JISAO data

Tropical rainfall indices from rain gauge observations, 1850-1996

Analyses | digital values for the Pacific and non-Pacific


The indices presented on this page capture ENSO-related tropical rainfall variability. The data is that of Dai et al., (1997) and is available online both in ASCII and in netCDF formats. This pair of indices is the latest in an evolution of indices that I have created based on different rain gauge data sets, and it may not be the last. The preceding efforts for tropical Pacific and the tropics not including the Pacific are available.

The averaging regions employed are:
tropical Pacific: 6.25N-6.25S, 163.75E-86.25W
tropical non-Pacific: 20N-20S, 78.75W-163.75E
The time series values are calculated with respect to a 1950-79 climatology.
I also tried a tropical Pacific index for the region centered slightly south of the equator (6.25N-11.25S, 163.75E-86.25W), but this was not as well correlated with the eastern eq. Pacific SST as the 6.25N-6.25S index.


Eastern Pacific cold tongue SST, tropical Pacific rain, and tropical non-Pacific rain (inverted)

Historical record: 1850-1996
Image of time series

Modern record: 1950-96
Image of 
time series

All series were filtered with successive 11- and 9-point running means for the first figure, and with successive 5- and 3-point running means for the second figure. All series were standardized by calendar month with respect to 1950-79. In addition, non-Pacific rainfall values in excess of 4 standard deviations are reduced to a magnitude of 4. All of the series capture the major ENSO warm and cold episodes between 1890 and 1996. The non-Pacific rainfall exhibits general dry anomalies since the 1980s. Aiguo Dai states that the "data after 1990 should be used with caution because station data have a very limited coverage for the latest several years." The non-Pacific rainfall values for 1850-70 seem suspcious.

References:

  • Dai, A., I. Y. Fung, and A. D. Del Genio, 1997: Surface observed global land precipitation variations during 1900-1988. J. Climate, 10, 2943-2962.
  • These indices are being written up in a paper by Mike Wallace and myself.

    
    
    
    Tropical Pacific index

    Number of observations

  • time series as a 4-column table: year, month, time series value (cm/month), and number of grid boxes contributing.
  • time series values (cm/month) as a single column
  • MATLAB ".mat" file containing both the rainfall and number of observations series
    
    
    The following index values are in mm/mon.
           jan  feb  mar  apr  may  jun  jul  aug  sep  oct  nov  dec
     1892   92 -149  -45  -62  184   99  111 -142 -102    2 -109  138
     1893 -252   64  -32 -164  -92  -22  -95  -64   -6  -96 -105 -132
     1894 -270 -247 -179 -192 -112   62  -83  -30  -74  -91  -83 -193
     1895   -1   67  -57 -189  -29  -54 -123  -95   19  -11  112   45
     1896   25  -53  -11  -59   61   -6  140   73  133  233   45  308
     1897 -106   47  -48 -121  -39   -3  -20 -124  -86    0   46 -240
     1898 -184   99 -180 -138 -110  -85 -102  -57 -103  -88  -99 -200
     1899 -260 -226 -189 -178  -74  178   41  165  -15   22  156  150
     1900 -165  501   91  156  240  125  -36  220  -25   -1  220    1
     1901   51   -1  202  -93   11  -57 -133  -70  -69 -103  -85  -78
     1902 -150 -122  -86  -14  263  155  287   38  298   -4  294   38
     1903  -37  119  -91  -20   46  -97 -105 -126 -112 -108  -81 -131
     1904 -165 -244 -149 -193   32  -62   42  100  155  -34  104  -33
     1905  129  194  106  332  125  175  190   26   84  358   82   80
     1906  205 -102  -61  -76  -98  -41 -119 -119  -94  -77  158  -43
     1907 -105  -76  -84 -119  -97  -60  -67  -81  -74   65   37  -59
     1908  314   33 -181 -147  -88   72  -77   -7  -55  -99  -91 -142
     1909 -154 -116  -61  -31 -108  -53  -10  -54  -56  -82  -83 -181
     1910 -169 -172 -110 -104   34   35  -20  -70  -75  -62  -72 -125
     1911  -73  -66  164  144   21   33  176    2  246  163   81  240
     1912  393  413  386  275  137   -8  -64  -58    9  137  -20  226
     1913  -46   33  -26 -156  -88  -88  -37   21   96   83   79  113
     1914  196  180  168  119  201  126  368   13   86   84  127  240
     1915  197  107  308  202  394  -16   68  -66  -78  -91 -104 -174
     1916  -57 -178 -136 -168 -109  -88 -111 -112 -100  -98 -106 -245
     1917 -222 -201 -168 -161  -59    0   20  -92  -27  -85  -88 -151
     1918 -212 -154   20 -145   14  120  304  402  201  212  137  192
     1919  299  290  202  170   20   58  154  114  133  144   27   71
     1920  -99  255  192   10  -74  133   -1  -58  -75  -97 -101 -175
     1921   61 -176 -155 -153 -104  -98  -43  -42  -31  -46  -51   65
     1922   46   -9  -92  -13   42   40   54    3  -54  -90  -31 -151
     1923 -156 -141    2  -64  -90   63  111  149   42   68  241  138
     1924  256    8  -20 -115 -104  -89  -72  -74  -80  -41  -99 -205
     1925 -201 -116 -135 -114   -5   25  -20   40   17  214   17  247
     1926  255  164  411  302   96   83  -26   27  -59  -67  -44 -181
     1927 -223 -182 -124 -170  -86  -68  -32  -43   11  -63   -2  131
     1928  286  172  -91  -76 -103  -55  -55  -78  -24  -33  -16   23
     1929  -40   99  -86  -96  -47    8   42   99   16  -20   52  155
     1930  210   92  180 -126   29   18  148  250  332  147  226  206
     1931  265   85  147  -76  -74   83  -59  -36  -89  -19  -84 -141
     1932   73   16   62   37   28  -14  -20  -45  -46  -73  -87 -179
     1933   23 -108  -83  -30  -14   30   66  -55  -83  -66  -86 -184
     1934 -195 -139  -99 -117  -26   38  -32  -28  -61  -74  -42  -74
     1935  -12  -36 -152 -100  -55  -37  -21  -73   21  -28  -22   30
     1936   62   19   19  -24    9  -48   -7  -16  -53  -38  114  -26
     1937   12    6  -66  -88  -82  -10  -25  -25    4  -46  -55 -150
     1938  -95 -126 -139  -97  -80  -52  -72  -57  -68  -70  -20  -84
     1939 -125 -139 -112  -68   20   -2   27   39   48  -22  154  199
     1940   80  205  135  285  135  197  128   83   92  222  206  217
     1941  168  175  290  128   67  198  154  122  230  107  188  -56
     1942  383  -88  105    3  -41  -77 -112  -23  -84  -64  -81 -167
     1943 -189  -86 -125  -58  -23  -14   53   54  -73  -54  -40   27
     1944  -14  -57  -88  -13   -7    6   25  -43  -48   -4  -46 -113
     1945 -104  -64  -93 -131   66   95   50    0  -61  -69  -48  -75
     1946  -32  -52   43   84   58  128  106   39   -4   47   87   -5
     1947  179  -41 -109  -41  -19   -1  -58  -56  -67  -45  -21  -20
     1948  103   62  142  119  141   72   -3  -40  -54  -64   23   26
     1949  160   22  106   -8  -22   21  -21  -76  -65  -56  -89 -158
     1950 -173 -125 -143 -113  -91  -72  -70  -55  -57  -58  -70 -118
     1951  -71 -110  -51    0  130  131  102  180   27   35   -4  109
     1952  102  -32  -20  -12  -21   17  -23    1  -26  -20   -2   11
     1953   48  201   25  169  172   26   38  122   85   78   29   76
     1954  -18  -67  -17  -36  -63  -54  -59  -38  -38  -51  -57 -111
     1955  -33 -106  -74  -35  -61  -49  -64  -55  -26  -52  -76 -137
     1956 -136 -102  -45   16  -10  -13  -35  -24  -18  -18  -45  -89
     1957 -101   29   17   21   78  103   92   24   76  120  200  134
     1958  107  128  147  170  128   89   49   11  -27  -20   56   58
     1959    9  163  118   -1   13   -1  -21  -54  -38   -8  -17   -5
     1960  100  -28  -46   13   18  -41  -10  -31  -31  -11  -19  -27
     1961    1   13   42  -30  -10   -5  -32   28  -39  -37   -3 -113
     1962  -68 -107  -56  -60  -48  -50   12  -30   -1  -55   -3 -102
     1963 -102 -110  -87  -85  -72   -4    3   55   61   80  101  138
     1964   92  122  -55 -112  -74  -77  -71  -33  -37  -60  -63  -62
     1965  -43   51   11   77    6   25  114  144  141  153  119   68
     1966  202   52  130  110    1  -27   78  -60  -39    1  -41  -47
     1967  -56  -56  -88  -19  -61  -21  -29  -51  -29  -38  -41   37
     1968    0  -31  -99 -129  -94  -62    4  -63  -17  -45   14  -48
     1969   66   92  174  106   46   26   -2  -32   30  -30   -8   54
     1970    2   33   15   78   -2  -27  -80  -52  -60  -80 -109 -173
     1971 -197 -136 -123  -70  -50  -41  -39    3  -66  -55  -58  -14
     1972    3  -76  -93  -58   96  103  140  116  227  189  129  275
     1973  197  201   54   -6    2  -40 -124  -65  -73  -72  -76 -141
     1974 -170  -95 -108  -59  -18  -31   14  -45  -45  -38  -68   16
     1975   44   -2   69   -9  -62   -9  -68  -80  -57  -70  -76 -128
     1976 -125 -105   22   34   57  111  103   93   92   40   50  104
     1977  177    5  114   84    8    9   77   15   42   43  141  130
     1978   98  118   69   -5  -52  -45  -57  -28  -46  -45  -25   10
     1979   43   80   99  -40   35   26  -45    2   -9  121   23   94
     1980   66   -5  197   18   51    1   33   60   -3   15   52   15
     1981  -51  -56   58  109    7    7  -62  -61  -64  -70  -58   33
     1982  -76  -54 -116  -87  -14    3  119   59   53   45   54   84
     1983  153  -12   41    8  172  271  153  -29   -1   13  -62  -49
     1984  -62  -76 -139  -81  -38  -48  -62  -70  -71   -1  -37  -31
     1985 -117  -96  -98  -80  -48  -18  -33  -25  -55  -21  -46  -62
     1986  -32 -127  -59  -37  -48   12   -5   28   93  -70   57  124
     1987   68  262   49  120   80  107  153   81   30  -21   -3   30
     1988   63   29  -55  -74  -18  -44  -67  -59  -47  -33 -100 -118
     1989 -146 -157 -112  -40  -63  -79  -57  -57  -35  -36   14  -29
     1990    1   41   86  111    1  -82  -25   12   67  -83   14   -3
     1991   31   87  517  -10   60   39   92  200  168 -131   40   -4
     1992  -79 -156  -23  158   46   48  -29  -13   -6   -1  -51  163
     1993  -58  119    9   80   41   46   29   44   11  101 -999  140
     1994   -1  -99  -74   28  -10  -27 -117    4   25   40  -66   57
     1995   21  -71 -104  228  -56  -16  -58  -40    5  -83  -86  -34
     1996  153  -15 -131   -3    6    8                              
    
    
    
    
    
    
    Tropical non-Pacific index

    Number of observations

  • time series as a 4-column table: year, month, time series value (cm/month), and number of grid boxes contributing.
  • time series values (cm/month) as a single column
  • MATLAB ".mat" file containing both the rainfall and number of observations series
    The values are in tenths mm/mon.
           jan  feb  mar  apr  may  jun  jul  aug  sep  oct  nov  dec
     1850 -111  -80  400  108 -341 -994 -381-1511    1 -212 -436 -281
     1851 -128  517  366  822  -50  167 -401-1249 -585 -327  150 -238
     1852 -468  504  618 -463 -140 -746 -874-1673  163  594  179  156
     1853 -328 -173    7 -114  199 -127 -648-1398 -620 -709 -246 -605
     1854   26  152 -365   12 -148 -302 -234 -270 -165 -107 -293 -382
     1855 -413  355  215   57 -750 -228-1081 -852 -308 -213 -627 -383
     1856 -270 -247 -299  443  380 -468 -303 -353 -447 -389 -188  576
     1857 -133  416   11 -367  905 -272 -702  144 -457  320 -237 -310
     1858 -154 -404 -220 -160  486 -487 -654 -647 -240  -48  211 -202
     1859 -409 -384 -253   71 -495   63 -424 -399   59 -188  -85 -323
     1860  110   35 -129 -218 -782 -728 -709 -495 -163  -25 -370  -32
     1861  285  176 -427   57 -884 -346 -416   15 -393 -555 -153 -268
     1862 -192 -127 -174 -670 -198 -143-1110  758 -170  312 -231 -343
     1863 -153 -213   -2   95 -578  694  291  -19 -375   74 -425 -221
     1864 -228 -273 -439 -312 -633  517  -45 -233  136 -366 -325 -268
     1865 -300 -295  123  242  203  -58 -109  318 -136   84   86   83
     1866   34  237  202   52   68  -64 -179 -110 -259  218  -71   98
     1867 -255  180   -1 -355 -210 -551 -518 -108  351   87 -461 -138
     1868 -138  -97  -82 -153 -183  439 -690 -311 -115 -249 -200 -165
     1869 -222   57 -105  -88 -425  441 -275 -216  156   82  -55  144
     1870  353  109 -304  -64  -28 -469 -223 -138  -20  577 -201    8
     1871  161  103   39   28  146  193 -218 -516   93 -239  153  101
     1872  144 -221 -249 -296 -247 -212   10   60  120 -183  279  197
     1873  220  127   99   19 -616  182 -219  -62 -203  194 -148   -6
     1874  -42  116 -243   58  209    4 -141 -128   26  348   10 -105
     1875 -193  270  -29  154 -143   21 -136 -288  189  -48  -87   16
     1876 -134   23  -15  -22  221 -114  260 -133  340 -116 -215   78
     1877  -52 -104  199 -380 -381  179 -412  -46   23 -207  -85 -207
     1878 -250 -508   96 -147   59  143 -103  437  447   83 -169   53
     1879  264 -107  535  205  482 -125   -8  480 -105  170  122  -13
     1880  295  -57  360  251   68 -166  324   69  171 -159  315  -74
     1881  116  -83  116   66  -49  201 -161   56  210 -308  260 -191
     1882  -11  174  139  119   97  313  378 -133  216  169  252  202
     1883 -199  105 -261  234   -2  230   31 -194  -53  122  139  -95
     1884 -129  154   13 -253  -87  -95  -79 -176 -164   55   93  249
     1885 -289  -77 -168  -41 -256  167 -100 -190 -263  134  -45  509
     1886 -267  145   54  -95   88  235   86  309   56  411  263  660
     1887 -163  158  188  197   26  144  130   19  102  104  141  399
     1888   -2 -144 -348  -28   71  178 -348 -167 -217 -168 -101   20
     1889 -313    3 -335  -28    6  234  185  126  206  142   89  336
     1890   90 -218  -64  -50  -17 -144   33 -203   43    8   -3 -240
     1891  224   93 -194  -31  132   87  -51 -237   24   26  -66  -70
     1892  135 -230   87  126  127 -165 -151  -71   50  230 -141   52
     1893  -72  -46   12  119   99  -59   62   88 -128  132  230   21
     1894  330  160   85  145 -137  371  -18 -102   62   25  107   43
     1895  154 -133   49  -97  -14  112   94   29  -32   64  -71   52
     1896  122  178   16   36   16  102 -231   55 -187 -215  122   51
     1897 -118   51 -172  -25  181  -72 -120   86  -35  -38 -178  262
     1898   24  139  111  148  129   45    9   59  120  -37   83  288
     1899   52 -132  352  138  -86 -134 -240 -156  -84   25 -139 -124
     1900   12 -282 -152  -45  -78   66   31  -16  -34 -177  -81 -138
     1901 -153  261  241   11  -89   32  121  -33 -109   32   47  -70
     1902  -22  106  -21 -151 -103 -209 -132  -83  -95 -176 -226 -146
     1903 -198  -97  -29  -60  -76  -53   94  121  -19  -84  -89  294
     1904  279  -38  151  146   13   99  -21 -162  -39   30 -187   -1
     1905 -195 -130 -225  -48  -19  -28  -46  -62  -70   -7  -85 -230
     1906  -51 -118  -74   93    9  152    6   34   22   23   24  122
     1907  -43  174    2   14  -25  -72  -74  -84 -197 -141  -11  215
     1908 -158   92  -68   21   95  -19   46   84  116  -37   24   69
     1909  -10  -16  -57   38  -40   79  186  124   74  136   59  -87
     1910   38   64   32   77   76  119  -42  197  167   46  111  152
     1911  -73    7  -92  -36  -69  -58 -151 -166 -102  -77 -153  -43
     1912 -103  169  -70 -151 -156  -26   46   -5 -128  -33   44  -26
     1913   89   52  127   30   18   16  -32 -152 -135  -89 -143  -18
     1914   96 -173 -136 -154 -220  -17  -15 -108 -142 -200 -170  -74
     1915 -183 -340 -338 -158  -75   70   -7 -127   92  -28   45   96
     1916  109 -109   99  -56  -21   93  109  128  211  232  159  249
     1917  262  113  150  -35  -54   57  -66  158  248   75   96  233
     1918  341   94 -114  -93   77   -8 -244  -75 -221 -207  -88 -103
     1919  -27 -114 -187 -191  -29 -112  -25 -140 -119 -187  -72  -20
     1920   40 -175  -29   30 -173  -33   29  -60   -3   -7    4  -42
     1921   59   93  239  -30  -66 -123   74    0   41   46  152   -4
     1922  -88   27   51  -91  -55 -105  -51  -69   99   51   85    2
     1923   84   -9  114   86  -42    5  111  -50 -116  -22 -101  -68
     1924  -99    5  138   21  -27   95   49   70   48  176  179  125
     1925   95   63  161    3 -133   38  -40  -28  -25   10  -29  -74
     1926  137  -41   78  -27  -16  -44  -26   19   34  -57 -104  192
     1927   39   12   52   24   27  -10  112  -34  -26   27  -18  -87
     1928  -27   62  152    5  -12  -77  -36   25  -54   42  -51   33
     1929   71   45  133  -21   24   53  -60   -4   -8 -108 -105    9
     1930  -59 -100  -48  -19   16  -16 -141 -196  -14    7  -73   36
     1931   22 -123  -43  -47  -52  -35   36   10   76   39   35    8
     1932   33 -143   19 -185   62  -76  -29 -167  -53   50   -3   87
     1933  -19  -83  -27  -14   27   59  104  130   47   37  143  148
     1934   77  111   86   69 -100   32   92  105   15   -8   63    5
     1935  -54  -43  142   34   65   73   34  -14  -16   20   50  -82
     1936  -55  -40   -8  -32  104   60  -60  -12  -83  -23  -56    6
     1937   60 -125  -83   67   31  -73   61  -49  -63  -39  -70   -4
     1938  -31  -54  -64   49  -11   -6  -23   11   70  -26  133   33
     1939   92   38   38   -9  -42  -61  -27  -25  -56  -37   41    4
     1940   72   13    5  -61   63  -44  -93  108 -113 -143 -128 -150
     1941  -82  -75  -24 -123  -33  -41 -142  -67  -99  -70   43  -28
     1942 -155  -60 -127  -24   37  -56  -36   10 -113   -4  -56  163
     1943   52   45    2  -16    9  -62  -68  -24   32   18   -9  -31
     1944 -155   58   28  -49  -91  -13  -24  -28  -24   33  -19   53
     1945   19   37   74  -96   21  -83   43   31  -27   29  -28   13
     1946   -5  -87 -176  -61  -23  -61  -95   11  -16  -57    6   43
     1947 -125   56  210   64  -43  -22   -1  143   76    8 -115   -7
     1948  -35   28  -23    2 -122  -23 -104  -35  -56  -67   16 -120
     1949 -129   16 -100   11  114  -34    8   11   37    3  -63  -63
     1950   92   43   78   51  -49  -47   62   82  115   52  -60   80
     1951  -22   -4  -90 -122   29  -31  -38 -103  -38   57   16  -35
     1952  -49   55  -47  -36   32   -2  -35   42   47   54    6  -58
     1953   40  -27   -6  -15  -13    3  113  -60  -65  -43   22   -5
     1954  -40   -9  -30   75   17   67   -5  174  104   57   14   88
     1955    2   96   26   64   95   78   72   15  161  106  135   -2
     1956  104   79   48  140   27  -12  -12  110   34   70   60  155
     1957   -9  -74   44  -65  -41  -12   33   -5 -132  -72 -126   82
     1958  -66  -97  -66  -13  -51  -20 -102   65 -107  -16  -73  -89
     1959  -18  -70  107    3   53  -19   91   12   37 -124  -13  -34
     1960   11   65   33   30   25   39   19  -50   41  -39   47  -22
     1961  -33  -44  -99   -9   -7   48   85   55   43  -23   17   74
     1962  194   -1  -28   -6   50    0   38   84   55  -40   16   50
     1963  112  168    4   49  -27  -63  -22   64  -70  -71  -63  -24
     1964  -82  -54  -11   26   43  -61   -9   11   77   93   25  -82
     1965  -42 -189   61  -74  -22  -25  -31 -204  -83  -84 -125   30
     1966 -158    5 -101  -93   14  -37  -15  -29  -94    9   15   35
     1967   86    3   46    3  -18   19   62   49  -34  -51   -8  -80
     1968   67   50  -14  -35 -106    0   59  -60  -28 -102  -46  -34
     1969  -70  -97  -86  -76   16  -16   73  -33  -46   19  -39    1
     1970  -33 -114  -48   64  -10    6  -65   90   51   92   42  -59
     1971   56   81   92  -16   30  117   -8   25   15   81  -22 -147
     1972  -45   52   -3  -68   -8 -113 -174 -209 -182 -199  -75  -72
     1973 -115 -132  -38    6   -9   23    0   80  145  144  140  151
     1974   -4  117   85   84  -89  -46   65   40   83  116  -26    7
     1975  -53  -26   47    6   18  103  111   91  155   32   42  143
     1976   91   68  107   18   88  -96 -162 -157 -234   -2   29  -91
     1977   15  179  -50  -29  -80  -74 -111  -24  -10    1  -23  -53
     1978  -15  -70  -10   21   27   40   19  -95   10  -52  -18   95
     1979  -15  -54  -51   16  -34  130 -111  -60  -49  -63   89 -105
     1980   98  124 -129 -118  -15  -28    9   35  -43  -57  -57    3
     1981   72    8  -82  -36  -58 -146 -108 -133   28  -47   32   91
     1982   37   22 -107  -24  -13  -45 -187 -147 -155 -118 -219 -188
     1983 -307 -295 -217 -166  -65 -128  -85  -81 -122  -86  -46   20
     1984   13   74  -42   61  -64  -92  -55 -189 -177  -40   -6  -53
     1985    1   -8   -5   18  -50  -91 -101  -24  -16  -51    7   -7
     1986   98  -96   19  -30  -91  -59 -191 -188  -83   74   37  -12
     1987  -84  -42  -29  -85  -86 -155 -168 -131 -191  -55  -91   -4
     1988 -214  -63  -46  -16 -137  -21   50  130   96    2   96   79
     1989   79  -19  128   70   42  -63  -13   31 -145  -45 -113   78
     1990  -20 -206 -239  -20  117   23 -228  -80 -110  -60 -137 -184
     1991   50   11  -31  -56 -160 -111  -77  -51 -228 -274 -210 -260
     1992 -296 -128 -392 -313 -194 -163 -132  -96 -148 -105 -170 -154
     1993 -199  -19 -189  -73 -176 -186  -77 -198 -167 -151  -86  -18
     1994 -146  -20  -59 -136 -119    5  -46  -29  -96 -189 -144 -177
     1995 -203  -86  -18 -152   80 -190  -94   79  -71    6  -31   18
     1996   -4  154  -40   80 -131 -182                              
    
    
    

    March 2002
    Todd Mitchell ( mitchell@atmos.washington.edu )
    JISAO data