Table provides the local correlation lengths obtained for each of the low-Σ GBs for each of the datasets. The most noteworthy observation is that these correlation lengths are different from one another and different from the respective global correlation lengths. While the local correlation lengths for the Σ3 GBs are similar to the global values for both datasets, other GBs have correlation lengths more than twice as large as the global correlation length (the Σ9 in the Ni dataset, and the Σ5 in the Fe dataset). The fact that certain local correlation lengths differ from the global correlation length suggests that a non-stationary Gaussian kernel (which depends on both relative distance and absolute location) may be a more appropriate choice than the stationary Gaussian kernel (Section S2.3).