(Table 1) Air-earth current density investigated during Atlantic Expedition 1973 of METEOR

One main point of our atmospheric-electric measurements over the Atlantic Ocean 1973 was the investigation of the air-earth current density above the sea. In addition to direct measurements at the water surface with a floating net, we calculated the air-earth current density from the electric field and the air conductivity measured simultaneously on board of the ship and during particular ascents in the free atmosphere. During all five ascents the air-earth current density did not change with altitude. For pure maritime air-conditions, the mean air-earth current density was found to be 2.9 pA/m**2. The mean hourly air-earth current density over the Atlantic shows nearly the same 24-hour pattern as measured by Cobb (1977) at the South Pole at the same time. When dust-loaden air masses of African origin reached the ship as well as under continental influence the mean air-earth current density was reduced to 2.1 pA/m**2. The global 24-hour pattern was modified by this continental influences. Finally, it is shown that the values of the air conductivity measured on board R. V. "Meteor" during our earlier expeditions have been influenced by the exhaust of the ship and must therefore be corrected. With this correction, our new mean values of the air-earth current density over the Atlantic are 2.6 pA/m**2 in 1965 and 2.0 pA/m**2 in 1969. From all measurements, the global air-earth current is estimated to be about 1250 A.

(Table 1) Age markers and errors for the last 1215 ka in IODP Exp302

Despite its importance in the global climate system, age-calibrated marine geologic records reflecting the evolution of glacial cycles through the Pleistocene are largely absent from the central Arctic Ocean. This is especially true for sediments older than 200 ka. Three sites cored during the Integrated Ocean Drilling Program's Expedition 302, the Arctic Coring Expedition (ACEX), provide a 27 m continuous sedimentary section from the Lomonosov Ridge in the central Arctic Ocean. Two key biostratigraphic datums and constraints from the magnetic inclination data are used to anchor the chronology of these sediments back to the base of the Cobb Mountain subchron (1215 ka). Beyond 1215 ka, two best fitting geomagnetic models are used to investigate the nature of cyclostratigraphic change. Within this chronology we show that bulk and mineral magnetic properties of the sediments vary on predicted Milankovitch frequencies. These cyclic variations record ''glacial'' and ''interglacial'' modes of sediment deposition on the Lomonosov Ridge as evident in studies of ice-rafted debris and stable isotopic and faunal assemblages for the last two glacial cycles and were used to tune the age model. Potential errors, which largely arise from uncertainties in the nature of downhole paleomagnetic variability, and the choice of a tuning target are handled by defining an error envelope that is based on the best fitting cyclostratigraphic and geomagnetic solutions.