Geology Reference
In-Depth Information
Tabl e 8 . 4
Comparison between the unsplit periods, T
0
, for four
Earth models and the observed value.
Unsplit period
Deviation
Error
Earth model
T
0
(hours)
Δ
T
0
(hours)
%
Observed
3.7985
Cal8
3.82470
0.0262
0.69
1066A
4.45471
0.65621
17.28
PREM
5.23836
1.43986
37.91
Core11
5.81973
2.02123
53.21
Tabl e 8 . 5
Profiles of pressure, density, melting temperature
and radial pressure gradient.
Radius
P
ρ
T
m
dP
/
dr
(10
11
Pa)
(10
3
kgm
−
3
)
(10
4
Pa
(km)
(K)
/
m)
1,216
3.300
12.20
4,961
−
5.600
−
1,371
3.223
12.14
4,905
6.094
−
1,571
3.094
12.03
4,824
6.737
1,821
2.916
11.84
4,710
−
7.507
2,171
2.636
11.52
4,521
−
8.479
2,571
2.278
11.11
4,258
−
9.421
2,971
1.886
10.62
3,936
−
10.12
3,171
1.681
10.33
3,751
−
10.34
3,371
1.473
10.01
3,551
−
10.47
3,486
1.350
9.860
3,429
−
10.56
analysis of Ekman boundary layer theory (Smylie and Palmer, 2007; Smylie
et al.
,
2009), leads to an expression for the kinematic viscosity, ν
b
, at the top of the fluid
outer core as
1225
I
c
Ω
ν
b
=
19
2
Q
2
W
,
(8.125)
0
(
b
)
b
8
9
√
3
2
2
+
8π
ρ
10
34
kgm
2
representing the total moment of inertia of the inner
and outer cores, ρ
0
(
b
)
with
I
c
=
917.95
×
10
3
kgm
−
3
=
9.82
×
the density at the top of the outer core
and
b
3486 km its radius. From Table 4.5,
Q
W
,the
Q
of the associated nearly
diurnal wobble of the prograde free core nutation (PFCN) is 11,879, leading to a
kinematic viscosity of 0.2685m
2
s
−
1
, while the
Q
of the associated nearly diurnal
wobble of the retrograde free core nutation (RFCN) is 10,152, leading to a kin-
ematic viscosity of 0.3677m
2
s
−
1
. The corresponding values of the dynamic vis-
cosities are 2637 Pa s and 3611 Pa s, respectively, with mean value 3124 Pa s.
=
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