Fig. 6

Correlation maps between the time coefficients of EOF1 and geopotential height (a) and zonal component of the wind field (b) at the 850 hPa level from 1951 to 2012. The contour interval is 0.1. The solid and dashed lines indicate positive and negative correlation coefficients, respectively. Correlation coefficients above 0.1 or below − 0.1 indicate a significant correlation at the two-sided 99% level according to Student’s t test