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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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Aerosol
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


    Primary marine aerosol
    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


    Aerosol source functions
    Aerosol source functions

    (Andreas, 1998)

    Gerrit de Leeuw


    Sea salt concentrations
    Sea salt concentrations

    Concentrations of sea salt aerosol measured at various locations are very variable;

    Gong et al., 1997

    Gerrit de Leeuw


    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


    Effect of water temperature on sea salt aerosol spectra produced from bubbles
    Effect of water temperature on sea salt aerosol spectra produced from bubbles

    23oC

    15oC

    5oC

    -2oC

    Mårtensson et al., 2003

    Gerrit de Leeuw


    Aerosol source functions1
    Aerosol source functions produced from bubbles

    “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


    Aerosol source functions2
    Aerosol source functions produced from bubbles

    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


    Aerosol source functions3
    Aerosol source functions produced from bubbles

    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


    Techniques
    Techniques produced from bubbles

    • 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


    Sea spray source functions
    Sea Spray Source Functions produced from bubbles

    • New experimental techniques:

      • Direct covariance

      • Bubbles

    • New experimental approaches

    • Modeling approaches

    Nilsson et al., 2003

    Gerrit de Leeuw


    Bubble measurements: produced from bubblesOptical, 15-500 m radiusCalibrated

    (Leifer et al., JAOTech 2003)

    Gerrit de Leeuw


    Particle flux parameterization
    Particle flux parameterization produced from bubbles

    • 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


    Particle flux parameters
    Particle flux parameters produced from bubbles

    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


    Particle parameterizations
    Particle parameterizations produced from bubbles

    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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