucleation
CCN concentration
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Nucleation and growth eventsNucleation and growth events
Laakso et al., 2004
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# of observed nucleation events
RITS94ACE1
INDOX99
Koponen02
Davison96
NAURU99
ACE-Asia
ACE1
ACE2NEAQS
Surface-based observations of particle formation rates
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H2SO4-H2O
Binary Homogeneous Nucleation (BHN)
H2SO4-H2O
NH3
Ternary Homogeneous Nucleation (THN)
Ion-Mediated Nucleation (IMN)
H2SO4-H2O
Ion
Organic-Enhanced Nucleation
H2SO4-H2O
Organics
unimportant, at least in lower troposphere
(Yu, JGR, 2006a, b)
important, based on recent modeling study
and measurements (Yu, ACP, 2006; Laakso
et al., ACP, 2007)
????
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In this study, the GEOS-3 grid with 2ox2.5o horizontal resolution and 30 vertical levels was used. Run the model from 07/2001-06/2002.
JIMN = J ([H2SO4], RH, T, Q, S0)
Nucleation rate look-up tables:
To study global nucleation, we coupled a nucleation module with GEOS-CHEM.
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Simulated annual mean nucleation rates averaged within the surface layer (0 – 150 m). Symbols are measured average local nucleation rate (typically over a window of several hours). Measurements over land are indicated by unfilled circles; circle size defines the number of nucleation events reported (refer to the lower scale), while color gives the average nucleation rate over the event ensemble.
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Vertical structure of predicted annual-mean zonally-averaged nucleation rates calculated using GEOS-Chem coupled to an ion-mediated nucleation sub-model.
Zonally-averaged latitudinal and vertical distribution of total ultrafine CN (> ~ 3-4 nm) aerosol concen-trations measured in situ during GLOBE, ACE-1, PEM-Tropics A and B, INTEX-A, and TRACE-P.
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Ratio of annual mean IMN rates integrated within the lowest 3 km of atmosphere (the source strength due to IMN, #/cm2day) to the annual mean rate of emission of
primary particles (source strength due to primary aerosol emission, #/cm2day).
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JIMN = J ([H2SO4], RH, T, Q, S0)
For each degree of surface warming, absolute RH could decrease 3%–5% in the upper troposphere and 3–10% in the middle troposphere (Minschwaner and Dessler, J. of Climate, 2004).
Annual mean percentage change in nucleation rates (zonal average): (a) per degree of temperature increase, and (b) per 1% decrease in mean absolute RH.
Aerosol generation over large regions of the atmosphere could decrease by 10–30% per degree of warming.
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REDUCEDnucleation &
aerosol abundance
LESS coolingdue to aerosol
radiative forcing
WARMER atmosphere
MOREgreenhouse
gases
MORE heat trapped inthe atmosphere
Positive Nucleation Feedback =
More Warming
Positive nucleation feedback: Implications for global warming
Decreasedrelative
humidity
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Summary
1. Formation and growth of ultrafine particles have been frequently observed in various locations. These particles may have important climatic and health effects.
2. We have studied new particle formation via ion-mediated nucleation in the global atmosphere by coupling nucleation module with GEOS-Chem. The spatial distributions of global IMN nucleation are consistent with existing measurements. IMN can lead to significant new particle formation in the global atmosphere.
3. We propose a positive climatic feedback mechanism involving nucleation and aerosol radiative forcing.
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Future Research
• Long-term trend of particle nucleation in the global atmosphere
• Growth and evolution of nucleated particles in the global atmosphere, focusing on contribution of nucleated particles to the abundance of CCN
• Key parameters controlling nucleation and CCN abundance, and implications for climate feedback mechanisms
(1) Positive nucleation-climate feedback
(2) DMS-climate feedback (CLAW hypothesis)
(3) Solar variation-aerosol-climate
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Thank You!
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Yu, JGR, 2002
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1010 10 10 10 10
dN/dlogDp (#/cm )3T270RH65S1E7C2.5E7D2.5
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Measurements of Measurements of ions, charged ions, charged
clusters/particles, clusters/particles, and total particlesand total particles Air Ion Spectrometer (0.46-55 nm)
PositivPositivee
6 nm
1 nm
3 nm
Balance Scanning Mobility Analyzer (0.4-7 nm)
NegatiNegativeve
1 nm
3 nm
6 nm
From Laakso et al., 2005. From Vana et al., 2005.
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From Hirsikko et al., 2007
Ions are involved in more than 90% of the particle formation days that can be clearly identified.
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Laakso et al., 2006
Nucleated particles are overcharged in 90% of the particle formation days that can be clearly identified.
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Pinker et al., Science, 2005