Averaging regions: 
Nino 1+2: 0-10S,    90-80W
Nino 3:   5N-5S,   150-90W
Nino 3.4: 5N-5S,  170-120W
Nino 4:   5N-5S, 160E-150W


      Nino 1+2 standard deviation (C) stratified by calendar month.
           Jan  Feb  Mar  Apr  May  Jun  Jul  Aug  Sep  Oct  Nov  Dec
1950-1979 0.75 0.66 0.73 1.00 1.17 1.19 1.19 1.02 0.91 0.91 0.90 0.90
1980-2001 1.18 0.94 1.02 1.41 1.58 1.57 1.54 1.38 1.20 1.20 1.30 1.30
1950-2001 0.96 0.82 0.90 1.20 1.36 1.36 1.34 1.17 1.03 1.04 1.09 1.10

      Nino 3 standard deviation (C) stratified by calendar month.
           Jan  Feb  Mar  Apr  May  Jun  Jul  Aug  Sep  Oct  Nov  Dec
1950-1979 0.93 0.68 0.44 0.53 0.63 0.67 0.75 0.85 0.87 0.89 1.03 1.08
1980-2001 1.33 1.02 0.81 0.79 0.92 0.91 0.90 0.96 1.00 1.14 1.30 1.43
1950-2001 1.11 0.84 0.64 0.66 0.80 0.78 0.81 0.89 0.93 1.00 1.15 1.23

      Nino 3.4 standard deviation (C) stratified by calendar month.
           Jan  Feb  Mar  Apr  May  Jun  Jul  Aug  Sep  Oct  Nov  Dec
1950-1979 1.05 0.79 0.59 0.53 0.52 0.53 0.60 0.72 0.80 0.88 1.04 1.06
1980-2001 1.32 1.12 0.87 0.70 0.72 0.79 0.80 0.89 0.87 1.10 1.25 1.36
1950-2001 1.16 0.93 0.72 0.61 0.63 0.65 0.69 0.79 0.84 0.97 1.13 1.19

      Nino 4 standard deviation (C) stratified by calendar month.
           Jan  Feb  Mar  Apr  May  Jun  Jul  Aug  Sep  Oct  Nov  Dec
1950-1979 0.77 0.70 0.57 0.50 0.47 0.43 0.47 0.50 0.61 0.70 0.76 0.76
1980-2001 0.82 0.82 0.73 0.64 0.55 0.54 0.54 0.56 0.54 0.72 0.81 0.82
1950-2001 0.79 0.75 0.64 0.57 0.51 0.49 0.52 0.54 0.61 0.72 0.79 0.80

Anomalies are calculated with respect to the indicated years.

Todd Mitchell, May 2002