Research ENSO/IOD years

Research classification of years when El Niño or La Niña and/or positive or negative Indian Ocean dipole occurred.
This table is an updated version of the original, and is for research purposes only. It does not attempt to estimate the level of certainty in the classification.

	negative IOD	no IOD	positive IOD
El Niño	1930	1888 1899 1905 1911 1914 1918 1940 1941 1965 1972 1986 1987	1877 1896 1902 1925 1957 1963 1982 1991 1997
No ENSO	1915 1958 1968 1974 1980 1985 1989 1992	1880 1881 1882 1883 1884 1895 1898 1900 1901 1904 1907 1908 1912 1920 1921 1927 1929 1931 1932 1934 1936 1937 1939 1943 1945 1947 1948 1951 1952 1953 1959 1960 1962 1966 1967 1969 1971 1976 1977 1979 1990 1993 1995 2001 2002 2003 2005 2006 2008	1885 1887 1891 1894 1913 1919 1923 1926 1935 1944 1946 1961 1983 1994 2004
La Niña	1906 1909 1916 1917 1928 1933 1942 1975 1988	1878 1879 1886 1889 1890 1892 1893 1897 1903 1910 1922 1924 1938 1949 1950 1954 1955 1956 1964 1970 1973 1981 1984 1996 1998 1999 2000 2007	1978

Click on individual years to see the time series on which the classification is based. This link gives a brief description of the plots.

Notes

This classification differs in about 19% of years from the original published version because a number of improvements have been made to the original algorithm (Ummenhofer et al. 2009). The years that differ should be considered as less robust in their classification.

Be aware that global warming makes it increasingly difficult to classify recent years because it adds a trend to the time series that may not be dynamically significant.

References

Original paper
Meyers, G.A., P.C. McIntosh, L. Pigot and M.J. Pook, 2007: The years of El Niño, La Niña and interactions with the tropical Indian Ocean. J. Climate, 20, 2872-2880.

Paper using these research categories
Ummenhofer, C.C., M.H. England, P.C. McIntosh, G.A. Meyers, M.J. Pook, J.S. Risbey, A. Sen Gupta and A.S. Taschetto, 2009: What causes southeast Australia’s worst droughts? Geophys. Res. Lett., 36, L04706, doi:10.1029/2008GL036801.