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Multi-scale modelling

CSC spring course
by

Kenty Ortega

on 27 June 2014

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Transcript of Multi-scale modelling

MULTI-SCALE MODELING
Multi
scale
modeling
Solving a physical problem which have important features at multiple scales
Temporal scales

Spatial scales
from nanoseconds to centuries
from nanometers to several kilometers
Some examples
Material properties
Quantum mechanical model
Molecular dynamics
Coarse-grained models
Continuum models
Biomedical modeling
Molecular scale
Molecular complexes
Sub-cellular
Cells
Multi-cell
Tissue
….
Metereology, climate
Global
Regional
local
Definition
From quantum mechanics to globlal climate
Largest source of uncertainties in global climate models (GCM)
How particles are formed in the atmosphere still unclear

Cloud Condensation Nuclei
2 nm
Framework
1 nm
100nm
CLIMATE
Quantum Mechanics
Mass spectroscopy
NEED CHARGE!!!!!
Classical Nucleation Theory
neutral air ions spectometer
Global Climate models
Cloud observations
Lidar
CCNC
1.1 nm
1.9 nm
NUCLEATION
Too big for QM
PSM can see them!!!!
Quantum mechanics
Measurements
Formation free energies of different clusters
Cluster distributions
Formation rates
-7.9 kcal/mol
-19.5 kcal/mol
-16.2 kcal/mol
Evaporation rates
CNT
Combine CNT and QM
Atmospheric Cluster Dynamics Code
Cluster distributions
Formation rates
Multi-scale approach
Validation
Predictions
Adding the last scale
Hyytiälä SMEAR II station in Finland
continuous aerosol particle size distribution measurements since 1996
trace gases, meteorology, fluxes
CLOUD chamber experiment in CERN (2009-)
sulphur dioxide converted to sulphuric acid by UV light + water
electric field to clear all ions
natural ionization by galactic cosmic rays (GCR)
CERN pion beam to produce extra ions
other atmospheric vapours: ammonia and dimethyl amine
Against what?
Cluster distribution
Ratios
Formation rates
Motivation
What?
Why?
J Kirkby et al. Nature 476, 429-433 (2011)
" However, for typical boundary-layer ammonia mixing ratios, below about 1p.p.b.v., ternary nucleation of NH3–H2SO4–H2O, with or without ions, is unable to explain atmospheric observations. This implies that other species, most probably organic compounds, are necessary for boundary-layer nucleation."
formation rates
Galactic Cosmic Rays role
presence of DMA can explain observations
Link charged and neutral CD
GCR less important if enough base is present
Complement MS techniques
Formation rates:
sulfuric acid
bases
ions
temperature
...
ACDC
GCM
F.R.= A*[SA]+B*[NH3]+c*[DMA]...
OBSERVATIONS
Too small for CNT
?
Too small for NAIS
MS only charged
Dr. I.K. Ortega
University of Helsinki
Charge
Evaporation rate = 2.2 E 10 1/s
Life time 0.22 ns
sampling time microseconds
Full transcript