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Global Constraints on Biogenic Particles

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

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Global Constraints on Biogenic Particles

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

  2. PRIMARY BIOLOGICAL AEROSOL PARTICLES (PBAP) ALGAE VIRUSES BACTERIA POLLEN FUNGUS Jaenicke [2005] suggests may be large (1000s Tg/yr) Elbert et al. [2007] suggest emission of fungal spores ~ 50 Tg/yr PLANT DEBRIS 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 • Mannitol is a unique tracer for fungal spores [Bauer et al., 2008; Elbert et al., 2007]: 1 pg mannitol = 38 pg OM • 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 Emission of 28 Tg/yr, but only 25% in fine mode (upper limit). Constant Emission Optimized Emission = f(LAI, H2O) Global Model: GEOS-Chem(2x2.5)

  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-3in Amazon (good agreement).

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 Hyytiala GEOS-Chem simulation unpublished data, Hanna Manninen Taiwan [Ho et al., 2005] Pronounced seasonality in extratropics (corresponding to vegetation cover), peaking in late-summer/fall as in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

  6. RELEVANCE TO GLOBAL OA BUDGET… FINE OA SOURCES COARSE OA SOURCE (Tg yr-1) (Tg yr-1) [Heald and Spracklen, GRL, 2009] Fungal spores make a modest (7%), but regionally important contribution to OA budget. Most larger than PM2.5. More observations needed to test… What about other PBAP types?

  7. BACTERIA AS A SOURCE OF PBAP? Simulated as 1 m particles (ECHAM/MESSy). Inverted for ecosystem emissions. x 103 m-3 [Burrows et al., ACP, 2009] Estimate global emissions of bacteria = 0.4-1.8 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)

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

  9. ICE NUCLEATION EFFICIENCY OF PBAP 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. Model study of relative IN efficiency (PBAP from Burrows et al, 2009; Heald and Spracklen 2009; Jacobson and Streets, 2009) [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?

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

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

  12. IS THE OCEAN AN IMPORTANT SOURCE OF PBAP? Previous estimates range from 2.3 to 75 TgC/yr No marine OA With marine OA OA Emissions Observations from 5 ship cruises show that marine OA from 2 schemes (based on MODIS / SeaWIFSchlorphyll-a) of ~8 TgC/yr are more than sufficient to reproduce sub-micron OA. [Lapina et al., ACP, in press] 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 (210-570 g/mol CO2). Is this an important source? Global Model: NCAR-CLM (2  x2.5 ) We estimate fungal biomass in soil emits ~1 Tg/yr of sesquiterpenes (6% of global source). Regionally/seasonally important source of SOA?

  14. + FEEDBACKS FROM CLIMATE CHANGE (moisture, precipitation, T, hv) ? SOA + oxidants ↓ OH = ↑ CH4 lifetime PBAP EMISSIONS: Particles Organics NOx … C5H8 O3 + oxidation DISTURBANCE: Fires, beetles, land use change ANTHROPOGENIC INFLUENCE

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