JISAO data
EOFs of global precipitation and the gridded data set
EOF 1 (ENSO) | EOF 2 (trend)

Analysis by Aiguo Dai, Inez Y. Fung, and Anthony D. Del Genio

Empirical Orthogonal Function (EOF) analysis is applied to a global, monthly precipitation data set of 2.5-degree latitude-longitude resolution for the period 1900-88 (Dai et al. 1997). Please address correspondence to Aiguo Dai (adai@ucar.edu).
EOF 1 (6.3% variance explained)

Historical Record: 1900-88

Modern Record: 1950-88

The "modern record" is just the last 39 years of the "historical record" principal component, with the anomalies calculated with respect to 1950-88.

Loading Vector
The principal component (time series): values * 1000 
        +0    1    2    3    4    5    6    7    8    9
 1900   87  -27  142   25    6  209   14   -5  -22 -129
 1910 -205   27   96   34  149  122 -129 -295  -25  210
 1920  -50 -147   39   24 -152  -29   77   19   10  -67
 1930   58   17   21 -117 -162    0  -50    4  -68  -88
 1940  130  197    2  -72   37  -11   31  -53    7  -44
 1950 -158   30  -57  -34 -133 -173 -212   63   57   13
 1960    1   13 -105  -42  -58  126   57  -25   11   52
 1970   32  -54  127   -4 -142  -93  -59  100   18   66
 1980   66   51  198  154   97   51  112  165  -80
EOF 2 (4.8% variance explained)

Historical Record: 1900-88

Loading Vector
The principal component (time series): values * 1000 
        +0    1    2    3    4    5    6    7    8    9
 1900  -36 -213 -154  -41 -124 -102  -75 -113 -124 -119
 1910 -175 -180  -62 -102  -84 -113  -85 -161 -180  -14
 1920 -143 -113  -61  -57 -183  -97  -50  -33  -99 -119
 1930  -56  -23  -19  -10  -86  -28  -91  -65  -73  -39
 1940  -24    4   -4  -36  -25   39  -13  -31   -8   -3
 1950   52   -7  -13  -10    3    8   35   52   72   59
 1960   20   80   38   14   44    6  102   91   72   55
 1970  110   60   42  213  135  154   69  155  163  137
 1980  103  171  164  250  182   90  104   58  106
The gridded precipitation data set:
Dai and collaborators have recently extended the data set to 1850-1996. Aiguo has asked that potential users be warned that "data after 1990 should be used with caution because station data have a very limited coverage for the latest several years".
FORTRAN binary
netCDF format (37 Mbytes). (Written February 1999) All errors in the netCDF file are due to Todd Mitchell.

Reference
Dai, A., I. Y. Fung, and A. D. Del Genio, 1997: Surface observed global land precipitation variations during 1900-1988. J. Climate, 10, 2943-2962.
February 1999
Todd Mitchell (mitchell@atmos.washington.edu)
JISAO data