The regression pattern of (a) TPT from MERRA data and (c) SST anomalies from HadISST data regressed on the PDO index (e). The PDO index is the leading PC of observed SST anomalies over the North Pacific (20°–70°N, 110°E–100°W) from the HadISST data for the period 1900–2014, with the seasonal cycle and the global mean removed. The PDO mode explains 27% of the variance of the SST anomalies. The thick black line in (e) represents the low-pass (6-year) filtered PDO index. The time series of TPTs are first low-pass filtered and then regressed onto the filtered PDO index. TPT anomalies are derived from the MERRA data. The black contour lines in (a) show the explained variance in percent, whereas stippling in (a) indicates the 95% significance level, with autocorrelation effects taken into account. (b,d,f) Same as (a,c,e), but for the Natural CESM experiment from 1955–2099. The right hand side number in (d) is the pattern correlation between (d,c). Maps were produced using licensed IDL (http://www.harrisgeospatial.com/ProductsandSolutions/GeospatialProducts/IDL.aspx), version 8.1.