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Parameterisation of particle fluxes

Parameterisation of particle fluxes. Gerrit de Leeuw. Aerosol. Particle fluxes are more complex than gas fluxes. Particles: Size from <10 nm to > 100 µm Chemical composition: Sea salt Inorganic salts Organics Hygroscopicity Primary marine aerosol Bubble mediated film and jet drops

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Parameterisation of particle fluxes

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  1. Parameterisation of particle fluxes Gerrit de Leeuw

  2. Aerosol Particle fluxes are more complex than gas fluxes Particles: • Size from <10 nm to > 100 µm • Chemical composition: • Sea salt • Inorganic salts • Organics • Hygroscopicity • Primary marine aerosol • Bubble mediated film and jet drops • Spume drops • Secondary production • Transport of anthropogenic and natural aerosol from land • Chemical transformation Gerrit de Leeuw

  3. Primary marine aerosol • Breaking waves are the major source of sea spray aerosol • At intermediate wind speeds, the bubbles produced by breaking waves are the dominant source of sea spray aerosol • Sea spray aerosol source functions estimates vary by many orders of magnitude; • Sea spray aerosol concentrations vary by one order of magnitude • Bubble concentrations vary by approx one order of magnitude Gerrit de Leeuw

  4. Aerosol source functions (Andreas, 1998) Gerrit de Leeuw

  5. Sea salt concentrations Concentrations of sea salt aerosol measured at various locations are very variable; Gong et al., 1997 Gerrit de Leeuw

  6. Bubbles Concentrations of bubbles , a major source for sea salt aerosol at lower wind speeds (<9 ms-1), are also very variable; Gerrit de Leeuw

  7. Effect of water temperature on sea salt aerosol spectra produced from bubbles 23oC 15oC 5oC -2oC Mårtensson et al., 2003 Gerrit de Leeuw

  8. Aerosol source functions “Traditional” interest is in very large particles contributing to heat and water vapour fluxes Currently more focus on submicron particles influencing climate and atmospheric chemistry Gerrit de Leeuw

  9. Aerosol source functions Since Andreas (1998), several independent determinations of the sea spray source function, using different techniques, have been published: • Smith and Harrison (1998) • De Leeuw et al., 2000 • Nilsson et al. (2001) • Reid et al. (2001) • Vignati et al. (2001) • Andreas et al. (2001) • Mårtensson et al. (2003) Results are converging to within one order of magnitude Gerrit de Leeuw

  10. Aerosol source functions Other studies are underway: • Field campaigns: • RED (Pacific) • Mace Head (Quest, NAMBLEX) • UNISOURCE (Duck, NC, Oct-Nov 2004) • Laboratory experiments: • Stockholm: bubble mediated in real sea water, water temp 2-22oC • Galway: bubble mediated, effects of organics Gerrit de Leeuw

  11. Techniques • Whitecap cover: W=W(u10, ….) Bubble-mediated source function dF/dr=F(…..) • Balance equation • Inverse modeling • Coastal boundary layer • Profile measurements • Eddy covariance Instrumentation • CLASP Gerrit de Leeuw

  12. Sea Spray Source Functions • New experimental techniques: • Direct covariance • Bubbles • New experimental approaches • Modeling approaches Nilsson et al., 2003 Gerrit de Leeuw

  13. Bubble measurements:Optical, 15-500 m radiusCalibrated (Leifer et al., JAOTech 2003) Gerrit de Leeuw

  14. Particle flux parameterization • Sea spray source functions are traditionally (mainly) parameterized in terms of wind speed U10 • Significant improvement of parameterization for whitecap cover W by including both oceanic and atmospheric parameters (Lafon, 2004; Woolf 2004): • Wave height • Friction velocity Gerrit de Leeuw

  15. Particle flux parameters Sea Spray workshop (Skipton, UK, May 2004) : • Wind speed • Fetch • Wave conditions (height, steepness, age, ….) • Atmospheric stability (air-sea temperature difference) • Micro-meteorological parameters (friction velocity, u*; roughness length, zo) • Bulk sea water temperature • Salinity • Saturation • Viscosity • Surfactants • Role of organics Gerrit de Leeuw

  16. Particle parameterizations Combine various techniques • Parameterization whitecap cover • Detailed laboratory experiments on bubble mediated production • Eddy covariance • REA • Chemical characterization With a comprehensive set of oceanic and atmospheric parameters Use of satellites to produce global data sets Gerrit de Leeuw

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