ATM-9707492 Nishiizumi, Kunihiko University of California, Berkeley Title: Cosmogenic Radionuclides in the GISP-II Ice Core 10Be, 26Al, and 36Cl This project is intended to provide a record of cosmogenic radionuclide concentrations in the Greenland summit ice cores as part of the GISP-II program. The investigators will measure annual profiles of 10Be and 36Cl in the entire 200 m shallow ice core which spans the time period from the present to about 700 years BP. These measurements will complete the cosmogenic nuclide measurements in the entire 3054 m GISP-II ice core. Cosmogenic radionuclides in polar ice cores have been used to study long-term variations in several important geophysical variables, including: solar activity, geomagnetic field, atmospheric circulation, snow accumulation rates, and others. The resulting time series of nuclide concentrations will be applied to three main problem areas: deducing the history of solar activity, deducing the history of variations in the geomagnetic field, and a detailed comparison of 10Be, 36Cl production and the 14C profile. Cosmogenic radionuclide concentrations will be used to study climate history through the effects of atmospheric circulation and of atmospheric chemistry on nuclide deposition. The measurements are to be carried out at the Lawrence Livermore National Laboratory (LLNL) accelerator mass spectrometry (AMS) facility. This proposed work will be undertaken in coordination with other GISP-II investigators.
