Geoscience Reference
In-Depth Information
Substituting gives:
"
#
t f
2N f
y 2
f
sin B
cos B f
t f
1
þ ʷ
:
ð
6
:
79
Þ
In the same way, we get:
cos B
cos B f
B f
B
cos B f þ
sin B f B f
B
2
3
t f 2
t f
ð
6
:
80
Þ
4
5 :
2M f N f y 2
2M f N f y 2
cos B f þ
sin B f
cos B f 1
þ
We replace l with Cartesian coordinates, and apply the second expression in
( 6.46 ) to get:
9
=
l 00 cos B f ρ 00
ρ 00
6N f
y 3
2t f þ ʷ
2
f
N f y
1
þ
þ
:
ð
6
:
81
Þ
l 00 cos 2 B f ρ 00 2
N f
;
y 2
Inserting ( 6.79 ), ( 6.80 ), and ( 6.81 ) into ( 6.78 ), and neglecting the terms
containing l 3
4 or higher powers yields:
ʷ
2
4
3
5
2
4
3
5
2
4
3
5
f
ρ 00
N f y
ρ 00
6N f
t f
2N f
1
3N f 2 y 2
y 3
2t f þʷ
2
f
y 2
2
2
f
ʳ 00
1
þ
t f
1
þʷ
1
þ
1
þ
3
ʷ
ρ 00 y
N f
t f ρ 00 y 3
6N f
ρ 00 y 3
2N f
t f 1
f þ ρ 00 y 3
t f 1
f :
2t f þʷ
f
t f 1
þ
þʷ
þ
3
ʷ
3N f
Finally one obtains:
,
ρ 00 y
N f
t f ρ 00 y 3
3N f
00
t f ʷ
2
f
ʳ
t f 1 þ
ð6:82Þ
or, if calculated to terms containing y 5 , then:
ʳ 00 ρ 00 y
N f
t f ρ 00 y 3
3N f
þ ρ 00 y 5
15N f
t f ʷ
2
f
5t f þ
3t f
t f 1
þ
t f 2
þ
:
ð
6
:
83
Þ
can achieve an accuracy of 1 00 if calculated from ( 6.82 ) and 0.001 00 from ( 6.83 ).
The subscript f indicates that the result is obtained from the footprint latitude, which
is similar to the meaning it carries in the formula for the inverse solution of the
Gauss projection.
ʳ
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