HIND_CTRL(uten 2005-2007) Z700 heterogeneous Anomaly Correlation(AC), 1-4 lead season

Following Becker et al. 2014 approach ( 10.1175/JCLI-D-13-00597.1 ) 1-4 lead seasonal forecast correlation. 

The correlation is between ERA5 reanalysis and ensemble mean of simulation members.