4th GEOS-Chem Users’ Meeting

Effect of Oceanic Organic Carbon Emissions on the Growth of Secondary Particles and Global CCN Abundance

Effect of Oceanic Organic Carbon Emissions on the Growth of Secondary Particles and Global CCN Abundance

Gan Luo and Fangqun Yu

ASRC, SUNY-Albany, 2009-04-07

Kaufman et al., Nature, 2002 Bennartz, JGR, 2006Aerosol Optical Thickness Cloud Fraction and Liquid Water Path

IntroductionSOA, formed from the oxidation of phytoplankton-produced isoprene, can affect chemical composition of marine CCN - Meskhidze and Nenes, Science, 2006

Marine organic aerosol: 75TgC/yr (Roelofs, ACP, 2008)Primary OC: 35~50TgC/yr; SOA produced by isoprene: 25~40 TgC/yr

Marine organic aerosol: 8TgC/yr (Spracklen et al., GRL, 2008)

Marine isoprene: in-situ 0.19TgC/yr (Broadgate et al, GRL, 1997); satellite 0.1TgC/yr (Palmer and Shaw, GRL, 2005); model 0.3~1.9TgC/yr (Arnold et al, ACP, 2009)

Large uncertainty of marine organic carbon emission

Observed α-pinene and isoprene over Southern Ocean - Yassaa et al., Environ. Chem., 2008

GEOS-Chem

Meteorology: GEOS-5, 4º×5º, 47 Layers

Emission: EDGAR+EPA/LNEI99+BRAVO+EMEP+STREETS+GFED2

Chemistry: photochemistry + online aerosol chemistry

Aerosol microphysics: Advanced Particle Microphysics

Marine emission of α-pinene and isoprene :

The emission scheme is based on chlorophyll concentration and 10 m wind speed

C is Chlorophyll from combined MODIS/SeaWiFS

2

12 2 2 110 103.0 10 0.24 0.061 , :pinene m m COF C W W Sc Sc unit kg m s

2

13 2 2 110 101.8 10 0.24 0.061 , :isoprene m m COF C W W Sc Sc unit kg m s

Yassaa et al., Environ. Chem., 2008

Compare with Ship Measurement

Shipboard measurements:1-20-2007 ~ 2-5-2007

OOMPH (Organics over the Ocean Modifying Particles in both Hemispheres) summer cruise in the Southern Ocean

GEOS-Chem

simulated daily averageof α-pinene and isoprene along the shipping route during the same period

Model simulation can capture the major variation of the two species

A

B

C

A

B

C

Global Distributions at Surface

127TgC/Yr 602TgC/Yr

127+35TgC/Yr 602+2.1TgC/Yr

Impact on Organic Chemistry Relative change Zonal average

Impact on Sulfur Chemistry Relative change Zonal average

Impact on CCN Abundance Relative change Zonal average

Summary

Marine α-pinene and isoprene emissions and the impacts on chemistry and aerosols have been simulated with GEOS-Chem

Marine emission:

α-pinene: 35TgC/yr, isoprene: 2.1TgC/yr

Marine α-pinene emission can increase SOA mass by up to 60% in the lower troposphere of Southern Hemisphere (40ºS-90ºS). It decreases OH concentration in the region by 1~10%. The associated changes in SO2 and H2SO4 concentrations result in an increase of nucleation rate over Antarctica by up to 10%, and total CCN over Antarctica enhanced by 3~5%

The impact of marine isoprene emission is small

The End

Acknowledgments:Funding support from NASA, NOAA, and NSF