We present a high-resolution Gravity Recovery and Climate Experiment (GRACE) mascon solution for Gulf of Alaska (GOA) glaciers and compare this with in situ glaciological, climate and other remote-sensing observations. Our GRACE solution yields a GOA glacier mass balance of -65 ± 11 Gta⁻¹ for the period December 2003 to...
A comprehensive study of the Gulf of Alaska (GOA) drainage basin was carried out to improve understanding of the coastal freshwater discharge (FWD) and glacier volume loss (GVL). Hydrologic processes during the period 1980–2014 were modeled using a suite of physically based, spatially distributed weather, energy-balance snow/ice melt, soil water...
The glaciated coastal mountain watersheds that drain into the Gulf of Alaska (GOA) provide a model laboratory to explore the challenges of hydrological modeling and study the impact of climate and glacier cover change on regional hydrology. The region is data-sparse and contains a complex assemblage of topography and land...
During summer 2007, perennial sea ice in the Beaufort Sea, Arctic Ocean, experienced an unprecedented amount of basal melt. It has previously been shown that this basal melt was linked to an increase in open-water fraction, increasing absorption of solar radiation into the ocean. GPS ice drifters, deployed around the...
Central to an understanding of evolution in sea-ice characteristics in response to climate change is an understanding of sea-ice dynamics. In this study, we investigate regional differences in ice dynamics in the Beaufort Sea and High Arctic using high-frequency ice buoy (beacon) data deployed during the SEDNA and IPY-CFL field...
While the impacts of long-term climate change trends on glacier hydrology have received much attention, little has been done to quantify direct glacier runoff contributions to streamflow. This paper presents an approach for determining glacier runoff contributions to streamflow and estimating the effects of increased temperature and decreased glacier area...
Changes in glacier length reflect the integrated response to local fluctuations in temperature and precipitation, but when do such changes indicate forced climate change, and when do they indicate natural variability? In this study, we simulate the past ~1000 years of glacier length variability across the globe using the 3-stage...
The movement of air in natural porous media is complex and challenging to measure. Yet gas transport has important implications, for instance, for the evolution of the seasonal snow cover and for water vapor transport in soil. A novel in situ multi-sensor measurement system providing high-resolution observation of gas transport...
During the last glacial period atmospheric carbon dioxide and temperature in Antarctica varied in a similar fashion on millennial time scales, but previous work indicates that these changes were gradual. In a detailed analysis of one event we now find that approximately half of the CO₂ increase that occurred during...
A major achievement in research supported by the Kluane Lake Research Station was the recovery, in 2001–02, of a suite of cores from the icefields of the central St. Elias Mountains, Yukon, by teams of researchers from Canada, the United States, and Japan. This project led to the development of...
In winter and spring, ice-coast interactions driven by winds and ocean currents cause sea ice fractures (leads) to form repeatedly along Arctic coastlines. These events are often associated with rapid and expansive changes in sea ice drift and state that are challenging to predict and represent in models. We investigate...
Recent observations of tidewater glaciers find that the currently accepted model for predicting ice melt vastly underestimates observed melt rates. The release of pressurized air bubbles into the ocean from pores in the ice is one process that can amplify glacier melt. To incorporate this process into models, we need...
Arctic-boreal regions are exhibiting the symptoms of profound ecological shifts as they experience pronounced warming. Wildlife in high-latitudes are one such harbinger of change, and their populations are undergoing range-shifts, declines, and extinctions in response to their rapidly altering habitats. As the circumpolar and boreal north is snow-covered for up...
Remotely sensed derivation of sea-ice thickness requires sea·ice density. Sea-ice density was estimated with three techniques during the second Sea Ice Physics and Ecosystem eXperiment (SIPEX-II, September-November 2012, East Antarctica). The sea ice was first-year highly deformed, mean thickness 1.2 m with layers, consistent with rafting, and 6-7/10 columnar ice...
The global cryosphere, defined as the world’s ice and snow covered regions, is a crucial water source for society and ecosystem functions, as well as an important regulator of the earth’s energy budget. Melt from glaciers and seasonal snow cover provides water for more than a sixth of the world’s...
Autonomous buoys were deployed in 2011 in the central Arctic: An Ice-Tethered Profiler (ITP) and Ice Mass Balance (IMB) buoys were deployed in the Makarov basin; a Polar Ocean Profiling System (POPS) and Ice Thickness (Ice-T) buoy were deployed on the Eurasian Basin. The two different sites were approximately 70km...
We report a decadally resolved record of atmospheric CO₂ concentration for the last 1000 years, obtained from the West Antarctic Ice Sheet (WAIS) Divide shallow ice core. The most prominent feature of the pre-industrial period is a rapid ∼7 ppm decrease of CO₂ in a span of ∼20–50 years at...
In the future, Earth will be warmer, precipitation events will be more extreme, global mean sea level will rise, and many arid and semiarid regions will be drier. Human modifications of landscapes will also occur at an accelerated rate as developed areas increase in size and population density. We now...
In late 2007, two massive icebergs, C19a and B15a, drifted into open water and slowly disintegrated in the southernmost Pacific Ocean. Archived acoustic records show that the high-intensity underwater sounds accompanying this breakup increased ocean noise levels at mid-to-equatorial latitudes over a period of ~1.5 years. More typically, seasonal variations...
We investigate the stability of marine ice sheets by coupling a gravitationally self-consistent sea level model valid for a self-gravitating, viscoelastically deforming Earth to a 1-D marine ice sheet-shelf model. The evolution of the coupled model is explored for a suite of simulations in which we vary the bed slope...
Ice-penetrating radar produces detailed images of the internal ice layers in a glacier. Because the layers form from each year's snowfall, the curving of the internal layers is a record of the climate conditions that the glacier experienced as it flowed throughout the millennia. The Hiawatha Glacier lies on top...
The topics in this dissertation center on the snow processes that dominate mountain environments in the Western U.S. and Alaska, particularly in locations lacking long-term observational datasets or locales that are difficult to access in-person. Some are currently glacierized or have been glaciated in the recent past. Each of the...
Accurate methods are needed to measure changing soil water content from meter to kilometer scales. Laboratory results demonstrate the feasibility of the heat pulse method implemented with fiber optic temperature sensing to obtain accurate distributed measurements of soil water content. A fiber optic cable with an electrically conductive armoring was...
Spatially isolated patches of soil located in Taylor Valley, McMurdo Dry Valleys, Antarctica, are sites of elevated salt content and soil moisture. During Antarctic spring, in the absence of snow melt, visibly wet (reduced albedo) patches of soil are present at the surface. The soil pore fluids are hypersaline and...
Trends and sources of lead (Pb) aerosol pollution in the North Pacific rim of North America from 1850 to 2001 are investigated using a high-resolution (subannual to annual) ice core record recovered from Eclipse Icefield (3017 masl; St. Elias Mountains, Canada). Beginning in the early 1940s, increasing Pb concentration at...
Climate model simulations and paleoclimate proxies are two tools that enable an understanding of the climate history of the Earth. When utilized together, they form a powerful paradigm for understanding past changes. Proxies are the only physical link to the past conditions on Earth, and models “fill in the gaps”...
During rapid variations of the atmospheric mixing ratio of a trace gas, diffusive transport in the porous firn layer atop ice sheets and glaciers alters the isotopic composition of that gas relative to the overlying atmosphere. Records of past atmospheric trace gas isotopic composition from ice cores and firn need...
This study tested multiple hydrologic mechanisms to explain snowpack dynamics in extreme
rain-on-snow floods, which occur widely in the temperate and polar regions. We examined 26, 10 day
large storm events over the period 1992–2012 in the H.J. Andrews Experimental Forest in western Oregon,
using statistical analyses (regression, ANOVA, and...
Full Text:
-arid mountain basin,
Ann. Glaciol., 32, 195–195, doi:10.3189/172756401781819751.
Marks, D., A
A primary focus of the US Global Ocean Ecosystem Dynamics
(GLOBEC) program was to identify the mechanisms of ecosystem response to large-scale
climate forcing under the assumption that bottom-up forcing controls a large
fraction of marine ecosystem variability. At the beginning of GLOBEC, the prevailing
bottom-up forcing hypothesis was that...
Raman spectra distributed temperature sensing (DTS) by fiber-optic cables has
recently shown considerable promise for the measuring and monitoring of surface and
near-surface hydrologic processes such as groundwater–surface water interaction,
borehole circulation, snow hydrology, soil moisture studies, and land surface energy
exchanges. DTS systems uniquely provide the opportunity to monitor...
Basal melting of ice shelves around Antarctica contributes to formation of Antarctic Bottom Water and can affect global sea level by altering the offshore flow of grounded ice streams and glaciers. Tides influence ice shelf basal melt rate (w(b)) by contributing to ocean mixing and mean circulation as well as...
The loss of Arctic sea ice has emerged as a leading signal of global warming. This, together with acknowledged impacts on other components of the Earth system, has led to the term “the new Arctic.” Global coupled climate models predict that ice loss will continue through the twenty-first century, with...
Snow water equivalent (SWE) is a critical measurement in hydrology and water resources management. Microwave remote sensing can estimate snow water equivalent (SWE). However, the algorithms used to estimate SWE require snow grain size information. Thus, determining snow grain size is pertinent to estimate SWE. Currently, there are several models...
Leads are long fractures wide enough for a ship to travel through the ice pack. Sea ice acts as a barrier between the ocean and the atmosphere, whereas leads allow the transfer of heat and moisture between the two. Leads play a role for marine mammals and are hunting grounds...
Terrestrial chronologies from southern Greenland provide a detailed deglacial history of the Greenland Ice Sheet (GIS). The northern GIS margin history, however, is less established. Here we present surface exposure ages from moraines associated with two large outlet glaciers, Petermann and Humboldt, in the northwestern sector of the GIS. These...
The Bering Sea Shelf transitions from ice-free to mostly ice-covered and back again over each winter. Sea ice coverage and the timing of ice melt play a critical role in determining shelf structure and consequently ecosystem response during the spring transition and summer. In this study, a 2-km resolution ocean...
We present a new high-precision, high-resolution record of atmospheric methane from the West Antarctic Ice Sheet (WAIS) Divide ice core covering 1000–1800 C.E., a time period known as the late preindustrial Holocene (LPIH). The results are consistent with previous measurements from the Law Dome ice core, the only other high-resolution...
In many partially glacierized watersheds glacier recession driven by a warming climate could lead to complex patterns of streamflow response over time, often marked with rapid increases followed by sharp declines, depending on initial glacier ice cover and rate of climate change. Capturing such “phases” of hydrologic response is critical...
Arrays of hydrophones were deployed within the Bransfield Strait and Scotia Sea (Antarctic Peninsula region) from 2005 to 2009 to record ambient ocean sound at frequencies of up to 125 and 500 Hz. Icequakes, which are broadband, short duration signals derived from fracturing of large free-floating icebergs, are a prominent...
Ice–ocean interactions have profound consequences for the ocean and climate, influencing the rate of sea level rise. Submarine melt is commonly parameterized using a three-equation formulation for the heat, salt, and momentum conservation equations coupled to a buoyant plume model, together called plume-melt theory. However, recent direct observations of terminus...
The West Antarctic Ice Sheet Divide (WAIS Divide, WD) ice core is a newly drilled, high-accumulation
deep ice core that provides Antarctic climate records of
the past ~68 ka at unprecedented temporal resolution. The
upper 2850 m (back to 31.2 ka BP) have been dated using
annual-layer counting. Here we...
The major purpose of this study was to determine if
there were significant differences in the self-concepts of
vocational education teacher-trainees, non-vocational education
teacher trainees and non-education students at
Montana State University.
Two hundred students were surveyed to determine if
there were any differences in self-concepts based on
either major...
Forest canopy cover presents a major challenge for remote sensing of fractional snow-covered area (ƒSCA). Snow cover is systematically underestimated where satellites sensors cannot penetrate the forest canopy. Current canopy adjustments scale observable ƒSCA with the vegetation fraction, assuming that snow cover distributions are similar between sub-canopy and open locations....
Antarctic Ice Sheet mass balance and, hence, sea level change is affected by the floating extensions of outlet glaciers and ice streams that take up about 44% of the coastline (Drewry et al., 1982) and are referred to as "ice shelves". Ice sheet mass loss accelerates when these ice shelves...
Reconstructing the sensitivity of past climate to forcings, and of ancient glaciers and ice sheets to this climate, can allow us to better understand the range of climate and cryosphere behavior we may see in the coming centuries. The Arctic is a region of particular importance due to its well-documented...
Rising global temperatures are having lasting effects on mountain snow environments in the form of diminishing snowpacks, shorter accumulation seasons, and shifts in meltwater timing. Seasonal snowpack is a vital source of water for natural and human systems. In the forested mountain landscapes of the Pacific Northwest seasonal snowmelt feeds...
Stratigraphy and chronology are essential to sedimentological study of Earth system histories. And, stratigraphy and chronology are often challenging and interesting problems themselves. The Quaternary (2.588 Ma - present) experienced paleoenvironmental and paleo-geomagnetic variability well outside the range of the recent instrumental record, providing the opportunity to place recent observations...
Relatively little is known about how various factors influence snow water storage in forested mountain landscapes in maritime (warm winter) climates. This study took advantage of multiple snow data sources including long-term data, synoptic sampling, remote sensing, and modeling to examine factors influencing snow dynamics in the H.J. Andrews Experimental...
This report, required by state law under HB3543, provides a comprehensive assessment of the state of science of climate change as it pertains to Oregon, covering the physical, biological, and social dimensions. The first chapter summarizes the current state of knowledge of physical changes in climate and hydrology, focusing on...
Atmospheric pressure changes do not stop at the permeable snow surface but rather propagate into it. These pressure changes range from high-amplitude, low-frequency events caused by seasonal cycles and synoptic weather systems to small-amplitude, high-frequency events caused by topographic features and turbulence. The effect of pressure changes on interstitial air...
The Last Interglacial (LIG) represents an invaluable case study to investigate the response of components of the Earth system to global warming. However, the scarcity of absolute age constraints in most archives leads to extensive use of various stratigraphic alignments to different reference chronologies. This feature sets limitations to the...
In the mountains of the Western US, shifts in the timing and magnitude of snow water equivalent (SWE) over the past century are well documented and attributed to climate warming, but the magnitude of sensitivity depends on elevation. We modeled the spatial distribution of SWE and its sensitivity to climate...
Funding agencies, specifically the National Science Foundation (NSF), are placing particular emphasis on the societal relevance and broader applications of scientific research, otherwise known as Broader Impacts (BIs). Scientists are required to address the BIs merit review criterion in their research proposals or they will not get funded. However, many...
Despite advances in the understanding of rain-on-snow storms and their resulting peak flows, little is understood about the response of snowmelt to precipitation and the relative timing of the two at multiple temporal scales within such events. To address this issue, climate, snowmelt, and streamflow data were analyzed for 26...
In many regions of the world, a significant portion of the surface water originates in mountain headwaters where the timing and magnitude of streamflow is largely dictated by the seasonal storage of precipitation as snowpack and long-term storage as glaciers. Accumulation, persistence, and melt of snow and ice are functions...