JISAO data
Sahel rainfall index (20-10N, 20W-10E), 1900 - 2007

analyses | digital values | applications

Big GIF | PDF | PNG | PS
The anomalies are with respect to 1900-2007 in this figure.
Precipitation was above the long-term mean from 1915 through the late 1930s, and the 1950s-1960s, afterwhich it was persistently below the longterm mean, with the largest negative anomalies in the early 1980s.


Big GIF | PDF | PNG | PS
The anomalies are with respect to 1950-2007 in this figure.

The averages are taken of gridded precipitation anomalies in the NOAA Global Historical Climatology Network. The data for the Sahel in this data set are "raw precipitation stations" and have not undergone any "homogeneity adjustments." The data is gridded to 5-degree latitude-longitude resolution, and the number of grid boxes contributing to the mean in each month is given below.


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Analyses of the climatology and latitudinal distribution of precipitation can be found in an earlier version of this WWW page, which served a timeseries calculated directly from station records.
Digital values:

The precipitation index is provided here in several formats. The anomalies are with respect to 1950-79.

  • A 4-column table: year, month, index value (cm).
  • A 1-column table, with only the index values (cm).
  • A table organized by years and months, with units of 0.1 mm.
    Averages are in 0.1 mm, so "-914" is -9.14 cm precipitation anomaly with respect to 1950-79. 
           jan  feb  mar  apr  may  jun  jul  aug  sep  oct  nov  dec
 1900   -8    6   -5   -8   96  198  513 -914 -182 -271  -38  -13
 1901   -8   -6   -5    9   64   78  376  226 -279 -199  -35  -13
 1902   -8   -6    3   -8 -115 -143  -14 -375 -722  -51  -36  -12
 1903   -8   -6   -9    5  187   37 -351 1062 -863 -291  -33  -15
 1904   -8   -6  -13  -23   98  199  -42  113 -636 -185   20   26
 1905   -5   10    0  -33  -92  293   64  178   19  254  -32    8
 1906   -6    1  -34   51  102  152  706  826 -168  -31    5  188
 1907   -6   -4  -11  -70 -109  -13 -499 -203  -92 -111  -24  -13
 1908   -7  -11   12  -31 -116  -63  -76  448  -73 -224  -17   10
 1909    3   -4    1  142   61  209  131  487   27  -91  -31   -4
 1910   -7   -8  -44  -20  -69  -71  220   78  -77 -236  -42  -16
 1911   -9  -11   21  100  208  -79 -199 -181 -292 -180    4  -10
 1912   -1   -9  -43   30 -167  -32 -357  257  -43 -147  -10    6
 1913    9  -10  -40  -24  -63 -153 -412 -328 -450 -199  -28   -4
 1914   -7  -11  -32  -62 -148  -21 -190   58  -44  -63   38  -11
 1915   -7   -9   32  139  104   95  -38  -37 -538 -147  -31   -9
 1916   -7   -9    2   94 -111 -118  -17  237  151 -277  -16   -9
 1917   -2   -2  -23  -38  234 -334 -180  232  277 -334  -11   -9
 1918   -5   -8  -12   -8  135  390  114  295  113  -10  -36  -11
 1919   -6   -7  -13  -33  127 -129   95 -362  -97 -128  -29  -11
 1920   -4    4  -22  -10    3  103 -269  434   39 -234  -29  -11
 1921   -5   -5    1  -10   19 -133 -309   82 -160 -163   32  -10
 1922    0   -7  -17   59  -60 -165  -15  113  382  147   25   -6
 1923   12   -7    3   79  -83  -88   13  129 -107   27   24   -5
 1924   15   28   -2  -10  -86  238  253   75  282 -136   13   -9
 1925   -2   -9   19  -29    4    5 -152   55   10  160   -8  -11
 1926   -4   -8  -11  -41  -13  217  -51 -270 -278 -204    3   -9
 1927   -4   -2  -31   22  113  172 -126  739  115  209   28   -7
 1928   -2   -9    4   32  -12  -47 -133  614 -180  100  -30  -10
 1929   -4   -7   10  -18   73  275  -48  414    4  -45  -39   -4
 1930    2   -2  -10   11  206    7  178  204   54   -7  -33   -9
 1931   -4   13  -13   39   51   21  204 -668  187 -167   38   -1
 1932    7   11   16  -14  113  -23   25  311  -21  -62  -11  -10
 1933    4    3    3    6  148  400  263  303 -125 -148  102    6
 1934   -5   -8    8  -15 -162   11 -109  212 -109  -57  -27  -11
 1935    7   -5   -1  -22  -73  108  129  621   12  -59  -10  -10
 1936   -4    2  -15   42  158  116  166  602  101  -58   69   -3
 1937   -4   -7   -1  -32  -63 -139  -70  104 -197  -25   -8   -8
 1938   -4   -8   46  -38  -33 -117   41  119   42   44   -8  -10
 1939   -4    3    7  -50   93  -41  -43  265  119   38  -14   -5
 1940    1   -9   -1  -29  -57    4 -295  219 -159  138  -20  -11
 1941   -1   -9   -5  -16   46   -3 -179 -474  -66 -248    5  -10
 1942   -3    5  -11   11   28 -202 -252   94 -498  -54   22   -2
 1943   -2   -2    4  -28    5  -31 -159  474  306    9  -13   68
 1944   -4   -7    3   -3 -171  -59 -329 -110  -15   81    3   -6
 1945   -4   -8  -21  -21  -52 -199   53  564   49  -28  -26  -11
 1946    3   -8  -11  -39  -62  -98   67  189  131   94  -27   -8
 1947   -3   -2  -27  -59 -166  -83 -225  259   31 -187   -3   -6
 1948   -3    4  -16  114  -28  272  -96   30 -347 -140  -28  -10
 1949   -2   -7    5   -4 -105  -99  -60  145 -452 -137   -7   34
 1950    2    0  -26  -45  -56 -107  152  927  318   91  -25   -8
 1951   -1    2   30  -20   83  -91 -192   29  238  708   73   -8
 1952   -4   -8  -20  -51   68  -78  184   85  811   65  -22   -5
 1953   -2   13    9  -30  221  273  333  -92   39   13   15   20
 1954   -3   58    5   51   55  100  388  660 -185  -67  120   -8
 1955    0   -5   47   32  -27  171  468    9  234   13  -21   25
 1956   -3    8   24    3  -85  -53   60  110  179  -68  -16   63
 1957   -1   -6   -1    4  160  136   69  107  257  292   13   -1
 1958    7   -3   -6   28  -59  152  167  799  -82  -80  126   -5
 1959   -2   -7  -11  -30   90 -110 -267  516   59 -234    8  -11
 1960   -4  -10   -5    6  -11   59  187 -199  122 -150   -9   -2
 1961   -1  -10  -12  -15  -85   77  215   54  -55 -256  -13   -6
 1962   -4   -8  -15   51   -2   75  -38  408 -124   38   77  -11
 1963   -3    8  -16   41  -42  -59  -56   52 -177  392  -29  -11
 1964   -3  -10    3  -20   40  160  176  338   37 -203  -28   47
 1965   25    4  -27  -55  -62  172 -209  245  191  -82  -22  -11
 1966   -4   -9    6   21    6  107 -502 -266  328  378  -26   -8
 1967   -4    0    9   10  -82   -9  -10  224  261   38  -19   -8
 1968   -4   48   38  171   21    9 -100 -604 -207 -123   -5    4
 1969   -4   -7   14  -24  -67  -59  207   39  -13  293   -4  -11
 1970   -4  -10  -13  -45   30 -230  -16 -132 -120 -269  -24  -11
 1971   -4    1   17    5 -102 -195 -176   26 -227 -260  -30    7
 1972    0   -4  -13   23   47  -24 -493 -661 -498  -92  -23    1
 1973   -4   -8  -17  -21  -58 -130 -206 -409 -462 -232  -29   -7
 1974   -4  -10   -3  -42  -97 -191   29   -6 -164 -147  -23  -11
 1975   -4   -8   -6  -30   12 -156  403 -264  -23 -182  -32  -10
 1976   10    5  -11   -2   34    5 -321 -477 -208  381   16    9
 1977    3   -9  -15  -74  -49 -155 -393 -543 -152 -205  -48   -9
 1978   -2   -7   20  117    8  -54  140 -478  -73   47   -3   -5
 1979   26  -10   -5  -55    9  206 -198 -499 -304  -97    4   -6
 1980   -1   11  -32  -41  -12  -91 -209 -264 -359 -194  -10   -8
 1981   -3   -6    9   25   72  -37    9 -396 -378 -202  -39  -11
 1982   -4    3   14   37  -56 -154 -372 -363 -561  -60  -38  -11
 1983   -4   -5  -21  -57  -87  -50 -467 -761 -507 -306  -38  -11
 1984   -4  -10   -2   -9   50 -109 -477-1051 -373 -174   -3  -11
 1985   -2   -8    4  -49 -149 -100  -66 -325 -321 -244  -38   -6
 1986   -4   -7  -21  -30  -38 -208 -280 -650   42 -162  -31  -12
 1987   -4   -9  -13  -89 -119  -66 -405 -544 -317 -102  -46  -11
 1988   -2   -6  -22   22 -134  -51 -166  182  -53 -241  -17  -12
 1989   -4   -7    4  -50 -125  -10 -165   18 -383  -52  -28    2
 1990    1  -11  -33  -23  -17 -181 -147 -535 -483 -189  -29  -10
 1991   -4    3   18    1  138  -79  -53 -266 -608   30  -45  -11
 1992   27   16  -28  -27   33  -94  -97 -349 -430 -192  -15  -12
 1993   -4   -6    2  -39 -126 -120  -50 -366 -332 -187  -14  -12
 1994   -4   -5  -15  -26  -57 -110 -160  -37  199  228   -5  -12
 1995   -4   -8    5   23  -31 -100 -273 -166 -173 -178  -23   58
 1996   -3   -3  -18  -15   20  -46 -222 -294 -138  -69  -23   -6
 1997   -2   -8    9   14   61  126 -519 -464 -176  -87  -28  -11
 1998   -2   -7  -25   13    2 -144 -358 -142  317 -155  -31  -10
 1999   -3   -7   -1  -19  -45 -237  111  433 -128  306  -15  -10
 2000    6   -8  -10  -34  -77  -44 -131 -312 -387   13  -13  -13
 2001   -6  -10  -19   56    5   53  -53 -425 -281 -191   -1  -11
 2002   32  -10  -10  -28 -101 -222 -215 -608 -323   80  -32   -6
 2003   -3    8    9    7  -48   90   26  -83  -23   17   -5  -11
 2004   77   17   -8   28  -39  -64  150 -280 -431 -298    0   -6
 2005    3   20    7  -16  -37  212  -35 -303 -158 -181  -25  -10
 2006   -6    4  -15  -44  -50  -69 -305 -291   35  -65  -35  -11
 2007   -7   -8  -22   46 -115 -232 -187   64 -285 -246   74  -12
    JJASO-means in 0.1 mm/month with respect to 1900-2007, so "-80" is -0.80 cm/month. 
    
        +0    1    2    3    4    5    6    7    8    9
 1900  -80   92 -210  -30  -59  213  348 -133   53  204
 1910   34 -135  -13 -257   -1  -82   46  -17  232  -73
 1920   66  -86  144   46  194   67  -66  273  122  171
 1930  138  -34   97  189   41  213  236  -14   77  119
 1940   32 -143 -131  171  -35  139  128   10   -5  -69
 1950  327  190  265  164  230  230   97  223  242   44
 1960   55   58  123   81  152  115   60  152 -154  144
 1970 -102 -115 -303 -237  -45    7  -73 -239  -33 -127
 1980 -172 -150 -251 -367 -386 -160 -200 -236  -15  -67
 1990 -256 -144 -181 -160   75 -127 -103 -173  -45  148
 2000 -121 -129 -206   57 -134  -42  -88 -126
    Same data as a 2-column table (year, value in cm/month).

    February 2008
    Todd Mitchell ( mitchell@atmos.washington.edu )
    JISAO data