Geoscience Reference
In-Depth Information
The value of t
o
is identi
ed with the year 1980, when the GHG concentrations
were known. To calculate
D
T
CO
2
, one can use a more accurate formula by Krapivin
(1993).
Among simple formulas of calculations of the latitudinal distribution of average
temperature over the globe one can indicate the schemes proposed by Sergin
(1974):
T
ðuÞ
¼T
g
þ cð
sin
2
u
T
sin
2
uÞ;
ð
1
:
10
Þ
where
ˆ
is the latitude in radians,
ʳ
is the pole-equator temperature difference,
ˆ
T
is
the latitude at which T(
ˆ
)=T
g
. The latitudinal temperature variations can be
described:
T
a
ðu;
t
Þ
¼T
e
2
u
ð
T
e
T
N
Þ=p
for the Northern hemisphere
;
T
a
ðu;
t
Þ
¼T
e
2
u
ð
T
e
T
S
Þ=p
for the Southern hemisphere
;
where
(
=
T
N
;
min
þ
2tT
N
;
max
T
N
;
min
t
D
;
t
2
0
½
;
0
;
5t
D
;
=
T
N
¼
T
N
;
min
þ
2 t
D
t
ð
Þ
T
N
;
max
T
N
;
min
t
D
;
t
2
ð
0
;
5t
D
;
t
D
;
(
T
S
;
max
þ
2tT
S
;
min
T
S
;
max
=
t
D
;
t
2
0
½
;
0
;
5t
D
;
=
t
D
;
T
S
¼
T
S
;
max
þ
2 t
D
t
ð
Þ
T
S
;
min
T
S
;
max
t
2
ð
0
;
5t
D
;
t
D
;
T
TN,min
(T
TS,min
) and T
N,max
(T
S,max
) are minimum and maximum temperatures at the
North (South) Pole, respectively,
°
C; t
ʔ
is the duration of the year in units of
measurements
ʔ
, T
e
is the equatorial temperature of the atmosphere,
°
C. Many
authors use the estimates T
TN,min
=
−
30
°
C, T
N,max
=0
°
C, T
TS,min
=
−
50
°
C, T
S,
max
=
C.
Of course, these zonally averaged temperatures scatter widely, which leads to
considerable errors. To more accurate re
−
10
°
C, T
e
=28
°
fl
ect the role of various factors in changes
of the basic climatic parameter
temperature, it is necessary to calculate the con-
tribution of each factor separately. This can be done with an assumed additivity of
the role of feedbacks:
—
ʔ
T
a,nal
=
ʔ
T
a
+
ʔ
T
ΔTa,feedback.
. In some models authors
introduce the feedback coef
cient
ʲ
:
ʔ
T
a,nal
=
ʲ · ʔ
T
a
. The
ʲ
parameter is
expressed through the ampli
cation index g:
ʲ
= 1/(1
−
g). The value of the g index
is equivalent
, which on a global scale is a function of T
a
. This
dependence can be roughly approximated by the formula
to albedo
ʱ
8
<
a
ice
for T
a
T
ice
;
að
T
a
Þ
¼
a
free
for T
a
T
free
;
:
a
free
þ
b
ð
T
free
T
Þ
for T
ice
\
T
a
\
T
free
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