Section 12.1: Objective Teleconnections
219
Figure 12.3: Correlations in hundredths between July-September sea level
press ure at 10° resolution and the index of Sahelian rainfall 1949-88, from
Ward, 1992. Correlations locally significant at 5% are shaded. A strong indication oE a link with the equatorial Atlantic and weaker evidence oE relations
with Northern Europe and the Indian sub-continent are evident.
11 )0 11 19 1 ,
-I II
) 4. 10 17 I) l' 11 2:0
) 10 U 1) U I'
11 )0 10 ,
series need not be the same physical variable that is used at the other gridpoint. For instance, one could use as a basis grid point time series a sea
surface temperature anomaly and correlate this series with sea level pressure
or upper air geopotential field. This aspect was investigated by Horel and
Wall ace (1980) to show the statistical relation between the tropical Pacific
SST and large scale anomalies in the atmosphere. They found that positive
anomalies in the Central Pacific are correlated with a system of alternating
anomalies that extend from the Pacific to the N orth Atlantic and that bring
elose resemblance to the PNA. After them the relation between SST and
atmospheric anomalies were investigated by Lanzante (1984), Wall ace and
Jiang (1987), Namias et a1. (1988), Wall ace et a1. (1990) and Wallace et
a1. (1992). The tele connections in atmosphere were further investigated by
Namias (1981), Esbensen (1984), Barnston and Livezey (1987) and Kushnir
and Wall ace (1989).
This technique of heterogenous 1 teleconnections has been used extensively
in the following years and the teleconnections have now been investigated in
many respect. Figure 12.3, from Ward (1992) shows heterogenous correlation in a slightly different format for a teleconnection map. In this case the
values of the correlation between the Sahelian rainfall series and sea level
pressure anomalies are displayed directly at 10° resolution. Large areas of
1 Teleconnections are named homogeneous if the index time series with which all values
in a field are correlated with, is derived from the same field. A teleconnection pattern in
which an index time series and a different field are examined is heterogenous.
219
Figure 12.3: Correlations in hundredths between July-September sea level
press ure at 10° resolution and the index of Sahelian rainfall 1949-88, from
Ward, 1992. Correlations locally significant at 5% are shaded. A strong indication oE a link with the equatorial Atlantic and weaker evidence oE relations
with Northern Europe and the Indian sub-continent are evident.
11 )0 11 19 1 ,
-I II
) 4. 10 17 I) l' 11 2:0
) 10 U 1) U I'
11 )0 10 ,
series need not be the same physical variable that is used at the other gridpoint. For instance, one could use as a basis grid point time series a sea
surface temperature anomaly and correlate this series with sea level pressure
or upper air geopotential field. This aspect was investigated by Horel and
Wall ace (1980) to show the statistical relation between the tropical Pacific
SST and large scale anomalies in the atmosphere. They found that positive
anomalies in the Central Pacific are correlated with a system of alternating
anomalies that extend from the Pacific to the N orth Atlantic and that bring
elose resemblance to the PNA. After them the relation between SST and
atmospheric anomalies were investigated by Lanzante (1984), Wall ace and
Jiang (1987), Namias et a1. (1988), Wall ace et a1. (1990) and Wallace et
a1. (1992). The tele connections in atmosphere were further investigated by
Namias (1981), Esbensen (1984), Barnston and Livezey (1987) and Kushnir
and Wall ace (1989).
This technique of heterogenous 1 teleconnections has been used extensively
in the following years and the teleconnections have now been investigated in
many respect. Figure 12.3, from Ward (1992) shows heterogenous correlation in a slightly different format for a teleconnection map. In this case the
values of the correlation between the Sahelian rainfall series and sea level
pressure anomalies are displayed directly at 10° resolution. Large areas of
1 Teleconnections are named homogeneous if the index time series with which all values
in a field are correlated with, is derived from the same field. A teleconnection pattern in
which an index time series and a different field are examined is heterogenous.