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differential equations that re
ect the balance relationships between corresponding
reservoirs. For example, oxygen and ozone cycles depend on the photosynthesis
both in oceans and on the land.
fl
1.7.3 Nitrogen Cycle Modeling
A comparative analysis of the model schemes of the
flux diagrams of nitrogen
compounds in nature proposed by various experts makes it possible to construct a
block-scheme presented in Fig.
1.35
. Here the atmosphere, soil, lithosphere, and
hydrosphere are considered as nitrogen reservoirs. Three
fl
first reservoirs are
described by 2-D models, and the hydrosphere is described by a 3-D multi-layer
model. The characteristics of nitrogen
fluxes between these reservoirs are given in
Table
1.11
. The equations of the model are written as
fl
@
@
t
þ
V
u
@
N
A
N
A
@u
þ
V
k
@
N
A
@k
8
<
H
20
H
16
;
ðu; kÞ2X
O
¼
H
1
þ
:
H
7
þ
H
19
H
8
H
9
þ
H
22
H
2
H
10
;
ðu; kÞ2X=X
O
@
N
S1
@
t
¼
H
8
þ
H
6
H
3
@
N
S2
@
t
¼ H
2
þ
H
3
þ
H
5
þ
H
9
H
6
H
7
H
11
H
21
@
N
U
@
t
þ
v
u
@
N
U
@u
þ
v
k
@
N
U
@k
¼ H
16
þ
H
4
;
U
þ
H
18
;
U
þ
H
11
H
17
;
U
H
20
H
14
;
UP
H
15
;
UP
@
@
t
þ
v
u
@
N
P
N
P
@u
þ
v
k
@
N
P
@k
¼
H
18
;
P
þ
H
4
;
P
þ
H
14
;
UP
þ
H
15
;
PL
H
17
;
P
H
14
;
PL
H
15
;
UP
@
N
L
@
t
¼ Q
L
þ
H
12
;
L
þ
H
14
;
PL
þ
H
15
;
LF
H
14
;
LF
H
15
;
PL
@
N
F
@
t
¼ Q
F
þ
H
12
;
F
þ
H
23
þ
H
14
;
LF
H
13
H
15
;
LF
where V(V
ˆ
, V
ʻ
) is the wind speed, v(v
ˆ
, v
ʻ
) is the current velocity in the ocean,
Q
L
and Q
F
are functions describing the mixing of the deep waters of the ocean.
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