IARC Seminar Series

The IARC Seminar Series highlights topics of science that are the foundation of IARC's community - atmosphere, oceans, terrestrial processes, and integrated system studies. Reporting on recent research, emerging projects, and ongoing scientific pursuits, the researchers at IARC as well as visiting researchers will present on a range of topics including observations from mooring tidal currents, the Arctic Next Generation Ecosystem Experiment, recent studies of Global Climate model predicts, Arctic sea ice loss, Alaska permafrost research, investigations into the methane research from Arctic peatlands, and more.

A list of seminar dates, participants, abstracts and biographies are listed here. Past seminars, including PDFs of presentations are also included.

2012-2013

August 1, 2012

Meso- and Submeso-scale Eddies in Coastal and Global Oceans: Observation, Modeling and Implications
Guest Speaker: Changming Dong, IGPP, UCLA
2:30 PM - 3:30 PM, 401 Akasofu Building

Ocean eddies have been found to be ubiquitous over the entire ocean. With the advance in the remote sensing technique, high resolution observational data become available, which allow us to collect mesoscale and submesoscale eddies from observations, such as, sea surface height, sea surface temperature, sea surface drifters. In this seminar, a serie of automated eddy detection schemes will be introduced, both in Eulerian and Lagrangian frames. The eddy data sets collected by these schemes can be applied to different fields, for example, it can be applied to estimate eddy-induced heat and salt transports in the global ocean.

August 28, 2012

Detecting summer-time ice reduction in the Arctic Ocean using multiple buoy systems
Guest Speaker: Yusuke Kawaguchi, JAMSTEC
1:30 PM - 2:30 PM, 401 Akasofu Building

We’re working on the problem of the summer ice retreat in the Arctic Ocean. This seminar will focus on an analysis of this decline using combined data of multi-kind buoys (POPS & ITP for sea water, multiple GPS drifters for ice movement, and ICE-T for ice thickness) that were deployed near the North Pole in April. The case of summer 2010, when a satellite detected unusually low ice concentration in the Eurasian Basin will be presented. We found that the regions were occupied by very young ice floes that migrated from the Laptev Sea following the Trans Polar Drift Stream current. The concentration of ice floes was effected by an extensive low pressure system covering the central and eastern Arctic Ocean persistently in mid-August. We also discuss the role of a shallow, seasonal mixed layer in the low, producing the anomalous ice reduction. The shallow, seasonal mixed layer led to rapid ice movement because of the conservation of momentum from the ice within the thin layer, with feedback to the ice. The layer allowed the ice to diverge increasingly in response to the low pressure system, resulting in a higher amount of solar energy input at the resultant open water, and eventually causing further ice melt.

September 10, 2012

Biogeochemistry of organic matter decomposition from permafrost in the NGEE-Arctic project
Guest Speaker: David E. Graham, Oak Ridge National Laboratory
10:00 AM - 11:00 AM, 501 Akasofu Building

The Next-Generation Ecosystem Experiments (NGEE Arctic) project combines field and laboratory studies, observations and multiscale model simulation to improve predictions of land and subsurface changes in high-latitude ecosystems. Biogeochemistry activities in this project include process studies and observations to initialize, parameterize and improve models. These tasks are increasing understanding of the microbial transformations of subsurface organic matter in active layer soils and thawed permafrost, and enhancing predictions of CO2, CH4, and N2O greenhouse gas feedbacks on changing Arctic ecosystems. We discuss recent core sampling activities at intensive study sites of polygonal tundra in the Barrow Environmental Observatory. Results from analyses of the frozen cores are characterizing the complex redox biogeochemistry that determines the fate of permafrost-sequestered organic matter in anoxic environments. We are developing new methods of controlled thawing in column mesocosms and anoxic incubations in microcosms to study these processes at a fine scale that can be upscaled through model simulations.

September 20, 2012

Geologic methane seepage through the cryosphere cap
Speaker: Katey Walter Anthony, INE/IARC
1:30 PM - 2:30 PM, 501 Akasofu Building

Glaciers, ice sheets, and permafrost form a 'cryosphere cap' that traps methane formed in the subsurface, restricting its flow to the Earth's surface and atmosphere. Despite model predictions that glacier melt and degradation of permafrost open conduits for methane's escape, there has been a paucity of field evidence for 'subcap' methane seepage to the atmosphere as a direct result of cryosphere disintegration in the terrestrial Arctic. Here, we document for the first time the release of sub-cryosphere methane to lakes, rivers, shallow marine fjords and the atmosphere from abundant gas seeps concentrated along boundaries of receding glaciers and permafrost thaw in Alaska and Greenland. Through aerial and ground surveys of 6,700 lakes and fjords in Alaska we mapped >150,000 gas seeps identified as bubbling-induced open holes in seasonal ice. Using gas flow rates, stable isotopes, and radiocarbon dating, we distinguished recent ecological methane from subcap, geologic methane. Subcap seeps had anomalously high bubbling rates, 14C-depletion, and stable isotope values matching microbial sources associated with sedimentary deposits and coal beds as well as thermogenic methane accumulations in Alaska. Across Alaska, we found a relationship between methane stable isotopes, radiocarbon age, and distance to faults. Faults appear to allow the escape of deeper, more 14C-depleted methane to the atmosphere, whereas seeps away from faults entrained 14C-enriched methane formed in shallower sediments from microbial decomposition of younger organic matter. Additionally, we observed younger subcap methane seeps in lakes of Greenland's Sondrestrom Fjord that were associated with ice-sheet retreat since the LIA. These correlations suggest that in a warming climate, continued disintegration of glaciers, permafrost, and parts of the polar ice sheets will weaken subsurface seals and further open conduits, allowing a transient expulsion of methane currently trapped by the cryosphere cap.

October 4, 2012

Past and present permafrost distribution in the Northern and Southern Hemisphere: Comparison of the GCM-based mapping with the observations
Speaker: Kazuyuki Saito, JAMSTEC/IARC
1:30 PM - 2:30 PM, 501 Akasofu Building

Large-scale modeling research, combining global climate models (GCMs) with land processes with physically-based permafrost dynamics, have not been extensively employed yet for evaluation of the long-term changes of permafrost and their impacts on climate. We employed both, a statistical (using near-surface atmospheric thermal indexes) and a physical method to reconstruct a frozen ground distribution, to compare the resulting global permafrost maps with the observation-based reconstruction for the late Quaternary conditions, i.e., 0ka (pre-industrial), 6ka (mid-Holocene), and 21ka (the last glacial maximum; LGM). Despite simplifications of the determining factors in the reality (e.g., vegetation, soil, snow, and topography), the statistical method produced reasonable results. Use of high-resolution topography data improved the regional details such as Andean permafrost and the northeastern Asian region including Japan islands.

October 11, 2012

An overview of ONR Global and a Strategic Update on the Arctic
Guest Speaker: Marvin Blake McBride, Office of Naval Research Global
2:30 PM - 3:30 PM, 401 Akasofu Building

The first part of the presentation will give an overview of the Office of Naval Research Global (ONRG) and present the funding programs that ONRG uses to collaborate with international researchers. It will also briefly highlight some recent basic research collaborations with international scientists. In general, the outcome of these basic research collaborations is the publication of the research in a scientific journal and/or presentation of research results at a conference.

The second part of this presentation will provide a brief overview of the history, status and future of the decline of Arctic sea ice. Both sea ice extent and volume are decreasing rapidly and continuing loss of sea ice implies that an increasing portion of the Arctic will be navigable for longer durations during the summer. While there is considerable uncertainty associated with the timing of this forecast, it is clear that the Arctic is and will continue to be more accessible. The potential for resource extraction, like oil, gas, and minerals, and the attraction of significantly shorter shipping routes, will likely attract commercial interests. The Office of Naval Research (ONR) and ONR Global is working to improve understanding of the Arctic environment and its processes to enable more accurate representation in models, leading to improved forecasts and predictions of the Arctic environment, which will help reduce the uncertainty of the forecasts for the Arctic.

October 18, 2012

Designing and optimizing arctic observing networks for science and stakeholders
Speaker: Hajo Eicken, GI/IARC
1:30 PM - 2:30 PM, 417 Akasofu Building

Improved understanding and effective responses to rapid Arctic environmental change require long-term observation data to track changes and improve models aimed at anticipating future change. At the same time, Arctic stakeholders and decision-makers have articulated pressing needs for information and data products that can help with adaptation and mitigation of change. This raises questions about how to best design, implement and optimize Arctic observing systems to provide such information, addressing the dual needs of science and stakeholders. In the presentation, I will report on a recent assessment conducted by a task force convened by the Study of Environmental Arctic Change (SEARCH) to explore this topic. Drawing on examples from sea ice research in the Pacific Arctic sector, potential paths forward towards implementation of a robust, sustainable observing network will be discussed.

October 25, 2012

PUFF Model Simulation of Airborne Ash Density Distribution: A Case Study for Sakura-Jima Japan
Guest Speaker: Hiroshi Tanaka, Center for Computational Science, University of Tsukuba, Japan
3:30 PM - 4:30 PM, 417 Akasofu Building

The volcanic ash-tracking model PUFF was developed in 1991 when Redoubt Volcano erupted and B-747 commercial jet plane encountered volcano’s ashes. The model has been operational at the Alaska Volcano Observatory (AVO) in collaboration with the Satellite Monitoring group. Recently, Eyjafjallajokull volcano erupted in April 2010 and caused enormous economic damage in Europe. It was suggested that the airborne ash density must be quantitatively estimated in a real-time base. Airlines are able to fly when the ash density is less than 2 mg/m3, not observable in the air at the time of the eruption.

In this study, we attempted to estimate the airborne ash density distribution using the simple PUFF model as a case study for Sakura-Jima volcano in Japan. We used as model inputs the 10 minutes intervals plume height and emission rate data estimated in 1985 by Dr. Eguchi, a Sakura-Jima volcanologist in Japan.

The PUFF model simulated the Sakura-Jima eruption for a year, providing the quantitative ash fall distribution and also the quantitative airborne ash density, , and the total ash fallout. We were able to compare model’s output to Dr. Eguchi’s in situ observations.

The result shows that the ash density distribution reaches more than 2 mg/m3 in the 3D perspective image. This distribution-modeling tool will be useful for commercial airlines, although the accuracy has to be enhanced by further sophistication of the model.

November 1, 2012

Seeking Inspired Creativity
Guest Speaker: Joe Kan, GI
1:30 PM - 2:30 PM, 501 Akasofu Building

Inspired creativity is the motivation by the desire to seek the truth of nature, to improve the socio-economic conditions and to attain personal growth through interactions with nature, humanity and beyond. This is a life-long learning process best start at an early age. One needs to take a balanced approach to developing the intellectual intelligence (IQ), the emotional intelligence (EQ) and the spiritual intelligence (SQ). If you don’t consider yourself a genius, developing habits conducive to inspired creativity to be discussed in this talk could be helpful. Creative habits can lead to incremental change in life. Wisdom acquired through faith can lead to transformative change of life. I will share some of my experiences in seeking inspired creativity in attaining personal growth and in improving research quality.

November 15, 2012

Climate change adaptation in Alaska: planning, research and action in the face of rapid climate and environmental change
Speaker: Sarah Trainor, ACCAP/IARC
1:30 PM - 2:30 PM, 501 Akasofu Building

Warming in Alaska and the Arctic has been documented to be greater than twice that of other regions. However, the growing literature on climate change adaptation includes very few studies documenting actions in response to climate change in the North. This paper reports the results of a multi-sectoral synthesis of climate adaptation in Alaska. We engaged semi-structured interviews with key informants in conjunction with document analysis and literature review. Our investigation reveals three major categories of response to environmental change in Alaska: 1) community and institutional strategic planning, 2) environmental research and monitoring and 3) other action.

This synthesis reveals a gap between climate adaptation planning, research, and action. Adaptive actions are most often response to immediate environmental conditions rather than implementation of deliberate or planned adaptations to climate change per se. While planning and monitoring occurs at the state-wide or regional level, adaptation actions occur most notably at the local scale. This implies the need for 1) organizations that can foster cross-scale collaboration and knowledge transfer and 2) better understanding of barriers to adaptation, cross-scale linkages, and the role of science in adaptive action.

November 29, 2012

Tales of climate, trees and people: research at the interface of climate science and resource management
Guest Speaker: Jeremy Littell, USGS
1:30 PM - 2:30 PM, 401 Akasofu Building

Climatic changes projected for the 21st century will likely cause ecosystem impacts that force re-examination of how we manage and use some natural resources. My past work has approached this problem in the forests, mountains, and rivers of the Pacific Northwest and northern U.S. Rockies. First, as a scientist, I have conducted research in Pacific Northwest paleoclimatology, the effects of historical and future climate on forest ecosystem processes (especially fire), and the role of climate in treeline establishment. Second, I have worked extensively with managers and decision makers to incorporate climate information in agency management and planning. In this talk, I summarize this body of work and discuss some possibilities for developing similar work in Alaska.

November 30, 2012

AGU poster session
Various Presenters
12:00 PM - 1:00 PM, 401 Akasofu Building

Bring your AGU poster to room 401 in IARC, between 12 and 1pm. This is a chance to practice presenting your poster and present your work to other people in IARC. If you do not have your poster, please come see and discuss with presenters.

December 13, 2012

Outreach education: to do or not to do
Speaker: Elena Sparrow, IARC
1:30 PM - 2:30 PM, 401 Akasofu Building

Science outreach got a boost when it was mandated by the National Science Foundation in the Broader Impacts criterion which is equal to the Scientific Merit criterion in the research grant application and funding process. NSF asks: “How will the project promote teaching and learning to advance discovery, and enhance scientific and technological understanding? How will the activities broaden the participation of underrepresented groups and benefit the broader society?”. Another important question is how do scientists view science outreach? There are numerous types of outreach: formal and informal education and public outreach using various strategies. I will share approaches, activities and programs that have been effective, what biologists and physicists think the barriers and challenges are to science outreach and some suggested solutions, and how I got hooked on science education outreach.

January 24, 2013

The Role of Ice Dynamics in Recent Sea Ice Change in the Beaufort Gyre
Speaker: Jennifer Hutchings, IARC
1:30 PM - 2:30 PM, 501 Akasofu Building

Since 1997 the Chukchi and Beaufort Seas have experienced a reduced perennial ice cover. ADer the record ArcEc sea ice minima of 2007, the seasonal ice zone in the Beaufort Sea has conEnued to expand, while pan-­‐ArcEc summer minimum ice cover is rebounding. The change in the Beaufort sea to an extensive seasonal ice cover is related to ice driD paMerns, with enhanced meridional driD a driver of the recent change. This ice driD has acted to create an ice pack younger than five years old in the central Beaufort Gyre, which is more vulnerable than the previous older pack to summer melt. Since 2007, Beaufort sea ice has not recovered due to a posiEve feedback between ice dynamics and thermodynamics. The Beaufort ice pack of reduced thickness and strength has responded with enhanced divergence, creaEng large areas of thin first year ice that melt out early in summer. This precondiEoning can enhance albedo feedback in summer, further thinning the ice pack. In-­‐situ observaEons of decreasing perennial ice concentraEon and thickness support this hypothesis. The Beaufort Sea ice circulaEon represents recirculaEon in the Beaufort Gyre. Hence this region of the ArcEc ice pack holds the key to understanding memory in the ice pack and inter-­‐annual to decadal variability.

February 7, 2013

Deep ice sheets, snowy mountains and wet tundra: some examples of cryosphere geophysics
Speaker: Alessio Gusmeroli, IARC
1:30 PM - 2:30 PM, 501 Akasofu Building

The Earth's cryosphere is particularly sensitive to environmental changes. It is important to develop useful tools that are capable of characterizing this system. Geophysical techniques such as penetrating radar (GPR) and seismic techniques use electromagnetic and elastic waves to explore the properties of the subsurface. In this presentation, we will illustrate recent applications of geophysical experiments in polar and sub-polar regions such as Antarctica, Greenland and Alaska. Examples will include measurements of ice-sheet fabric; ice-sheet depth; rheology of sub-glacial sediments; snow depth profiling on glaciers and in the tundra; soil thaw depth measurements; river and lake ice profiling; glacier-bed imaging and determination of the glacier thermal regime.

February 13, 2013

We can see Alaska: The Submeter Resolution Arctic
Guest Speaker: Paul Morin, Polar Geospatial Center
11:00 AM - 12:00 PM, 401 Akasofu Building

Near full sub-meter optical imagery coverage of the arctic is now available to U.S. federally-funded researchers free of charge through a web-based mapping application/viewer, an OGC-compliant web services, as well as ortho-rectified scenes and mosaics. Approximately 50% of the entire Arctic has been imaged in stereo including Greenland’s ablation zone and coastal Alaska. One off shoot of the sub-meter imagery is the automated extraction of 2m posting elevation models for the 30% of Alaska and Greenland as well as 15% of Antarctica without human intervention. The PGC’s products and services as well as access to submeter imagery and tasking will be discussed.

February 14, 2013

Heat flux calculation and analysis for the Mackenzie, Yukon, and Lena rivers
Guest Speaker: Daqing Yang, National Hydrology Research Center (Canada)/IARC
2:00 PM - 3:00 PM, 501 Akasofu Building

This study analyzes long-term (40-60 years) discharge and water temperature records collected near the basin outlets of the Yukon and Mackenzie rivers. It defines seasonal cycles of discharge, water temperature (WT), and heat flux (HF) for the basins, and compares their main features with the Lena River in eastern Siberia, so as to understand their similarity and difference. Both rivers have similar hydrographs, i.e. low flows in winter and high discharge in summer, with the peak flood in June due to snowmelt runoff. Mackenzie River has many large lakes and they sustain the higher base flows over the fall/winter season. Mackenzie basin is large with high precipitation, thus producing 50% more discharge to the Arctic Ocean. The WT regimes are also similar between the 2 rivers. Yukon River WT is about 2-3C warmer than the Mackenzie over the open water months. Both rivers have the highest WT in the mid summer and they transport large amount of heat to the ocean system. Yukon River monthly HF is lower by 10-60% than the Mackenzie mainly due to small discharge. Mackenzie River heat transport peaks in July, while the Yukon HF reaches the maximum in June and July. These results provide critical new knowledge of river thermal condition and energy transport to the northern seas. They are useful for large-scale climate/ocean model development and validation, and climate/hydrology change research in the northern regions. 

March 7, 2013

Why should you publish Open Access (OA)? Selection criteria for assessing where to publish?
Speaker: Flora Gabrowska, Keith B. Mather Library/UAF
1:30 - 2:30 PM, 417 Akasofu Building

The benefits to everyone of OA scholarly publication have been well documented, particularly the increased impact factor. OA is no longer new but it has yet to take over from the long established, traditional Toll Access model whereby scholars _GIVE_ their manuscripts of their research findings to journals, often paying page charges and signing over copyright to the publisher, who then sells the content to the very same universities where most of the work is done.

Literally thousands of new journals have appeared and continue to pop up like mushrooms overnight as new business opportunities are perceived in the OA Author Pay model. As research scientists you will be solicited to submit your breakthrough research, referee manuscripts as well as to join the editorial board, all without charge, especially once you have established your scientific reputation. What should you look for? How should you evaluate these publishing/professional opportunities?

In this seminar we will review the good, the bad and the ugly of scholarly communication. It’s The Wild West gone global!

March 21, 2013

Atmospheric Moisture Transport and its Impact on the Hydrological Cycle over the North Pacific: Roles of Pacific Decadal Oscillation and El Nino
Speaker: Cecilia Borries, IARC
1:30 PM - 2:30 PM, 417 Akasofu Building

Increasing air temperatures cause changes in the hydrological cycle by giving the atmosphere a greater moisture-holding capacity. Along with the greenhouse-gas-emissions forced long-term trends, the atmospheric temperature and water content over the North Pacific can also fluctuate under climate patterns such as the Pacific Decadal Oscillation (PDO) and El Nino-Southern Oscillation (ENSO).

In order to better understand the role which these climatic patterns play in the North Pacific water budgets and pathways, we employed the NCAR Community Atmosphere Model 5.0 (CAM) and conducted sensitivity experiments to examine how atmospheric moisture transport responds to sea surface temperature (SST) anomalies associated with the PDO and ENSO phase transitions. We have found that changes in the storm tracks over the North Pacific due to changes in the sea surface temperatures vary the amount of moisture transport into Alaska.

As the PDO phase shifts from negative to positive, the moisture transport into Alaska tends to increase in both phases of ENSO. As the ENSO phase changes, the moisture transport decreases in all seasons during a negative PDO phase and increases in most seasons during a positive PDO phase. This study has important implications for improving understanding of precipitation events.

April 3rd

Microstructural models and the physical properties of sea ice
Speaker: Malcolm Ingham, Victoria University, Wellington, NZ
1:00 PM - 2:00 PM, 401 Akasofu Building

A simple microstructural model of sea ice based on dc resistivity data has been developed. Its efficacy can be assessed by its ability to predict other physical properties of sea ice. It is found that the model produces an excellent fit to the observed variation of thermal conductivity with temperature down to temperatures of about -20 °C and, for brine volume fractions above about 5%, is also able to predict the dependence of permeability on brine volume fraction. The microstructural model also gives good predictions of the specific heat capacity below -3 °C, and of the variation of the imaginary part of variation of the dielectric permittivity with frequency.

There are two principal failures of the model: a significant underestimation of the specific heat capacity at temperatures above about -3 °C, and a poor fit to the real part of the permittivity. These are believed to arise, respectively, from the complexity of the melting process of sea ice at high temperature, and the inability to model the effects of space charge polarization.

April 18, 2013

Polar amplification: major drivers and implications for global climate
Speaker: Vladimir Alexeev, IARC
1:30 PM - 2:30 PM, 401 Akasofu Building

Surface albedo feedback is widely believed to be the principal contributor to polar amplification. However, a number of studies have shown that coupled ocean‐atmosphere models without ice albedo feedbacks still produce significant polar amplification in 2xCO2 runs due to atmospheric heat transports and their interaction with surface conditions. The relative importance of atmospheric heat transport and surface albedo is assessed in a hierarchy of models. While both processes are shown to contribute to the polar amplified response of the model, feedback analysis points to a tendency for surface albedo to mask the effect of atmospheric heat transport in the full model.

Global climate models predict polar amplified pattern of warming in the Northern Hemisphere (NH) high- to middle latitudes during boreal winter. However, recent trends in observed NH winter surface land temperatures diverge from these projections. For the last two decades, large-scale cooling trends have existed instead across large stretches of eastern North America and northern Eurasia. We argue that this unforeseen trend is probably not due to internal variability alone. Delayed freeze-up in the Arctic and the consequent heat input in the atmosphere lead to significant changes in the circulation caused by a number of factors. Those factors include a direct response to the heat anomaly over the open ocean and a dynamic response to changes in the snow cover in northern Eurasia. Understanding this counterintuitive response to radiative warming of the climate system has the potential for improving climate predictions at seasonal and longer timescales.

Joseph Casas

April 25, 2013

Arctic Collaborative Environment (ACE) Joint Capability Technology Demonstration (JCTD)
Speaker: Joseph C. Casas, NASA Marshall Space Flight Center
10:00 AM - 11:00 AM, 401 Akasofu Building

The ACE JCTD provides an internet-based, open-access, Arctic- focused, environmental research and decision-support system that integrates data from existing remote sensing assets, products from existing and new environmental models, and in-situ reporting to provide monitoring, analysis, and visualization based on earth observation data and modeling.

These products will be layered within Google Earth and integrated into a community-based collaborative communication and coordination environment available to anyone with access to the public Internet.

The goal of the ACE JCTD is to enable local, regional, and international cooperation and coordination on long-term environmental planning and near-term actions in response to climatic and environmental changes occurring in the Arctic Region. The intention is to transition the ACE system to the US National Ice Center, a globally recognized provider of Arctic Environmental Products, jointly operated by the National Oceanic and Atmospheric Administration, the US Coast Guard, and the US Navy.

Jinho Ahn

April 25, 2013

"Bipolar seesaw" and atmospheric CO2 during the last Ice Age
Speaker: Jinho Ahn, Seoul National University, Korea
11:00 AM - noon, 417 Akasofu Building

Previous ice core studies revealed strong one-to-one coupling of climate in Antarctica and Greenland in a manner of a “bipolar seesaw” during the last glacial period (EPICA community members, 2006). Considering strong positive correlation between Antarctic temperature and atmospheric CO2 concentration during long Greenlandic stadials (cold periods) associated with Heinrich events (Ahn and Brook, 2008; Bereiter et al., 2013), small CO2 increases might be expected during short Greenlandic stadials.

Here we present an unprecedented high resolution of atmospheric CO2 records from the Siple Dome ice core, Antarctica for 22-40 ka. We find that CO2 does not increase during the short stadials. We suggest that the lack of CO2 increases during the short stadials is owing to weak climate forcings and/ or weak sensitivity of carbon cycles. It is likely that a certain threshold of climate forcing is required to increase CO2 over centennial variability.

Our results may help to better understand the mechanisms for carbon cycles and inter-hemispheric climate link associated with abrupt climate change.

chas jones simon filhol

May 2, 2013

Hydrology / Snow
Speakers: Chas Jones, IARC / Simon Filhol, IARC
1:30 PM - 2:30 PM, 501 Akasofu Building

Integrating local knowledge and scientific observations to model driftwood harvest from the Yukon River in a changing climate
Speaker: Chas Jones, IARC

Villages in rural Alaska are decreasing their dependence upon expensive fossil fuels by generating heat and/or electricity with wood fired boilers fed by driftwood, a cheap and easily accessed wood source. At the same time, however, the character of summer discharge in the Yukon River appears to be changing in a manner that is negatively affecting their driftwood harvest.

Residents of Tanana, Alaska typically harvest driftwood from the Yukon River during high flow events associated with spring break‐up and the “June rise,” but these annual events have become less predictable. This study analyzes the nature of the timing of flood events in the Yukon River with the goal of understanding if the perceived changes in driftwood availability are related to river hydrology and how future changes in hydrology may affect the driftwood harvest and the livelihoods of rural Alaskans.

Data gathered from interviews is integrated with USGS gaging station data, U.S. Census data, and a numerical model of driftwood harvest rates to estimate changes in driftwood harvest rates for the USGS period of record (1977 and 2012).

Winter evolution of the boreal snowpack 2011-2012 revealed by terrestrial LiDAR, time-lapse photography, and snowpits
Speaker: Simon Filhol, IARC

During winter 2011-2012, we periodically scanned the snow surface of a boreal forest with a terrestrial LiDAR (Light Detection and Ranging), accompanied with time-lapse photography and snowpit measurements. The experimental site is located near Fairbanks, Alaska, a typical boreal forest underlain by permafrost with sparse black spruce, larch, willow, and dwarf birch.

The LiDAR scans revealed with high accuracy (±2cm) and high resolution (<10cm) the thickening of the snowpack as well as temporal changes in snow distribution. Snow accumulated differently on and around vegetation depending on plant size relative to snow depth, plant mechanical properties, and the canopy structure (height, density).

Time-lapse photography captured several spruce tree loading and unloading events. Due to the bending of the shorter, more supple shrubs, there was the formation of consistent air gap at the base of the snow. This gap decreased with time, stabilizing at about 10% of the total snow depth by the end of winter.

A preliminary conceptual model synthetizing the interactions of snow and boreal vegetation is described.

Hiroyuki Wakabayashi

June 17, 2013

A Study on Improving Sea Ice Monitoring with SAR Data at Lake Saroma
Speaker: Hiroyuki Wakabayashi, Nihon University/IJIS
3:00 PM - 4:00 PM, 417 Akasofu Building

The main objective of this research is to investigate the possible use of synthetic aperture radar (SAR) data to monitor sea ice in the southern region of the Sea of Okhotsk. We would like to find out the suitable observation parameters for monitoring sea ice in relatively thin sea ice area. In-situ data collections on Lake Saroma were carried out in mid February 2012, which were simultaneously with ENVISAT/ASAR and RADARSAT-2 observations. We found that RADARSAT-2 VV to HH co-pol backscattering ratio decreases as the ice thickness. We will use the measured dielectric constant of the ice surface for improving the backscattering coefficient model for thin sea ice.

August 16, 2013

Filtering GPS noise from Lagrangian observations at submesoscale
Speaker: Max Yaremchuk, Naval Research Laboratory, Stennis Space Center
1:30 PM - 2:30 PM, 401 Akasofu Building

A variational method for removing positioning errors (PEs) from drifter trajectories is proposed. The technique is based on the assumption of statistical independence of the PEs and drifter accelerations. The method allows reconstruction of an approximate probability density function of the accelerations consistent with the known experimental data while keeping the difference between the filtered and observed trajectory within the error bars of the positioning noise.

Performance of the method is demonstrated in an application to real data acquired during the Grand Lagrangian Deployment (GLAD) experiment in the Northern Gulf of Mexico in 2012. Applications of the technique to temporal regridding of the drifter trajectories and spatial spatial filtering filtering of the data acquired acquired by towed platforms platforms is discussed.