Aspects of climate variability in the North Atlantic sector: Discussion and relation to the Greenland Ice Sheet Project 2 high-resolution isotopic signal

This paper reviews aspects of climate variability in the North Atlantic sector that may influence the seasonal to decadal scale isotopic signal in the Greenland Ice Sheet Project 2 (GISP2) ice core. Interpretation of the isotopic signal and its spatial applicability at the seasonal level requires investigation into synoptic scale climatology. We discuss possible climatic influences of (1) likely source regions of precipitation reaching the GISP2 site, (2) the characteristics of cyclone activity over the North Atlantic sector, and (3) changes in major atmospheric features such as the mean sea level Icelandic Low and Azores High pressure systems, the North Atlantic Oscillation, and the Baffin trough. Next, we evaluate correlations between the GISP2 deuterium isotopic signal and coastal temperatures with atmospheric pressure patterns, thereby deriving climatic interpretations of the high-resolution isotopic record. The GISP2 site is influenced by both the Icelandic Low to the southeast and Davis Strait/Baffin Bay storms to the southwest and west. The North Atlantic Oscillation influences the GISP2 isotopic signal through the seesaw in winter temperatures between west Greenland and northern Europe. Agreement in excursion directions of GISP2 isotopes and east Greenland and Iceland temperature records is associated with different positions of the Baffin trough in winter and also with anomalous 500-mbar net geostrophic flow. Linkages between isotopic excursion direction and atmospheric variability need to be explored further by comparison with additional seasonal data sets from other Greenland ice cores.