http://hdl.handle.net/2122/111 Search the Channel search http://www.earth-prints.org/simple-search http://hdl.handle.net/2122/5891 Title: Radar systems for Glaciology<br/><br/>Authors: Zirizzotti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Urbini, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Cafarella, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Baskaradas, J. A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia<br/><br/>Editors: Kouemou, G.<br/><br/>Abstract: This chapter deals with radar systems, measurements and instrumentationemployed to study the internal core and bedrock of ice sheets in glaciology. The Earth's ice sheets are in Greenland and Antarctica. They cover about 10% of the land surface of the planet. The total accumulated ice comprises 90% of the global fresh water reserve. These ice sheets, associated with the ocean environment, provide a major heat sink which significantly modulates climate.Glaciology studies aim to understand the various process involved in the flow (dynamics), thermodynamics, and long-term behaviour of ice sheets.Studies of large ice masses are conducted in adverse environmental conditions (extreme cold, long periods of darkness). The development of remote sensing techniques have played an important role in obtaining useful results. The most widely used techniques are radar systems, employed sincethe 1950s in response to a need to provide a rapid and accurate method of measuring ice thickness. Year by year, polar research has become increasingly important because of global warming. Moreover, the discovery ofnumerous subglacial lake areas (water entrapped beneath the ice sheets) hasattracted scientific interest in the possible existence of water circulationbetween lakes or beneath the ice (Kapitsa et al., 2006; Wingham et al., 2006; Bell et al., 2007). Recent studies in radar signal shape and amplitude could provide evidence of water circulation below the ice (Carter 2007, Oswald and Gogineni 2008).In this chapter the radar systems employed in glaciology, radio echo sounding (RES), are briefly described with some interesting results. RES are active remote sensing systems that utilize electromagnetic waves that penetrate the ice. They are used to obtain information about the electromagnetic properties of different interfaces (for example rock-ice, ice-water, seawater-ice) that reflect the incoming signal back to the radar.RES systems are characterized by a high energy (peak power from 10 W to 10 KW) variable transmitted pulse width (about from 0.5 ns to several microseconds) in order to investigate bedrock characteristics even in the thickest zones of the ice sheets (4755 m is the deepest ice thickness measured in Antarctica using a RES system). Changing the pulse length or the transmitted signal frequencies it is possible to investigate particular ice sheet details with different resolution. Long pulses allows transmission of higher power than short pulses, penetrating the thickest parts of the icesheets but, as a consequence, resolution decreases. For example, the GPR system, commonly used in geophysics for rock, soil, ice, fresh water, pavement and structure characterization, employs a very short transmitted pulse (0.5 ns to 10 ns) that allow detailing of the shallow parts of an ice sheet (100-200 m in depth) (Reynolds 1997). Consequently, in recent years,GPR systems are also employed by explorers to find hidden crevasses on glaciers for safety. RES surveys have been widely employed in Antarctic ice sheet exploration andthey are still an indispensable tool for mapping bedrock morphologies and properties of the last unexplored continent on Earth. The advantage of using these remote sensing techniques is that they allow large areas to be covered, in good detail and in short times using platforms like aeroplanesand surface vehicles. http://hdl.handle.net/2122/3314 Title: Late Cenozoic climate history of the Ross Embayment from the AND -1B drill hole: Culmination of three decades of Antarctic margin drilling<br/><br/>Authors: Naish, T. R.; Antarctic Research Centre, Victoria University of Wellington, Wellington, New Zealand - Geological and Nuclear Sciences, Lower Hutt, New Zealand; Powell, R. D.; Department of Geology and Environmental Geosciences, Northern Illinois University, DeKalb, IL, USA; Barrett, P. J.; Antarctic Research Centre, Victoria University of Wellington, Wellington, New Zealand; Levy, R. H.; ANDRILL Science Management Office, University of Nebraska-Lincoln, Lincoln, United States; Henrys, S.; Antarctic Research Centre, Victoria University of Wellington, Wellington, New Zealand; Wilson, G. S.; Department of Geology, University of Otago, Dunedin,New Zealand; Krissek, L. A.; Department of Geosciences, The Ohio State University, Columbus, OH, USA; Niessen, F.; Department of Marine Geophysics, Alfred Wegener Institute, Bremerhaven, Germany; Pompilio, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Ross, J.; New Mexico Geochronology Research Laboratory, Socorro; Scherer, R.; Department of Geology and Environmental Geosciences, Northern Illinois University, DeKalb, IL, USA; Talarico, F.; Università di Siena, Dipartimento di Scienze delle Terra, Siena, Italy; Pyne, A.; Antarctic Research Centre, Victoria University of Wellington, Wellington, New Zealand; the ANDRILL-MIS Science team; http://www.andrill.org/support/references/appendixc.html<br/><br/>Editors: Cooper, A. K.; Raymond, C. R.; ISAES Editorial Team<br/><br/>Abstract: Because of the paucity of exposed rock the direct physical record of Antarctic Cenozoic glacial history has become known only recently and then largely from off-shore shelf basins through seismic surveys and drilling. The number of holes has been small and largely confined to three areas (McMurdo Sound, Prydz Bay and Antarctic Peninsula), but even in McMurdo Sound, where Oligocene and early Miocene strata are well-cored, the Late Cenozoic is poorly known and dated. The latest Antarctic geological drilling program, ANDRILL, successfully cored a 1285m-long record of climate history spanning the last 13 m.y. from sub-sea floor sediment beneath the McMurdo Ice Shelf (MIS), using drilling systems specially developed for operating through ice shelves. The cores provide the most complete Antarctic record to date of ice sheet and climate fluctuations for this period of Earth’s history. The >60 cycles of advance and retreat of the grounded ice margin preserved in the AND¬1B record the evolution of the Antarctic ice sheet since a profound global cooling step in deep sea oxygen isotope records ~14 m.y. ago. A feature of particular interest is a ~90m-thick interval of diatomite deposited during the warm Pliocene, and representing an extended period (~200,000 years) of locally open water, high phytoplankton productivity and retreat of the glaciers on land.