magnetometer channel and the gravitational-wave channel at each site, as described in [@mag_TF_measurements]. Finally, we combine these results to produce an estimate for the amount of correlated magnetic noise, which we express in terms of an effective gravitational-wave energy density $\Omega_{\rm mag}(f)$ $$\Omega_{\rm mag}(f) = \frac{ |T_1(f)| |T_2(f)| {\rm Re}[M_{12}(f)]}{\gamma_T(f) S_0(f)} .$$ We show $\Omega_{\rm mag}(f)$ in Fig. \[fig:schumann\], alongside the measured O1+O2 PI curve and the projected design-sensitivity PI curve. The trend for the magnetic noise lies significantly below the O1+O2 PI curve, indicating that correlated magnetic noise is more than an order of magnitude below the sensitivity curve in O2, although it may be an issue for future runs. Experimental improvements can mitigate this risk by further reducing the coupling of correlated noise. From O1 to O2, for instance, the magnetic coupling was reduced by approximately an order of magnitude, as indicated by the dotted and dot-dashed curves in Fig. \[fig:schumann\]. Additionally, work is ongoing to develop Wiener filtering to subtract Schumann noise [@Schumann_2; @Schumann_3; @Schumann_4], and to develop a parameter estimation framework to measure or place upper limits on the level of magnetic contamination [@meyers_thesis]. This work will take advantage of low noise LEMI-120 magnetometers [@lemi] that 