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3 added 335 characters in body

I've implemented the Earth harmonics calculation in JGM-3 model, using the coefficients from here

2    0   -0.10826360229840e-02     0.0
2    1   -0.24140000522221e-09     0.15430999737844e-08
2    2    0.15745360427672e-05    -0.90386807301869e-06
3    0    0.25324353457544e-05     0.0


Now, I want to switch to EGM2008, the coefficients are taken from here (Tide-free).

2    0   -0.484165143790815e-03    0.000000000000000e+00
2    1   -0.206615509074176e-09    0.138441389137979e-08
2    2    0.243938357328313e-05   -0.140027370385934e-05
3    0    0.957161207093473e-06    0.000000000000000e+00


There is a major difference. Probably, I should make some operations on the coefficients? For example, multiply $$C_{20}$$ by $$\sqrt{5}$$?

Multiplied all coefficients of EGM2008 by $$\sqrt{2*degree+1}$$, got

2   0   -1.082626173852220E-03  0.0000000000000E+00
2   1   -4.6200632349558E-10    3.0956435701202E-09
2   2   5.4546274930574E-06 -3.1311071889349E-06
3   0   2.5324105185677E-06 0.0000000000000E+00


Especially for $$C_{21}$$ and $$C_{22}$$ the difference is still major.

Extra

To calculate the Earth gravity potential in JGM-3, the equation was used: $$U_{har}=\frac{\mu}{r}[1+\sum_{i=2}^d\sum_{j=0}^o (\frac{R_{eq}}{r})^iP_{ij}(\sin\phi)(S_{ij}\sin{j\lambda}+C_{ij}\cos{j\lambda})]$$,

As you see, the argument of Lejendre polynom $$P_{ij}$$ is $$sin\phi$$.

However, here for EGM2008 it's said to use $$cos\phi$$. Is it specific for EGM2008 model?

I've implemented the Earth harmonics calculation in JGM-3 model, using the coefficients from here

2    0   -0.10826360229840e-02     0.0
2    1   -0.24140000522221e-09     0.15430999737844e-08
2    2    0.15745360427672e-05    -0.90386807301869e-06
3    0    0.25324353457544e-05     0.0


Now, I want to switch to EGM2008, the coefficients are taken from here (Tide-free).

2    0   -0.484165143790815e-03    0.000000000000000e+00
2    1   -0.206615509074176e-09    0.138441389137979e-08
2    2    0.243938357328313e-05   -0.140027370385934e-05
3    0    0.957161207093473e-06    0.000000000000000e+00


There is a major difference. Probably, I should make some operations on the coefficients? For example, multiply $$C_{20}$$ by $$\sqrt{5}$$?

Extra

To calculate the Earth gravity potential in JGM-3, the equation was used: $$U_{har}=\frac{\mu}{r}[1+\sum_{i=2}^d\sum_{j=0}^o (\frac{R_{eq}}{r})^iP_{ij}(\sin\phi)(S_{ij}\sin{j\lambda}+C_{ij}\cos{j\lambda})]$$,

As you see, the argument of Lejendre polynom $$P_{ij}$$ is $$sin\phi$$.

However, here for EGM2008 it's said to use $$cos\phi$$. Is it specific for EGM2008 model?

I've implemented the Earth harmonics calculation in JGM-3 model, using the coefficients from here

2    0   -0.10826360229840e-02     0.0
2    1   -0.24140000522221e-09     0.15430999737844e-08
2    2    0.15745360427672e-05    -0.90386807301869e-06
3    0    0.25324353457544e-05     0.0


Now, I want to switch to EGM2008, the coefficients are taken from here (Tide-free).

2    0   -0.484165143790815e-03    0.000000000000000e+00
2    1   -0.206615509074176e-09    0.138441389137979e-08
2    2    0.243938357328313e-05   -0.140027370385934e-05
3    0    0.957161207093473e-06    0.000000000000000e+00


There is a major difference. Probably, I should make some operations on the coefficients? For example, multiply $$C_{20}$$ by $$\sqrt{5}$$?

Multiplied all coefficients of EGM2008 by $$\sqrt{2*degree+1}$$, got

2   0   -1.082626173852220E-03  0.0000000000000E+00
2   1   -4.6200632349558E-10    3.0956435701202E-09
2   2   5.4546274930574E-06 -3.1311071889349E-06
3   0   2.5324105185677E-06 0.0000000000000E+00


Especially for $$C_{21}$$ and $$C_{22}$$ the difference is still major.

Extra

To calculate the Earth gravity potential in JGM-3, the equation was used: $$U_{har}=\frac{\mu}{r}[1+\sum_{i=2}^d\sum_{j=0}^o (\frac{R_{eq}}{r})^iP_{ij}(\sin\phi)(S_{ij}\sin{j\lambda}+C_{ij}\cos{j\lambda})]$$,

As you see, the argument of Lejendre polynom $$P_{ij}$$ is $$sin\phi$$.

However, here for EGM2008 it's said to use $$cos\phi$$. Is it specific for EGM2008 model?

2 added 1 character in body

I've implemented the Earth harmonics calculation in JGM-3 model, using the coefficients from here

2    0   -0.10826360229840e-02     0.0
2    1   -0.24140000522221e-09     0.15430999737844e-08
2    2    0.15745360427672e-05    -0.90386807301869e-06
3    0    0.25324353457544e-05     0.0


Now, I want to switch to EGM2008, the coefficients are taken from here (Tide-free).

2    0   -0.484165143790815e-03    0.000000000000000e+00
2    1   -0.206615509074176e-09    0.138441389137979e-08
2    2    0.243938357328313e-05   -0.140027370385934e-05
3    0    0.957161207093473e-06    0.000000000000000e+00


There is a major difference. Probably, I should make some operations on the coefficients? For example, multiply $$C_{20}$$ by $$\sqrt{5}$$?

Extra

To calculate the Earth gravity potential in JGM-3, the equation was used: $$U_{har}=\frac{\mu}{r}[1+\sum_{i=2}^d\sum_{j=0}^o (\frac{R_{eq}}{r})^iP_{ij}(\sin\phi)(S_{ij}\sin{j\lambda}+C_{ij}\cos{j\lambda})]$$,

As you see, the argument of Lejendre polynom $$P_{ij}$$ is $$sin\phi$$.

However, here for EGM2008 it's said to use $$cos\phi$$. Is it specific for EGM2008 modemodel?

I've implemented the Earth harmonics calculation in JGM-3 model, using the coefficients from here

2 0 -0.10826360229840e-02 0.0
2 1 -0.24140000522221e-09 0.15430999737844e-08
2 2 0.15745360427672e-05 -0.90386807301869e-06
3 0 0.25324353457544e-05 0.0


Now, I want to switch to EGM2008, the coefficients are taken from here (Tide-free).

2    0   -0.484165143790815e-03    0.000000000000000e+00
2    1   -0.206615509074176e-09    0.138441389137979e-08
2    2    0.243938357328313e-05   -0.140027370385934e-05
3    0    0.957161207093473e-06    0.000000000000000e+00


There is a major difference. Probably, I should make some operations on the coefficients? For example, multiply $$C_{20}$$ by $$\sqrt{5}$$?

Extra

To calculate the Earth gravity potential in JGM-3, the equation was used: $$U_{har}=\frac{\mu}{r}[1+\sum_{i=2}^d\sum_{j=0}^o (\frac{R_{eq}}{r})^iP_{ij}(\sin\phi)(S_{ij}\sin{j\lambda}+C_{ij}\cos{j\lambda})]$$,

As you see, the argument of Lejendre polynom $$P_{ij}$$ is $$sin\phi$$.

However, here for EGM2008 it's said to use $$cos\phi$$. Is it specific for EGM2008 mode?

I've implemented the Earth harmonics calculation in JGM-3 model, using the coefficients from here

2    0   -0.10826360229840e-02     0.0
2    1   -0.24140000522221e-09     0.15430999737844e-08
2    2    0.15745360427672e-05    -0.90386807301869e-06
3    0    0.25324353457544e-05     0.0


Now, I want to switch to EGM2008, the coefficients are taken from here (Tide-free).

2    0   -0.484165143790815e-03    0.000000000000000e+00
2    1   -0.206615509074176e-09    0.138441389137979e-08
2    2    0.243938357328313e-05   -0.140027370385934e-05
3    0    0.957161207093473e-06    0.000000000000000e+00


There is a major difference. Probably, I should make some operations on the coefficients? For example, multiply $$C_{20}$$ by $$\sqrt{5}$$?

Extra

To calculate the Earth gravity potential in JGM-3, the equation was used: $$U_{har}=\frac{\mu}{r}[1+\sum_{i=2}^d\sum_{j=0}^o (\frac{R_{eq}}{r})^iP_{ij}(\sin\phi)(S_{ij}\sin{j\lambda}+C_{ij}\cos{j\lambda})]$$,

As you see, the argument of Lejendre polynom $$P_{ij}$$ is $$sin\phi$$.

However, here for EGM2008 it's said to use $$cos\phi$$. Is it specific for EGM2008 model?

1

# JGM-3 vs EGM2008 coefficients

I've implemented the Earth harmonics calculation in JGM-3 model, using the coefficients from here

2 0 -0.10826360229840e-02 0.0
2 1 -0.24140000522221e-09 0.15430999737844e-08
2 2 0.15745360427672e-05 -0.90386807301869e-06
3 0 0.25324353457544e-05 0.0


Now, I want to switch to EGM2008, the coefficients are taken from here (Tide-free).

2    0   -0.484165143790815e-03    0.000000000000000e+00
2    1   -0.206615509074176e-09    0.138441389137979e-08
2    2    0.243938357328313e-05   -0.140027370385934e-05
3    0    0.957161207093473e-06    0.000000000000000e+00


There is a major difference. Probably, I should make some operations on the coefficients? For example, multiply $$C_{20}$$ by $$\sqrt{5}$$?

Extra

To calculate the Earth gravity potential in JGM-3, the equation was used: $$U_{har}=\frac{\mu}{r}[1+\sum_{i=2}^d\sum_{j=0}^o (\frac{R_{eq}}{r})^iP_{ij}(\sin\phi)(S_{ij}\sin{j\lambda}+C_{ij}\cos{j\lambda})]$$,

As you see, the argument of Lejendre polynom $$P_{ij}$$ is $$sin\phi$$.

However, here for EGM2008 it's said to use $$cos\phi$$. Is it specific for EGM2008 mode?