ATOC 4720: class 17

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ATOC 4720 class 17

• Atmospheric aerosols
• Effects on atmospheric phenomena

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Total concentration
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Concentration vary with location and
time. Generally,
Over the ocean
Rural land areas
Polluted air
gt10km, H7km lt5km, H3km.
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Size spectra
lt0.2um
0.2-2um gt2um
Similar
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Sources and sinks
Aitken nuclei
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Combustion processes (human activities, Forest
fires, volcanoes, gas-to-particle Conversion)
2 Large to giant aerosol wind blown
dust, emission of pollens, and spores from
plants Ocean bursting of Air bubbles (under
high windspeed) urban Industrial processes.
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Sinks Aitken nuclei--big aerosols
Precipitation and gravity. Global
Precipitation 80-90 10-20
gravitational settling.
Aitken nuclei lt1hour in polluted Air or in
clouds Large days Giant minutes-hours-days.
Life time
Level-dependent
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Average Residence Time of Aerosols in Atmosphere
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TRANSPORT
Desert Aerosol Transport over North Africa and
the Mediterranean.
The 2D distribution of aerosols Concentration
for the period from August, 1996 to April, 2000
(top panel). Main source regions of the
UV-absorbing aerosols can be inferred, and these
regions are marked in the bottom panel.
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Desert Aerosol Transport over North Africa and
the Mediterranean.
Largest values Tend to be along The dust plume
trajectories
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Effects on atmospheric phenomena
1 Clouds and precipitation
Good Precitaion bad acid rain
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2 Electricity electric field and
conductivity measurements of
electricity may indicate aerosol
concentration
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nuclei
Electric field
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3 Radiation
Scattering absorption of solar radiation
Important for the earths radiation budget Qr
at the earths surface can cause SST (sea
surface temperature) variability, And thus force
variability in atmospheric Circulation and
convection affecting Climate.
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4 Chemistry
Liquid aerosol absorbs gases react Solid
aerosol provide surfaces upon which Gases can be
absorbed and react
Aerosol sulfur dioxide from polluted air
accumulate in stable (T-inversion), moist
airsulfur dioxide is converted to
sulfatessmog
1952 Landon smog caused 4000 people death.
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