Entity

Time filter

Source Type

West Side Highway, AK, United States

The University of Alaska Southeast is a public, four year university that is part of the University of Alaska System. The main campus is located in Juneau, Alaska and the university has extended campuses in Sitka and Ketchikan. The University of Alaska Southeast is abbreviated as UA Southeast, Alaska Southeast, or UAS.UAS was established on July 1, 1987 with the restructuring and consolidation of the former University of Alaska Juneau, Ketchikan Community College, and Islands Community College .UAS is accredited by the Northwest Commission on Colleges and Universities. Wikipedia.


Amundson J.M.,University of Alaska Southeast
Journal of Glaciology | Year: 2016

I explore the tidewater glacier cycle with a 1-D, depth- and width-integrated flow model that includes a mass-flux calving parameterization. The parameterization is developed from mass continuity arguments and relates the calving rate to the terminus velocity and the terminus balance velocity. The model demonstrates variable sensitivity to climate. From an advanced, stable configuration, a small warming of the climate triggers a rapid retreat that causes large-scale drawdown and is enhanced by positive glacier-dynamic feedbacks. Eventually, the terminus retreats out of deep water and the terminus velocity decreases, resulting in reduced drawdown and the potential for restabilization. Terminus readvance can be initiated by cooling the climate. Terminus advance into deep water is difficult to sustain, however, due to negative feedbacks between glacier dynamics and surface mass balance. Despite uncertainty in the precise form of the parameterization, the model provides a simple explanation of the tidewater glacier cycle and can be used to evaluate the response of tidewater glaciers to climate variability. It also highlights the importance of improving parameterizations of calving rates and of incorporating sediment dynamics into tidewater glacier models. © The Author(s) 2016. Source


Grant
Agency: NSF | Branch: Standard Grant | Program: | Phase: OFFICE OF MULTIDISCIPLINARY AC | Award Amount: 96.81K | Year: 2015

Non-Technical:
This award is jointly funded by the Condensed Matter Physics Program and the Office of Multidisciplinary Affairs in MPS and the Artic Natural Sciences Program in GEO. The polar regions of our planet are home to many dynamic physical processes. Although the word glacier may invoke connotations of stoic and slow-moving mountains of ice whose changes are indistinguishable to the eye, this is not always the case. Among the most active regions of glaciological activity are the massive coastal fjords in Greenland. Rivers of ice which are 5-10 km wide and up to 1 km deep are rapidly flowing towards the ocean. At the end of these glaciers, where the ice meets the sea, icebergs are constantly breaking off or calving into the ocean. Approximately 30-50% of all ice discharged into the ocean occurs through calving, as opposed to other mechanisms such as melting. Unfortunately, the physical processes which control calving are not well understood. One possible influence is the presence of an ice mélange, which is a floating layer of icebergs and sea ice extending many kilometers away from the front of the glacier. The mélange is essentially a large-scale, quasi-two dimensional granular material, which can potentially have a large impact on calving rates and our ability to detect iceberg calving. This collaborative project aims to determine the correct physical description of ice mélange mechanics, as well as its influences on iceberg calving. This is accomplished through an interdisciplinary combination of satellite imagery, small-scale laboratory experiments, and theoretical modeling. By bringing together ideas in condensed matter physics to study large-scale glaciological processes, the project sheds new light on the underlying mechanisms which shape the polar regions of our planet.

Technical:
The primary goal of this project is to characterize the rheology of ice mélange, a closely-packed granular material composed of icebergs and sea ice that is found in fjords throughout Greenland. Ice mélange is unique among granular materials in that it contains exceptionally large clasts (10s to 100s of meters in scale in all directions), is constrained to flow in a quasi-two-dimensional setting, and floats in its own melt. Seasonal variations in ice mélange motion and extent are well-correlated with seasonal variations in iceberg calving rates, suggesting that ice mélange is an important control on outlet glacier and ice sheet stability. The dynamics, energetics, and oceanographic consequences of ice mélange are essentially unexplored. The research teams aim is to study ice mélange by combining analysis of field observations with laboratory experiments and numerical modeling. Satellite imagery, along with previously collected time lapse photography and terrestrial radar data, is analyzed to produce ice mélange velocity fields and quantify iceberg-size distributions. This work provides new insights into ice mélange kinematics and composition, and serves as a benchmark for laboratory and numerical modeling experiments. In addition, experiments are conducted in which synthetic icebergs in a water tank are pushed by a model terminus. These experiments study jamming of particles that model icebergs during and between calving events to investigate stress transmission through ice mélange. Finally, numerical experiments are performed in which ice mélange is simulated using discrete particle and continuum models adapted from previous work on granular materials. The model rheology can be adjusted to find a description of ice mélange that is consistent with field observations and laboratory experiments.


Grant
Agency: NSF | Branch: Continuing grant | Program: | Phase: ECOSYSTEM STUDIES | Award Amount: 97.92K | Year: 2016

Coastal margins are dynamic zones at the interface between land and ocean, where fresh water and nutrients, like carbon, iron and nitrogen, flow downstream from coastal watersheds into the nearshore marine environment. The links between terrestrial and marine ecosystems are especially tight in the coastal temperate rainforests of Alaska and British Columbia. Abundant rainfall moves nutrients held in glaciers, dense forests, and wetlands to estuaries and fjords, supporting productive fisheries and robust marine mammal populations. This region includes the largest remaining old-growth forests in North America; has among the highest rates of glacier melt on the planet; supports billion-dollar fishing and tourism industries; and is home to tens of thousands of people who depend on natural resources for their livelihoods. Because the movement of fresh water and nutrients plays a key role in these linked ecosystems, climate-driven changes in this flow may impact coastal ecosystems and the human communities that depend on them. The Coastal Rainforest Margins Research Network is an international research collaborative that will facilitate a better understanding of these processes and impacts. This Network will establish a core community of scientists and stakeholders to function as an information and guidance resource for ecosystem management and community adaptation into the future. An improved understanding of this ecosystem will help build resilience in local communities and ecosystems in a warming and increasingly variable climate. Additionally, it will provide a foundation for understanding climate-driven changes within coastal temperate rainforests and coastal margins worldwide.

The Coastal Rainforest Margins Research Network will be composed of research communities organized within key disciplines, including hydrology, forest ecology, soil science, biogeochemistry, and near-shore marine ecology. These disciplinary communities will address critical information gaps, develop regional collaborations, and synthesize knowledge regarding water, carbon, and nutrient fluxes in a landscape where intense transformations and rapid transfers between terrestrial and freshwater environments control the delivery of these materials to the coastal ocean. The Network will achieve these goals through three main activities: 1) structured information exchanges among Network participants, including regular teleconferences, research webinars, field site visits, web-hosted meetings, and annual multi-day workshops that bring the entire Network together; 2) creation of working groups to develop data collection, management and sharing protocols; and 3) development of outreach products useful to Network members as well as policy-makers and resource managers.


Grant
Agency: NSF | Branch: Standard Grant | Program: | Phase: ARCTIC NATURAL SCIENCES | Award Amount: 111.75K | Year: 2013

This proposal addresses the feedbacks between glacier erosion and glacier dynamics. It does so by measuring the spatial and temporal patterns of sediment erosion, properties of basal till, basal water pressure, basal motion, ice deformation, surface velocities, surface mass balance, and changes in surface elevation and terminus position. This will be accomplished through a comprehensive observational program using radio echo sounding, reflection seismics, borehole observations, GPS, satellite remote sensing, and airborne LiDAR and digital photogrammetry. All observations will be interpreted with the help of numerical models that explore the effects of changing boundary conditions and the longer term evolution, taking into account the effects of sediment excavation. The work will be carried out at Taku Glacier, Southeast Alaska where all relevant processes are currently active. This project will impact model studies on glacier and ice sheet evolution, as well as interpretations of sedimentary records from past glaciations.
This proposal will be closely coordinated with activities of the Juneau Icefield Research Program, an annual educational program for high school and college students on the Juneau Ice field.


Grant
Agency: NSF | Branch: Standard Grant | Program: | Phase: SEES Hazards | Award Amount: 479.12K | Year: 2016

Humans have a long history of controlling or hunting predators which has resulted in many of these animal populations being classified as threatened, endangered or extinct. Recent reintroduction of some species allows for an examination of their role in the ecosystem, potential for conflict with humans, and possible strategies for future coexistence of humans and predators. This project will use sea otters in Southeast Alaska as a model system, combining ecology, economics, and Alaskan Native traditional knowledge to learn more about the role of marine predators in coastal sustainability. Between the mid-1700s and 1900, sea otters were hunted to extinction in Southeast Alaska for their highly valuable fur. In the 1960s, these animals were reintroduced in the region, and their population has grown from roughly 400 to more than 25,000 individuals. The recovery of sea otters in Southeast Alaska provides an opportunity to understand their ecological role in coastal ecosystems, while simultaneously evaluating their interactions with people who depend on coastal resources for their livelihood. Because otters eat shellfish, fishermen and people who harvest shellfish have growing concerns that the increase in sea otters is affecting their livelihood and food resources. At the same time, hunting pressure on sea otters has intensified from coastal Alaskan Natives who can legally harvest sea otters for their fur. The project will involve collaboration with Alaska Native communities and elders. In addition, it will support a team of scientists that includes undergraduate researchers, graduate students, two postdoctoral scholars, and two junior faculty members. One of the graduate students is from a group underrepresented in science, and the investigators plan to build on their track record of recruiting and retaining students from programs for Alaskan Natives.

The objective of this project is to document the role of apex predators and environmental drivers on changes in nearshore marine resources, ecosystems, and humans using an interdisciplinary approach that integrates ecological studies, traditional knowledge interviews, and ecosystem services quantification and valuation. This research examines changes in the marine environment over a period of time in which sea otters were extinct and then recolonized. The absence and then expansion of sea otters into different areas over time allows for a space-for-time substitution in which the longer-term effects of sea otters can be seen in areas occupied longer. Analyses of historical data provide an opportunity to describe changes in kelp distribution and abundance and subsistence harvests over the last 30-100 years. Quantification and valuation of ecosystem services from sea otters, including seagrass, kelp, and fish, will provide information on the potential benefits of sea otter recolonization. The integration of ecological, anthropological and economic approaches will lead to a better understanding of the reciprocal feedbacks between humans, apex predators and environmental drivers. Collaborations with Alaska Native communities throughout the project include consultation with community members and tribal elders about project goals and results, with the ultimate goal of informing resource management to improve the sustainability of rural coastal communities and nearshore ecosystems.

Discover hidden collaborations