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Global Constraints on Biogenic Particles Goldschmidt Conference August 19, 2011 Colette L. Heald Photo courtesy: Cam McNaughton (taken from NASA’s DC-8)

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Presentation on theme: "Global Constraints on Biogenic Particles Goldschmidt Conference August 19, 2011 Colette L. Heald Photo courtesy: Cam McNaughton (taken from NASA’s DC-8)"— Presentation transcript:

1 Global Constraints on Biogenic Particles Goldschmidt Conference August 19, 2011 Colette L. Heald Photo courtesy: Cam McNaughton (taken from NASA’s DC-8) Dominick V. Spracklen (Leeds), Kateryna Lapina (CSU) PBAP E=? SOA P=~100 Tg/yr biogenic?

2 PRIMARY BIOLOGICAL AEROSOL PARTICLES (PBAP) POLLEN BACTERIA VIRUSES FUNGUS ALGAE PLANT DEBRIS Jaenicke [2005] suggests may be large (1000s Tg/yr) Elbert et al. [2007] suggest emission of fungal spores ~ 50 Tg/yr PBAP estimates ~1000 Tg/yr would swamp all other sources of organic aerosol. KEY QUESTION: what is the size (lifetime) of these particles??

3 FIRST SIMULATION OF FUNGAL SPORE PBAP Emission of 28 Tg/yr, but only 25% in fine mode (upper limit). I.Mannitol is a unique tracer for fungal spores [Bauer et al., 2008; Elbert et al., 2007]: 1 pg mannitol = 38 pg OM II.Optimize model emissions as a function of meteorological and phenological parameters (wind, T, humidity, radiation, surface wetness, precipitation, leaf area index, water vapour concentrations, boundary layer depths) to match global observations of mannitol in PM Global Model: GEOS-Chem(2  x2.5  ) Constant Emission Optimized Emission = f(LAI, H 2 O)

4 WHERE ARE FUNGAL SPORES AN IMPORTANT SOURCE OF ORGANIC AEROSOL? Generally contribute ~10% to fine mode surface OA, but > 30% in tropics. Gilardoni et al. (2011) report coarse PBAP ~2.4  gm -3 in Amazon (good agreement).

5 WHEN ARE FUNGAL SPORES AN IMPORTANT SOURCE OF ORGANIC AEROSOL? Pronounced seasonality in extratropics (corresponding to vegetation cover), peaking in late-summer/fall as in measurements. Taiwan Hyytiala [Sousa et al., 2008] [Ho et al., 2005] unpublished data, Hanna Manninen Porto, Portugal GEOS-Chem simulation

6 RELEVANCE TO GLOBAL OA BUDGET… Fungal spores make a modest (7%), but regionally important contribution to OA budget. Most larger than PM 2.5. More observations needed to test… What about other PBAP types? FINE OA SOURCES COARSE OA SOURCE (Tg yr -1 ) [Heald and Spracklen, GRL, 2009]

7 BACTERIA AS A SOURCE OF PBAP? Estimate global emissions of bacteria = Tg/yr. Not significant by MASS. Lifetime suggests potential long-range transport. Jacobson and Streets [2009] estimate 84.5 Tg/yr pollen (but 30  m) [Burrows et al., ACP, 2009] Simulated as 1  m particles (ECHAM/MESSy). Inverted for ecosystem emissions. x 10 3 m -3

8 BIOGENIC ORGANIC AEROSOL OVER THE AMAZON [Poschl et al., Science 2010] These observations confirm that there is very little PBAP (mass or number) in the fine mode. But lots in the coarse mode (IN?) *10 day pristine period in March 2008.

9 ICE NUCLEATION EFFICIENCY OF PBAP [Hoose et al., ERL, 2010] Observations suggest that significant fraction of IN are biological, but model estimate that even with max IN efficiency PBAP contributes < 1% to mean total immersion freezing rate. Perhaps regionally important? Model study of relative IN efficiency (PBAP from Burrows et al, 2009; Heald and Spracklen 2009; Jacobson and Streets, 2009) Amazon: Prenni et al. [2009] show that local biological particles contribute to IN and becomes dominant (over dust) at warmer temperatures (> -25 ° C) Wyoming (ICE-L): Pratt et al. [2009] estimated that 1/3 of IN were PBAP.

10 FUNGAL PBAP IS A REGIONALLY IMPORTANT CONTRIBUTOR TO SUPER-MICRON NUMBER While (fungal) PBAP only contributes < 1 % of total super-micron aerosol number globally, regionally can exceed 50% at surface (20% aloft) Global Model: GLOMAP (2.8  x2.8  ) Fraction of super-micron aerosol number at surface PBAP super-micron number (surface) Fraction of super-micron aerosol number aloft (7km) DUST [Spracklen and Heald, in prep]

11 MARINE PBAP Ocean Surfactant Layer (with Organics) WIND Sea-spray emission [O’Dowd et al., 2004] Under biologically active conditions, OA has been observed to dominate sub-micron aerosol mass. SeaWIFS SPRING (high biological activity)

12 IS THE OCEAN AN IMPORTANT SOURCE OF PBAP? Previous estimates range from 2.3 to 75 TgC/yr No marine OAWith marine OA Observations from 5 ship cruises show that marine OA from 2 schemes (based on MODIS / SeaWIFS chlorphyll-a) of ~8 TgC/yr are more than sufficient to reproduce sub- micron OA. [Lapina et al., ACP, in press] OA Emissions Measurements from: J.D. Allan, H. Coe, G. McFiggans, S.R. Zorn, F. Drewnick, T.S. Bates, L.N. Hawkins, L.M. Russell

13 FUNGUS AS A SOURCES OF SESQUITERPENES TOO! Horvath et al, [JGR, in press] measured significant SQ emissions from soil (  g/mol CO 2 ). Is this an important source? We estimate fungal biomass in soil emits ~1 Tg/yr of sesquiterpenes (6% of global source). Regionally/seasonally important source of SOA? Global Model: NCAR-CLM (2  x2.5  )

14 DISTURBANCE: Fires, beetles, land use change EMISSIONS: Particles Organics NOx … + oxidants + oxidation O3O3 ANTHROPOGENIC INFLUENCE ↓ OH = ↑ CH 4 lifetime + FEEDBACKS FROM CLIMATE CHANGE (moisture, precipitation, T, hv) ? PBAP SOA C5H8C5H8


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