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Leipzig Graduate School for Clouds, Aerosol & Radiation: Mineral Dust. A. Macke, IfT Leipzig presented by H. Herrmann, IfT Leipzig. Berlin, 23.09.2011. Leipzig Graduate School. A Leibniz Graduate School on Atmospheric Research

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Leipzig Graduate School for Clouds, Aerosol & Radiation: Mineral Dust

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Leipzig Graduate School for Clouds, Aerosol & Radiation:

Mineral Dust

A. Macke, IfT Leipzig

presentedby H. Herrmann, IfT Leipzig

Berlin, 23.09.2011

Leipzig Graduate School

  • A Leibniz Graduate School on Atmospheric Research

  • Integratingexpertise in atmosphericresearch in Leipzig atthe University andthe IfT togetherwith University expertisefromphysicsandchemistry

  • University partners:

    • Leipzig Meteorology (LIM)

    • Profs. Haase and Grundmann (PhysicsFaculty)

    • Prof. Abel (Physical Chemistry, Chemistry Faculty)

  • Leibniz Partner:

    • IfT Leipzig with all itsthreedepartments

  • Combiningstructuredandcross-compartimentalPh.D. educationwithresearchat a frontlineatmosphericsciencestopic – mineraldust

  • The research: Why care about mineral dust ?

    • Atmosphere

      • radiation

      • watercycle

      • chemistry

    • Health

      • airquality, bacteria

    • Economy

      • transportation

      • solar energy

    • Climate

      • desertification

    • Fertilization

      • ocean & land

    The Leipzig Graduate School


    Leipzig University Research Groups

    Solid State Physics

    (Haase, Grundmann)

    Microwave Remote Sensing


    Clouds &






    Global Modelling


    IfT Research Groups

    Regional Modelling


    Vis & IR Remote

    Sensing (Ansmann,Deneke)




    Clouds &



    Multiphase Chemistry



    Dust Surface Chemistry

    Dust and Ice Formation

    Cloud and Dust Particle Interaction

    Non-spherical Dust

    Absorbing Dust

    Polarization in radiative transfer in modeling and observations

    • Non-spherical (mineral dust, vulcanic ash, ice crystals, ...) particles polarize light in a characteristic manner

    • Active/passive polarized remote sensing offers new and largely unexplored detection possibilities

    • Objectives

      • Heterogeneous ice formation (mandatory condition for precipitation in mid latitudes)

      • determine volcanic ash concentration

      • determine the effect of Saharan mineral dust on cloud formation and microphysics over the Atlantic Ocean

      • distinguish mineral dust from biomass burning and other aerosols


    4 Feb 2008, SAMUM 2, Cape Verde


    liquid water0.0





    marine particles0.01

    Time (UTC = Local Time)

    Absorbing Aerosols: Effect on atmospheric dynamics and cloud properties

    • Absorbing aerosol (soot, mineral dust) affects climate by heating the atmosphere, changing cloudiness and circulation

    • Net effect strongly depends on vertical placement of aerosol layers; it is expected to be warming but offsetting effects exist

    • Objectives

      • Quantification of aerosol absorption (including mineral dust as natural background) in climate models

      • Characterization of altitude and placement of aerosol layers with respect to clouds

      • Assessment of climate effects by aerosol-climate modeling

    Satellitedataanalysis (A-Train): Anthropogenicabsorbingaerosolforcing


    Albedo reduction


    Seasonal mean TOA absorption effect

    Peters, Quaas, Bellouin, ACP 2011


    regional to global distribution

    Indirect aerosol effect: diagnostics from combination of ground and satellite data

    • Amount in type of aerosol particles effect size and concentration of cloud droplets and thus cloud brightness (first indirect aerosol effect, Twomey effect)

    • Passive satellite measurements of cloud particles and cloud brightness very indirect and uncertain

    • Increasing load of mineral particles from various sources

    • Objectives

      • Combine active and passive ground and satellite based observations to more accurately determine the indirect aerosol effect

      • Identify and analyze situations with mineral dust advection over measurement site Leipzig




    ship tracks

    Heterogeneous chemistry at (modified) mineral dust surfaces

    • Mineral Dust is an active player in atmospheric composition change

    • Trace gases can be taken up at the surface and undergo chemical change

    • Key components of mineral dust are suspected to be photocatalysts: surface-bound OH available (!)

    • Objectives

      • Investigate uptake of key atmospheric tracegases (NOx, SO2, Organics) und realistic conditions (T, RH)

      • Study chemical processing directly

      • Deliver key process parameters (Reaction rates, uptake and mass accommodation coefficients)

    Knudsen Cell – IfT Chemistry

    Pressure: 10-5bis 10-3 mbar = mean free pathlength of molecules is bigger than the cell dimension = there are mainly gas-surface collisions rather than gas-gas collisions

    Determination of (reactive) uptake-coefficients γ

    Rate constants

    Detection limit: 1010molec cm-3

    T Range: -140 bis 425 °C


    Gas inlet


    Sample holder


    Physical Chemistry – Abel: Detectionandchemicalinvestigationoftroposphericparticlesandofreactionsneartheirinterfaces

    • AFM on mineralparticles, togetherwithlocal Raman spektroscopy (TERS). Withthismethod, chemicalconversions on nano-particles (and on nano-particlescoatedwithice) canbeinvestigated

    • Röntgen microscopyat BESSY

    • Photoelectronspektroscopy(ESCA) tofollowreactions in a time-resovedmanner on wetmineralnanoparticlesembeddedinto a microwaterjet (forthestudyofreactionsnearthewater-interface) or on solid interfacesandsurfaces.

    • Measuringthekineticsofchemicalreactionswith/withoutthepresenceofmineralicnanoparticlesby time-resolvedspectrocopicmethod in a Laval nozzleexperiment (alternativelybydispersionbyultrasound)

    MassSpectrometry Imaging (MSI) und chemische Analyse von Nanoteilchen

    Heterogeneous ice nucleation and solid state physics

    • Heterogeneous ice nucleation at mineral dust particles is one of the most important ice formation processes in the atmosphere

    • Heterogeneous ice formation not well understood because

      • of the insufficiency of existing techniques concerning the in-situ observation of ice nucleation processes

      • the distinction between ice and water on micrometer scales, as well as mass, and mass growth measurements are not possible

    • Objectives

      • Adapt a temporally high resolution Streak camera to directly infer ice formation and growth for individual drops and defined ice nuclei (dust particles)

      • Establish the nuclear magnetic resonance technique to determine ice mass

    Leipzig Aerosol Cloud Interaction Simulator (LACIS)

    NMR spectra for

    water and ice



    Leipzig Graduate School crosscutting / connectivity

    Leipzig Graduate School Structure

    • Accompanying lectures from Master modules in Meteorology, Chemistry, Solid State Physics

    • Ring-lecture of supervisors on recent research results

    • Supervisor team for each PhD student

    • Active participation in relevant international conferences and summer schools

    • Workshops jointly with supervisor teams

    • PhD-only workshop, Supervisor-only workshop

    • Participation in IfT/LIM PhD seminar

    • 3 month visit at specified guest institutes

    • Participation in “Research Academy Leipzig”

    • Family- and dual-career friendly work conditions

    Leipzig longtermperspectives

    • Establish the “Leipzig Center for Clouds, Aerosols and Radiation”

    • Open paths for joint University-Leibniz Research & Teaching

      • Share laboratories

      • Combine knowledge

      • create Leibniz/university supervisor teams

    • Follow-Up Graduate School on “Clouds, Aerosols and Radiation” with new focus

    • Basis for a Leibniz-Campus jointly with Leipzig University

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