THE NORTH-ATLANTIC OSCILLATION SIGNATURE IN DEUTERIUM AND DEUTERIUM EXCESS SIGNALS IN THE GREENLAND ICE-SHEET PROJECT-2 ICE CORE, 1840-1970

The Greenland Ice Sheet Project 2 (GISP2) core can enhance our underst anding of the relationship between parameters measured in the ice in c entral Greenland and variability in the ocean, atmosphere, and cryosph ere of the North Atlantic Ocean and adjacent land masses. Seasonal (su mmer, winter) to annual responses of deltaD and deuterium excess isoto pic signals in the GISP2 core to the seesaw in winter temperatures bet ween West Greenland and northern Europe from A D. 1840 to 1970 are inv estigated. This seesaw represents extreme modes of the North Atlantic Oscillation, which also influences sea surface temperatures (SSTs), at mospheric pressures, geostrophic wind strength, and sea ice extents be yond the winter season. Temperature excursions inferred from the delta D record during seesaw/extreme NAO mode years move in the same directi on as the West Greenland side of the seesaw. Symmetry with the West Gr eenland side of the seesaw suggests a possible mechanism for damping i n the ice core record of the lowest decadal temperatures experienced i n Europe from A.D. 1500 to 1700. Seasonal and annual deuterium excess excursions during seesaw years show negative correlation with deltaD. This suggests an isotopic response to a SST/ land temperature seesaw. The isotopic record from GISP2 may therefore give information on both ice sheet and sea surface temperature variability. Cross-plots of delt aD and d show a tendency for data to be grouped according to the preva iling mode of the seesaw, but do not provide unambiguous identificatio n of individual seesaw years. A combination of ice core and tree ring data sets may allow more confident identification of GA and GB (extrem e NAO mode) years prior to 1840.