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analyses | digital values | applications
The averaging region is based on the rotated principal component analysis of average June through September African rainfall in Janowiak (1988). Stations within 20-8N, 20W-10E are obtained from the National Center for Atmospheric Research World Monthly Surface Station Climatology (WMSSC), and 14 were chosen which had complete or almost complete records for 1950-93. The stations are listed below. [I created this index in 1996. As of 2001 there are more than 70 stations in the WMSSC with long records that could be used in this index. For this update, I used only the original 14 stations, and for 2000-present the index is only based on 9-11 stations.]
annual total
WMO* Station location years rain (cm)
1 610360 TILLABERY Niger (14.2N, 1.5E) 1951-2002 43
2 610430 TAHOUA Niger (14.9N, 5.3E) 1921-2002 38
3 610800 MARADI Niger (13.5N, 7.1E) 1932-2002 53
4 612260 GAO Mali (16.3N, 0.1W) 1919-2002 23
5 612700 KITA Mali (13.1N, 9.5W) 1931-2002 103
6 612720 SEGOU Mali (13.4N, 6.2W) 1907-2002 69
7 612930 KOUTIALA Mali (12.4N, 5.5W) 1921-2002 99
8 614980 KIFFA Mauritania (16.6N, 11.4W) 1922-98 30
9 616410 DAKAR Senegal (14.7N, 17.5W) 1898-2002 47
10 616540 THIES Senegal (14.8N, 17.0W) 1918-73 65
11 616660 DIOURBEL Senegal (14.8N, 16.3W) 1919-99 60
12 653060 KANDI Benin (11.1N, 2.9E) 1921-2002 103
13 653190 NATITINGUE Benin (10.3N, 1.4E) 1921-2002 129
14 655020 OUGIHOUA Upper Volta (13.6N, 2.4W) 1920-2002 65
* World Meteorological Organization
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The monthly rainfall totals for these stations are provided here as a 16-column table. The columns are year, month, Tillabery, Tahoua, ... The rainfall is in 0.1 mm, I have set the trace and missing observations to 0.1 mm and NaN, respectively.
Maps of climatological Africa rainfall are also available.
The individual time series are standardized for each calendar month with respect to the years 1950-93. The index value is taken as the mean of the available stations for each year and month. The final index is standardized by calendar month with respect to 1898-1993.
Additional information on African rainfall variability can be
obtained from:
Reference:
Janowiak, J. E., 1988: An investigation of interannual rainfall
variability in Africa. J. Climate, 1, 240-255.
Digital values:
The timeseries is standardized separately for each calendar month with respect to 1898-1993. Values are given for all calendar months even though it is extremely rare if not unheard of for it to rain during the months November through February. The use of normalized values in the index exacerbates the errors in these months. Index values for these calendar months should be used with great care if not ignored altogether.
The rainfall index is provided in several formats.
jan feb mar apr may jun jul aug sep oct nov dec
1898 -13 -47 -13 -30 -34 62 -107 62 -102 -98 -19 -24
1899 -12 -47 -13 656 -34 250 60 -48 -77 177 -19 70
1900 -13 174 -13 -30 -34 -4 65 -131 213 -43 -19 -24
1901 -13 -47 -13 -30 -34 250 72 -99 31 -105 -11 -24
1902 -13 -47 -13 -30 829 -70 -42 -24 -47 65 -19 -24
1903 -13 -47 -13 -30 -34 -32 -182 107 -67 -105 -19 -24
1904 -13 -47 -13 -30 -34 -51 5 183 -126 -103 38 147
1905 -13 273 967 -30 -34 52 23 -5 -173 304 -19 18
1906 -13 -47 -13 -30 5 43 296 354 -4 -45 -15 840
1907 -12 -35 -13 -54 -69 134 15 -108 176 -16 -14 -24
1908 -13 -35 -13 -50 -55 12 -5 82 -10 -10 -19 65
1909 -13 -35 -13 7 -1 105 226 79 -30 59 -19 -24
1910 -13 -35 -13 -54 -17 -103 47 -86 -86 -104 -19 -24
1911 -13 -35 -13 -38 216 -54 -1 -79 -88 -68 -17 -24
1912 -13 -35 -13 -27 -49 -30 -49 29 -105 -76 -19 -24
1913 -8 -35 -13 -54 -63 10 -79 -35 -136 -99 -19 -24
1914 -13 -35 -13 -54 -11 45 -54 -12 -82 43 6 -24
1915 -13 -47 -13 -30 -34 -80 513 338 -24 -78 -19 -24
1916 -13 27 -13 -30 -34 99 -45 -83 -85 -80 -19 -24
1917 -13 -47 -13 -30 -34 476 -127 171 272 -110 -19 -24
1918 -12 -41 -13 -35 -42 162 -59 182 62 178 -19 -27
1919 -14 -42 -12 -34 24 -4 97 -139 -31 -56 -19 -29
1920 -14 -1 -12 -42 -7 -44 -24 64 26 -15 -18 -27
1921 -12 -36 -11 -17 -26 -50 -139 -47 31 11 956 -28
1922 6 -16 -12 8 -36 -56 13 -1 87 25 -7 -20
1923 3 -40 -10 75 -32 -64 -10 48 -47 -11 -18 -23
1924 21 630 -10 2 76 69 67 38 74 -86 -9 -24
1925 -8 -40 -11 -52 -15 -61 -18 -9 -45 102 -14 -29
1926 -14 -39 -13 -53 -8 12 -6 -93 -101 -99 -12 -29
1927 -13 -11 -13 39 67 172 -102 174 40 126 -4 -13
1928 -13 -35 -11 74 -36 -51 -59 109 -79 75 -18 -29
1929 -9 -38 -3 -26 -17 174 -60 37 -32 0 -16 3
1930 11 -42 -13 12 19 -33 13 41 73 -67 -5 -29
1931 -14 62 -12 222 -13 -47 -5 -118 44 -86 -14 -11
1932 964 20 -12 -56 43 -39 17 -20 6 51 -17 -29
1933 -11 -38 -12 -10 68 209 109 57 -23 -58 42 -29
1934 -13 -41 -8 -35 -74 -4 -18 -2 -23 -13 -14 -29
1935 80 19 -6 -28 -52 87 118 130 -32 37 -11 -29
1936 -14 -15 -12 57 71 73 84 126 9 -18 24 -29
1937 -13 -40 -12 -62 48 -86 18 -50 -5 -2 -8 -29
1938 -13 -40 55 -41 -33 -99 44 -45 16 16 93 -29
1939 -13 -3 -5 -55 11 -101 -12 55 107 120 -16 -26
1940 -8 -40 -11 -31 -5 45 -73 8 -3 144 -16 -28
1941 -13 -37 -10 -41 23 -70 -21 -145 12 -89 -4 -26
1942 -13 23 -13 20 22 -128 -57 6 -152 -29 11 52
1943 -13 46 -11 -31 66 -28 -61 79 142 30 -19 322
1944 -14 -41 -12 519 -81 -74 -81 -1 75 74 -18 -22
1945 -13 -39 -13 -38 -14 -96 68 19 155 23 -14 -30
1946 -11 -39 -11 -44 -77 -57 24 8 79 151 -19 -30
1947 -13 8 -13 -39 -66 -78 -55 -4 69 -46 3 -29
1948 -13 -19 -12 78 40 209 20 22 -109 -89 -9 -29
1949 -13 -35 -10 17 -68 -81 -5 2 -141 -54 -1 59
1950 -8 -31 -13 -15 -32 -59 59 189 138 97 -14 -18
1951 -10 -33 -4 -52 93 -70 -12 15 203 360 12 -28
1952 -13 -38 -13 71 31 -50 30 64 288 66 -19 -26
1953 -13 -34 -8 -56 56 115 126 -18 50 -38 -16 -14
1954 -12 362 -7 48 -26 28 117 107 -20 15 35 -29
1955 -8 39 -8 13 1 71 158 18 144 173 -16 2
1956 -11 81 -11 -26 -51 -49 78 28 50 26 -15 67
1957 -12 -39 -9 -7 116 83 56 17 110 164 -7 -1
1958 -10 -38 -12 -29 -41 45 21 150 43 -21 14 -27
1959 -6 76 -11 -20 25 -68 -32 61 61 -82 -14 -29
1960 -13 -39 -10 -50 -13 -6 86 -43 59 -50 -11 8
1961 -8 -42 -12 -55 -39 31 87 12 55 -116 -20 -29
1962 -14 -24 -12 71 -34 34 72 78 35 81 19 -28
1963 -13 45 -13 42 -21 -38 -16 29 -19 232 -19 -29
1964 -9 -39 -9 44 14 36 88 88 24 -45 -13 213
1965 2 30 -13 -33 -16 113 -78 6 84 -45 -20 -29
1966 -13 -40 -11 -28 -40 -18 -146 -57 165 176 -18 -14
1967 -13 -10 -7 -19 -55 -57 0 44 240 -13 -17 -4
1968 -13 337 -10 157 -9 -9 -24 -126 -17 -48 -16 -29
1969 -13 -37 -12 -20 -51 -54 132 -16 13 160 -10 -29
1970 -13 -40 -11 -17 -29 -123 1 -17 40 -101 -18 -29
1971 -13 -20 -6 -35 -41 -96 -20 -65 -92 -104 -18 -8
1972 -9 -38 -13 -15 7 63 -150 -166 -129 10 15 9
1973 -13 -40 -13 -37 -54 -60 -92 -81 -127 -90 -19 -29
1974 -13 -41 -12 -33 -26 -76 41 8 8 -51 -19 -28
1975 -13 -33 -10 -39 14 -54 63 5 -44 -76 -11 -27
1976 -13 -34 -12 -39 62 -38 -81 -123 10 240 -13 -20
1977 -6 -41 -11 -40 -39 -80 -16 -77 -4 -91 -16 -6
1978 -13 -40 -1 179 2 -103 124 -110 -23 6 -7 -17
1979 -5 -42 -11 -29 11 195 -60 -156 -51 -23 -10 -27
1980 -13 -39 -13 -38 -77 -12 -91 -12 -101 -50 -17 -30
1981 -13 -46 -9 10 81 -37 -57 -78 -58 -56 -19 -29
1982 -13 191 -8 12 -46 -99 -130 -107 -186 -5 -19 -29
1983 -13 -43 -11 -43 -48 -35 -110 -159 -160 -106 -17 -28
1984 -13 -41 -9 -22 79 -91 -141 -177 3 -69 -17 23
1985 -13 -5 -7 -47 -77 23 -53 -89 -108 -111 -18 15
1986 -13 -37 -9 59 63 -96 -140 -124 92 -17 -12 -29
1987 -13 -34 -10 -57 -51 -67 -158 -110 -59 -59 -18 -29
1988 -13 -13 -13 8 -50 -104 -54 -10 52 -90 -19 -28
1989 -13 -41 -6 -37 -51 -17 -54 44 -80 -17 -17 40
1990 -12 -41 -10 -17 -30 -63 -61 -118 -90 -60 -17 -28
1991 -13 51 -10 -41 108 -4 82 15 -150 110 -22 -34
1992 -5 192 -13 -24 52 -77 -23 -64 -97 -67 0 -27
1993 -13 -22 -9 -50 -88 -4 -79 -100 -87 -66 -18 -1
1994 -13 96 -7 -32 -18 -83 -16 58 95 173 -18 -20
1995 -13 -45 -1 58 -20 -88 -53 38 -68 -43 -19 88
1996 -13 -40 -13 -7 29 13 -94 -96 56 36 -19 -29
1997 -11 -41 132 -8 -11 50 -91 -79 -107 -46 -5 -29
1998 34 2468 -13 -30 42 47 -119 -8 174 23 -19 -28
1999 -13 -40 172 -43 17 -107 21 71 135 74 1175 -29
2000 -12 -36 -13 -29 -21 -10 4 -82 -151 6 -21 -29
2001 -13 -45 -10 -48 758 -27 52 -47 161 -103 -13 -28
2002 81 -47 54 -48 -49 -97 -49 -104 -62 169 -17 -8
2003 53 -44 -3 9 -32 121 -10 9 -4 145 -12 -29
2004 -5 44 -13 -11 48 -11 -79 -57 -167 -97 24 3741
The number of gauges contributing in the last few years:
jan feb mar apr may jun jul aug sep oct nov dec
1990 13 11 13 13 9 9 9 11 13 13 12 10
1991 12 10 12 9 12 11 2 5 11 6 2 2
1992 9 7 7 7 11 11 9 10 12 10 11 8
1993 9 11 13 11 11 9 9 11 12 11 7 11
1994 13 10 5 10 12 11 13 13 10 13 12 12
1995 13 6 10 12 13 11 11 12 11 13 13 12
1996 13 11 13 10 12 11 11 12 13 11 12 11
1997 11 11 12 13 12 10 4 9 12 8 9 9
1998 11 11 10 10 9 8 10 11 13 12 8 9
1999 12 12 10 9 11 10 9 10 10 8 8 9
2000 6 9 9 8 7 10 9 8 10 11 3 10
2001 9 8 10 9 3 11 7 9 9 9 10 10
2002 4 6 12 9 10 9 9 7 9 9 9 9
2003 8 6 5 6 10 10 6 11 10 9 11 6
2004 1 8 7 8 3 4 9 9 6 6 5 4
Standardized JJASO-averages * 100. -64 is -0.64 standard deviations for 1898.
Standardization with respect to 1898-1993.
+0 1 2 3 4 5 6 7 8 9
1890 -64 126
1900 35 52 -41 -97 -32 70 224 70 24 153
1910 -115 -101 -80 -118 -21 233 -68 238 183 -46
1920 3 -67 24 -29 57 -11 -100 143 -2 42
1930 10 -74 5 102 -21 119 95 -44 -24 59
1940 42 -110 -126 57 -2 59 71 -40 18 -98
1950 148 173 139 82 86 196 47 150 83 -21
1960 16 25 105 66 66 28 42 74 -78 82
1970 -70 -132 -130 -157 -25 -37 3 -93 -37 -33
1980 -93 -100 -184 -199 -166 -118 -99 -158 -72 -43
1990 -136 18 -114 -117 79 -75 -29 -95 41 67
2000 -81 13 -49 91 -143