JISAO data



Pacific/North American (PNA) index, 1948 - October 2010

Digital values | DJF-averages | NDJFM-averages


This page contains the PNA index derived from the formula in Wallace and Gutzler (1981):
PNA = 0.25 * [ Z(20N,160W) - Z(45N,165W) + Z(55N,115W) - Z(30N,85W) ]
where Z are standardized 500 hPa geopotential height values.

A different formulation of the PNA index, namely as the second principal component of Northern Hemisphere extratropical sea-level pressure anomalies, is provided in this link.

The time series for each of the 4 grid points are standardized for each calendar month using 1948-2007 as the climatology, and the resulting PNA series is normalized using the standard deviation of the combined December, January, February values of 1948-2007. The choice of 1948-2007 for the climatology is arbitrary. The data employed is the NCEP / NCAR reanalysis.



Image characterized 
below.
Big GIF | JPG | PDF | PS
PNA series plotted for all calendar months, with positive and negative values during November through March indicated by red and blue shading, respectively.


Image characterized 
below.
Big GIF | JPG | PDF | PS

PNA pattern in December, January, February presented as correlation map
Image for the Northern 
Hemisphere domain poleward of 20N.
PostScript file | JPEG | PNG
Pattern plotted as a regression map. Red, black, and blue contours on the maps indicate positive, zero, and negative isopleths, respectively. Contour interval of 0.35 for correlations and 2 dam for regressions. Variability of the PNA pattern explains over 50% of the December, January, February interannual variability at its four centers of action.


The time series:
  • Make your own PNA index. Download 6-column table: year, month, geopotential height data (m) for 20N,160W; 45N,165W; 55N,115W; and 30N,85W, respectively. NaN for missing data.
  • table organized by years and months
  • 3-column table: year, month, PNA-value
  • 1-column table: just the PNA values

    Digital values * 100
           jan  feb  mar  apr  may  jun  jul  aug  sep  oct  nov  dec
     1948   11 -145 -172 -154   80   66  -18  -50  -38   29  -81 -135
     1949 -115 -149   16   79   22  -70  -20   41   75  -88  133 -141
     1950 -266  -38   29  -37  -61   53   34   99  146  -22  -57   73
     1951  -23  -86 -112   81  126    9    2   -5   77   -5   52 -118
     1952 -109   27  -93   80  -44  -96  -16    4   79  141   69  114
     1953   64   35  -92   64   46  -41   69   33   38  171   94   33
     1954  -98   53  -68 -150   26   -2  -67  -59  -57   96  211  -11
     1955   38 -145 -166  -79  -45   49  -24   19  -35  -18  -95  -72
     1956   -7 -174  -28   33  -18  -22   13   43  -15 -127  119   -9
     1957 -140 -149   61  -46   87    9   27  -22  118  184   47  -24
     1958  198  144   -8   80   75   73   30   31  -43   -4  -73   63
     1959  -38  -94  107   17  -39    9   40 -144  -42   36   41   46
     1960   18   63   36   32   20  -25  104  -56   36   52  -34  109
     1961  132    6   38  -39   41   59   36  105 -146 -163  -79  -46
     1962  -17  -79  -44   15 -157  -56  -32  -44  -38   40   79   58
     1963  -13  145 -144  -72 -118  -54  -69   49   92   42   22  167
     1964   16   82 -130 -119 -152   18  -24  -84  -85   60  -71 -130
     1965   -9 -152   12  -91 -126   23    1   -2  -95   35  -56  -95
     1966   41  -82   67  -13   -8   82   12   37  115  -37  -97   39
     1967  -54   -9 -174 -214  -29   53  -48   90  163  -10  -38 -117
     1968 -106  145   45 -115   40    6   22  -57  -27  -26  127  -94
     1969 -181   -3   75   56   72  149  -30  -19   24   68   97  147
     1970   35  132  106 -105   -6  108   27  -11 -103  -74  -57 -149
     1971 -132   22   -6  -18   57  -55   26   -3 -111  -95  -62 -246
     1972 -186  -98   23 -147   62  -32  -53   53 -139  -38   43  -72
     1973   25   87  -43   43   22   10  -22  -37   37  -91 -194   38
     1974 -165  -32  -77   -7 -102  -38  -34    1  -32   61  -35   35
     1975 -118  -67  -70 -118  -25  -48  106 -100   48 -125  -69  -19
     1976   -1 -135 -145   -6   10  -83   39   -8   80   66  139   69
     1977  144  174 -128  -15  -39  -14 -139    1 -108   55   26  -11
     1978  118  169   73  -15  -30 -101  -12  -88  -31   24 -107 -123
     1979  -13 -117   50  -86   48 -108    7   26   66  108   59   15
     1980  -25  135  -48  190   75  -89  -78 -101  -68  128   95   78
     1981  218   25  181  -92  159  -45  -28  121   30 -122   93   28
     1982  -89 -136 -135  -95    1   29    1  -40   48  -38  -18   42
     1983  156  175  231   88   30   96  -19  -43  -60  -34  131  -31
     1984   42   89  159  112  -39    3   15  -22  -50  -34    1 -196
     1985  137 -106  -98  -72  -48  -53   74  -45  -95 -158 -174  127
     1986  133   26  116  -51   33    9  -73   73 -129  117  -83  111
     1987  107   35  109  140  -80  -17   19  -51   80   89  101   -7
     1988   36   73   90   91   71  103    5   43  -35   80  -59  -16
     1989 -116 -107  -54  -33  -93   -8   -1   60   33  -94  -32   89
     1990  -95 -132   38   56  -24  -73   40   42   49  -98 -149 -162
     1991  -21   73  -98   31  -18  -84  -12   27   33  -64   48  -17
     1992  111   51  169   66    4  107  -60   34 -163   24   10 -161
     1993  -57   74  116  160  103   10  -97   19  -85   31  -45   87
     1994   22 -132   49   27   53  -54   23   66   49    8 -180   74
     1995  141   23   47    5   63  157   -4 -106  144  -55   24  121
     1996  -31   -2   17  122  -40  -60  -19    7   19  -37  -57  -96
     1997   33   27  -81  112  -39  109    1   25   76   53   84  129
     1998   90  211  143  103   12  -71   83   28   24   -9  -40  -55
     1999  -27    6   -4  -41  -40  -51  -95   56   83  -14   -1   13
     2000  -67   64   49   15  -71  -67  -33  -97    2  -21   42   99
     2001  145  -93   60  -89   25 -119  -44    2   60  -70   73   10
     2002  -33   24 -110  -91 -102   86   54   37  -58   -3  170  115
     2003  138   26   26  -12  -19   39   43   83   96  126 -145   45
     2004    3   83  -47   97 -128  -19   83   79  -23 -104   -5   21
     2005  -25   -6  124  140  166   22  -56   17  -91   29   -6  151
     2006    6  -33  -83  -20   32  107   49  -82   94  -63  -22   98
     2007   20    0   -3  106   75    6  142  -76 -109  -16  -10  -91
     2008  -72    0   23  -90   93  -67  -12   98   37   24   83 -106
     2009   32  -93 -144  -42  -11   63  124   54  135    9  -47   53
     2010  158  193  172   42    9    7    6  -40   10  111          
    
    Reference:
    Wallace, J. M., and D. S. Gutzler, 1981: Teleconnections in the geopotential height field during the Northern Hemisphere Winter. Mon. Wea. Rev., 109, 784-812.
    
    
    December-January-February averages

    Similar characteristics 
to the monthly data.
    Big GIF | JPG | PDF | PNG | PS

    The 1948 value is the average index value for January and February 1948; and is ascribed to the year of the January. The time series is standardized with respect to the entire record.

  • The time series as a 2-column table (year, data value).
    
    
    Digital values * 100 +0 1 2 3 4 5 6 7 8 9 1940 -89 -176 1950 -196 -16 -89 93 -6 -52 -112 -132 139 -31 1960 55 108 -63 83 116 -129 -61 -11 -35 -123 1970 138 -115 -234 17 -71 -67 -69 169 121 -112 1980 54 141 -88 164 43 -73 125 111 44 -106 1990 -61 -49 63 -64 -11 104 38 -16 189 -34 2000 4 66 0 122 57 -6 54 51 -73 -74 2010 177

    
    
    November through March averages

    Similar characteristics 
to the monthly data.
    Big GIF | JPG | PDF | PNG | PS

    The 1948 value is is the average PNA value for January through March 1948; and is ascribed to the year of the January. The time series is standardized with respect to the entire record.

  • The time series as a 2-column table (year, data value).
    
    
    Digital values * 100 +0 1 2 3 4 5 6 7 8 9 1940 -169 -153 1950 -94 -67 -80 62 4 -24 -124 -39 118 -12 1960 67 82 -87 41 51 -116 -42 -97 -24 -25 1970 170 -107 -188 13 -142 -85 -122 131 123 -102 1980 45 197 -79 193 128 -87 75 92 97 -117 1990 -44 -118 119 -6 -6 34 42 -57 216 -40 2000 19 83 -12 156 -20 35 11 30 -50 -75 2010 174

    November 2010
    Todd Mitchell ( mitchell@atmos.washington.edu )
    JISAO data