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New Particle Formation in the Global Atmosphere

New Particle Formation in the Global Atmosphere. Fangqun Yu Atmospheric Sciences Research Center, State University of New York at Albany Zifa Wang Institute of Atmospheric Physics, Chinese Academy of Sciences Richard Turco

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New Particle Formation in the Global Atmosphere

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  1. New Particle Formation in the Global Atmosphere Fangqun Yu Atmospheric Sciences Research Center, State University of New York at Albany Zifa Wang Institute of Atmospheric Physics, Chinese Academy of Sciences Richard Turco Dept. of Atmospheric and Oceanic Sciences, University of California at Los Angeles

  2. IPCC, 2007 Aerosol second indirect forcing ?? CCN concentration Nucleation

  3. Nucleation and growth events Laakso et al., 2004

  4. Surface-based observations of particle formation rates ACE2 NEAQS ACE-Asia INDOX99 RITS94 ACE1 NAURU99 Koponen02 ACE1 Davison96 # of observed nucleation events

  5. important, based on recent modeling study and measurements (Yu, ACP, 2006; Laakso et al., ACP, 2007) unimportant, at least in lower troposphere (Yu, JGR, 2006a, b) Binary Homogeneous Nucleation (BHN) H2SO4-H2O Ternary Homogeneous Nucleation (THN) NH3 H2SO4-H2O Ion-Mediated Nucleation (IMN) Organic-Enhanced Nucleation Ion Organics H2SO4-H2O H2SO4-H2O ????

  6. To study global nucleation, we coupled a nucleation module with GEOS-CHEM. 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. Nucleation rate look-up tables: JIMN = J ([H2SO4], RH, T, Q, S0)

  7. 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.

  8. 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. • Vertical structure of predicted annual-mean zonally-averaged nucleation rates calculated using GEOS-Chem coupled to an ion-mediated nucleation sub-model.

  9. 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).

  10. JIMN = J ([H2SO4], RH, T, Q, S0) Annual mean percentage change in nucleation rates (zonal average): (a) per degree of temperature increase, and (b) per 1% decrease in mean absolute RH. 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). Aerosol generation over large regions of the atmosphere could decrease by 10–30% per degree of warming.

  11. Positive nucleation feedback: Implications for global warming MORE greenhouse gases MORE heat trapped in the atmosphere WARMER atmosphere Decreased relative humidity Positive Nucleation Feedback = More Warming REDUCED nucleation & aerosol abundance LESS cooling due to aerosol radiative forcing

  12. Summary • Formation and growth of ultrafine particles have been frequently observed in various locations. These particles may have important climatic and health effects. • 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. • We propose a positive climatic feedback mechanism involving nucleation and aerosol radiative forcing.

  13. 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

  14. Thank You!

  15. Yu, JGR, 2002

  16. T270RH65S1E7C2.5E7D2.5

  17. Balance Scanning Mobility Analyzer (0.4-7 nm) Air Ion Spectrometer (0.46-55 nm) 6 nm 3 nm 1 nm Negative 6 nm 3 nm 1 nm Positive From Laakso et al., 2005. Measurements of ions, charged clusters/particles, and total particles From Vana et al., 2005.

  18. Ions are involved in more than 90% of the particle formation days that can be clearly identified. From Hirsikko et al., 2007

  19. Nucleated particles are overcharged in 90% of the particle formation days that can be clearly identified. Laakso et al., 2006

  20. Pinker et al., Science, 2005

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