Simple atmospheric models

1
Simple atmospheric models

• References
• Barry RG, Chorley RJ (1998) Atmosphere, weather
  climate 148 ff.
• Graedel TE, Crutzen PJ (1994) Chemie der
  Atmosphäre pp. 335369
• Jacob DJ (1999) Introduction to atmospheric
  chemistry pp. 2239
• Seinfeld JH, Pandis SN (1998) Atmospheric
  chemistry and physics pp. 11931244

2
Simple atmospheric models

• Processes to be considered
• Emissions Anthropogenic biogenic geogenic
• Chemistry reactions within atmosphere
• Transport wind related
• Deposition dry wet interception
  scavenging
• Mathematical model

3
Elements of a mathematical atmospheric transport
model
from Seinfeld Pandis (1998)
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Model scales
from Seinfeld Pandis (1998)
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Lagrange Euler Puff
Langrangian model Simulation of changes in
chemical composition of an air parcel on its way
through the atmosphere. Variable locations and
times no mass exchange (trajectories)
Eulerian model Simulation of changes in an array
of fixed computation cells. Calculation of all
locations at all times

• Puff model
• Puff embedded in field with smaller turbulent
  eddies
• Puff embedded in larger eddies
• Puff in equal sized eddies

after Seinfeld Pandis (1998)
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Box models
Limnology
Atmospheric sciences
from Graedel Crutzen (1994)
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Box model equations (1)
Well mixed box with length l and height h i
species with concentration i u air
velocity i0 upstream concentration of i Si
emission source term Ci chemical loss or
production of i wv ventilation (mixing)
velocity (exchange with outside) i0
concentration of i above box wai surface
deposition velocity
after Graedel Crutzen (1994)
¹
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Box model equations (2)
Ci chemical loss or production of i Pi
production of species Qi species chemical
lifetime
Pi production of species kjl reaction
coefficients of species j with l or i with j kj
photolysis rates by solar radiation
Qi species chemical lifetime kjl reaction
coefficients of species j with l or i with j kj
photolysis rates by solar radiation
after Graedel Crutzen (1994)
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Box models

• 0-dimensional model concentrations are equal
  everywhere, and therefore a function of time
  only ci(t)
• 1-dimensional column model concentrations are
  functions of height and time horizontally
  homogenous ci(z, t)
• 2-dimensional model species concentrations are
  uniform along one dimension, variable with time
  and other dimension ci(x, z, t) Often applied
  for global models assuming equal conditions in
  longitude, but variable in latitude and altitude
• 3-dimensional model most complex ci(x, y, z, t)

after Seinfeld Pandis (1998)
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1D-Box column model
Ozone concentration change scenaria dependent
on CFCl3 and Cl2CF2 emissions
after Brühl and Crutzen 1988 in Graedel Crutzen
(1994)
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2D-Box regional model
Ozone concentration (ppbv) at three times of day
(0800, 1200, 2400) within an urban
tropospheric chemistry 2D-model. Note
development over daily cycle.
after Graedel and Schiavone 1982 in Graedel
Crutzen (1994)
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3D-Box global model
a)
b)

• Average zonal mixing in October dependency on
  latitude and height (conc. in ppbv).
• Calculated isoquotes for N2O on September 14,
  dependent on latitude and longitude at a scale
  height of 31 km (conc. in ppbv).

after Mahlmann et al. 1986 in Graedel Crutzen
(1994)
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3D-Box Puff model
Dissipation and concen-tration changes of the
conservative tracer Perfluoromethylcyclo-hexane,
emitted over three hours at a single point
source. Observations at 86 stations in NE USA
blue line shows observation results in 10-14
mol tracer mol-1 Black lines Puff model
calculations
after Brost et al. 1988 in Graedel Crutzen
(1994)
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General (Global) Circulation model (GC)
Interactions among relevant physical processes
from Druyan et al. 1975 in Barry Chorley (1998)
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GC model coupling types
Swamp ocean
Mixed layer, slab ocean
from Meehl 1992 in Barry Chorley (1998)
Ocean GCM
SST sea surface temperature
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Atmosphereocean interaction processes
from NASA in Barry Chorley (1998)
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3D-GC model
after Saltzman 1983 in Barry Chorley (1998)
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Statistical models

• Receptor modelling
• Chemical mass balance (CMB)
• Factor analysis
• Probability distribution for air pollutant
  concentration
• Log-normal distribution
• Non-normal distribution
• Parameter estimation
• Which is the appropriate distribution?
• Exceedance of critical levels
• Other forms of air quality standards
• Averages
• maxima

after Seinfeld Pandis (1998)
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Critical loads and levels decision pathway
Convention on long-range transboundary air
pollution Task force on mapping critical
levels/loads
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Critical loads and levels types of crit. load
maps
Convention on long-range transboundary air
pollution Task force on mapping critical
levels/loads