1. ATOC 4720: class 17 Atmospheric aerosols
Effects on atmospheric phenomena

2. Total concentration

3. >10km, H=7km; <5km, H=3km.
Concentration vary with location and time.
Generally,
Over the ocean:
Rural land areas:
Polluted air:
>10km, H=7km;
<5km, H=3km.

4. Size spectra
<0.2um;
0.2-2um;
>2um
Similar

5. Sources and sinks: Aitken nuclei [1]
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.

6. Level-dependent: Sinks: Aitken nuclei--big aerosols:
Precipitation and gravity.
Global: Precipitation 80-90%;
10-20%: gravitational settling.
Life time:
Aitken nuclei: <1hour in polluted
Air or in clouds;
Large: days;
Giant: minutes-hours-days.
Level-dependent:

7. Average Residence Time of Aerosols in Atmosphere

8. 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.

9. Desert Aerosol Transport over North Africa and the Mediterranean.
Largest values
Tend to be along
The dust plume
trajectories

10. Effects on atmospheric phenomena
[1] Clouds and precipitation:
Good: Precitaion; bad: acid rain

11. [2] Electricity: electric field
and conductivity;
measurements of
electricity may indicate aerosol
concentration;

12. nuclei
Electric field

13. [3] Radiation Scattering & absorption of solar radiation:
Important for the earth’s radiation budget;
Qr at the earth’s surface can cause
SST (sea surface temperature) variability,
And thus force variability in atmospheric
Circulation and convection: affecting
Climate.

14. [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 air==sulfur dioxide is converted
to sulfates==smog;
1952 Landon smog caused 4000 people death.