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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 • 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 Topic Leipzig University Research Groups Solid State Physics (Haase, Grundmann) Microwave Remote Sensing (Pospichal) Clouds & Radiation (Wendisch) Physical Chemistry (Abel) Global Modelling (Quaas) IfT Research Groups Regional Modelling (Tegen) Vis & IR Remote Sensing (Ansmann,Deneke) Cloud Laboratory (Stratmann) Clouds & Radiation (Macke) Multiphase Chemistry (Herrmann) Projects 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
PolarizationLidar 4 Feb 2008, SAMUM 2, Cape Verde depolarizationratio: liquid water0.0 ice0.4-0.6 mineraldust0.3 biomassburning 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
Satellitedataanalysis (A-Train): Anthropogenicabsorbingaerosolforcing Albedoenhancement Albedo reduction [Wm-2] Seasonal mean TOA absorption effect Peters, Quaas, Bellouin, ACP 2011 Brightnesseffectedbyabsorbingaerosols 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
Cloudradiativeeffects illustrative example: 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 Movablestamp Gas inlet Toanalytics Sample holder Equipwithilluminationoftargettostudyheterogeneousphotochemicalreactions
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 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 Streak Camera
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