PDO index is defined as the projections of the ERSST V5 monthly SSTA onto the 1st EOF pattern of North Pacific 20ºN-60ºN. 1900-1993 DATA from ERSST V3b is used to derived the climatology and the 1st EOF pattern. Reference: Wen, C., A. Kumar, and Y. Xue, 2014: Factors contributing to uncertainty in Pacific decadal oscillation index. Geophys. Res. Lett., 41, 7980–7986, doi:https://doi.org/10.1002/2014GL061992 ERSST.V5 : Huang, B., Peter W. Thorne, et. al, 2017: Extended Reconstructed Sea Surface Temperature version 5 (ERSSTv5), Upgrades, validations, and intercomparisons. J. Climate Smith, T. M., Reynolds, R. W., Peterson, T. C., and Lawrimore, J. ( 2008), Improvements to NOAA's historical merged land-ocean surface temperature analysis (1880-2006), J. Clim., 21( 10), 2283– 2296. Year Month PDO 1950 1 -1.78 1950 2 -2.20 1950 3 -1.75 1950 4 -1.73 1950 5 -2.83 1950 6 -2.01 1950 7 -3.15 1950 8 -2.28 1950 9 -2.00 1950 10 -1.70 1950 11 -1.38 1950 12 -1.12 1951 1 -1.11 1951 2 -1.48 1951 3 -1.51 1951 4 -1.05 1951 5 -0.91 1951 6 -1.38 1951 7 -0.06 1951 8 -1.49 1951 9 -0.48 1951 10 -0.14 1951 11 -0.39 1951 12 -1.55 1952 1 -2.18 1952 2 -1.13 1952 3 -1.50 1952 4 -1.51 1952 5 -1.55 1952 6 -1.69 1952 7 -1.60 1952 8 -1.07 1952 9 -0.86 1952 10 -0.56 1952 11 -0.29 1952 12 -0.72 1953 1 -0.10 1953 2 -0.21 1953 3 -0.89 1953 4 -0.52 1953 5 -0.10 1953 6 -0.14 1953 7 0.23 1953 8 -0.74 1953 9 -0.84 1953 10 -1.06 1953 11 -0.31 1953 12 -0.09 1954 1 -1.03 1954 2 -0.74 1954 3 -0.80 1954 4 -1.05 1954 5 -0.54 1954 6 0.47 1954 7 -0.04 1954 8 -0.19 1954 9 -0.98 1954 10 0.04 1954 11 0.70 1954 12 0.23 1955 1 -0.19 1955 2 -0.90 1955 3 -1.10 1955 4 -1.99 1955 5 -1.54 1955 6 -2.00 1955 7 -2.52 1955 8 -2.43 1955 9 -2.25 1955 10 -3.14 1955 11 -2.45 1955 12 -2.18 1956 1 -2.11 1956 2 -2.10 1956 3 -2.64 1956 4 -2.36 1956 5 -1.54 1956 6 -2.17 1956 7 -1.58 1956 8 -0.94 1956 9 -0.28 1956 10 -1.62 1956 11 -2.21 1956 12 -1.34 1957 1 -1.42 1957 2 -1.52 1957 3 -0.72 1957 4 -0.56 1957 5 0.14 1957 6 1.25 1957 7 0.49 1957 8 0.38 1957 9 1.81 1957 10 1.43 1957 11 1.20 1957 12 0.24 1958 1 0.76 1958 2 1.09 1958 3 0.84 1958 4 0.84 1958 5 1.51 1958 6 1.48 1958 7 0.53 1958 8 1.17 1958 9 1.02 1958 10 0.43 1958 11 0.43 1958 12 1.18 1959 1 1.09 1959 2 0.55 1959 3 0.11 1959 4 0.03 1959 5 0.16 1959 6 0.20 1959 7 -0.24 1959 8 -0.19 1959 9 -0.38 1959 10 0.89 1959 11 1.14 1959 12 0.91 1960 1 0.32 1960 2 0.72 1960 3 0.51 1960 4 0.53 1960 5 0.75 1960 6 1.03 1960 7 -0.29 1960 8 0.03 1960 9 -0.68 1960 10 -0.17 1960 11 -0.01 1960 12 0.16 1961 1 1.02 1961 2 1.15 1961 3 1.01 1961 4 0.62 1961 5 -0.20 1961 6 -0.58 1961 7 -0.87 1961 8 -0.63 1961 9 -1.06 1961 10 -1.72 1961 11 -1.25 1961 12 -1.75 1962 1 -1.12 1962 2 -0.91 1962 3 -0.94 1962 4 -0.85 1962 5 -1.11 1962 6 -1.86 1962 7 -1.91 1962 8 -0.71 1962 9 -1.43 1962 10 -1.53 1962 11 -0.32 1962 12 -0.32 1963 1 -0.09 1963 2 -0.01 1963 3 -0.28 1963 4 -0.21 1963 5 -1.07 1963 6 -0.75 1963 7 -1.21 1963 8 -0.97 1963 9 1.03 1963 10 0.29 1963 11 -0.30 1963 12 0.40 1964 1 0.31 1964 2 0.21 1964 3 -0.53 1964 4 -1.04 1964 5 -2.08 1964 6 -0.86 1964 7 -0.95 1964 8 -1.42 1964 9 -1.12 1964 10 -0.58 1964 11 -0.68 1964 12 -0.81 1965 1 -1.07 1965 2 -0.55 1965 3 -0.15 1965 4 -0.01 1965 5 -0.48 1965 6 -0.71 1965 7 -0.65 1965 8 0.64 1965 9 0.94 1965 10 0.51 1965 11 0.46 1965 12 0.21 1966 1 -0.58 1966 2 -0.21 1966 3 -0.65 1966 4 -0.15 1966 5 -0.54 1966 6 -0.02 1966 7 0.10 1966 8 -0.03 1966 9 -0.07 1966 10 -0.36 1966 11 -0.62 1966 12 -0.24 1967 1 -0.28 1967 2 -0.19 1967 3 -0.64 1967 4 -0.94 1967 5 -1.54 1967 6 -1.52 1967 7 -1.39 1967 8 -1.66 1967 9 -0.68 1967 10 -0.09 1967 11 0.06 1967 12 -0.90 1968 1 -0.85 1968 2 -0.32 1968 3 0.00 1968 4 -0.61 1968 5 -0.70 1968 6 -0.07 1968 7 0.48 1968 8 0.14 1968 9 0.33 1968 10 0.08 1968 11 0.27 1968 12 0.04 1969 1 -0.34 1969 2 -0.65 1969 3 -0.51 1969 4 -0.41 1969 5 -0.38 1969 6 1.03 1969 7 -0.20 1969 8 -0.57 1969 9 -0.68 1969 10 1.27 1969 11 0.85 1969 12 1.27 1970 1 1.31 1970 2 1.28 1970 3 1.48 1970 4 0.60 1970 5 -0.58 1970 6 -0.09 1970 7 -0.66 1970 8 -1.39 1970 9 -1.39 1970 10 -1.08 1970 11 -0.84 1970 12 -1.01 1971 1 -1.26 1971 2 -1.38 1971 3 -1.31 1971 4 -1.37 1971 5 -1.32 1971 6 -1.57 1971 7 -2.09 1971 8 -0.17 1971 9 0.18 1971 10 -0.04 1971 11 -1.14 1971 12 -1.82 1972 1 -1.88 1972 2 -1.59 1972 3 -1.23 1972 4 -1.33 1972 5 -1.81 1972 6 -1.64 1972 7 -1.21 1972 8 0.21 1972 9 0.26 1972 10 0.23 1972 11 0.26 1972 12 -0.09 1973 1 0.18 1973 2 -0.07 1973 3 -0.32 1973 4 -0.74 1973 5 -0.94 1973 6 -0.98 1973 7 -0.71 1973 8 -0.77 1973 9 -0.36 1973 10 -0.80 1973 11 -1.13 1973 12 -0.91 1974 1 -0.87 1974 2 -1.31 1974 3 -1.06 1974 4 -0.50 1974 5 -0.52 1974 6 -0.42 1974 7 0.12 1974 8 0.07 1974 9 0.66 1974 10 0.15 1974 11 0.57 1974 12 0.18 1975 1 -0.54 1975 2 -0.68 1975 3 -0.74 1975 4 -1.43 1975 5 -1.66 1975 6 -1.35 1975 7 -0.58 1975 8 -0.95 1975 9 -1.16 1975 10 -1.34 1975 11 -1.49 1975 12 -1.53 1976 1 -1.11 1976 2 -0.91 1976 3 -1.02 1976 4 -0.96 1976 5 -0.73 1976 6 -1.01 1976 7 0.59 1976 8 1.43 1976 9 0.99 1976 10 1.48 1976 11 1.55 1976 12 1.32 1977 1 1.42 1977 2 1.72 1977 3 1.01 1977 4 0.30 1977 5 0.06 1977 6 0.28 1977 7 0.34 1977 8 0.35 1977 9 -0.32 1977 10 -0.48 1977 11 0.06 1977 12 0.16 1978 1 0.77 1978 2 1.06 1978 3 1.51 1978 4 1.29 1978 5 1.05 1978 6 0.54 1978 7 -1.21 1978 8 -0.45 1978 9 -0.47 1978 10 0.19 1978 11 0.09 1978 12 -0.48 1979 1 -0.17 1979 2 -0.88 1979 3 -0.22 1979 4 0.23 1979 5 0.87 1979 6 0.40 1979 7 0.53 1979 8 0.37 1979 9 1.08 1979 10 1.45 1979 11 0.80 1979 12 0.39 1980 1 0.45 1980 2 1.06 1980 3 1.16 1980 4 1.40 1980 5 1.39 1980 6 -0.27 1980 7 0.22 1980 8 0.28 1980 9 0.15 1980 10 1.44 1980 11 1.03 1980 12 0.60 1981 1 1.29 1981 2 1.43 1981 3 1.62 1981 4 1.46 1981 5 1.58 1981 6 1.88 1981 7 1.14 1981 8 0.36 1981 9 0.74 1981 10 0.02 1981 11 0.64 1981 12 0.87 1982 1 0.30 1982 2 0.02 1982 3 0.09 1982 4 -0.19 1982 5 -0.60 1982 6 -0.61 1982 7 0.67 1982 8 0.62 1982 9 1.06 1982 10 0.60 1982 11 -0.19 1982 12 0.42 1983 1 0.75 1983 2 1.48 1983 3 2.24 1983 4 1.92 1983 5 1.61 1983 6 2.23 1983 7 2.88 1983 8 1.77 1983 9 0.90 1983 10 0.97 1983 11 1.35 1983 12 1.71 1984 1 1.42 1984 2 1.36 1984 3 1.76 1984 4 1.32 1984 5 1.19 1984 6 -0.01 1984 7 0.13 1984 8 0.58 1984 9 0.60 1984 10 0.67 1984 11 0.61 1984 12 0.51 1985 1 0.87 1985 2 0.61 1985 3 0.05 1985 4 -0.07 1985 5 -0.21 1985 6 0.41 1985 7 0.92 1985 8 0.75 1985 9 0.58 1985 10 0.43 1985 11 -0.63 1985 12 0.29 1986 1 1.06 1986 2 1.65 1986 3 1.89 1986 4 1.40 1986 5 1.06 1986 6 0.88 1986 7 1.51 1986 8 0.35 1986 9 0.41 1986 10 1.14 1986 11 1.64 1986 12 1.64 1987 1 1.67 1987 2 1.92 1987 3 1.89 1987 4 2.01 1987 5 1.64 1987 6 0.84 1987 7 2.36 1987 8 2.63 1987 9 2.32 1987 10 1.45 1987 11 1.42 1987 12 1.38 1988 1 0.86 1988 2 1.13 1988 3 1.22 1988 4 1.02 1988 5 1.00 1988 6 0.79 1988 7 0.53 1988 8 -0.11 1988 9 -0.18 1988 10 0.04 1988 11 0.08 1988 12 -0.06 1989 1 -0.96 1989 2 -1.13 1989 3 -0.79 1989 4 0.04 1989 5 0.10 1989 6 0.18 1989 7 0.81 1989 8 -0.08 1989 9 -0.32 1989 10 -0.42 1989 11 -0.73 1989 12 -0.06 1990 1 -0.32 1990 2 -0.71 1990 3 -0.54 1990 4 0.36 1990 5 0.13 1990 6 0.01 1990 7 0.11 1990 8 0.10 1990 9 0.14 1990 10 -0.68 1990 11 -1.57 1990 12 -1.93 1991 1 -1.57 1991 2 -0.76 1991 3 -0.63 1991 4 -1.04 1991 5 -1.04 1991 6 -1.87 1991 7 -1.22 1991 8 -0.14 1991 9 0.74 1991 10 0.46 1991 11 0.37 1991 12 -0.14 1992 1 0.30 1992 2 0.46 1992 3 0.47 1992 4 0.92 1992 5 1.59 1992 6 1.38 1992 7 1.72 1992 8 1.24 1992 9 0.83 1992 10 1.41 1992 11 1.29 1992 12 0.51 1993 1 0.02 1993 2 0.41 1993 3 0.69 1993 4 1.32 1993 5 2.17 1993 6 2.24 1993 7 1.70 1993 8 2.27 1993 9 1.58 1993 10 1.46 1993 11 1.08 1993 12 0.75 1994 1 0.97 1994 2 0.51 1994 3 0.59 1994 4 0.87 1994 5 0.83 1994 6 0.18 1994 7 -0.67 1994 8 -0.54 1994 9 -1.12 1994 10 -0.68 1994 11 -1.55 1994 12 -1.87 1995 1 -0.37 1995 2 0.57 1995 3 0.95 1995 4 1.04 1995 5 1.33 1995 6 1.50 1995 7 1.62 1995 8 0.61 1995 9 1.56 1995 10 0.96 1995 11 0.29 1995 12 0.41 1996 1 0.89 1996 2 1.08 1996 3 1.13 1996 4 1.52 1996 5 2.15 1996 6 1.12 1996 7 0.67 1996 8 -0.27 1996 9 0.41 1996 10 0.62 1996 11 0.51 1996 12 0.11 1997 1 0.72 1997 2 0.59 1997 3 0.84 1997 4 1.07 1997 5 1.84 1997 6 2.60 1997 7 1.72 1997 8 2.56 1997 9 2.00 1997 10 2.12 1997 11 1.69 1997 12 1.46 1998 1 1.61 1998 2 2.19 1998 3 2.03 1998 4 0.94 1998 5 0.22 1998 6 -0.03 1998 7 -0.39 1998 8 0.09 1998 9 -0.69 1998 10 -1.51 1998 11 -0.42 1998 12 -0.53 1999 1 -0.35 1999 2 -0.50 1999 3 -0.37 1999 4 -1.05 1999 5 -1.56 1999 6 -1.76 1999 7 -1.10 1999 8 -1.08 1999 9 -1.29 1999 10 -1.92 1999 11 -1.73 1999 12 -1.46 2000 1 -1.70 2000 2 -0.70 2000 3 -0.03 2000 4 -0.05 2000 5 -0.26 2000 6 -0.38 2000 7 -1.03 2000 8 -1.10 2000 9 -0.87 2000 10 -1.13 2000 11 -0.66 2000 12 0.20 2001 1 0.85 2001 2 0.52 2001 3 0.37 2001 4 -0.48 2001 5 -0.38 2001 6 -0.65 2001 7 -1.59 2001 8 -0.87 2001 9 -1.09 2001 10 -1.02 2001 11 -0.54 2001 12 -0.49 2002 1 0.27 2002 2 -0.56 2002 3 -0.29 2002 4 -0.44 2002 5 -0.82 2002 6 -0.70 2002 7 -0.18 2002 8 0.51 2002 9 0.25 2002 10 0.27 2002 11 1.29 2002 12 1.89 2003 1 1.94 2003 2 1.75 2003 3 1.68 2003 4 0.91 2003 5 0.59 2003 6 -0.10 2003 7 0.71 2003 8 1.08 2003 9 0.26 2003 10 1.05 2003 11 -0.01 2003 12 -0.19 2004 1 -0.06 2004 2 0.36 2004 3 0.47 2004 4 0.52 2004 5 0.80 2004 6 -0.26 2004 7 -0.02 2004 8 0.43 2004 9 0.23 2004 10 -0.40 2004 11 -0.94 2004 12 -0.39 2005 1 0.11 2005 2 0.38 2005 3 1.13 2005 4 0.72 2005 5 1.49 2005 6 0.83 2005 7 0.17 2005 8 0.04 2005 9 -0.60 2005 10 -1.58 2005 11 -1.57 2005 12 0.10 2006 1 0.85 2006 2 0.90 2006 3 -0.04 2006 4 0.15 2006 5 0.35 2006 6 0.52 2006 7 0.84 2006 8 -0.14 2006 9 -0.93 2006 10 -0.12 2006 11 -0.43 2006 12 0.01 2007 1 -0.11 2007 2 -0.03 2007 3 -0.34 2007 4 0.22 2007 5 0.30 2007 6 0.33 2007 7 0.95 2007 8 0.54 2007 9 -0.49 2007 10 -1.86 2007 11 -1.16 2007 12 -0.69 2008 1 -1.13 2008 2 -0.99 2008 3 -0.65 2008 4 -1.14 2008 5 -0.95 2008 6 -1.48 2008 7 -1.28 2008 8 -1.00 2008 9 -1.18 2008 10 -1.33 2008 11 -1.20 2008 12 -1.03 2009 1 -1.50 2009 2 -1.31 2009 3 -1.42 2009 4 -1.51 2009 5 -0.75 2009 6 -0.44 2009 7 -0.18 2009 8 0.17 2009 9 1.01 2009 10 0.43 2009 11 -0.45 2009 12 0.08 2010 1 0.64 2010 2 0.96 2010 3 0.72 2010 4 0.84 2010 5 0.57 2010 6 -0.15 2010 7 -1.30 2010 8 -1.42 2010 9 -1.75 2010 10 -0.94 2010 11 -1.04 2010 12 -1.64 2011 1 -1.39 2011 2 -0.99 2011 3 -0.70 2011 4 -0.54 2011 5 -0.45 2011 6 -0.99 2011 7 -1.86 2011 8 -1.83 2011 9 -1.82 2011 10 -1.43 2011 11 -2.53 2011 12 -2.19 2012 1 -1.57 2012 2 -0.89 2012 3 -1.00 2012 4 -0.33 2012 5 -1.22 2012 6 -1.02 2012 7 -1.65 2012 8 -1.66 2012 9 -2.03 2012 10 -0.55 2012 11 -0.23 2012 12 -0.98 2013 1 -0.64 2013 2 -0.78 2013 3 -0.76 2013 4 -0.16 2013 5 -0.06 2013 6 -1.06 2013 7 -1.09 2013 8 -1.18 2013 9 -0.61 2013 10 -1.24 2013 11 -0.97 2013 12 -1.04 2014 1 -0.60 2014 2 -0.25 2014 3 0.70 2014 4 0.80 2014 5 1.41 2014 6 -0.27 2014 7 0.46 2014 8 0.55 2014 9 0.74 2014 10 1.42 2014 11 1.40 2014 12 1.89 2015 1 1.64 2015 2 1.73 2015 3 1.66 2015 4 1.25 2015 5 0.76 2015 6 0.93 2015 7 1.58 2015 8 1.34 2015 9 1.35 2015 10 1.08 2015 11 0.36 2015 12 0.63 2016 1 1.29 2016 2 1.89 2016 3 2.37 2016 4 2.42 2016 5 2.08 2016 6 1.02 2016 7 0.74 2016 8 -0.13 2016 9 -0.40 2016 10 -0.08 2016 11 1.24 2016 12 0.86 2017 1 0.44 2017 2 0.69 2017 3 0.80 2017 4 1.15 2017 5 0.94 2017 6 0.58 2017 7 -0.12 2017 8 -0.05 2017 9 0.31 2017 10 -0.21 2017 11 -0.43 2017 12 -0.07 2018 1 0.44 2018 2 0.10 2018 3 -0.23 2018 4 -0.23 2018 5 0.00 2018 6 -0.53 2018 7 0.07 2018 8 0.03 2018 9 -0.08 2018 10 -0.41 2018 11 -0.58 2018 12 -0.09 2019 1 0.04 2019 2 -0.15 2019 1 0.06 2019 2 -0.11 2019 3 0.32 2019 4 0.62 2019 5 0.59 2019 6 0.09 2019 7 0.76 2019 8 0.39 2019 9 0.28 2019 10 -0.69 2019 11 -0.47 2019 12 0.05 2020 1 -0.96 2020 2 -0.81 2020 3 -0.95 2020 4 -0.74 2020 5 -0.14 2020 6 -0.63 2020 7 -0.75 2020 8 -0.95 2020 9 -0.86 2020 10 -0.56 2020 11 -1.77 2020 12 -1.07 2021 1 -0.38 2021 2 -0.68