JISAO data
Eq. Pacific zonal wind anomaly index, 1800 - June 2005
Analyses | Data
An ENSO zonal wind anomaly index is calculated for the region 8N-8S, 150E-140W from the International Comprehensive Ocean-Atmosphere Data Set (ICOADS) data. This region was chosen from a map of zonal wind regressed onto an index of eastern equatorial Pacific SST for the period 1950-79. The anomalies are with respect to a 1950-79 climatology.

Historical record
Image of time series.
PNG | PS
The index has been smoothed for this figure with successive 11- and 7-point running means. The larger amplitudes in the 1850s and 1860s are probably due to the small number of grid boxes contributing to the average (the number of observations contributing are documented below). This series exhibits year to year ENSO variability, and a decadal tendency for easterly anomalies in 1850-90 and westerly anomalies during 1900-1950.

Modern record
Image of time series.
PNG | PS
The index has been smoothed with a 3-point running mean for this figure and captures the major ENSO episodes in this part of the record.

For this update, I have concatenated the NCEP near-real time marine record of 2003-June 2005 onto the ICOADS record. The NCEP data is not the NCEP - NCAR reanalysis, but are marine observations processed in the same manner as ICOADS. The NCEP record spans 1991-2005, and anomalies from it are correlated with ICOADS-based anomalies at 0.94.


PNG | PS
Reference
The index was developed for an unpublished paper on the chronology of ENSO in the tropics by myself and Mike Wallace.
Data:
The digital values are provided in several formats.
  • 4-column table year, calendar month, wind anomaly (m/s), number of observations.
  • 1-column table wind anomaly (m/s) for 1800-2005.
  • wind anomaly as a year-month table
  • wind number of observations as a year-month table

    Digital values of the index in cm/s.
    Missing data are indicated by blanks.
           JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC
 1850  -56  159  359  349  142  -98 -341 -399 -328  188  127   56
 1851  -47 -236   31 -101  265  199   19   53   11   22  -59     
 1852  110      -155    7      -177  405                 101   76
 1853  -14       -95  188 -364  222  -78 -518        35       -89
 1854  457       455            -69  125       126       104  117
 1855 -269   94  345        66      -106       376  258  -22     
 1856        49   25 -166 -107 -321 -300  -16 -197  -34  -15     
 1857             83            142            173               
 1858        91   59   25  -74   79 -125 -216 -282  -19 -240 -347
 1859 -196  -32 -137 -201  106  107 -256  240 -240 -164  154     
 1860                                                            
 1861 -274 -406                               -111           -224
 1862                           -26            -65               
 1863                  39   33                                   
 1864       387  154            363   87      -132  189          
 1865                                                            
 1866 -477            -96 -507                                   
 1867                                                            
 1868                                                   -178     
 1869       318  115  -57  272                -117      -162  -82
 1870 -262 -294  -42 -144       417  -20  -62                 141
 1871        70 -108 -113 -236 -162        93  105  -72          
 1872      -298  -92  161 -112 -146    7  -90 -196 -102 -283 -265
 1873 -176  -71 -177 -120 -106  -56 -136 -145      -224  103 -276
 1874 -109  -86  -54   58            201             52   85  -17
 1875           -326 -423           -302  -22  119             56
 1876                      263    6                              
 1877  -47      -246             87  353  266  334            404
 1878  702  563       193  128   92      -157  -15  -84      -250
 1879 -138 -151  -62       -43 -331  -73      -394 -216   17     
 1880       -88 -316  -93  -71  156 -105                -130  170
 1881       -17  115   75 -170   -2        -7 -109   39  278 -365
 1882      -188 -208   24   61  128 -195  -46      -186          
 1883  247                 -18    8    6  154    3   22  -63  101
 1884  219  111   94   19  150  115  150  224  132  128        86
 1885  166  -21  241                     -177  -72  205  177 -160
 1886        71    8   95   18    0 -122   18 -163 -239 -285   31
 1887  -95  -13  273  -49  109  -26    8   99 -124   53   11 -128
 1888            275  -95  120  122   26   87  226  162  156  175
 1889  440       118  163  228  -75  124   79 -286 -219 -169 -103
 1890 -297  353  223                -152 -420                    
 1891                      -41                     -261   -3     
 1892        16  -64       -52  -14      -288      -196          
 1893       -62            -32 -108  158  -19 -333  142  -65     
 1894 -290 -409 -224            -52       135   79  -91          
 1895   23  -45       -84      -192 -101  653      -235       120
 1896   10  117       -16  474  132            104   28  156   18
 1897            156   50    2   56  279   56   70  -41    6 -210
 1898   66 -224  -22 -113  -78 -179  -53  116   86 -344  -62   46
 1899 -136  -30 -171  -25 -136    6  -51   -5  -77  -16   90  213
 1900  466   84  402  152    7   39   -7  208  -39    0   61  115
 1901    5  368  117   95  -12 -127  109  -44 -185  -16 -154  423
 1902  116   43   47   12  222   41  151   -9  263  136  100   68
 1903 -117  162  125  216   72  -65 -106 -145 -220  142  -61   38
 1904 -323  -53    4  -54  -62   97   90    2   93   23  172   56
 1905  174  170  159  -40  198  -70  -98  -41    4    2   97   21
 1906  106  231   92   20  135  -98 -182   21  -51  -36  -81  172
 1907  204 -155  -28   57  187  -32   52  131   31   94  -16  -12
 1908  128  -45   52  -87  -46  109  -33  -53   36   22  -71   49
 1909  -40 -206  -48  154  200   25  -55  -35  -90  -88 -133  157
 1910 -126  -96   95 -193  -55  118  138  -64   69  -28 -146  -20
 1911  -39   87  213  -20  117   82   65   24  367  183  301  294
 1912  279  151   55   80  154  246   65  -56  162  131  -71  128
 1913  127  119   59   30   62   48   48  117   58  134   23   24
 1914  155  171  265  253  201  190  249  282  315  366  211   84
 1915  189  329  287  257 -105   48   66  107 -105   17  249  164
 1916  124  -11   67    0   50  -80 -148   75 -153 -120  -51 -202
 1917 -211  -34    8   17   14  -83   10 -109  173 -222  224 -139
 1918   -1  203   88  223  214  191  -23  238  318  216  103  114
 1919   93   49   70  128   25  124 -321            -32  191  -52
 1920  193  183  110   34  211   86   72  296   60   66  107  213
 1921  -31  -53  -87   -3    5  112  -22   43   84   90   69  -24
 1922  145  -20   28  130  106   41   63   69 -128    1  -73   -1
 1923   91  173  182  157   86   55   85   99   36  159  133   67
 1924  294   50  132   70   27  100   -5   20    6  -41   23  -14
 1925  114   23  119  187  115   38  193   44  252   91  218   87
 1926  151  153  165  166  -92  105  111   61  -51  100   30   15
 1927   77   71   -1  147  114   86  -26   62  157   22   87   34
 1928  137    2   64   94  151   80   12   43   -3  -62  110   39
 1929  135  181  123   29   76    5   64   75  126   29  134  185
 1930  165  158  215  143  125  130   90  104  158  177  144   77
 1931  127   86   61  188  154   29  116   67  -84   54  161   17
 1932  113  184  110  128   44   71    4  110  -44   60   21   27
 1933   55  -45   -3    2  -16  -23  -68   16  -56  -85  -10  -28
 1934 -170  -75  -70   34   48   27   30  -27   -3   -7   -2   30
 1935   80  102   68   45    9   20  -38  105   75  -20   22   23
 1936  104   62   83  -48  -33    2   29   96    1  -19   85   43
 1937   63  106   47    9   35   47   -1  -37   -1  -30  -27   -5
 1938  -23   59   65  -37   41   25  -50  -90 -109  -33   -1 -111
 1939  -10   -8   88   33    1  -29   -8   45   73   15   16  106
 1940   69  207  166   70   59   63  113  146  194  295  133  303
 1941  149  248  145   78   27  162  230  176  255  177   91  247
 1942  114  269  146  162  120  151   50   96   85   -4   90   53
 1943  209  139  153  111   86  124   86   35   46    9  -73  128
 1944   85    8   43   16   21   27   33   24   37   44   63  -21
 1945  -98  -73  -43   53   14 -214 -150  -64  -95 -156  -46  -91
 1946 -137  -89 -118    2      -434   82  217  -74  101  -35 -180
 1947  272  222  -19 -248  179 -123  -17  -57  -62 -192 -604  -76
 1948  236  547       -76  -89  119 -196  389   65 -167       244
 1949   96  -27   60  -55   46   -2    9   97  -50  -39 -109  -34
 1950  138  -65   61   -9  -84 -105 -108  -40   82   49  -50  -98
 1951  -20  -44  152   37   78  -11   -5  166   23  191  160  102
 1952   85  -75    3  124   59  120   24  -29   95   63   19  -75
 1953  -53  100    4   42  176   16  -24   29   17   32    8  303
 1954  -69   68  117  -43  -79  -58  -51  -48  -59   -4  -94 -158
 1955 -110   25  -37  -79  -57  -50   94  -55 -210 -183  -58  -33
 1956  -55   10 -187 -130  -61   15  -46  -70  -36  -86   44  -37
 1957   -1   72    7   14   87    1  -11   36  213  187  309  127
 1958  141   81  112   59   91   60   61   51   70   -1  120  119
 1959   59  118   -4   61  -10   16   41   21   -2   39  -39  -19
 1960 -129  -25   50  -19  -66   21  -25  -26  -74   46 -117   19
 1961   82 -121  128  -54   -9   24   29   -2   33   -3   47  -19
 1962 -116   11  -48   27  -48   61  -51  -14  -81 -101  -22   43
 1963    5   68  -39   50   31  115   93   79  165  173  132   76
 1964   11  -11   -6  -76   21  -10  -74 -106 -131  -60  -60   55
 1965   91  -25   34   21   24   74  135  155  176   69   59  -23
 1966   99   30  -23    4  112   77  -31  -60   43  -19  -47  -74
 1967 -156  -53   23   51   11  -15   16   67   39   56  -15   -3
 1968  -21   73  -85   96   13    8  -41   32   26   15   96   29
 1969  110  134   -7   50  -40  -13  -23   88   52   37  -43   25
 1970   39   63  -57 -106  -64  -70  -18 -146  -83 -148 -146 -148
 1971  -79 -145  -41  -33 -114 -114  -78  -79 -144  -92  -25  -48
 1972   73  -78   25  115  193   40  162  141  130  145   38   95
 1973  -40   37  -81 -126  -77  -84  -70 -129 -173 -125 -146 -161
 1974  -84 -167   25  -40  -45  -22  -71  -70  -83 -126  -69  -28
 1975  -25 -135 -147 -141  -74 -146 -122 -106 -218 -181 -160 -248
 1976  -30   50  -25  116   32   46  129   37  134  -40    6   18
 1977  -48 -128   86    1  -14   54   25   33   78   21   85  111
 1978  -27  122  -43   -1 -104  -14   -3  -26  -63  -24   33  -49
 1979  129   10    2  -13   18  -37   45   71  -20   68  -66  101
 1980   56   33   97    8   92   -6   81  -60   51   26   26  -91
 1981   75  130   47   68 -140  -34 -111   39  -84  -28  -88   40
 1982  -27  116  103    8  124  135  209  222  217  248  172   12
 1983   56   38   65   18  -11  -11  -48  -98  -99  -41   -6  -33
 1984 -126 -124 -142 -173 -125  -37  -74   -6 -101  -31   -1  -43
 1985  128 -130   84  -34   23   10   59  -49  -15   45   37   44
 1986  -11  130 -120  109  177  -15  205  182  226  119  247  288
 1987    0  309  177  213  148   32  140  102  147  106   86   45
 1988   28   98  -80   23  -54   25  -97 -106 -206 -125 -192  -49
 1989  -78  -35  -34  -35  -76  -15  -81  -37  -46 -110   -1   51
 1990   62  215   98    4   30  -12   77  -52   41  -17   90  117
 1991   18   45  147  116   70   82   55  -31   92   79  138  178
 1992  254  162  187  152  151   56  136   13  112    3  139   90
 1993   76  175  233  193  134  142   75  194   65  117   29   20
 1994   36  -26   50   33   64   17   91  109   68  205  175  178
 1995  121  147   27   77   50  -55  -43 -129 -142 -133  -94   27
 1996  -23  -58    5  -29   11  -74  -92  -74 -121 -136  -44   25
 1997  110  -44  296  182  158  272   91  297  268  354  270  232
 1998  309  213  230   84    2  -90  -98  -57 -130 -134 -144 -131
 1999 -142  -46 -103 -110  -82  -65 -162 -129  -79 -203 -153 -180
 2000 -105 -184  -89 -114  -71 -111  -53  -97  -70 -151 -137  -90
 2001 -161 -147  -61  -72   22  -23   36   -4  -29   36  -33  181
 2002   28   97   37   18  125   -5  198  125  245  311   85  130
 2003  107   21   36   45   -7  101   22   67   19   40   59  -19
 2004   93   52   89  118  -35   56   78  103    6   84   48   93
 2005   68  172   44   33   34  -37
    Number of observations.
           Jan  Feb  Mar  Apr  May  Jun  Jul  Aug  Sep  Oct  Nov  Dec
 1850    6    2   14    4   16    2    9    9    3   21   28    9
 1851    1   17    8   17    4    8   44   36   33   41   12    0
 1852    2    0    3    6    0    4    5    0    0    0   14   14
 1853   13    0    8    5    6    3   13    1    0   12    0   11
 1854    5    0    3    0    0    7    1    0   20    0    3    2
 1855    5   10    4    0    2    0   45    0   61   15   35    0
 1856    0   77   79   18   10   11   37    6   34  102   67    0
 1857    0    0   20    0    0   94    0    0   55    0    0    0
 1858    0   52   10   32   14   49   85   74   38   40   34   56
 1859    6   16   70   52  112   47   71   34   58   19    3    0
 1860    0    0    0    0    0    0    0    0    0    0    0    0
 1861   22   65    0    0    0    0    0    0    4    0    0   23
 1862    0    0    0    0    0   55    0    0   10    0    0    0
 1863    0    0    0   74   80    0    0    0    0    0    0    0
 1864    0    3   70    0    0   16   72    0   52   27    0    0
 1865    0    0    0    0    0    0    0    0    0    0    0    0
 1866   45    0    0    6    6    0    0    0    0    0    0    0
 1867    0    0    0    0    0    0    0    0    0    0    0    0
 1868    0    0    0    0    0    0    0    0    0    0   21    0
 1869    0   31   28   30   76    0    0    0    4    0   69   57
 1870   52   62  181   19    0    6   87    3    0    0    0    7
 1871    0    7    2   12    5   37    0   12    2    7    0    0
 1872    0    1   10   33   13   32   15    2   18   39   15    6
 1873   17   25   23    7   57   11   20   42    0   14   56   11
 1874   10    4    2    7    0    0    1    0    0   35    7   11
 1875    0    0   10    2    0    0   41   54   65    0    0    7
 1876    0    0    0    0   57   72    0    0    0    0    0    0
 1877    6    0    4    0    0   47    3   52   64    0    0   56
 1878  160   28    0   99   13    6    0   82   16   45    0    6
 1879    9    2   23    0   20   39   11    0    1    1   55    0
 1880    0    8    3   10   21   11    7    0    0    0   10   17
 1881    0    6   15   49    5   12    0   79   31  102    1   36
 1882    0    3    4   31   45    2   66    9    0   34    0    0
 1883    9    0    0    0    2   77  218  179  157  171   78   35
 1884    8   39    3   78  207  351  143  328  147  101    0   48
 1885   38   12   65    0    0    0    0   22   82    1   11  133
 1886    0    2   12   16   31  208   96   59   10   77    5   87
 1887  201   11   23  133   25   73  146  117   70   73   66   78
 1888    0    0   11   86  165   40   67   58   10  174    2   41
 1889    7    0   77  130   55   71   33  145   10   50   17   61
 1890   31    5    7    0    0    0   35    2    0    0    0    0
 1891    0    0    0    0   45    0    0    0    0   39    2    0
 1892    0    7    3    0   41   67    0   41    0   65    0    0
 1893    0    7    0    0   46    1    3   47   31    4   23    0
 1894   61   31    5    0    0   39    0   16   28   36    0    0
 1895    7    3    0    1    0    1   38    1    0    5    0    7
 1896    4   56    0   50    1    9    0    0   41   75    5   12
 1897    0    0   39   45  253  261   90   39  111   21   23   39
 1898   19   31   29   57   96   58   61  105   44   31   64   45
 1899   58   66   95  106   91   34   53   62  125  146   49   79
 1900   35   43   60   89   61   68   59   60   40   67   58   64
 1901   71   52   54   56   48   50   18   55   49   55   83   41
 1902   40   37   31   30  139   62  131   63   10   61   97   25
 1903   11   27   70   31  122   24   33   21   42   40   24   16
 1904   33   26   19   19  187  145  152  163  123  169   63   51
 1905   43   17   45   51  102   21   36   37   35   26   62   35
 1906   23   34   34   31  123   68   12   65  140   56    7   28
 1907   35    3   43   45   36   41   62   60   77    8   60  110
 1908   32   29   46   38    8   37   65   34   29  130  113   22
 1909   35   23   45  129   94   32  142   35  119   56   15   71
 1910  152   92   67   28   66  101  104   17    9   36  143   82
 1911   38    7   50   94  131   59   12   15    9   25   40   31
 1912   58   49   29   61  151  144  132  156  143  133   69   78
 1913   38   85   64   63   96  185   20   53   56   53   50   57
 1914   28   76  103   34   30   45   35   19   34   68   81  235
 1915   87   11   45   35   64   90   32  100   64   40   17   12
 1916   15   61   17   27   29   37   54    6   38   13   33   34
 1917  106   37  105   29    6   47   68   48    2   86   17   54
 1918   33   99  119  189   49  131   92  127   61   78   69   51
 1919   54   34   52   71   81   26   45    0    0    8   65   58
 1920   21   72   39    7   18   19   28   17   13   45   10   34
 1921   37   41   75   54   74   67   49   78  107   87   46   67
 1922   82   99   97   60   81   47   72  107   62   84   88  107
 1923  107   97  130   75  130  130   82  111  122  164  128  100
 1924   67  104   95   86   86  170  108   99  113   81  145   96
 1925   88   86   77   71  115   79  106   88   79   91  116   94
 1926  113   90  132   85   67   79  193  160  107  190  147  172
 1927   77  117  152  139  139  127  102  195  141  205  127  253
 1928  174  168  168  147   87   97  131  126  154  144  152  112
 1929  147  228  206  177  116   97  143  214  140  166  158  116
 1930  204  245  155  116   84  108  134  202  150  123  132  156
 1931  199  187  191  174  187  164  192  236  198  213  156  203
 1932  179  138  163  150  138  143  173  120  114  145  143  172
 1933  250  249  287  260  256  112  223  245  250  196  308  214
 1934  241  192  374  253  183  237  356  302  329  261  319  211
 1935  363  405  330  309  315  312  449  338  276  428  344  339
 1936  410  345  340  239  374  282  351  365  345  314  314  210
 1937  431  415  236  214  242  318  421  445  329  195  302  132
 1938  298  148  265  201  286  202  182  158  134   93   71  152
 1939   88   89  162  122  189  175  143  121  135  133  166  152
 1940  289  177  172  220  226  166  229  144   84  165  114  252
 1941  246  141   78  161  160  179  206  337  253  164  297   79
 1942  299  302  430  286  452  184  367  227  251  396  340  289
 1943  193  246  203  290  236  257  280  261  622  457 1235  869
 1944 1258 1585 2066 1853 1465 1050  800 1249 1382  880  848  523
 1945  501  182  433  157  171  115  108   77  120  161  232  111
 1946    5   24   47   47    0    2   20   25    4    3   17    9
 1947   25  197   67   23  119  152   16   86   15   59    2    8
 1948   75    5    0    8   12    1   26    9   42    7    0    1
 1949   51   61   36   58   71   91  294   87   85   84  196  131
 1950   28  145   86   51  266   53   96  108   91   35   91  114
 1951   87  112   36   68   47   95   50   74   86  132   47   99
 1952  123  189  140  159   98   84   89  153   76   60   59   41
 1953   62   63   81   76   79   73   86  114  146  149  126  106
 1954  114  106  155  215  110  197  210  128  238  126   98   50
 1955   50   98   66  127  111  128  109  179  158   69  146  303
 1956  147  238  235  149   92  139  229  245  348  232  286  255
 1957  307  158  395  358  239  273  274  323  323  336  276  408
 1958  251  448  481  573  390  375  365  503  380  579  495  374
 1959  245  439  410  441  418  459  458  441  401  392  397  524
 1960  372  368  384  430  444  357  567  473  473  507  445  558
 1961  511  378  496  546  597  565  564  579  560  599  519  548
 1962  430  364  512  577  626  544  681  561  497  468  417  455
 1963  515  419  427  353  406  380  336  419  402  494  403  451
 1964  773  636  725  579  652  525  613  686  726  685  679  692
 1965  653  541  660  606  627  712  495  660  491  631  603  583
 1966  590  644  669  531  607  515  647  580  565  557  546  488
 1967  643  941  777  829  702  796  906  639  745  778  803  641
 1968  627  575  627  598  870  814  717  705  725  868  669 1063
 1969  678  852  831  588  960  695 1003  758  864  738  912  574
 1970  870  752  738  854  817  822  801  932  760  800  616 1007
 1971  842  723  695  761  650  730  647  734  854  895  722  693
 1972  991  946  995  715  670  697  746  951  922  700  885  717
 1973  894  877  838  765  999 1075  712  862  781  920  992 1054
 1974  627  850  953  780 1703  667  634  721  751  923 1597  983
 1975  835  919  799  791  923  835  832  767 1055  953  936  982
 1976  955  924  939  793  767  898  774  743  761  903  820 1102
 1977  542  817  860  813  642  719  605  855  645  742  911  844
 1978  796  922  905  739  644  572  784  656  755  702  756  883
 1979 1190 1180  904  868 1015 1118  769 1028  871  991  810 1227
 1980  975 1789  964  969  934  918  797  710  691  853  805  840
 1981  800  990  935  977  852  791  824  873  846  917 1122  627
 1982  661 1029  765  929  858  721 1028  780  709  790  845  772
 1983  888  864  977  941  797  849  858  946  758  885 1076  832
 1984  925  786  911  923 1100 1062 1068 1063 1052 1233 1185 1171
 1985  943 1043 1115 1096  955 1078 1235 1130  929 1070 1300 1051
 1986 1419 1384 1214  995 1083 1318 2610 2731 2744 2803 2766 2649
 1987 3044 2951 3355 2711 2717 1678 1824 2088 1932 2024 2014 2192
 1988 1973 2465 1847 1684 1433 1660 2473 2626 2510 2081 2429 2850
 1989 2659 2741 2905 2642 2792 2460 3327 3841 3795 3628 3230 3647
 1990 3741 3417 3046 2681 4183 4159 4968 2999 3869 4653 4155 4329
 1991 4039 3511 3700 3839 4716 4924 5769 6403 6434 6473 6124 6089
 1992 5207 5354 9015 8799 9716 9526 97001033913754157941555916091
 1993155921352815758175811686616431167111602313805122381464916787
 1994176691491516074152981655016090156791491213377148451633217491
 1995177631589116641154741729816592164061798516303165251526016525
 1996186511600815792138901412312274128901633117325179441757516808
 1997166361594716792155821568212656137461482814887138121288913327
 1998 4017 3672 3062 2666 2675 2873 3185 3224 2927 3204 3106 3493
 1999 3669 3307 3378 2891 3631 3938 4272 4131 4051 4332 3832 3870
 2000 3775 3202 3389 3381 3824 3635 3610 3624 3279 3658 3662 4082
 2001 4031 4250 4801 4479 3817 3634 5117 5052 4642 5204 4870 4881
 2002 5012 4603 4082 4948 4639 4821 6000 5520 4209 4533 4573 4268
 2003 4363 4186 4433 4379 4323 4185 4190 4423 4108 3915 3562 4166
 2004 3781 4061 4263 4507 4770 4326 5695 5227 4822 4851 4881 5005
 2005 5148 5922 6607 6454 6248 6496    0    0    0    0    0    0
    August 2005
    Todd Mitchell ( mitchell@atmos.washington.edu )
    JISAO data