PDO reconstruction (dashed) from 1790-1979 based on the 9 tree-ring series and 2 PDSI series. Three of the shorter tree-ring chronologies were eliminated to develop a longer alternative model (solid) going back to 1700.
Smoothed versions of the two reconstructions along with the smoothed instrumental record (pink) are shown below.
TREE-RING LABORATORY, LAMONT-DOHERTY EARTH OBSERVATORY OF COLUMBIA UNIVERSITY. ROUTE 9W, PALISADES, NEW YORK 10964
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Last Updated: November, 2000 (David)