Sahel rainfall index

Sahel rainfall index (20-10N, 20W-10E), 1900 - August 2009

analyses | digital values | applications

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Data as a 2-column table (year, value in cm/month).
The anomalies are with respect to 1900-2009. 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 1950-2009 in this figure.

The averages are taken of gridded rain gauge 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.".

Big GIF | PDF | PNG | PS

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 3-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 "-917" is -9.17 cm precipitation anomaly with respect to 1950-79.

       jan  feb  mar  apr  may  jun  jul  aug  sep  oct  nov  dec
 1900   -6    7   -6  -10   98  200  514 -917 -185 -275  -43  -15
 1901   -8   -7   -6   10   68   78  378  229 -280 -201  -39  -15
 1902   -5   -8    4   -9 -116 -147  -15 -378 -729  -52  -40  -14
 1903   -7   -8  -12    6  187   36 -353 1066 -870 -298  -37  -16
 1904   -7   -8  -16  -27   98  203  -40  114 -642 -188   18   28
 1905   -3   11   -1  -34  -93  295   64  179   18  257  -32    8
 1906   -6    2  -36   51  103  153  708  829 -171  -31    7  191
 1907   -4   -5  -12  -73 -114  -14 -505 -206  -92 -116  -25  -15
 1908   -7  -15   15  -32 -120  -65  -77  450  -74 -230  -19   11
 1909    3   -4    2  144   60  213  131  488   28  -93  -33   -3
 1910   -7  -10  -44  -21  -70  -72  222   76  -79 -239  -45  -17
 1911   -8  -14   21  101  212  -78 -199 -182 -296 -183    4   -9
 1912    0  -12  -45   29 -169  -31 -359  257  -45 -151  -14    4
 1913   14  -12  -40  -25  -65 -152 -414 -329 -453 -203  -32   -2
 1914   -7  -12  -34  -66 -152  -19 -193   57  -46  -64   41  -12
 1915   -6  -10   34  140  107   96  -40  -37 -541 -150  -35  -11
 1916   -6   -8    4   95 -113 -118  -15  237  152 -280  -16  -10
 1917    0   -1  -26  -40  235 -338 -178  234  278 -338  -13   -8
 1918   -3  -10  -13  -10  137  394  117  298  115   -7  -40  -13
 1919   -6   -9  -15  -35  131 -130   94 -364 -100 -124  -30  -13
 1920   -3    6  -25  -10    2  101 -273  434   40 -237  -29  -14
 1921   -6   -7    1  -11   16 -134 -314   81 -163 -165   31  -10
 1922    1   -8  -17   60  -61 -168  -16  117  384  149   29   -6
 1923   16   -8    3   82  -86  -93   12  133 -108   30   24   -4
 1924   19   30   -3  -13  -90  239  255   77  284 -138   14   -9
 1925   -1  -10   20  -30    3    6 -154   57   12  163   -9  -12
 1926   -6   -9  -12  -43  -15  220  -53 -272 -282 -208    3  -10
 1927   -6   -2  -33   25  117  173 -127  742  116  214   30   -6
 1928   -1  -10    4   33  -13  -47 -136  617 -182  102  -33  -10
 1929   -6   -8   14  -17   76  279  -48  414    4  -46  -41   -3
 1930    5   -1  -12   10  208    8  179  205   57   -4  -35   -8
 1931   -6   17  -15   42   51   21  206 -673  187 -171   38   -2
 1932   10   13   18  -16  114  -22   26  313  -21  -62  -11  -11
 1933    7    4    3    8  152  404  262  306 -126 -151  105    7
 1934   -5  -10    9  -15 -166   12 -111  215 -109  -58  -29  -12
 1935   11   -5   -2  -23  -75  111  132  624   15  -58  -11  -11
 1936   -6    3  -16   45  160  118  170  603  103  -59   73   -1
 1937   -6   -7   -2  -34  -64 -141  -69  106 -201  -26   -7   -9
 1938   -5   -9   49  -38  -34 -117   44  119   42   47   -6  -12
 1939   -5    4    9  -52   96  -44  -42  269  121   40  -16   -3
 1940    1  -10   -3  -30  -58    3 -298  220 -160  141  -21  -11
 1941   -1  -10   -5  -19   47   -3 -179 -477  -65 -252    5  -10
 1942   -2    7  -11   11   29 -206 -253   97 -503  -51   23    0
 1943   -1    0    6  -29    6  -30 -160  478  308   12  -12   71
 1944   -6   -9    2   -1 -173  -60 -333 -111  -14   85    3   -5
 1945   -6  -10  -23  -22  -53 -204   53  566   50  -26  -27  -13
 1946    6  -10  -11  -39  -63 -100   68  192  133   98  -29  -10
 1947   -4   -2  -29  -63 -168  -84 -227  262   33 -192    0   -6
 1948   -5    6  -19  120  -29  276  -97   30 -350 -144  -30  -12
 1949    0   -9    7   -4 -107 -101  -61  146 -456 -141   -6   36
 1950    3    0  -28  -48  -58 -106  154  930  321   94  -26  -10
 1951    1    3   34  -22   86  -94 -195   32  241  711   76   -8
 1952   -4   -8  -21  -53   71  -81  188   86  814   68  -23   -5
 1953   -3   15   11  -31  224  276  338  -91   41   15   16   20
 1954   -5   61    8   54   56  102  390  661 -188  -65  125   -9
 1955    0   -4   49   33  -26  174  469   10  237   16  -22   26
 1956    0    9   25    2  -86  -55   61  113  182  -68  -16   69
 1957    1   -6   -1    4  162  140   71  109  261  296   17    0
 1958   10   -2   -6   29  -59  156  167  800  -82  -81  129   -5
 1959   -2   -5  -13  -32   92 -113 -270  518   62 -238    8  -13
 1960   -6  -11   -5    4  -10   62  190 -201  124 -152   -8    1
 1961   -2  -11  -13  -15  -90   80  219   54  -57 -260  -13   -7
 1962   -6  -10  -16   52   -3   74  -37  411 -125   41   80  -14
 1963   -2    9  -19   43  -41  -58  -56   52 -178  396  -32  -14
 1964   -2  -11    4  -20   42  163  177  342   38 -208  -32   51
 1965   30    5  -29  -58  -64  176 -211  249  195  -83  -21  -14
 1966   -6  -11    7   21    7  111 -506 -267  330  381  -28   -7
 1967   -6    1   11   11  -85   -8   -9  226  262   38  -18   -9
 1968   -6   52   38  175   22    9 -101 -610 -211 -125   -6    5
 1969   -4   -8   14  -25  -71  -60  209   41  -10  297   -4  -13
 1970   -6  -11  -13  -45   32 -235  -14 -133 -120 -273  -25  -13
 1971   -6    2   18    5 -104 -200 -176   28 -230 -264  -31    8
 1972    2   -4  -12   25   47  -22 -499 -669 -505  -95  -25    0
 1973   -6   -9  -19  -21  -61 -133 -209 -413 -467 -235  -32   -8
 1974   -6  -12   -4  -45  -99 -197   31   -4 -167 -149  -25  -13
 1975   -6  -10   -7  -32   13 -160  405 -266  -25 -186  -34  -10
 1976   11    6  -10   -1   34    6 -325 -480 -210  384   17    9
 1977    4  -11  -17  -75  -51 -160 -399 -544 -152 -209  -50   -9
 1978   -3   -7   21  123   10  -55  142 -483  -72   48   -3   -3
 1979   28  -12   -6  -59   13  208 -204 -503 -307  -97    6   -4
 1980   -1   14  -35  -42  -13  -92 -211 -264 -363 -195  -10   -6
 1981   -3   -4   10   27   76  -38   11 -400 -383 -207  -42  -13
 1982   -6    4   14   39  -54 -156 -377 -367 -567  -58  -41  -12
 1983   -6   -4  -20  -60  -87  -51 -470 -767 -511 -310  -41  -13
 1984   -6  -11   -2   -9   52 -109 -485-1058 -377 -177   -2  -13
 1985   -3  -10    5  -51 -151 -103  -66 -327 -326 -249  -40   -6
 1986   -6   -6  -23  -32  -39 -211 -283 -657   43 -164  -32  -14
 1987   -6  -10  -12  -92 -122  -66 -408 -550 -321 -102  -50  -13
 1988   -3   -5  -23   23 -136  -51 -168  184  -55 -246  -19  -13
 1989   -6   -6    6  -53 -129   -8 -167   21 -389  -51  -30    2
 1990    1  -12  -35  -24  -19 -185 -148 -541 -489 -192  -32   -9
 1991   -4    3   19    1  141  -81  -53 -270 -615   33  -49  -12
 1992   29   17  -29  -28   36  -98  -98 -351 -436 -196  -14  -13
 1993   -5   -7    0  -41 -130 -124  -50 -369 -335 -190  -17  -13
 1994   -5   -5  -15  -26  -59 -113 -162   78  201  234   -7  -14
 1995   -5  -10    4   25  -30 -103 -277 -174 -172 -176  -23   59
 1996   -3   -2  -20  -15   21  -45 -225 -294 -138  -68  -24   -4
 1997   -3  -10    9   15   63  129 -526 -468 -178  -87  -26  -13
 1998    0   -6  -27   11    2 -148 -360 -143  319 -158  -34  -11
 1999   -3   -9    0  -20  -46 -240  112  435 -131  310  -17  -13
 2000   10   -9  -11  -34  -79  -45 -133 -315 -394   12  -11  -12
 2001   -5  -11  -22   55    5   51  -52 -384 -284 -194   -1  -12
 2002   35  -12  -12  -28 -102 -226 -358 -613 -328   84  -35   -2
 2003   -2    7    7   11  -50   90   28  -85  -23   19   -2  -13
 2004   84   19   -8   28  -41  -64  153 -284 -439 -303    1   -6
 2005    5   24   10  -17  -39  215  -33 -305 -161 -184  -26  -13
 2006  -10    5  -15  -46  -51  -69 -308 -295   36  -67  -39  -13
 2007   -8   -9  -23   46 -119 -236 -191   65 -288 -250   76  -12
 2008   -7    7   -7  -51   -1  103   51   -2 -277  -18  -34   -5
 2009   -5    0    7  -47  -63  106 -265  -92

JJASO-means in 0.1 mm/month with respect to 1900-2008, so "-80" is -0.80 cm/month.
2009 is derived from June through August.


        +0    1    2    3    4    5    6    7    8    9
 1900  -81   92 -213  -32  -59  214  349 -135   52  205
 1910   33 -136  -14 -259   -1  -83   47  -17  235  -73
 1920   65  -87  145   46  195   68  -67  275  122  172
 1930  140  -34   98  190   41  217  238  -15   78  120
 1940   33 -144 -132  173  -35  139  130   10   -6  -71
 1950  330  190  267  168  232  233   98  227  244   43
 1960   56   59  124   83  154  117   61  153 -156  147
 1970 -103 -117 -306 -240  -45    5  -73 -241  -33 -129
 1980 -174 -152 -254 -370 -390 -163 -203 -238  -16  -67
 1990 -260 -146 -184 -162   99 -129 -103 -175  -46  148
 2000 -124 -121 -237   57 -136  -42  -89 -128   23  -32

Same data as a 2-column table (year, value in cm/month).

Todd Mitchell ( mitchell@atmos.washington.edu )

JISAO data