From Figure 1 in Smerdon et al. (GRL, 2011) showing grid cell correlation coefficients in a pseudoproxy experiment testing the Mann et al. (Nature, 1998) method.  The experiment used the NCAR CCSM 1.4 millennial simulation as the model testbed and pseudoproxies with a signal-to-noise ratio of 0.5 by standard deviation.  Pseudoproxies were sampled from locations approximating the most populated nest in the Mann et al. (Nature, 1998) multi-proxy network and are shown as black squares in the figure.