Leipzig Graduate School for Clouds, Aerosol & Radiation: Mineral Dust
description
Transcript of Leipzig Graduate School for Clouds, Aerosol & Radiation: Mineral Dust
Leipzig Graduate School for Clouds, Aerosol & Radiation:
Mineral Dust
A. Macke, IfT Leipzigpresented by H. Herrmann, IfT Leipzig
Berlin, 23.09.2011
Leipzig Graduate School
● A Leibniz Graduate School on Atmospheric Research● Integrating expertise in atmospheric research in Leipzig at the
University and the IfT together with University expertise from physics and chemistry
● University partners: Leipzig Meteorology (LIM) Profs. Haase and Grundmann (Physics Faculty) Prof. Abel (Physical Chemistry, Chemistry Faculty)
● Leibniz Partner: IfT Leipzig with all its three departments
● Combining structured and cross-compartimental Ph.D. education with research at a frontline atmospheric sciences topic – mineral dust
The research: Why care about mineral dust ?
● Atmosphere radiation water cycle chemistry
● Health air quality, bacteria
● Economy transportation solar energy
● Climate desertification
● Fertilization ocean & land
The Leipzig Graduate School
Global Modelling(Quaas)
Clouds & Radiation
(Wendisch)
Microwave Remote Sensing
(Pospichal)
Physical Chemistry
(Abel)
Solid State Physics (Haase,
Grundmann)
Leipzig University Research Groups
Non-spherical Dust
Absorbing Dust
Cloud and Dust Particle Interaction
Dust Surface
Chemistry
Dust and Ice
Formation
Projects
Topic
Clouds & Radiation(Macke)
Regional Modelling
(Tegen)
Vis & IR Remote Sensing
(Ansmann,Deneke)
Cloud Laboratory(Stratmann)
Multiphase Chemistry
(Herrmann)
IfT Research Groups
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
Time (UTC = Local Time)
depolarization ratio: liquid water0.0
ice0.4-0.6
mineral dust 0.3 biomass burning
aerosol 0.02
marine particles 0.01
● 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
Absorbing Aerosols: Effect on atmospheric dynamics and cloud properties
Satellite data analysis (A-Train): Anthropogenic absorbing aerosol forcing
Albedo enhancement
Albedo reduction
Seasonal mean TOA absorption effect
[Wm-2]
Peters, Quaas, Bellouin, ACP 2011
Brightness effected by absorbing aerosols 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
Cloud radiative effects
illustrativeexample: 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: 10-5 bis 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 γRate constants Detection limit: 1010 molec cm-3
T Range: -140 bis 425 °C
Movable stamp Gas inlet
To analytics
Sample holder
Equip with illumination of target to study heterogeneous photochemical reactions
13/30
Physical Chemistry – Abel: Detection and chemical investigation of tropospheric particles and of reactions near their interfaces
• AFM on mineral particles, together with local Raman spektroscopy (TERS). With this method, chemical conversions on nano-particles (and on nano-particles coated with ice) can be investigated
• Röntgen microscopy at BESSY
• Photoelectron spektroscopy (ESCA) to follow reactions in a time-resoved manner on wet mineral nanoparticles embedded into a micro water jet (for the study of reactions near the water-interface) or on solid interfaces and surfaces.
• Measuring the kinetics of chemical reactions with/without the presence of mineralic nanoparticles by time-resolved spectrocopic method in a Laval nozzle experiment (alternatively by dispersion by ultrasound)
Mass Spectrometry 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 forwater and ice
StreakCamera
Leipzig Graduate School cross cutting / connectivity
Work Packages
Non-spherical Dust
Absorbing Dust
Cloud and Dust Particle Interaction
Dust Surface Chemistry
Dust and Ice Formation
Non-spherical Dust
vertical structure, model eval.
cloud particle modification
non-sphericity & surface chemistry
ice formation & atm. condition
Absorbing Dust
correlate absorption & polarization
dust entraine-ment & ice formation
identify dust contact with cloud drops
semidirect vs indirect aerosol effect
Cloud and Dust Particle Interaction
cloud bottom & top properties
top-of-cloud dust from obs, cloud props
macroscopic cloud props & chemistry
cloud life cycle & ice formation
Dust Surface Chemistry
polarization by surface films
change in absorption by surface mod.
ice formation, activation of advected dust
chemistry at ice surfaces
Dust and Ice Formation
ice formation in the polari-zation signal
ice formation after dust entrainement
ice formation in dust plumes
surface modi-fication and ice formation
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
● 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