Sulfur Isotopic Measurements from a West Antarctic Ice Core: Implications for Sulfate Source and Transport

Measurements of delta(34)S covering the years 1935-76 and including the 1963 Agung (Indonesia) eruption were made on a West Antarctic firn core, RIDSA (78.73 degrees S, 116.33 degrees W; 1740m a.s.l.), and results are used to unravel potential source functions in the sulfur cycle over West Antarctica. The delta(34)S values Of SO42- range from 3.1 parts per thousand to 9.9 parts per thousand. These values are lower than those reported for central Antarctica, from near South Pole station, of 9.3-18.1 parts per thousand (Patris and others, 2000). While the Agung period is isotopically distinct at South Pole, it is not in the RIDSA dataset, suggesting differences in the source associations for the sulfur cycle between these two regions. Given the relatively large input of marine aerosols at RIDSA (determined from Na+ data and the seasonal SO42- cycle), there is likely a large marine biogenic SO42- influence. The delta(34)S values indicate, however, that this marine biogenic SO42-, with a well-established delta(34)S of 18 parts per thousand, is mixing with SO42- that has extremely negative delta(34)S values to produce the measured isotope values in the RIDSA core. We suggest that the transport and deposition of stratospheric SO42- in West Antarctica, combined with local volcanic input, accounts for the observed variance in delta(34)S values

Collaborative Research: Asian Ice Core Array (AICA)--Reconstruction of Past Physical and Chemical Climate over Asia

Funding is provided to help the researchers build on success using ice cores for understanding past physical and chemical climate change from Antarctica, Arctic, North Pacific and Asia by analyzing and interpreting a new array of Asian ice cores. The researchers plan to use five existing ice cores and collect one new ice core to enhance the reconstruction of environmental conditions over Asia. The primary research questions for the Asian Ice Core Array (AICA) research include: (1) Asian climate variability - How do major Asian circulation features (i.e., Asian monsoon, Westerlies, polar air masses, Siberian and Tibetan Highs) vary on annual to longer scales? What factors (i.e., solar variability, volcanic activity, greenhouse gases) control changes in the major circulation features impacting Asia? What is the association between Asian climate and global circulation features? Can Asian climate be simulated and predicted from the state of past atmospheric circulation patterns (analog modeling)? How does the interaction between tropical and extra-tropical circulation impact climate over Asia? What are the regional climatic changes to be expected in near future based on trends? Are Asian climate change events related to climate change in other regions?(2) Environmental change over Asia - How have natural versus anthropogenic sources for chemical species notably sulfate, nitrate, and select heavy metals and trace and major elements varied in the atmosphere over central Asia? Are spatial and temporal variations in contaminants related to changes in contaminant source areas or production? Have changes in atmospheric circulation impacted distribution of chemical species in the atmosphere over central Asia?Scientifically, ice cores from Asian glaciers could provide a source of high-resolution records of seasonal to millennial climate dynamics and atmospheric chemistry. This is important because the Eurasian continent is the largest landmass in the World and exerts substantial influence on atmospheric and terrestrial systems and the 2.5 billion people living in the region. Changes in environment over this region could have dramatic impacts on humans and ecosystems. Unpredictable changes in water resources and desertification over this heavily populated region may have significant global consequences. The results from AICA could be of interest to climatologists, paleoclimatologists, atmospheric chemists, geochemists, climate modelers, solar-terrestrial physicists, and environmental statisticians. Educationally, the research project will support two PhD students as well as several undergraduate students for three years. This will help provide a rich research experience for the graduate and undergraduate students. Also, this project has strong ties to colleagues in China and Europe and offers intellectual and financial leveraging to aid in the success of the project

Roosevelt Island Climate Evolution Project (RICE): US Deep Ice Core Glaciochemistry Contribution (2011- 2014)

This award supports a project to analyze a deep ice core which will be drilled by a New Zealand research team at Roosevelt Island. The objectives are to process the ice core at very high resolution to (a) better understand phasing sequences in Arctic/Antarctic abrupt climate change, even at the level of individual storm events; (b) determine the impact of changes in the Westerlies and the Amundsen Sea Low on past/present/future climate change; (c) determine how sea ice extent has varied in the area; (d) compare the response of West Antarctica climate to other regions during glacial/interglacial cycles; and (e) determine how climate of the Ross Sea Embayment changed during the transition from Ross Ice Sheet to Ross Ice Shelf. The intellectual merit of the RICE deep ice core project is that it is expected to provide a 30kyr long (and possibly 150kyr long) extremely high-resolution view of climate change in the Ross Sea Embayment Region and data essential to test and understand critical questions that have emerged as a consequence of the recent synthesis of Antarctic and Southern Ocean climate change presented in the Scientific Commission for Antarctic Research document: Antarctic Climate Change and the Environment (ACCE, 2009). Ice core processing and analysis will be performed jointly by University of Maine and the collaborators from New Zealand. Co-registered sampling for all chemical analyses will be accomplished by a joint laboratory effort at the IGNS NZ ice core facility using a continuous melter system developed by the University of Maine. The RICE deep ice core record will provide information necessary in unraveling the significance of multi-millennial underpinning for climate change and in the understanding of observed and projected climate change in light of current dramatic human impact on Antarctica and the Southern Ocean. The broader impacts of the project include the fact that two CCI graduate students will be funded through the project, and will be involved in all aspects of field research, core sampling, sample processing, analytical and numerical analyses, data interpretation, writing of manuscripts, and presentation of results at national and international conferences. Data and ideas developed in this project and associated work will be used in several courses taught at the University of Maine. Innovative cyberinfrastructure will be incorporated into this work and ground breaking analytical technologies, and data access/storage tools will be used

Roosevelt Island Climate Evolution Project (RICE): US Deep Ice Core Glaciochemistry Contribution (2011- 2014)

This award supports a project to analyze a deep ice core which will be drilled by a New Zealand research team at Roosevelt Island. The objectives are to process the ice core at very high resolution to (a) better understand phasing sequences in Arctic/Antarctic abrupt climate change, even at the level of individual storm events; (b) determine the impact of changes in the Westerlies and the Amundsen Sea Low on past/present/future climate change; (c) determine how sea ice extent has varied in the area; (d) compare the response of West Antarctica climate to other regions during glacial/interglacial cycles; and (e) determine how climate of the Ross Sea Embayment changed during the transition from Ross Ice Sheet to Ross Ice Shelf. The intellectual merit of the RICE deep ice core project is that it is expected to provide a 30kyr long (and possibly 150kyr long) extremely high-resolution view of climate change in the Ross Sea Embayment Region and data essential to test and understand critical questions that have emerged as a consequence of the recent synthesis of Antarctic and Southern Ocean climate change presented in the Scientific Commission for Antarctic Research document: Antarctic Climate Change and the Environment (ACCE, 2009). Ice core processing and analysis will be performed jointly by University of Maine and the collaborators from New Zealand. Co-registered sampling for all chemical analyses will be accomplished by a joint laboratory effort at the IGNS NZ ice core facility using a continuous melter system developed by the University of Maine. The RICE deep ice core record will provide information necessary in unraveling the significance of multi-millennial underpinning for climate change and in the understanding of observed and projected climate change in light of current dramatic human impact on Antarctica and the Southern Ocean. The broader impacts of the project include the fact that two CCI graduate students will be funded through the project, and will be involved in all aspects of field research, core sampling, sample processing, analytical and numerical analyses, data interpretation, writing of manuscripts, and presentation of results at national and international conferences. Data and ideas developed in this project and associated work will be used in several courses taught at the University of Maine. Innovative cyberinfrastructure will be incorporated into this work and ground breaking analytical technologies, and data access/storage tools will be used

Collaborative Proposal: 2000+ Year Detailed, Calibrated Climate Reconstruction from a South Pole Ice Core Set in an Antarctic - Global Scale Context

This award supports a project to examine an existing ice core of opportunity from South Pole (SPRESO core) to develop a 2000+ year long climate record. SPRESO ice core will be an annually dated, sub-annually-resolved reconstruction of past climate (atmospheric circulation, temperature, precipitation rate, and atmospheric chemistry) utilizing continuous, co-registered measurements (n=45) of: major ions, trace elements, and stable isotope series, plus selected sections for microparticle size and composition. The intellectual merit of this project relates to the fact that few 2000+ year records of this quality exist in Antarctica despite increasing scientific interest in this critical time period as the framework within which to understand modern climate. The scientific impact of this ice core investigation are that it will provide an in-depth understanding of climate variability; a baseline for assessing modern climate variability in the context of human activity; and a contribution to the prediction of future climate variability. The broader impact of this work is that the proposed research addresses important questions concerning the role of Antarctica in past, present, and future global change. Results will be translated into publicly accessible information through public lectures, media appearances, and an extensive outreach activity housed in our Institute. Our ice core activities provide a major basis for curriculum in K-12 and University plus a basis for several field and laboratory based graduate theses and undergraduate student projects. The project will support one PhD student for 3 years and undergraduate salaries. The Climate Change Institute has a long history of gender and ethnically diverse student and staff involvement in research

COLLABORATIVE RESEARCH: Microparticle/tephra analysis of the WAIS Divide ice core

This award supports a project to perform continuous microparticle concentration and size distribution measurements (using coulter counter and state-of-the-art laser detector methods), analysis of biologically relevant trace elements associated with microparticles (Fe, Zn, Co, Cd, Cu), and tephra measurements on the WAIS Divide ice core. This initial three-year project includes analysis of ice core spanning the instrumental (~1850-present) to mid- Holocene (~5000 years BP) period, with sample resolution ranging from subannual to decadal. The intellectual merit of the project is that it will help in establishing the relationships among climate, atmospheric aerosols from terrestrial and volcanic sources, ocean biogeochemistry, and greenhouse gases on several timescales which remain a fundamental problem in paleoclimatology. The atmospheric mineral dust plays an important but uncertain role in direct radiative forcing, and the microparticle datasets produced in this project will allow us to examine changes in South Pacific aerosol loading, atmospheric dynamics, and dust source area climate. The phasing of changes in aerosol properties within Antarctica, throughout the Southern Hemisphere, and globally is unclear, largely due to the limited number of annually dated records extending into the glacial period and the lack of atephra framework to correlate records. The broader impacts of the proposed research are an interdisciplinary approach to climate science problems, and will contribute to several WAIS Divide science themes as well as the broader paleoclimate and oceanographic communities. Because the research topics have a large and direct societal relevance, the project will form a centerpiece of various outreach efforts at UMaine and NMT including institution websites, public speaking, local K-12 school interaction, media interviews and news releases, and popular literature. At least one PhD student and one MS student will be directly supported by this project, including fieldwork, core processing, laboratory analysis, and data interpretation/publication. We expect that one graduate student per year will apply for a core handler/assistant driller position through the WAIS Divide Science Coordination Office, and that undergraduate student involvement will result in several Capstone experience projects (a UMaine graduation requirement). Data and ideas generated from the project will be integrated into undergraduate and graduate course curricula at both institutions

A New Mt. Logan Ice Core Record - Change in Climate and Chemistry of the Atmosphere for the North Pacific

Mt. Logan, in the St. Elias Range, southeast Alaska, offers a unique opportunity for monitoring climate change and change in the atmospheric chemistry of the Gulf of Alaska and the North Pacific. In 1980, a 103-meter (M) ice core was recovered from Mt. Logan which spanned AD 1689-1980. It revealed well-defined annual layers, calibrated through the identification of radioactive bomb and volcanic horizons, allowing continuous, sub-seasonal sampling for stable isotopes and ion chemistry. The -29 degree C mean annual temperature at the site assures that the soluble, insoluble, and isotopic components of the core are well preserved. In 2001 and 2002, a new ice core to bedrock (190 M) was recovered from the Prospector-Russel Col area of Mt. Logan by the Geological Survey of Canada. Based on known accumulation rates and preliminary ice flow modeling, the new ice core record may span the entire Holocene and possibly into the Late Glacial. The Principal Investigators will develop and interpret detailed time series over the last 1000-2000 years, including multi-annual to decadal, through the Holocene and perhaps into the Late Glacial for major ions, stable isotopes, trace elements, and tephra utilizing state-of-the-art technology. Intellectual Merit: Interpretations resulting from this research will invoke calibrations between ice core measurements and instrumental series of sea level pressure and temperature first defined by associations found utilizing the 1980 Mt. Logan core. These interpretations will be enhanced by state-of-the-art environmental statistics, comparison with two cores developed by collaborators working at lower elevations in the same region (King Col and Eclipse Icefield), and comparison with other paleoclimate records from the North Pacific, as well as a global array of Holocene records. The highly detailed understanding of the different controls on the upwind side of the United States and Canada, developed from the new Mt. Logan record, should contribute to understanding future change in climate. This research will contribute directly to the understanding of: 1) recent North Pacific climate variability; 2) Northern Hemisphere to global Holocene climate variability; and 3) change in the chemistry of the atmosphere.Broader Impacts: This activity builds on two decades of ice core research which focuses on understanding natural climate variability in regions that record change in major atmospheric circulation patterns and change in the chemistry of the atmosphere. This project will provide support for the activities of two young faculty members (Kreutz and Kurbatov), full support for a Ph.D. student, partial support for several undergraduate/graduate students to participate in laboratory, data interpretation, and publication activities, and a request for instrumentation to enhance University of Maine ice core capabilities and efficiency. All data and interpretations will be shared in accordance with NSF policies

The Mass Function of Dark Halos in Superclusters and Voids

A modification of the Press-Schechter theory allowing for presence of a background large-scale structure (LSS) - a supercluster or a void, is proposed. The LSS is accounted as the statistical constraints in form of linear functionals of the random overdensity field. The deviation of the background density within the LSS is interpreted in a pseudo-cosmological sense. Using the constraints formalism may help us to probe non-trivial spatial statistics of haloes, e.g. edge and shape effects on boundaries of the superclusters and voids. Parameters of the constraints are connected to features of the LSS: its mean overdensity, a spatial scale and a shape, and spatial momenta of higher orders. It is shown that presence of a non-virialized LSS can lead to an observable deviation of the mass function. This effect is exploited to build a procedure to recover parameters of the background perturbation from the observationally estimated mass function.Comment: 23 pages, 6 figures; to be appeared in Astronomy Reports, 2014, Vol. 58, No. 6, pp. 386-39

Schottky-based band lineups for refractory semiconductors

An overview is presented of band alignments for small-lattice parameter, refractory semiconductors. The band alignments are estimated empirically through the use of available Schottky barrier height data, and are compared to theoretically predicted values. Results for tetrahedrally bonded semiconductors with lattice constant values in the range from C through ZnSe are presented. Based on the estimated band alignments and the recently demonstrated p-type dopability of GaN, we propose three novel heterojunction schemes which seek to address inherent difficulties in doping or electrical contact to wide-gap semiconductors such as ZnO, ZnSe, and ZnS