地球空间环境与大地测量教育部重点实验室

三轴分层地球模型及自转理论

 基于Chen & Shen [2010, New estimates of the inertia tensor and rotation of the triaxial nonrigid Earth. Journal of Geophysical Research, 115, B12419, doi:10.1029/2009JB007094] 的理论,结合IAU2000AR06章动-进动模型(国际天文学会推荐的标准模型)采用的MHB2000分层地球模型和目前精度最高的EGM2008EIGEN-6C等静态全球重力场模型,求解三轴分层地球的各圈层(地幔、外核和内核)的动力学形状参数,包括主惯性矩和动力学扁率(参见 1)。进而对比研究了三轴性对地球自转理论的影响(参见 2),指出在三轴地球框架下,需要考虑被传统自转理论忽略的地核形变效应。该成果参见陈巍等 [2013, 地球三轴性及频率依赖响应对极移的影响, 中国地球物理学会第二十九届年会, 中国云南昆明, 20131012-16]

 

 1  三轴分层地球的动力学形状参数

Parameter

Value

Principal inertia moments of the whole Earth (× 1037 kg m2)

A

8.0100829

B

8.0102594

C

8.0364807

Principal inertia moments of the mantle (× 1037 kg m2)

Am

7.0985591

Bm

7.0987194

Cm

7.1225467

Principal inertia moments of the core (× 1036 kg m2)

Ac

9.1152379

Bc

9.1153996

Cc

9.1393399

Principal inertia moments of the fluid outer core (× 1036 kg m2)

Af

9.0567171

Bf

9.0568779

Cf

9.0806773

Principal inertia moments of the solid inner core (× 1034 kg m2)

As

5.8520816

Bs

5.8521767

Cs

5.8662552

Polar ellipticity of the whole Earth

3.2845161 × 10–3

Equatorial ellipticity of the whole Earth

2.2033010 × 10–5

Polar ellipticity of the fluid core

2.6455744 × 10–3

Equatorial ellipticity of the fluid core

1.7746896 × 10–5

Polar ellipticity of the solid core

2.4219766 × 10–3

Equatorial ellipticity of the solid core

1.6246969 × 10–5

 

 2  三轴地球与旋转对称地球的自转理论的比较

For triaxial Earth (All parameters take the values listed in Table 1)

For symmetric Earth (All parameters take the values listed in Table 2)

Dynamic  equation

   

                   

Transfer function   

        

      

  

                  

Effective excitation

       

               

Chandler frequency

  

                    

Free core nutation frequency

 

              

 

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