The high toxicity and ability to be transported over long distances and biomagnify up food chains have earned Mercury (Hg) recognition as a contaminant of global concern. The Arctic region is particularly vulnerable to Hg with high levels of Hg being detected in marine mammals. The importance of the cryosphere, especially sea ice, has often been neglected in considerations of the extent to which atmospherically derived Hg impinges on the underlying marine system. This thesis reports the first systematic study of Hg transport in the Arctic cryosphere (sea ice, brine, snow, and melt ponds) conducted in the Amundsen Gulf from February to June 2008. Hg concentrations in bulk first-year sea ice were generally low (0.5 – 4 ng L-1), with the highest concentration in the surface granular ice layer. The highest concentrations of Hg were found in sea ice brine (up to 70 ng L-1). Atmospheric mercury depletion events (AMDEs) appear not to be an important factor in determining Hg in sea ice, with the exception of in frost flowers. Evidence of Hg accumulation during melt – refreezing cycles is seen in multi-year ice. Significant impact of AMDEs is observed on Hg concentrations in snow. Rates of deposition of atmospheric Hg ranged from 200 – 784 ng m-2 into the top 1 cm of snow. Although photo reduction and reemission to the atmosphere does occur, a considerable fraction of deposited Hg is retained in the snowpack due to subsequent burial. At one station it is estimated that less than 50% of the deposited Hg is re-emitted to the atmosphere. It is suggested that in the Beaufort Sea, where AMDEs occur frequently due to dynamic nature of the sea ice environment, a larger than suspected portion of atmospherically deposited Hg can be retained in the snowpack and enter the underlying marine system upon melt later in the season.

The high toxicity and ability to be transported over long distances and biomagnify up food chains have earned Mercury (Hg) recognition as a contaminant of global concern. The Arctic region is particularly vulnerable to Hg with high levels of Hg being detected in marine mammals. The importance of the cryosphere, especially sea ice, has often been neglected in considerations of the extent to which atmospherically derived Hg impinges on the underlying marine system. This thesis reports the first systematic study of Hg transport in the Arctic cryosphere (sea ice, brine, snow, and melt ponds) conducted in the Amundsen Gulf from February to June 2008. Hg concentrations in bulk first-year sea ice were generally low (0.5 – 4 ng L-1), with the highest concentration in the surface granular ice layer. The highest concentrations of Hg were found in sea ice brine (up to 70 ng L-1). Atmospheric mercury depletion events (AMDEs) appear not to be an important factor in determining Hg in sea ice, with the exception of in frost flowers. Evidence of Hg accumulation during melt – refreezing cycles is seen in multi-year ice. Significant impact of AMDEs is observed on Hg concentrations in snow. Rates of deposition of atmospheric Hg ranged from 200 – 784 ng m-2 into the top 1 cm of snow. Although photo reduction and reemission to the atmosphere does occur, a considerable fraction of deposited Hg is retained in the snowpack due to subsequent burial. At one station it is estimated that less than 50% of the deposited Hg is re-emitted to the atmosphere. It is suggested that in the Beaufort Sea, where AMDEs occur frequently due to dynamic nature of the sea ice environment, a larger than suspected portion of atmospherically deposited Hg can be retained in the snowpack and enter the underlying marine system upon melt later in the season.

No description available.

Near-surface air temperature (SAT) over Greenland has important effects on mass balance of the ice sheet, but it is unclear which SAT datasets are reliable in the region. Here extensive in-situ SAT measurements are used to assess monthly mean SAT from seven global reanalysis datasets, four gridded SAT analyses, one satellite retrieval and two dynamically downscaled reanalyses. Strengths and weaknesses of these products are identified, and their biases are found to vary by season and glaciological regime. MERRA2 reanalysis overall performs best with mean absolute error less than 2 °C in all months. Ice sheet-average annual mean SAT from different datasets are highly correlated in recent decades, but their 1901–2000 trends differ in sign. Compared with the MERRA2 climatology combined with gridded SAT analysis anomalies, thirty-one earth system model historical runs from the CMIP5 archive reach ~5 °C for the 1901–2000 average bias and have opposite trends for a number of sub-periods.

Polar sea ice measurements are an important contribution to global climate models. Passive and active microwave remote sensing instruments are used to track global trends in polar sea ice growth and retreat from day to day. A scatterometer sea ice extent data set is valuable for comparison with other radiometer data sets and ground based measurements. This scatterometer sea ice record began with the NASA Scatterometer (NSCAT) and continued with the Quick Scatterometer (QuikSCAT) data set. The Ku-band Oceansat-2 scatterometer (OSCAT) is very similar to the Quick Scatterometer, which operated from 1999 to 2009. OSCAT continues the Ku-band scatterometer data record through 2014 with an overlap of eighteen days with QuikSCATs mission in 2009. This thesis discusses a particular climate application of the time series for sea ice extent observation. In this thesis, a QuikSCAT sea ice extent algorithm is modified for OSCAT. Gaps in OSCAT data are accounted for using a reverse time processing approach. The data gaps are filled in to support sea ice extent mapping. The data set is validated with overlapping data from QuikSCAT as well as the sea ice extent data set calculated from Special Sensor Microwave Imager data by the NASA Team algorithm.Data from the Advanced Scatterometer (ASCAT), which operates at C-band, are processed using a Bayesian classification algorithm for a stand-alone C-band sea ice extent product to continue scatterometer sea ice extent observation past 2014. ASCAT azimuth dependence data is developed for use as a parameter in the ASCAT sea ice extent algorithm. Image dilation and erosion techniques are employed to smooth the sea ice edge and correct misclassifications. ASCAT sea ice extent data is validated to overlapping OSCAT data.

Snow and glaciers are considered the most important sources of the estimated 32-60% of global water resources which are provided by mountains. Consequently, snow and glaciers have regularly been the focus of climate change studies in mountain regions. Rock glaciers are a type of ice-debris landform characterized by creeping ice-rich permafrost. Recognition of the hydrological significance of rock glaciers is increasing and is of particular relevance to the Arid Andes, where rock glaciers cover greater area than glaciers by an order of magnitude. Little research exists on the hydrological significance of rock glaciers beyond potential water storage capacities and their runoff pathways. Additional knowledge and research approaches pertaining to the seasonal hydrological contributions and climatic sensitivities of rock glaciers are necessary for improved water resource planning in many regions around the world. This work explored the feasibility of utilizing the energy and water balance model GEOtop to quantify the thermal and hydrological dynamics of rock glaciers under several climate scenarios. Weather data was generated with the intermediate-stochastic weather generator AWE-GEN for a site in the Southeast Swiss Alps, which marked a novel approach in studies of rock glaciers. Weather data for a reference (REF) scenario was generated which approximates conditions during the observation period (1985 to 2012). AWE-GEN produced time series of weather data for the REF scenario with statistical properties of precipitation in close agreement with observations. Air temperature had substantial inaccuracies with mean annual air temperature (MAAT) cooler by 1.82 C due to negative temperature biases in summer months which are attributed to difficulties in estimating parameters of the weather generator model caused by local climatic factors. The influence of climate change was also examined. Data for 8 climate change scenarios were generated by specifying change factors for mean monthly air temperature. MAAT in the climate change scenarios was within +/-0.12 C of the speci ed change factor from MAAT in the REF scenario. The thermal and hydrological evolution of rock glacier soils were simulated for 50 years under the climatic forcing of the REF scenario followed by 50 years under each climate change scenario. Mean annual ground surface temperature (MAGST), active layer depth (Dal), permafrost total ice content (IWEtot), and the potential summer runoff contribution (MELTsum) were quanti ed and compared before and after the onset of the climate change conditions. Air temperature increases in the climate change scenarios were amplified in MAGST. Stable rock glacier points were resistant to changes in Dal and IWEtot under any annual, summer, and winter mean air temperature increase of 1 C, and summer and winter mean air temperature increases of 3 C despite notable changes in MAGST and MELTsum. Under warming scenarios, the greatest increase in MELTsum occurred for high elevation rock glacier points with the mean possible runoff contribution increasing 88% under 3 C of warming, which corroborates with increased runoff from high elevation permafrost in the Colorado Rockies in recent decades.

Warming over the past century has been greatest in high-latitudes over land and a number of environmental indicators suggest that the Arctic climate system is in the process of a major transition. Given the magnitude of observed and projected changes in the Arctic, it is essential that a better understanding of the characteristics of the Arctic climate system be achieved. In this work, I report on modifications to the UVic Earth System Climate model to allow it to represent regions of perennially-frozen ground, or permafrost. I examine the model’s representation of the Arctic climate during the 20th Century and show that it capably represents the distribution and thermal state of permafrost in the present-day climate system. I use Representative Concentration Pathways to examine a range of possible future permafrost states to the year 2500. A suite of sensitivity experiments is used to better understand controls on permafrost. I demonstrate the potential for radical environmental changes in the Arctic over the 21st Century including continued warming, enhanced precipitation and a reduction of between 29 and 54 % of the present-day permafrost area by 2100. Model projections show that widespread loss of high-latitude wetlands may accompany the loss of near surface permafrost. / Graduate

Despite their central importance to the Earth system, nowhere within the literatures of Polar Studies or the Humanities does there exist a comprehensive cultural and scientific history of ice sheets that takes into consideration both Greenland and Antarctica, or that is not constrained to a particular exploratory, technological, or geopolitical period or framing. My thesis addresses this lacunae by contributing a bi-polar, empirical history and analysis of the different scientific and cultural processes, transformations, and discontinuities through which ice sheets have been transformed from unexplored realms of the imagination, into tangible, material objects of investigation and meaning. Its scope extends from early Greek mapping to 1970. Within this timeframe, it identifies three broad phases in the perception of ice sheets. The first, preceding their earliest physical exploration, corresponds to the perception of ice sheets as one-dimensional realms defined and bounded by the human imagination. The second phase, associated with their early surface exploration between 1870 and 1930, corresponds to the perception of ice sheets as undifferentiated, two-dimensional 'topographies of absence', best characterized by their horizontal desolation. The third phase, triggered by the deployment of new technologies of sub-surface investigation such as seismic sounding, radio echo sounding (RES), and the practice of ice coring, corresponds to the perception of ice sheets as three-dimensional, super-massive, and interdependent objects of internal and material complexity. Although primarily rooted in archival research and the study of first hand textual and visual materials, my arguments and observations also draw on secondary literatures from the history of science and technology, geopolitics, visual culture, and the geography of space and place. These literatures allow me to contextualize and substantiate my analysis of historical processes within broader perspectives, notably Humboldtian science, Romanticism, visual abstraction, scientific imagery, and the Cold War.

Air, ground surface and top of permafrost temperatures (TTOP) were measured at 58 sites in three areas of Yukon and northern British Columbia in order to: (1) explore relationships between climate-permafrost transfer functions and environmental variables, (2) assess and validate the TTOP-model, and (3) attempt the first implementation of the TTOP-model (Smith and Riseborough, 1996, 2002) for these regions with complex terrain. The strongest factors controlling climate-permafrost transfer functions are elevation and land cover, though slope, aspect, topographic position and surficial geology were also investigated. In 1000 iterations of the model using random equally possible scenarios, 64% of the TTOP-model predictions were within ±1°C of measured values, a result that is 6% better than applying a simple 3°C “total offset” to the mean annual air temperature. A sensitivity analysis confirmed that the TTOP-model is most sensitive to changes in snow, thermal conductivity of the ground and summer air temperatures. A land cover driven TTOP-model was then developed and implemented. The model correctly predicts high likelihoods of permafrost (> 0.8) for sites with permafrost present and low likelihoods (< 0.4) for non-permafrost sites.

Glaciers are the essential source of fresh water not only to human sustenance, but it is also vital for all lifeforms on earth. Glaciers are also key components in understanding rapid changes in climate. This makes understanding of glacier mass, extent, and overall state essential. In this dissertation, the objective was to analyze the state of snow and ice masses in the mid (California) and low latitude (Chile/Argentina) western American regions using geospatial technology. This study also analyzed the effects of anomalies in snow mass on the regional agricultural practices in California’s Central Valley. In the Southern Andes, the digital elevation models from Shuttle Radar Topographic Mission (SRTM) (the year 2000) were compared with the elevation footprints from the Geoscience Laser Altimeter System (GLAS) campaign for the years 2004 through 2008. Generally, in all sub-regions, the elevation values were lower than the elevation for the year 2000, which demarcates continuous recession of ice mass in the Andean region. Also, this study quantified snow cover extent and mass balance variation in the Sierra Nevada and Mt. Shasta regions in California. To unearth anomalies in snow mass, study used digital elevation models generated from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) between the year 2000 and 2015. A remarkable reduction in snow cover extent of about 80% was observed in the studied watersheds of California. Lastly, the impacts of snow mass anomalies on the total water storage (TWS) and agriculture land cover in the California’s Central Valley were quantified and geo-visualized. The study noticed the change in the land cover area of about 20% (6993 sq.km) due to the alteration of Agriculture land to impervious land covers. Most of the change in the agriculture land cover of about 4402 sq.km occurred in the San Joaquin and Tulare Basins of southern Central Valley region. This dissertation concludes that the increased temperature in the Andes and California has adversely impacted Cryosphere components in the region in the past decade. Besides, it provides valuable insights into the changing state of cryosphere components and highlights impacts of anomalies in TWS on a billion-dollar agricultural industry.