Figure plan for decadal hindcast
    following Bethke et al.(2021) 10.5194/gmd-14-7073-2021

1. ACC and dACC
    ACC use ensemble mean
    time: lead year 1, 2-5, 6-9
    dACC with Persistance, historical and analysis 
    variables: SST,      T300, S300, SSH,     T2m (SAT)
    obs:       ERSSTv5   EN4   EN4   ARMOR-3D L4HadCRUT4
    Needs:
        1. ensmean and mean with lead years
            Capable for 1+ member and make persistance(from obs)
            agg. with lead year. casename = runname(leadYear, case)
            output t,y,x, where t is forecast time (year or years average)
            cdo?
        2. ACC
            cdo?
        3. plot it (NCL)
        3. historical ACC
        4.