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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

A. Macke, IfT Leipzig

presentedby H. Herrmann, IfT Leipzig

Berlin, 23.09.2011

leipzig graduate school
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
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
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
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
polarization lidar

4 Feb 2008, SAMUM 2, Cape Verde


liquid water0.0




aerosol 0.02

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
satellite data analysis a train anthropogenic absorbing aerosol forcing
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
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
cloud radiative effects



ship tracks

heterogeneous chemistry at modified mineral dust surfaces
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
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)
heterogeneous ice nucleation and solid state physics
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
Leipzig Aerosol Cloud Interaction Simulator (LACIS)

NMR spectra for

water and ice



leipzig graduate school structure
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 long term perspectives
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