Geology Reference
In-Depth Information
Beaufort
2
3
4
5
6
7
8
9
80
70
60
16
50
12
40
30
8
20
4
10
0
0
5
10
15
20
25
Wind speed (m s
−
1
)
Figure 6 Air-sea transfer velocities for carbon dioxide at 201C as a function of wind
speed at 10 m (m s
1
or Beaufort Scale). The graph combines experimental
data (points) and a theoretical line
(From Watson et al.
16
) (Reprinted by permission from Nature (London),
349, 145; Copyright
r
1991 Macmillan Magazines Ltd.)
1
K
ð
T
Þ
w
¼
1
ak
w
þ
1
Hk
a
¼
r
w
þ
r
a
Typical values of scavenging ratio
17
lie within the range 300-2000.
Scavenging ratios are rather variable, dependent upon the chemical
nature of the trace substance (particle or gas, soluble or insoluble, etc.)
and the type of atmospheric precipitation. Incorporation of gases and
particles into rain can occur both by in-cloud scavenging (also termed
rainout) and below-cloud scavenging (termed washout).
Numerical modellers often find it convenient to describe wet deposi-
tion by a scavenging coefficient, actually a first order rate constant for
