< p >一个模型,将帮助你是无可否认的日期(1981)初步参考地球模型。It provides density models for the inner and outer core as functions of distance from the center of the Earth: $$ \rho = \begin{cases} 13.0885 - 8.8381 x^2 & \quad \phantom{000}0\phantom{.0} \le r \le 1221.5 \\ 12.5815 - 1.2638 x - 3.6426 x^2 - 5.5281 x^3 & \quad 1221.5 \le r \le 3480.0 \end{cases} $$ where - $\rho$ is the density in grams per cubic centimeter,
- $r$ is distance from the center of the Earth to the point of interest in kilometers, and
- $x$ is the normalized radius: $x\equiv\frac r {6371}$.
Note that this results in a slight density discontinuity at the boundary between the inner and outer core (1221.5 km). That's intentional. There have been later upgrades to the PREM, but the PREM is where it all starts.
Reference:
Dziewonski, Adam M., and Don L. Anderson. "Preliminary reference Earth model." Physics of the earth and planetary interiors 25.4 (1981): 297-356.