As an additional example for our work with the IRI Data Library, here is Will's code that maps the correlation between precipitation in the Sahel region of Africa with sea-surface temperatures in the Atlantic Ocean.
SOURCES .UEA .CRU .TS3p1 .monthly .pre
X (20W) (20E) RANGEEDGES
Y (10N) (20N) RANGEEDGES
T (Jan 1950) (Dec 2009) RANGEEDGES
SOURCES .NOAA .NCDC .ERSST .version3b .anom
X 220.0 384.0 RANGEEDGES
Y -75 75 RANGEEDGES