Atmospheric Chemistry and Dynamics
Condensed Course of the Universities of Cologne and Wuppertal in
cooperation with the Institutes Stratosphere (IEK-7) und Troposphere
(IEK-8) of the Forschungszentrums Jülich
Prüfungsrelevanz
Universität zu Köln - "Physik der Erde und der Atmosphäre"
Für das Masterprogramm "Physik der Erde und der Atmosphäre" und dem "International Master
of Environmental Sciences" der Universität zu Köln können 3 Kreditpunkte erworben werden.
Der Leistungsnachweis erfolgt in einem Fachgespräch.
Universität Wuppertal
Der Kompaktkurs ist Bestandteil des "Schwerpunkts Atmosphärenphysik" im Rahmen
des "Master-Studiengangs Physik" an der Bergischen Universität Wuppertal.
Mit der Teilnahme können 5 Leistungspunkte erworben werden.
Der Leistungsnachweis erfolgt in einem Fachgespräch.
The Atmosphere
NASA
Atmosphere
~ 100 km
Earth Radius
6370 km
NASA Space Shuttle Endeavour
Atmospheric Chemistry and Dynamics
Schematic view of the components of the climate system,
their processes and interactions.
Gas Phase Composition of the Atmosphere
%
x 10-6
x 10-9
x 10-12
N2
O2
Ozone
others
Smoke from forest fires near Sydney (Dec. 2001)
Aerosols
= particles suspended in air
Aerosol Concentrations
Typical U.S. aerosol size distributions by volume
URBAN
RURAL
Vertical Profiles of Pressure and Temperature
Mesophere
Stratopause
Stratosphere
Tropopause
Troposphere
Ideal Gas Law
applicable to the atmosphere
Assumption: gas is infinite compressible
.
R : universal gas constant
in dry air :
287.05 J kg-1 K-1
Example:
Pressure at ground : 1000 hPa, T = 280 K  r = 1.244 kg m-3
stratosphere: 0.10 hPa, T = 230 K  r = 0.015 kg m-3
Hydrostatic Equilibrium -- Barometric Height Equation
Air Pressure
 Gravity
Pressure change at infinitesimal
change of height :
Considering the ideal gas law:
Integration yields the
barometric height equation:
scale height
Scale Height
RT
h scale height H 
 7.4 km (T  250 K)
Mag
Scale height is not constant ! Real application must include the
temperature gradient (lapse rate) :
in the troposphere
in the tropospause region
in the stratosphere
 section above pb at the temperature Tb :
with
Atmospheric Mass (ma)
m
pb =
ma g
Radius of Earth:
6378 km
Average Pressure at Ground:
984 hPa
A
4 R PpSb
18
ma 
 5.2  10 kg
g
2
Total mole number of air in the atmosphere
ma
Na 
 1.8  1020 moles
Ma
Molar Mass of Air
Ma = 28.6 g/mol
Mass Distribution of the Atmosphere
50 km
Stratosphere
~ 18% air mass
Troposphere
~ 82% air mass
12 km
Temperature (K)
Ground
Solar Flux at the Top of the Atmosphere
and at Ground
ideal black body (T = 5900K)
Intensity
extraterrestrial solar spectrum
Ozone
terrestrial solar spectrum
Water vapor
CO2
Wavelength / nm
http://de.wikipedia.org
Vertical Distribution of Ozone in the Atmosphere
Ozone
Layer
measured STRATOSPHERIC OZONE LAYER
1 “Dobson Unit (DU)” = 0.01 mm ozone at STP = 2.69x1016 molecules cm-2
THICKNESS OF OZONE LAYER IS MEASURED AS A COLUMN CONCENTRATION
UV Absorption by Ozone
UV-C
100-280 nm
UV-B
280-320 nm
UV-A
320-380 nm
Solar Irradiance with Altitude
biological damage
Vertical Profile of Temperature
and Water Vapour
Saturation vapour
pressure of liquid H2O
Murray' s formula
VERTICAL PROFILE OF TEMPERATURE
Mean values for 30oN, March
Radiative
cooling
Altitude, km
- 3 K km-1
2 K km-1
Radiative heating:
O3 + hn e O2 + O
O + O2 + M e O3+M
heat
Radiative
cooling
- 6.5 K km-1
Latent heat release
Surface heating
Variations in Tropopause with Latitude
Net Radiation
Solar Radiation
Modis Satellite Data: Surface Temperature
Transport of Energy
http://modis-atmos.gsfc.nasa.gov/
THE HADLEY CIRCULATION (1735):
COLD
Explains:
• Intertropical Convergence
Zone (ITCZ)
• Wet tropics, dry poles
HOT
COLD
Problem: does not account
for Coriolis force.
Meridional transport of air
between Equator and poles
would result in unstable
longitudinal motion.
Time Scales for Transport
in the Troposphere
1-2 months
2 weeks
1-2 months
1 year
TYPICAL TIME SCALES FOR VERTICAL
MIXING in the troposphere
• Estimate time Dt to travel Dz by analogy with molecular
diffusion:
2
Dz 

Dt 
2K z
with K z
=
5
10 cm s
tropopause
(10 km)
10 years
5 km
“planetary 2 km
boundary layer”
0 km
1 month
1 week
1 day
2 -1
Gobal Change of the
Atmospheric Composition
Development of Greenhouse Gases
from
IPCC 2007
Expected global temperature increase
+1°C to +6°C until 2100
Stratospheric Ozone Depletion
Atmospheric CFC Load
Antarctic Ozone Hole
Messungen
Vorhersagen
from WMO Report 2003
Total ozone column in October
above Halley Bay
after Jones & Shanklin, 1995
Increase of Tropospheric Ozone
Tropospheric ozone
is part of
photochemical smog
(toxic air pollutants)
Parrish et al., 2008; Volz & Kley, 1988
Guangzhou in Pearl-River Delta, South China
Extreme Air Pollution
Megacities > 10 Mio Inhabitants
Peak loads of pollutants
encountered in summer:
O3
100 - 150 ppb
CO
1 – 5 ppm
PM2.5 100 – 250 mg/m3