Appendix A

Independent Forecasts 1993 - Present

Though the intention of the ENSO-CLIPER methodology was not to create a superior ENSO forecast, the regressions so far have offered predictions of SST anomalies which have been quite satisfactory and competitive with more sophisticated methodologies (see section 5). Shown in Tables A1 through A5 are the independent predictions (January 1993 - Present) of Niño-4, Niño-3.4, Niño-3, Niño-1+2, and SOI, respectively. This period of ENSO history is very difficult to forecast. Long running warm conditions existed in the eastern equatorial Pacific for most of late 1990 through early 1995. During this period, persistence was a dominant mode. Following a final resurgence of warm conditions in late 1994, cold conditions quickly developed in the later half of 1995. The forecast of ENSO conditions was quite difficult during this period as evidenced by some large errors experienced by other forecast schemes (see Barnston 1994, 1995).

Lead(Seasons)
DateObs 012 34567
JFM 93 0.42 0.29
FMA 93 0.40 0.29
MAM 93 0.48 0.26
AMJ 93 0.53 0.39 0.22
MJJ 93 0.60 0.52 0.17
JJA 93 0.60 0.73 0.28
JAS 93 0.66 0.86 0.55-0.14
ASO 93 0.60 0.70 0.76 0.07
SON 93 0.62 0.51 1.26-0.16
OND 93 0.57 0.66 1.19 0.61-0.17
NDJ 93 0.49 0.46 0.86 0.93 0.24
DJF 93 0.27 0.29 0.31 1.08 0.51
JFM 94 0.07 0.41 0.31 0.83 0.16-0.11
FMA 94 0.04 0.08 0.29 0.46 0.65 0.19
MAM 94 0.18-0.06 0.05 0.14 0.68 0.48
AMJ 94 0.35 0.02 0.25-0.03 0.25 0.33 0.29
MJJ 94 0.56 0.20-0.01-0.03 0.23 0.05 0.27
JJA 94 0.78 0.47-0.07-0.11 0.03 0.05-0.05
JAS 94 0.90 0.60-0.12-0.05-0.21-0.17 0.31 0.49
ASO 94 0.96 0.77 0.04-0.03-0.22 0.24 0.08 0.08
SON 94 1.04 1.16 0.37-0.22 0.02 0.10 0.10 0.10
OND 94 1.16 1.10 0.58-0.02-0.13-0.48 0.03 0.39 0.63
NDJ 94 1.18 0.89 0.72-0.03-0.25-0.41-0.26-0.16 0.08
DJF 94 1.06 0.88 1.02 0.23-0.09-0.12-0.21-0.37 0.50
JFM 95 0.92 0.87 0.74 0.37-0.20-0.12-0.47-0.44-0.05
FMA 95 0.73 0.73 0.57 0.39-0.07-0.21 0.08-0.26-0.10
MAM 95 0.58 0.73 0.49 0.41 0.15 0.14-0.01-0.14-0.25
AMJ 95 0.46 0.54 0.80 0.20-0.03 0.13 0.16 0.05-0.21
MJJ 95 0.39 0.26 0.66 0.20 0.18-0.08-0.02 0.05 0.08
JJA 95 0.23 0.21 0.64 0.20 0.08 0.06-0.02 0.19 0.18
JAS 95 0.04 0.37 0.43 0.25 0.00-0.19 0.32 0.17 0.54
ASO 95-0.16 0.12 0.20 0.33-0.04 0.18 0.09 0.09 0.09
SON 95-0.29-0.05 0.27 0.56 0.28 0.12 0.12 0.12 0.34
OND 95-0.33-0.26 0.24 0.38 0.19-0.24-0.06 0.41 0.18
NDJ 95-0.29-0.35 0.16 0.06 0.59-0.27-0.30 0.25 0.09
DJF 95-0.35-0.34-0.15-0.20 0.68-0.02 0.31 0.17 0.52
JFM 96-0.43-0.29-0.42-0.14 0.09 0.08-0.38-0.42 0.17
FMA 96-0.46-0.25-0.24 0.02-0.07 0.39 0.31-0.31 0.33
MAM 96-0.35-0.34-0.25 0.05-0.13 0.54 0.10 0.26 0.15
AMJ 96-0.20-0.23-0.18-0.28-0.14 0.26 0.49 0.20-0.20
MJJ 96-0.11-0.20-0.07-0.23 0.08 0.06 0.27 0.15 0.09
JJA 96-0.01-0.14-0.15-0.14 0.11 0.08 0.10 0.24-0.11
JAS 96 0.02-0.14-0.06-0.13-0.30 0.06-0.11 0.21 0.50
ASO 96 0.03-0.02-0.12-0.02-0.22-0.08 0.11 0.11 0.11
SON 96-0.01 0.19 0.03-0.04-0.29 0.14 0.14 0.14 0.31
OND 96 0.01 0.09-0.02-0.05-0.48-0.32-0.20 0.20
NDJ 96 -0.03 0.12-0.06 0.21-0.22 0.08 0.10 0.11
DJF 96 0.04 0.21-0.01 0.08-0.21 0.15 0.26 0.29
JFM 97 0.21-0.02-0.03 0.06-0.25-0.15-0.07
FMA 97 0.00 0.33 0.03 0.22 0.10 0.04 0.15
MAM 97 0.17 0.09 0.04 0.24-0.01 0.15 0.21
AMJ 97 0.28 0.23 0.18 0.15 0.16-0.05
MJJ 97 0.25 0.32 0.01 0.16 0.17 0.10
JJA 97 0.28 0.30 0.08 0.03 0.32 0.26
JAS 97 0.39 0.35 0.23 0.49-0.07
ASO 97 0.38 0.29 0.11 0.11 0.11
SON 97 0.31 0.13 0.13 0.13 0.68
OND 97 0.63 0.39 0.31 0.64
NDJ 97 0.48 0.31 0.37 0.10
DJF 97 0.28 0.40 0.35 0.51
JFM 98 0.38 0.37 0.12
FMA 98 0.39 0.25 0.42
MAM 98 0.26 0.32 0.27
AMJ 98 0.28 0.24
MJJ 98 0.25 0.10
JJA 98 0.19-0.02
JAS 98 0.14
ASO 98 0.11
SON 98 0.19
Table A1: Niño-4 independent forecasts 1993 through early 1996. The date of the verification is listed in the first column follows by the observed value in the second column followed by the 0 through 7 lead forecast values.

Lead(Seasons)
DateOBS 01234567
JFM 93 0.29 0.17
FMA 93 0.54 0.13
MAM 93 0.87 0.20
AMJ 93 0.98 0.44 0.01
MJJ 93 0.83 0.76 0.19
JJA 93 0.45 0.95 0.31
JAS 93 0.33 1.29 0.70-0.18
ASO 93 0.29 0.43 1.04-0.46
SON 93 0.36 0.63 1.50 0.43
OND 93 0.30 0.34 1.46 1.11-0.33
NDJ 93 0.20 0.39 0.89 1.39 0.40
DJF 93 0.03 0.35 0.31 1.51 0.49
JFM 94-0.04 0.20 0.54 1.25 0.88-0.21
FMA 94 0.00-0.15 0.25 0.52 0.77 0.31
MAM 94 0.19-0.14 0.05 0.51 0.75-0.24
AMJ 94 0.33-0.01-0.03-0.09 0.23 0.09 0.10
MJJ 94 0.35 0.00-0.11 0.17 0.10 0.15 0.31
JJA 94 0.40 0.42-0.21-0.01 0.09 0.09 0.54
JAS 94 0.42 0.86 0.12-0.11-0.48-0.42 0.37 0.59
ASO 94 0.61 0.22 0.06-0.50-0.75-0.09 0.17 0.16
SON 94 0.86 0.51 0.50-0.32-0.67-0.35-0.22 0.83
OND 94 1.13 0.68 0.73 0.25-0.25-0.81-0.75 0.49 0.11
NDJ 94 1.21 0.83 0.88-0.26-0.33-0.52-0.39-0.56 0.33
DJF 94 1.02 1.15 0.36 0.52-0.34-0.39-0.28-0.24 0.84
JFM 95 0.71 0.94 0.65 0.46 0.23-0.14-0.57-0.38 0.22
FMA 95 0.45 0.42 0.49 0.51-0.09-0.03 0.05-0.20-0.27
MAM 95 0.23 0.62 0.44 0.57 0.16-0.28-0.17 0.09-0.05
AMJ 95 0.11 0.19 0.36 0.08-0.18-0.14 0.05 0.14 0.14
MJJ 95 0.01 0.20 0.74 0.27 0.02 0.34 0.04 0.14 0.14
JJA 95-0.14-0.09 0.39 0.13 0.10 0.10 0.45 0.32 0.38
JAS 95-0.35 0.06-0.17 0.12-0.29-0.40 0.39 0.19 0.70
ASO 95-0.63-0.18 0.05 0.27-0.71 0.12 0.50 0.27 0.11
SON 95-0.82-0.30-0.05 0.52-0.44-0.38 0.25 0.66 0.43
OND 95-0.93-0.72 0.16 0.05 0.07-0.63-0.72 0.55 0.11
NDJ 95-0.88-0.96 0.08 0.16 0.81-0.36-0.47 0.09 0.49
DJF 95-0.88-0.73-0.08-0.07 0.58 0.34-0.01 0.29 0.74
JFM 96-0.74-0.59-0.48-0.09 0.09 0.10-0.43-0.06 0.59
FMA 96-0.57-0.39-0.44 0.04 0.10 0.53 0.26-0.25 0.28
MAM 96-0.36-0.50-0.17 0.01-0.01 0.37-0.02 0.22 0.22
AMJ 96-0.23-0.18-0.20-0.20-0.07 0.39 0.44 0.22 0.14
MJJ 96-0.15-0.21 0.02 0.07 0.13 0.46 0.30 0.14 0.15
JJA 96-0.12-0.22 0.14-0.18 0.10 0.10 0.24 0.26-0.18
JAS 96-0.13-0.32 0.29 0.00-0.37-0.13-0.15 0.16 0.63
ASO 96-0.26-0.16-0.18 0.00-0.57-0.08 0.05 0.37 0.12
SON 96-0.30-0.19 0.22 0.19-0.43 0.20 0.33 0.34 0.35
OND 96 -0.15-0.23 0.59 0.04-0.47-0.26-0.31 0.14
NDJ 96 -0.34 0.05-0.03 0.37-0.14-0.10 0.05 0.18
DJF 96 -0.20-0.06-0.19 0.22 0.01 0.28 0.34 0.37
JFM 97 -0.10-0.12 0.49 0.09-0.33-0.08-0.24
FMA 97 -0.13 0.05 0.05 0.33 0.23 0.10 0.07
MAM 97 0.13 0.23 0.06-0.11 0.07 0.25 0.28
AMJ 97 0.31 0.21-0.01 0.03 0.29 0.14
MJJ 97 0.15 0.46 0.44 0.20 0.14 0.14
JJA 97 0.19 0.10 0.10 0.51 0.63 0.33
JAS 97 0.41 0.39 0.28 0.62-0.09
ASO 97 0.37 0.54 0.77 0.01 0.10
SON 97 0.59 0.43 0.61 0.78 0.87
OND 97 0.62 0.60 0.47 0.11
NDJ 97 0.46 0.78 0.45 0.20
DJF 97 0.58 0.37 0.73 0.84
JFM 98 0.55 0.60 0.37
FMA 98 0.46 0.34 0.25
MAM 98 0.41 0.23 0.40
AMJ 98 0.23 0.14
MJJ 98 0.13 0.14
JJA 98 0.16 0.24
JAS 98 0.24
ASO 98 0.09
SON 98 0.21
Table A2: Same as Table A1 except for Niño-3.4.

Nino 3.4 - Independent ENSO-CLIPER forecasts

Nino 3.4 - Independent ENSO-CLIPER forecasts 
--------------------------------------------
(deg C anomalies for a 1961-90 base period for 0 
through 7 seasons lead time)

Target OBS 0 1 2 3 4 5 6 7 Period (C) lead lead lead lead lead lead lead lead ------ ---- ---- ---- ---- ---- ---- ---- ---- ---- JFM 93 0.3 0.1 FMA 93 0.6 0.1 MAM 93 0.9 0.2 AMJ 93 1.0 0.4 0.0 MJJ 93 0.9 0.7 0.2 JJA 93 0.5 0.9 0.3 JAS 93 0.4 1.2 0.7 -0.2 ASO 93 0.3 0.4 1.0 -0.5 SON 93 0.4 0.6 1.4 0.4 OND 93 0.4 0.3 1.4 1.1 -0.4 NDJ 93 0.2 0.4 0.8 1.4 0.4 DJF 93 0.1 0.3 0.3 1.5 0.4 JFM 94 0.0 0.2 0.5 1.2 0.8 -0.2 FMA 94 0.1 -0.2 0.2 0.5 0.8 0.3 MAM 94 0.2 -0.2 0.0 0.5 0.7 -0.3 AMJ 94 0.4 0.0 -0.1 -0.1 0.2 0.0 0.1 MJJ 94 0.4 0.0 -0.2 0.1 0.1 0.1 0.3 JJA 94 0.5 0.4 -0.2 0.0 0.1 0.1 0.5 JAS 94 0.5 0.8 0.1 -0.2 -0.5 -0.5 0.3 0.6 ASO 94 0.7 0.2 0.0 -0.5 -0.8 -0.1 0.1 0.1 SON 94 0.9 0.4 0.4 -0.4 -0.7 -0.4 -0.3 0.8 OND 94 1.2 0.6 0.7 0.2 -0.3 -0.8 -0.8 0.5 0.1 NDJ 94 1.3 0.8 0.8 -0.3 -0.4 -0.6 -0.4 -0.6 0.3 DJF 94 1.1 1.1 0.3 0.5 -0.4 -0.4 -0.3 -0.3 0.8 JFM 95 0.8 0.9 0.6 0.4 0.2 -0.2 -0.6 -0.4 0.2 FMA 95 0.5 0.4 0.5 0.5 -0.1 0.0 0.0 -0.2 -0.3 MAM 95 0.3 0.6 0.4 0.5 0.1 -0.3 -0.2 0.0 -0.1 AMJ 95 0.1 0.2 0.3 0.0 -0.2 -0.2 0.0 0.1 0.1 MJJ 95 0.0 0.2 0.7 0.2 0.0 0.3 0.0 0.1 0.1 JJA 95 -0.1 -0.1 0.4 0.1 0.1 0.1 0.4 0.3 0.4 JAS 95 -0.3 0.0 -0.2 0.1 -0.3 -0.4 0.4 0.2 0.7 ASO 95 -0.6 -0.2 0.0 0.2 -0.8 0.1 0.5 0.2 0.1 SON 95 -0.8 -0.4 -0.1 0.5 -0.5 -0.4 0.2 0.6 0.4 OND 95 -0.9 -0.8 0.1 0.0 0.0 -0.7 -0.8 0.5 0.1 NDJ 95 -0.8 -1.0 0.0 0.1 0.8 -0.4 -0.5 0.0 0.4 DJF 95 -0.8 -0.8 -0.1 -0.1 0.5 0.3 0.0 0.2 0.7 JFM 96 -0.7 -0.6 -0.5 -0.1 0.1 0.1 -0.5 0.0 0.6 FMA 96 -0.5 -0.4 -0.5 0.0 0.1 0.5 0.2 -0.3 0.3 MAM 96 -0.3 -0.5 -0.2 0.0 0.0 0.3 -0.1 0.2 0.2 AMJ 96 -0.2 -0.2 -0.2 -0.2 -0.1 0.4 0.4 0.2 0.1 MJJ 96 -0.1 -0.2 0.0 0.0 0.1 0.4 0.3 0.1 0.1 JJA 96 0.0 -0.2 0.1 -0.2 0.1 0.1 0.2 0.2 -0.2 JAS 96 -0.1 -0.4 0.2 0.0 -0.4 -0.2 -0.2 0.1 0.6 ASO 96 -0.2 -0.2 -0.2 0.0 -0.6 -0.1 0.0 0.3 0.1 SON 96 -0.3 -0.2 0.2 0.1 -0.5 0.1 0.3 0.3 0.3 OND 96 -0.3 -0.2 -0.3 0.6 0.0 -0.5 -0.3 -0.3 0.1 NDJ 96 -0.4 -0.4 0.0 -0.1 0.3 -0.2 -0.1 0.0 0.1 DJF 96 -0.4 -0.2 -0.1 -0.2 0.2 0.0 0.2 0.3 0.3 JFM 97 -0.3 -0.3 -0.1 -0.2 0.5 0.1 -0.4 -0.1 -0.3 FMA 97 0.1 -0.2 -0.2 0.0 0.0 0.3 0.2 0.1 0.0 MAM 97 0.5 0.0 0.1 0.2 0.0 -0.2 0.1 0.2 0.2 AMJ 97 1.0 0.4 0.0 0.3 0.2 0.0 0.0 0.2 0.1 MJJ 97 1.5 0.9 0.2 0.1 0.4 0.4 0.2 0.1 0.1 JJA 97 1.9 1.5 0.5 0.2 0.1 0.1 0.5 0.6 0.3 JAS 97 2.2 1.7 0.9 0.3 0.4 0.4 0.2 0.6 -0.1 ASO 97 2.4 2.3 1.2 0.4 0.3 0.5 0.7 0.0 0.1 SON 97 2.6 2.1 2.0 0.7 0.5 0.4 0.6 0.7 0.8 OND 97 2.6 2.2 2.8 2.4 0.8 0.6 0.6 0.4 0.1 NDJ 97 2.8 2.6 3.1 1.5 0.9 0.4 0.7 0.4 0.2 DJF 97 2.5 2.2 2.8 2.5 0.8 0.5 0.3 0.7 0.8 JFM 98 2.1 1.8 1.5 2.0 1.3 0.5 0.5 0.6 0.3 FMA 98 1.6 1.3 1.4 1.6 0.8 0.4 0.4 0.3 0.2 MAM 98 1.1 1.2 0.8 0.8 0.9 0.3 0.4 0.2 0.4 AMJ 98 0.4 0.8 0.2 0.0 0.6 0.2 0.2 0.2 0.1 MJJ 98 -0.3 0.5 0.3 0.2 0.4 -0.1 0.2 0.1 0.1 JJA 98 -1.0 -0.2 0.0 -0.5 0.1 0.1 0.4 0.2 0.2 JAS 98 -1.1 -0.6 -0.1 -0.9 -0.6 -0.5 0.3 0.1 0.2 ASO 98 -1.1 -1.2 -0.3 -0.5 -0.2 -0.2 0.0 0.1 0.0 SON 98 -1.1 -1.8 -1.2 -0.1 -0.8 -0.5 -0.4 0.5 0.2 OND 98 -1.4 -1.7 -1.7 -0.8 -1.7 -1.0 -0.9 0.4 0.1 NDJ 98 -1.5 -1.1 -2.0 -0.8 -1.3 -0.6 -0.2 -0.1 0.6 DJF 98 -1.5 -1.1 -1.6 -0.9 -0.1 -1.5 -0.8 -0.3 0.6 JFM 99 -1.2 -1.0 -1.1 -1.1 -0.5 -1.4 -0.7 -0.7 -0.1 FMA 99 -0.9 -0.7 -0.5 -1.0 -0.4 -0.9 -0.4 -0.4 -0.2 MAM 99 -0.7 -0.9 -0.3 -0.6 -0.4 -0.7 -0.8 -0.4 -0.2 AMJ 99 -0.8 -0.5 -0.5 -0.6 -0.5 -0.8 -0.6 -0.4 0.2 MJJ 99 -0.7 -0.5 -0.6 0.0 -0.2 -1.0 -0.5 0.2 0.2 JJA 99 -0.9 -0.4 -0.5 0.0 0.1 0.1 -0.9 -0.7 -0.1 JAS 99 -0.9 -0.2 -0.1 0.0 -0.4 0.0 -0.7 -0.5 -0.6 ASO 99 -0.9 -0.7 -0.6 -0.3 0.3 0.2 -0.4 0.3 0.1 SON 99 -1.0 -0.8 -0.5 -0.9 0.1 0.5 -0.4 -1.6 -1.1 OND 99 -1.3 -0.7 -0.7 -0.6 0.0 -0.3 0.0 -1.5 0.2 NDJ 99 -1.6 -1.0 -0.7 -0.9 -1.0 0.6 0.0 -0.5 -1.2 DJF 99 -1.6 -0.9 -0.9 -0.6 -0.9 0.6 0.5 -0.5 -1.7 JFM 00 -1.4 -1.0 -0.4 -0.5 -0.4 0.1 -0.2 0.2 -1.0 FMA 00 -1.0 -1.0 -0.4 -0.3 -0.4 -0.3 -0.4 0.4 0.1 MAM 00 -0.7 -0.7 -0.3 -0.1 -0.2 -0.1 0.3 0.2 0.0 AMJ 00 -0.5 -0.4 -0.2 -0.1 -0.2 0.3 0.3 0.3 0.2 MJJ 00 -0.4 -0.4 -0.3 0.0 -0.1 0.4 0.2 0.2 0.2 JJA 00 -0.3 -0.4 -0.1 0.5 0.1 0.1 0.2 0.3 0.2 JAS 00 -0.3 0.2 0.2 0.4 0.5 0.4 0.1 0.2 0.3 ASO 00 -0.4 -0.3 0.1 -0.3 0.4 0.5 0.0 0.1 SON 00 -0.1 -0.4 -0.4 0.2 0.2 0.5 0.2 0.3 OND 00 -0.1 0.2 0.7 0.7 0.6 0.3 0.1 NDJ 00 -0.5 -0.1 -0.1 0.1 0.4 0.9 0.1 DJF 00 -0.6 0.0 -0.3 0.7 0.8 0.7 0.4 JFM 01 0.0 0.2 0.7 0.6 0.8 0.3 FMA 01 -0.2 0.0 -0.1 0.6 0.2 0.5 MAM 01 0.1 0.1 0.3 0.4 0.3 0.3 AMJ 01 -0.1 0.0 0.2 0.3 0.1 MJJ 01 -0.2 0.2 0.1 0.1 0.1 JJA 01 0.1 0.1 0.6 0.4 0.4 JAS 01 0.2 0.3 0.1 0.3 ASO 01 0.2 0.6 0.3 0.0 SON 01 0.1 0.8 0.8 0.4 OND 01 0.4 0.6 0.0 NDJ 01 0.2 0.6 0.8 DJF 01 0.5 1.1 1.0 JFM 02 0.6 0.4 FMA 02 0.0 0.2 MAM 02 0.2 0.5 AMJ 02 0.1 MJJ 02 0.1 JJA 02 0.0

Lead(Seasons)
Date 01234567
JFM 93 0.25-0.05
FMA 93 0.65 0.08
MAM 93 1.03 0.22
AMJ 93 1.09 0.66 0.22
MJJ 93 0.77 0.79 0.25
JJA 93 0.30 0.96 0.40
JAS 93 0.10 1.17 0.67-0.65
ASO 93 0.15 0.22 0.84-0.73
SON 93 0.23 0.50 1.42 0.42
OND 93 0.26 0.61 1.79 0.79-0.41
NDJ 93 0.20 0.41 0.98 1.30-0.35
DJF 93 0.06 0.27 0.33 1.47 0.47
JFM 94-0.04 0.06 0.23 1.09 0.40-0.19
FMA 94-0.20-0.14 0.23 0.45 0.44 0.28
MAM 94-0.08-0.38-0.07 0.12 0.57 0.12
AMJ 94-0.01-0.16-0.33-0.32-0.25 0.08 0.11
MJJ 94-0.05-0.35-0.24-0.13-0.19-0.10 0.14
JJA 94-0.21 0.00-0.32-0.58-0.17-0.27 0.05
JAS 94-0.25 0.58-0.13-0.52-0.64-0.58-0.06 0.07
ASO 94 0.10-0.41-0.33-1.14-0.73-0.13 0.00 0.15
SON 94 0.51 0.34 0.46-0.39-0.92-0.39-0.39 0.06
OND 94 0.84 0.63 0.94 0.00-0.28-0.76-0.57 0.44 0.10
NDJ 94 0.91 0.67 1.02 0.10-0.58-0.37-0.30 0.15 0.23
DJF 94 0.81 0.83 0.58 0.53-0.29-0.64-0.03-0.15 0.13
JFM 95 0.52 0.90 0.32 0.68 0.10-0.10-0.40 0.03 0.39
FMA 95 0.15 0.24 0.36 0.45-0.03 0.03 0.14 0.21 0.20
MAM 95-0.22 0.34 0.14 0.14 0.47 0.14-0.03 0.14 0.14
AMJ 95-0.33-0.06 0.49-0.30-0.36 0.05 0.07 0.13 0.13
MJJ 95-0.32 0.20 0.85-0.08-0.22 0.27 0.20 0.12 0.12
JJA 95-0.37-0.74 0.50-0.13 0.34-0.35 0.21 0.28 0.09
JAS 95-0.57-0.14-0.14-0.31-0.46-0.56 0.19 0.07 0.07
ASO 95-0.76-0.19-0.68-0.17-0.80 0.10 0.53 0.08 0.08
SON 95-0.85-0.44-0.08 0.50-0.42-0.42 0.05 0.26 0.38
OND 95-0.85-0.45-0.04 0.29 0.00-0.61-0.20 0.51 0.10
NDJ 95-0.77-0.80-0.02 0.04 0.69-0.41 0.38 0.60 0.13
DJF 95-0.64-0.66-0.04-0.01 0.54-0.41 0.55 0.28 0.35
JFM 96-0.42-0.41-0.28 0.13 0.02 0.08-0.28 0.03 0.58
FMA 96-0.43-0.21-0.25 0.10 0.27 0.54 0.13 0.45 0.54
MAM 96-0.42-0.23 0.04 0.13-0.04 0.13 0.09 0.13 0.13
AMJ 96-0.50 0.04 0.25-0.15-0.15 0.40 0.48 0.13 0.13
MJJ 96-0.39-0.02 0.17 0.02 0.08 0.15 0.00 0.11 0.12
JJA 96-0.34-0.38 0.13-0.13 0.45-0.05-0.09 0.20 0.08
JAS 96-0.35-0.41 0.16-0.28-0.45-0.24-0.11 0.06 0.07
ASO 96-0.42-0.18-0.55-0.25-0.43-0.14 0.26 0.04 0.08
SON 96-0.46-0.49 0.18 0.15-0.48 0.15 0.04-0.12 0.31
OND 96 -0.45-0.41 0.20 0.01-0.43-0.47-0.29 0.12
NDJ 96 -0.39-0.06-0.23 0.25 0.06 0.11 0.05 0.09
DJF 96 -0.29-0.23 0.25 0.22-0.36 0.38 0.17-0.06
JFM 97 -0.15 0.24 0.33 0.09-0.23-0.46-0.35
FMA 97 -0.09 0.05 0.18 0.27 0.13 0.04-0.06
MAM 97 0.08 0.13-0.04 0.13 0.11 0.13 0.13
AMJ 97 0.30 0.44 0.07 0.02 0.12 0.12
MJJ 97 0.30 0.28 0.21 0.02 0.10 0.11
JJA 97 0.43 0.04 0.27 0.31 0.60 0.07
JAS 97 0.43 0.41 0.09 0.05 0.05
ASO 97 0.33 0.55 0.53 0.11 0.06
SON 97 0.49 0.39 0.38 0.41 0.80
OND 97 0.57 0.26 0.43 0.10
NDJ 97 0.49 0.67 1.05 0.21
DJF 97 0.65 0.60 0.53 0.53
JFM 98 0.46 0.00 0.36
FMA 98 0.12 0.38 0.44
MAM 98 0.25 0.11 0.11
AMJ 98 0.10 0.10
MJJ 98 0.09 0.10
JJA 98 0.13 0.06
JAS 98 0.04
ASO 98 0.05
SON 98 0.16
Table A3: Same as Table A1 except for Niño-3.

Lead(Seasons)
DateOBS 01234567
JFM 930.31-0.28
FMA 930.78-0.12
MAM 930.94 0.54
AMJ 930.89 0.96-0.56
MJJ 930.65 1.12-0.58
JJA 930.38 0.81 0.52
JAS 930.23 0.34 0.64-0.68
ASO 930.25 0.48 0.38-0.28
SON 930.13 0.80 1.45 0.41
OND 93-0.06 0.55 0.51 0.60-0.36
NDJ 93-0.18-0.12 0.37 0.69 0.05
DJF 93-0.16-0.11 0.22 0.93 0.21
JFM 94-0.30-0.79-0.31 0.35-0.01-0.27
FMA 94-0.66-0.81-0.55-0.13-0.05-0.05
MAM 94-0.95-0.79-1.27-0.04-0.04-0.04
AMJ 94-0.79-0.92-1.72-0.63-0.96 0.00 0.00
MJJ 94-0.55-0.52-1.28-1.00 0.05 0.05 0.49
JJA 94-0.61-0.69-0.70-1.15 0.04 0.04 0.04
JAS 94-0.63 0.02-0.61-1.55-0.79-0.63-0.30 0.05
ASO 94-0.25-0.11-0.54-0.26-0.55-0.32-0.29 0.06
SON 940.38 0.19-0.01-0.38-0.80 0.07 0.07 0.72
OND 940.83 0.41 0.69-0.06-0.22-0.47-0.12 0.42 0.07
NDJ 940.89 0.52 0.45-0.09-0.18 0.05 0.04 0.17 0.04
DJF 940.82 0.63 0.47 0.28-0.09-0.23 0.05-0.35-0.21
JFM 950.43 0.12-0.65 0.36 0.00-0.21-0.01-0.41 0.20
FMA 95-0.21-0.12-0.79-0.18-0.03-0.03-0.03-0.03 0.06
MAM 95-0.76 0.23-0.52-0.01-0.01-0.01-0.01 0.00 0.00
AMJ 95-0.83 0.22-0.69-1.13-0.48 0.02 0.02-0.05 0.03
MJJ 95-0.59-1.04-0.28-1.59 0.07 0.07 0.14 0.07 0.08
JJA 95-0.46-1.07 0.04-0.76 0.05 0.05 0.05 0.05 0.07
JAS 95-0.36-0.04 0.04-0.89-0.95-0.60 0.34 0.05 0.07
ASO 95-0.38-0.19-0.47 0.34-0.43-0.37 0.20 0.06 0.06
SON 95-0.27-0.31-0.70 0.49-0.29 0.07 0.07 0.65 0.44
OND 95-0.37-0.13 0.71 0.33 0.12-0.30-0.19 0.41 0.07
NDJ 95-0.39-0.48-0.01 0.05 0.13 0.05 0.03 0.52 0.03
DJF 95-0.25-0.53 0.27-0.09 0.28 0.35 0.01-0.01 0.03
JFM 96-0.11-0.29-0.09-0.14-0.01-0.10-0.02-0.11 0.19
FMA 96-0.50-0.29-0.35 0.32-0.05-0.05-0.05-0.05 0.52
MAM 96-0.82-0.10-0.28-0.03-0.03-0.03-0.03-0.03-0.03
AMJ 96-1.20 0.16-0.23 0.51 0.48 0.00 0.00 0.23 0.01
MJJ 96-1.14-1.45-0.18-0.12 0.05 0.05 0.51 0.05 0.07
JJA 96-1.17-0.58 0.49 0.31 0.03 0.03 0.03 0.03 0.05
JAS 96-1.10-0.87 0.14-0.10-0.15-0.28 0.10 0.04 0.05
ASO 96-0.89-0.86-0.55 0.28-0.02 0.02-0.22 0.05 0.05
SON 96-0.93-0.74-0.12 0.15-0.47 0.08 0.08 0.25 0.41
OND 96 -0.71-0.66 0.10-0.15-0.37-0.81-0.23 0.08
NDJ 96 -0.56-0.59-0.09 0.15 0.07 0.05 0.00 0.05
DJF 96 -0.64-0.22 0.08 0.08-0.30-0.16-0.01-0.21
JFM 97 -0.22-0.02 0.00-0.05-0.01 0.00-0.70
FMA 97 -0.18 0.19-0.05-0.05-0.05-0.05-0.31
MAM 97 -0.05-0.05-0.05-0.05-0.04-0.04
AMJ 97 -0.17 0.06-0.02-0.02-0.59-0.01
MJJ 97 0.05 0.04 0.04 0.20 0.04 0.05
JJA 97 -0.11 0.02 0.02 0.02 0.02 0.04
JAS 97 0.14 0.41 0.00 0.03 0.05
ASO 97 0.03 0.27-0.82 0.04 0.04
SON 97 0.44 0.07 0.07 0.82 0.78
OND 97 0.36-0.32 0.26 0.07
NDJ 97 0.06 0.04 0.79 0.04
DJF 97 0.11-0.06 0.27 0.00
JFM 98 -0.01 0.16 0.19
FMA 98 -0.06-0.06 0.39
MAM 98 -0.07-0.06-0.06
AMJ 98 0.26-0.04
MJJ 98 0.01 0.03
JJA 98 0.00 0.01
JAS 98 0.02
ASO 98 0.02
SON 98 0.11
Table A4: Same as Table A1 except for Niño-1+2.

Lead(Seasons)
DateOBS 01234567
JFM 93-1.20-0.53
FMA 93-1.33-0.66
MAM 93-1.10-0.29
AMJ 93-1.20-0.16 0.17
MJJ 93-1.03-0.73 0.48
JJA 93-1.33-1.20 0.09
JAS 93-1.13-1.68-0.68 0.38
ASO 93-1.26-1.30-1.20 0.20
SON 93-0.83-0.94-1.63-0.34
OND 93-0.57-0.93-1.19-0.61 0.13
NDJ 93-0.17-0.80-1.21-1.08 0.12
DJF 93-0.13-0.27-0.82-1.56-0.44
JFM 94-0.60-0.21-0.38-1.57-0.93 0.24
FMA 94-1.10-0.19-0.80-1.07-1.00-0.42
MAM 94-1.40 0.07 0.01-0.19-0.91-0.82
AMJ 94-1.23 0.10 0.02 0.03-0.20-0.38-0.52
MJJ 94-1.23 0.24 0.70 0.57-0.13-0.04-0.04
JJA 94-1.60-0.53 0.57-0.10-0.08-0.08-0.08
JAS 94-1.80-1.25 0.03 0.24 0.52 0.03-0.49-0.47
ASO 94-1.73-1.39-0.14 0.72 0.21 0.34-0.30-0.07
SON 94-1.36-1.46-1.00 0.32 0.36 0.43 0.13-0.08
OND 94-1.30-1.46-1.01-0.21 0.07 0.43-0.02-0.13-0.13
NDJ 94-0.97-1.42-1.20 0.15 0.72 0.24 0.34 0.57-0.15
DJF 94-0.90-0.75-1.31-0.60-0.05 0.03 0.40 0.07-0.20
JFM 95-0.33-1.31-0.86-1.01 0.14 0.12 0.19-0.04 0.22
FMA 95-0.47-1.39-0.51-1.09 0.03 0.19-0.08 0.20 0.46
MAM 95-0.53-0.90-0.42-0.47-0.15-0.20 0.12-0.14 0.03
AMJ 95-0.67-0.58-0.35-0.33 0.21-0.35-0.11-0.09-0.09
MJJ 95-0.20 0.03 0.29 0.46 0.16-0.06-0.06-0.38-0.07
JJA 95 0.00 0.06 0.10-0.13-0.11-0.11-0.11-0.41-0.12
JAS 95 0.17-0.09-0.34-0.09 0.27 0.26-0.49 0.21-0.08
ASO 95 0.00-0.09-0.11 0.31 0.14 0.38-0.68-0.10-0.86
SON 95 0.03-0.11 0.06-0.46 0.06 0.24 0.23-0.10-0.46
OND 95-0.37 0.06-0.03 0.24-0.28 0.11 0.12-0.98-0.14
NDJ 95 0.03 0.36-0.11-0.15 0.33 0.19-0.34-0.13-0.15
DJF 95 0.00 0.30-0.15-0.07-0.58-0.14 0.48 0.24-0.20
JFM 96 0.53 0.25 0.63-0.16-0.35-0.11 0.31-0.01-0.24
FMA 96 0.37-0.02 0.49-0.20-0.27-0.95-0.59 0.25-0.30
MAM 96 0.43 0.40 0.16 0.05 0.08-0.43-0.50-0.17 0.11
AMJ 96 0.53 0.32 0.26 0.39 0.12 0.12-0.48-0.11-0.11
MJJ 96 0.57 0.28 0.67 0.44-0.05-0.09-0.09 0.00-0.10
JJA 96 0.70-0.08 0.03-0.16-0.14-0.14-0.14-0.44-0.15
JAS 96 0.57 0.50-0.13 0.08 0.41 0.88 0.26 0.14-0.12
ASO 96 0.47 0.11 0.37 0.45-0.01 0.35-0.08-0.14-0.14
SON 96 0.27 0.04-0.06-0.18 0.14 0.10 0.10-0.13-0.42
OND 96 -0.02 0.31-0.18 0.00 0.42 0.63 0.16-0.17
NDJ 96 -0.02-0.32-0.05-0.28-0.01-0.08 0.50-0.17
DJF 96 -0.02-0.04-0.28-0.29 0.26-0.10 0.08-0.22
JFM 97 -0.04-0.43-0.45-0.19-0.28 0.66 0.40
FMA 97 -0.30-0.37-0.12-0.37 0.17-0.22 0.30
MAM 97 -0.34-0.29-0.08-0.61-0.22-0.18 0.01
AMJ 97 -0.35-0.17-0.18-0.53-0.13-0.13
MJJ 97 -0.29-0.31-0.09-0.09-0.31-0.10
JJA 97 -0.15-0.14-0.14-0.14-0.69-0.14
JAS 97 -0.43 0.25-0.30-0.34-0.11
ASO 97 -0.41-0.93-0.74-0.14-0.69
SON 97 -0.58-0.55-0.14-0.12-0.91
OND 97 -0.47 0.08-0.05-0.17
NDJ 97 -0.50-0.07-0.42-0.17
DJF 97 -0.49-0.55-0.24-0.21
JFM 98 -0.52-0.03 0.00
FMA 98 -0.71-0.51-0.56
MAM 98 -0.48-0.16-0.18
AMJ 98 -0.11-0.11
MJJ 98 -0.08-0.09
JJA 98 -0.16-0.13
JAS 98 -0.09
ASO 98 -0.17
SON 98 -0.20
Table A5: Same as Table A1 except for SOI.

Examination of these few actual independent forecasts shows that the statistical estimates of Root Mean Square Error (RMSE) from hindcast results has been quite accurate, though slightly underestimating independent RMSE values. For example, the RMSE values for Niño-3.4 for lead times zero through seven are 0.33, 0.54, 0.72, 0.77, 0.74, 0.74, 0.77, and 0.79, respectively. These are lower than the RMSE values generated by persistence for the zero through two leads which are 0.36, 0.61, 0.78, 0.99, 0.86, 0.87, 0.86, and 0.91, respectively. After lead two, the ENSO-CLIPER RMSE values are 10-40 percent smaller than those for persistence. All forecasts seem to exhibit similar error patterns with the largest errors during the early summer of the 1994 warm event which followed warm conditions in 1993. The probable cause of the increase in overall RMSE was likely the non-climatological nature of the 1993-1994 period when warm conditions persisted. The errors of these schemes tend to be biennial in nature as expected for the dominant time scale of variation of the ENSO phenomenon.