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Extratropic mean normalized anomalies in the summer (JJA) NDVI (dotted green line) and the summer temperature (dotted red line, weighted by NPP) (a) and in the spring (MAM) NDVI (dotted green line) and the spring temperature (dotted red line, weighted by NPP) (b). Regressions against time for the periods 1982–1991 and 1994–2002 are shown by solid lines, and r values, with corresponding color. The period 1992–1993, which was influenced by the Mount Pinatubo eruption, is marked in gray.
