PDO-ENSO years
Below are tables that categorize past winters according to the phase of
the ENSO and PDO. Table 1 shows the breakdown of ENSO/PDO winters assuming
the PDO pattern is truly regime-like, with continuous epochs switching phase
in 1925, 1947, and 1977. Table 2 shows the breakdown when we use November-March
values of our PDO index to identify the phase of the PDO for individual
winters.
Data series used in the construction of this table are:
Note: the year listed includes the fall of the year prior and winter of the listed year (e.g., "2005" refers to the fall of 2004 and winter 2005)
Table 1: Extreme ENSO winters identified as those years for
which the Dec-Feb NINO3.4 exceeds 0.5 standard deviations, or about
0.47 degrees C. For this table, the PDO phases are taken to be the
continuous epochs listed in the first row.
|
Negative PDO: 1900-1924, 1947-1976, 1999-2002
|
Positive PDO: 1925-1946, 1977-1998, 2003-2005*
|
| La Niña |
1904 1907 1909 1910 1911 1917 1918 1921 1923 1950 1951 1955 1956
1963 1965 1968 1971 1972 1974 1975 1976 1999 2000 2001 |
1925 1932 1934 1938 1939 1943 1944 1945 1984 1985 1986 1989 1996 |
| ENSO Neutral |
1901 1902 1908 1913 1916 1922 1947 1948 1949 1953 1954 1957 1960
1961 1962 1967 2002 |
1927 1928 1929 1933 1935 1936 1937 1946 1979 1981 1982 1990 1991
1993 1994 1997 2004 |
| El Niño |
1900 1903 1905 1906 1912 1914 1915 1919 1920 1924 1952 1958 1959
1964 1966 1969 1970 1973 |
1926 1930 1931 1940 1941 1942 1977 1978 1980 1983 1987 1988 1992
1995 1998 2003 2005 |
* It is believed that the PDO shifted to cool phase in mid-1998, but a recent (mid-2002) shift back to warm phase PDO makes it difficult to determine at this time if the 1998 shift was a true shift to a cold phase.
Table 2: Winter seasons as characterized by objective
measures of the PDO and ENSO. (Oct-Mar PDO > 0.5 standard deviations,
Dec-Feb NINO3.4 > 0.5 standard deviations, which is about 0.47 degrees
C).
|
PDO: negative |
PDO: neutral |
PDO: positive |
| La Niña |
1917 1918 1950 1951 1956 1963 1965 1971 1972 1974 1976 1989 1999
2000 |
1904 1907 1910 1911 1921 1923 1925 1932 1934 1938 1943 1944 1945
1955 1968 1975 1996 2001 |
1909 1939 1984 1985 1986 |
| ENSO neutral |
1946 1949 1954 1957 1962 1967 1990 1991 |
1901 1916 1928 1929 1933 1947 1948 1953 1961 1979 1982 1993 1997
2002 |
1902 1908 1913 1922 1927 1935 1936 1937 1960 1981 1994 2004 |
| El Niño |
1952 1964 1966 1969 1995 |
1900 1903 1912 1915 1919 1920 1930 1958 1959 1973 1978 1992 2005 |
1905 1906 1914 1924 1926 1931 1940 1941 1942 1970 1977 1980 1983
1987 1988 1998 2003 |
Questions? send email to Nathan Mantua (mantua@atmos.washington.edu)
February 2, 2006
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