CHAPTER 2 . The Chemical and Physical Properties of Marine Aerosols: An Introduction
51
0.70
'0 nss-S0 4
0.60
...
E C"I 0.50
,a.
"0
~ 0.40
:v
'" 0::
!?
.!:!
E
.D
:>
VI
0.30
0.20
0.10
0.00
• Sea salt
• Residual mass
4().-60· N
20-40 0 N
0-20· N
0-20· 5
20-40° 5
Lattitude (Pacific Ocean)
4().-6O°S
60-70· 5
Fig. 2.6. Latitudinal distribution of submicrometre aerosol concentrations over the Pacific Ocean (redrawn from Table 3 in Quinn et al. 2000)
2.2.3
Sea Salt Aerosol and New Particle Production
In remote ocean regions, the optical properties of the MBL are largely controlled by
the concentration of sea salt aerosol and by nss-SO~- particles produced from the oxidation ofDMS emitted from the ocean (see the following section). For example, Quinn
et al. (1998) show that in some areas, sea salt aerosol is the dominant light scattering
aerosol. Sea salt is also important as a source of cloud condensation nuclei (O'Dowd
and Smith 1993). Because of the importance of sea salt in climate, there is great interest in developing models that can accurately reproduce sea salt aerosol distributions
on a global scale. But the development of such models is hampered by the dearth of
accurate and precise sea salt size and concentration data on the oceans.
Although it is clear that nss-SO~- and sea salt aerosols are important, it is significant that a very large fraction of the radiatively important submicrometre aerosol over
the oceans is largely uncharacterized as shown in Fig. 2.6. One of the major objectives
in marine aerosol studies today is to focus on this important aerosol component.
2.3
The Oceanic Atmospheric Sulphur Cycle
There is great interest in the role of SO~- in aerosols because of its role in climate-related processes. As stated earlier, most of the SO~- aerosol mass produced from the
oxidation of gaseous precursors (e.g. S02' DMS) is in the size range 0.1-1.0 Ilm diameter; particles in this size range are very efficient in the scattering and absorption of
solar radiation. Also, because sulphate particles are hygroscopic, they can play an important role in cloud nucleation processes. Consequently, sulphates - both natural and
anthropogenic - could have a large impact on climate.
51
0.70
'0 nss-S0 4
0.60
...
E C"I 0.50
,a.
"0
~ 0.40
:v
'" 0::
!?
.!:!
E
.D
:>
VI
0.30
0.20
0.10
0.00
• Sea salt
• Residual mass
4().-60· N
20-40 0 N
0-20· N
0-20· 5
20-40° 5
Lattitude (Pacific Ocean)
4().-6O°S
60-70· 5
Fig. 2.6. Latitudinal distribution of submicrometre aerosol concentrations over the Pacific Ocean (redrawn from Table 3 in Quinn et al. 2000)
2.2.3
Sea Salt Aerosol and New Particle Production
In remote ocean regions, the optical properties of the MBL are largely controlled by
the concentration of sea salt aerosol and by nss-SO~- particles produced from the oxidation ofDMS emitted from the ocean (see the following section). For example, Quinn
et al. (1998) show that in some areas, sea salt aerosol is the dominant light scattering
aerosol. Sea salt is also important as a source of cloud condensation nuclei (O'Dowd
and Smith 1993). Because of the importance of sea salt in climate, there is great interest in developing models that can accurately reproduce sea salt aerosol distributions
on a global scale. But the development of such models is hampered by the dearth of
accurate and precise sea salt size and concentration data on the oceans.
Although it is clear that nss-SO~- and sea salt aerosols are important, it is significant that a very large fraction of the radiatively important submicrometre aerosol over
the oceans is largely uncharacterized as shown in Fig. 2.6. One of the major objectives
in marine aerosol studies today is to focus on this important aerosol component.
2.3
The Oceanic Atmospheric Sulphur Cycle
There is great interest in the role of SO~- in aerosols because of its role in climate-related processes. As stated earlier, most of the SO~- aerosol mass produced from the
oxidation of gaseous precursors (e.g. S02' DMS) is in the size range 0.1-1.0 Ilm diameter; particles in this size range are very efficient in the scattering and absorption of
solar radiation. Also, because sulphate particles are hygroscopic, they can play an important role in cloud nucleation processes. Consequently, sulphates - both natural and
anthropogenic - could have a large impact on climate.