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

IPCC, 2007

Aerosol second indirect forcing ??

Nucleation

CCN concentration

Nucleation and growth eventsNucleation and growth events

Laakso et al., 2004

# of observed nucleation events

RITS94ACE1

INDOX99

Koponen02

Davison96

NAURU99

ACE-Asia

ACE1

ACE2NEAQS

Surface-based observations of particle formation rates

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)

????

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.

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.

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.

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).

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.

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

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.

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

Thank You!

Yu, JGR, 2002

1010 10 10 10 10

dN/dlogDp (#/cm )3T270RH65S1E7C2.5E7D2.5

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.

From Hirsikko et al., 2007

Ions are involved in more than 90% of the particle formation days that can be clearly identified.

Laakso et al., 2006

Nucleated particles are overcharged in 90% of the particle formation days that can be clearly identified.

Pinker et al., Science, 2005