CHAPTER 2 • The Chemical and Physical Properties of Marine Aerosols: An Introduction
47
extremely low, in most samples near the detection limit (Savoie et al. 1994). The great
differences between the hemispheres is also reflected in the latitudinal distribution
of NO; and nss-SO~- in marine aerosols based on data compiled from measurements
made on islands and aboard ships (Heintzenberg et al. 2000).
The aerosol data in Table 2.1 are consistent with the picture that we obtain from
satellites (Fig. 2.3 and Fig. 2.4). They show that the highest levels of aerosol are found
in the Northern Hemisphere, that the continents are the dominant sources of the aerosol that is most visible in satellite products, that dust is one of the most dominant aerosol species, and that pollution aerosols are a major factor in many regions. In contrast,
aerosol concentrations in the Southern Hemisphere are often extremely low.
2.1.5
Temporal Variability of Marine Aerosols
The satellite data in Figs. 2.3 and 2.4 show that aerosol concentrations are highly variable on a seasonal basis. They are also variable on shorter time scales. Figure 2.5 shows
daily aerosol concentrations of nss-SO~-, NO; and MSA measured over a four year
_ 25 j
'i'
E 20
CI
:J.
-
15
~
-a 10
;;
~ 5
l!! 01
",11, '.~~WthillCII"" •. '9I(';' .... II'l'..II ..... '''''''' . . ,"" , .... ~
2-Jan-91 3-Jul-91
2-Jan-92 2-Jul-92 1-Jan-93 3-Jul-93 ' -Jan-94 3-Jul-94 2-Jan-95
1.0 - r - - - -- -- - - - - , , - - - - - - - - - - - - - - - - - - - - ,
0.9
;;;- 0.8
E 0.7
CI 0.6
3 0.5
« 0.4
~ 0.3
0.2
0.1
0.0 I , "
,,~.
"
....... - tt:::'lr.
,"II"':' ~ ~
, ..
2-Jan-91 3-Jul-91
2-Jan-92 2-Jul-92 l-Jan-93 3-Jul-93 l -Jan-94 3-Jul-94 2-Jan-95
6 Tj--------------------------------------------------------,
;;;- 5
E 4
CI
3 3
1\1
~ 2
.t::
Z
1
o 1
,t.\o''''4~t "' ...... ' 1M ~d~ "I,~J
2-Jan-91 3-Jul-91
2-Jan-92 2-Jul-92 l -Jan-93 3-Jul-93 1-Jan-94 3-Jul-94 2-Jan-95
Fig. 2.5 a. Aerosol concentrations of nss-sulphate, MSA, and nitrate at the coastal site of Heimaey (Iceland), North Atlantic. Each point is data from a single daily sample collected when wind is blowing directly from the ocean to the sampling site (D. L. Savoie and J. M. Prospero, unpublished data)
47
extremely low, in most samples near the detection limit (Savoie et al. 1994). The great
differences between the hemispheres is also reflected in the latitudinal distribution
of NO; and nss-SO~- in marine aerosols based on data compiled from measurements
made on islands and aboard ships (Heintzenberg et al. 2000).
The aerosol data in Table 2.1 are consistent with the picture that we obtain from
satellites (Fig. 2.3 and Fig. 2.4). They show that the highest levels of aerosol are found
in the Northern Hemisphere, that the continents are the dominant sources of the aerosol that is most visible in satellite products, that dust is one of the most dominant aerosol species, and that pollution aerosols are a major factor in many regions. In contrast,
aerosol concentrations in the Southern Hemisphere are often extremely low.
2.1.5
Temporal Variability of Marine Aerosols
The satellite data in Figs. 2.3 and 2.4 show that aerosol concentrations are highly variable on a seasonal basis. They are also variable on shorter time scales. Figure 2.5 shows
daily aerosol concentrations of nss-SO~-, NO; and MSA measured over a four year
_ 25 j
'i'
E 20
CI
:J.
-
15
~
-a 10
;;
~ 5
l!! 01
",11, '.~~WthillCII"" •. '9I(';' .... II'l'..II ..... '''''''' . . ,"" , .... ~
2-Jan-91 3-Jul-91
2-Jan-92 2-Jul-92 1-Jan-93 3-Jul-93 ' -Jan-94 3-Jul-94 2-Jan-95
1.0 - r - - - -- -- - - - - , , - - - - - - - - - - - - - - - - - - - - ,
0.9
;;;- 0.8
E 0.7
CI 0.6
3 0.5
« 0.4
~ 0.3
0.2
0.1
0.0 I , "
,,~.
"
....... - tt:::'lr.
,"II"':' ~ ~
, ..
2-Jan-91 3-Jul-91
2-Jan-92 2-Jul-92 l-Jan-93 3-Jul-93 l -Jan-94 3-Jul-94 2-Jan-95
6 Tj--------------------------------------------------------,
;;;- 5
E 4
CI
3 3
1\1
~ 2
.t::
Z
1
o 1
,t.\o''''4~t "' ...... ' 1M ~d~ "I,~J
2-Jan-91 3-Jul-91
2-Jan-92 2-Jul-92 l -Jan-93 3-Jul-93 1-Jan-94 3-Jul-94 2-Jan-95
Fig. 2.5 a. Aerosol concentrations of nss-sulphate, MSA, and nitrate at the coastal site of Heimaey (Iceland), North Atlantic. Each point is data from a single daily sample collected when wind is blowing directly from the ocean to the sampling site (D. L. Savoie and J. M. Prospero, unpublished data)