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Articles 1 - 22 of 22
Full-Text Articles in Glaciology
Toward The Significance Of Crevasse Orientation In Low And High Crevassed Regions On The Kennicott Glacier, Alaska, Usa, Claire A. Sturm
Toward The Significance Of Crevasse Orientation In Low And High Crevassed Regions On The Kennicott Glacier, Alaska, Usa, Claire A. Sturm
DePaul Discoveries
Supraglacial landforms serve as potential indicators of underlying bedrock morphology and glacier dynamics. The distribution and morphology of crevasses are closely associated with stress fields and ice-flow regimes, representing processes of stable glaciers, in contrast to their reduced occurrence in stagnant or receding ice masses. The orientation and density of crevasses influence a glacier’s ability to absorb solar energy, as they facilitate movement of meltwater down to subglacial rivers. Beyond the meltwater acting as a lubricant for basal sliding, the slope of the bedrock further impacts the local velocity and ice deformation of a glacier. The study of ice-fracturing mechanics …
How’S It Growing? Tools For Observing Snow And Sea Ice In A Changing Arctic Ocean, Ian Alexander Raphael
How’S It Growing? Tools For Observing Snow And Sea Ice In A Changing Arctic Ocean, Ian Alexander Raphael
Dartmouth College Ph.D Dissertations
September Arctic sea ice extent has diminished by roughly 50% in the 45 years since satellite observations began. The Arctic Ocean may experience ice-free summers within the next decade, with implications for habitat, resource extraction, geopolitics, and local and global climate change. To predict how Arctic sea ice will change in the future, we need to understand its behavior in the present. In situ sea ice mass balance measurements (snow accumulation, ice growth, snow and ice surface melt, and bottom melt) are essential for studying the processes driving rapid changes in the ice pack, and for validating remote sensing measurements …
Reducing Uncertainty In Sea-Level Rise Prediction: A Spatial-Variability-Aware Approach, Subhankar Ghosh, Shuai An, Arun Sharma, Jayant Gupta, Shashi Shekhar, Aneesh Subramanian
Reducing Uncertainty In Sea-Level Rise Prediction: A Spatial-Variability-Aware Approach, Subhankar Ghosh, Shuai An, Arun Sharma, Jayant Gupta, Shashi Shekhar, Aneesh Subramanian
I-GUIDE Forum
Given multi-model ensemble climate projections, the goal is to accurately and reliably predict future sea-level rise while lowering the uncertainty. This problem is important because sea-level rise affects millions of people in coastal communities and beyond due to climate change's impacts on polar ice sheets and the ocean. This problem is challenging due to spatial variability and unknowns such as possible tipping points (e.g., collapse of Greenland or West Antarctic ice-shelf), climate feedback loops (e.g., clouds, permafrost thawing), future policy decisions, and human actions. Most existing climate modeling approaches use the same set of weights globally, during either regression or …
Characterization Of Site-Specific Vegetation Activity In Alaskan Wet And Dry Tundra As Related To Climate And Soil State, Michael Gregory Brown, Kyle C. Mcdonald, Reiner Zimmermann, Nicholas Steiner, Stephanie Devries, Laura Bourgeau-Chavez
Characterization Of Site-Specific Vegetation Activity In Alaskan Wet And Dry Tundra As Related To Climate And Soil State, Michael Gregory Brown, Kyle C. Mcdonald, Reiner Zimmermann, Nicholas Steiner, Stephanie Devries, Laura Bourgeau-Chavez
Advanced Science Research Center
We present discrete (2-h resolution) multi-year (2008–2017) in situ measurements of seasonal vegetation growth and soil biophysical properties from two sites on Alaska's North Slope, USA, representing dry and wet sedge tundra. We examine measurements of vertical active soil layer temperature and soil moisture profiles (freeze/thaw status), woody shrub vegetation physiological activity, and meteorological site data to assess interrelationships within (and between) these two study sites. Vegetation phenophases (cold de-hardening start, physiological function start, stem growth start, stem growth end, physiological function end, cold hardening completion) were found to have greater interannual day of year (DOY) occurrence variability at the …
Drought-Induced Biomass Burning As A Source Of Black Carbon To The Central Himalaya Since 1781 Ce As Reconstructed From The Dasuopu Ice Core, Joel D. Barker, Susan Kaspari, Paulo Gabrielli, Anna Wegner, Emilie Beaudon, M. Roxana Sierra-Hernández, Lonnie Thompson
Drought-Induced Biomass Burning As A Source Of Black Carbon To The Central Himalaya Since 1781 Ce As Reconstructed From The Dasuopu Ice Core, Joel D. Barker, Susan Kaspari, Paulo Gabrielli, Anna Wegner, Emilie Beaudon, M. Roxana Sierra-Hernández, Lonnie Thompson
Geological Sciences Faculty Scholarship
Himalayan glaciers are melting due to atmospheric warming, with the potential to limit access to water for more than 25 % of the global population that resides in these glacier meltwater catchments. Black carbon has been implicated as a factor that is contributing to Himalayan glacier melt, but its sources and mechanisms of delivery to the Himalayas remain controversial. Here, we provide a 211-year ice core record spanning 1781–1992 CE for refractory black carbon (rBC) deposition from the Dasuopu glacier ice core that has to date provided the highest-elevation ice core record (7200 m). We report an average rBC concentration …
Carbonaceous Matter In The Atmosphere And Glaciers Of The Himalayas And The Tibetan Plateau: An Investigative Review, Chaoliu Li, Fangping Yan, Shichang Kang, Caiqing Yan, Zhaofu Hu, Pengfei Chen, Shaopeng Gao, Chao Zhang, Cenlin He, Susan Kaspari, Aron Stubbins
Carbonaceous Matter In The Atmosphere And Glaciers Of The Himalayas And The Tibetan Plateau: An Investigative Review, Chaoliu Li, Fangping Yan, Shichang Kang, Caiqing Yan, Zhaofu Hu, Pengfei Chen, Shaopeng Gao, Chao Zhang, Cenlin He, Susan Kaspari, Aron Stubbins
Geological Sciences Faculty Scholarship
Carbonaceous matter, including organic carbon (OC) and black carbon (BC), is an important climate forcing agent and contributes to glacier retreat in the Himalayas and the Tibetan Plateau (HTP). The HTP – the so-called “Third Pole” – contains the most extensive glacial area outside of the polar regions. Considerable research on carbonaceous matter in the HTP has been conducted, although this research has been challenging due to the complex terrain and strong spatiotemporal heterogeneity of carbonaceous matter in the HTP. A comprehensive investigation of published atmospheric and snow data for HTP carbonaceous matter concentration, deposition and light absorption is presented, …
Mass And Number Size Distributions Of Rbc In Snow And Firn Samples From Pine Island Glacier, West Antarctica, Luciano Marquetto, Susan Kaspari, Jefferson Cardia Simões
Mass And Number Size Distributions Of Rbc In Snow And Firn Samples From Pine Island Glacier, West Antarctica, Luciano Marquetto, Susan Kaspari, Jefferson Cardia Simões
Geological Sciences Faculty Scholarship
An extended‐range Single Particle Soot Photometer (SP2) coupled to a Marin‐5 nebulizer was used to measure the refractory black carbon (rBC) mass and number size distributions in 1,004 samples from a West Antarctica snow/firn core. The SP2 was calibrated using Aquadag and a Centrifugal Particle Mass Analyzer for BC particles ranging from 0.5 to 800 fg. Our results indicate a significant contribution of rare, large particles of mass‐equivalent diameter (DBC) > 500 nm to the total rBC mass (36%), while small particles (DBC < 100 nm) are abundant but contribute <8% to total rBC mass. We observed a primary mass median diameter of 162 ± 40 nm, smaller than reported for snow in other regions of the globe but similar to East Antarctica rBC size distributions. In addition, we observed other modes at 673, 1,040, and >1,810 nm (uncontained mode). We compared two sets of samples from different seasons …
The Post-Wildfire Impact Of Burn Severity And Age On Black Carbon Snow Deposition And Implications For Snow Water Resources, Cascade Range, Washington, Ted M. Uecker, Susan D. Kaspari, Keith N. Musselman, S. Mckenzie Skiles
The Post-Wildfire Impact Of Burn Severity And Age On Black Carbon Snow Deposition And Implications For Snow Water Resources, Cascade Range, Washington, Ted M. Uecker, Susan D. Kaspari, Keith N. Musselman, S. Mckenzie Skiles
Geological Sciences Faculty Scholarship
Wildfires in the snow zone affect ablation by removing forest canopy, which enhances surface solar irradiance, and depositing light absorbing particles [LAPs, such as black carbon (BC)] on the snowpack, reducing snow albedo. How variations in BC deposition affects post-wildfire snowmelt timing is poorly known and highly relevant to water resources. We present a field-based analysis of BC variability across five sites of varying burn age and burn severity in the Cascade Range, Washington State, United States. Single particle soot photometer (SP2) analyses of BC snow concentrations were used to assess the impact of BC on snow albedo, and radiative …
Climate From The Mcmurdo Dry Valleys, Antarctica, 1986–2017: Surface Air Temperature Trends And Redefined Summer Season, Maciej K. Obryk, Peter T. Doran, Andrew G. Fountain, M. Myers, Christopher P. Mckay
Climate From The Mcmurdo Dry Valleys, Antarctica, 1986–2017: Surface Air Temperature Trends And Redefined Summer Season, Maciej K. Obryk, Peter T. Doran, Andrew G. Fountain, M. Myers, Christopher P. Mckay
Geology Faculty Publications and Presentations
The weather of the McMurdo Dry Valleys, Antarctica, the largest ice‐free region of the Antarctica, has been continuously monitored since 1985 with currently 14 operational meteorological stations distributed throughout the valleys. Because climate is based on a 30‐year record of weather, this is the first study to truly define the contemporary climate of the McMurdo Dry Valleys. Mean air temperature and solar radiation based on all stations were −20°C and 102 Wm−2, respectively. Depending on the site location, the mean annual air temperatures on the valleys floors ranged between −15°C and −30°C, and mean annual solar radiation varied …
Quantifying The Effects Of Wind Regimes And Temperature On Surface Melt Over The Antarctic Peninsula (1982–2017) Through Modeling, Remote Sensing And In-Situ Data, Rajashree Datta
Dissertations, Theses, and Capstone Projects
Surface melting over the Antarctic Peninsula (AP) plays a crucial role for the stability of ice shelves and dynamics of grounded ice, hence modulating the mass balance in a region of the world which is particularly sensitive to increasing surface temperatures. Understanding the processes that drive melting using surface energy and mass balance models is fundamental to improving estimates of current and future surface melting and associated sea level rise through ice-shelf collapse. This is even more important in view of the specific challenges presented by how circulation patterns over the topographically-complex Antarctic Peninsula, especially foehn winds, impact surface melt. …
Spectral Signatures Of Submicron Scale Light-Absorbing Impurities In Snow And Ice Using Hyperspectral Microscopy, Farra Dal Anna, Susan Kaspari, James Beach, Thomas D. Bucheli, Michael Schaepman, Margit Schwikowski
Spectral Signatures Of Submicron Scale Light-Absorbing Impurities In Snow And Ice Using Hyperspectral Microscopy, Farra Dal Anna, Susan Kaspari, James Beach, Thomas D. Bucheli, Michael Schaepman, Margit Schwikowski
Geological Sciences Faculty Scholarship
Light-absorbing impurities (LAI) can darken snow and ice surfaces, reduce snow/ice albedo and accelerate melt. Efforts to allocate the relative contribution of different LAI to snow/ice albedo reductions have been limited by uncertainties in the optical properties of LAI. We developed a new method to measure LAI spectral reflectance at the submicron scale by modifying a Hyperspectral Imaging Microscope Spectrometer (HIMS). We present the instrument’s internal calibration, and the overall small influence of a particle’s orientation on its measured reflectance spectrum. We validated this new method through the comparison with a field spectroradiometer by measuring different standard materials. Measurements with …
Optimized Method For Black Carbon Analysis In Ice And Snow Using The Single Particle Soot Photometer, I. A. Wendl, James A. Menking, R. Färber, M. Gysel, Susan D. Kaspari, M. J. G. Laborde, M. Schwikowski
Optimized Method For Black Carbon Analysis In Ice And Snow Using The Single Particle Soot Photometer, I. A. Wendl, James A. Menking, R. Färber, M. Gysel, Susan D. Kaspari, M. J. G. Laborde, M. Schwikowski
All Faculty Scholarship for the College of the Sciences
In this study we attempt to optimize the method for measuring black carbon (BC) in snow and ice using a Single Particle Soot Photometer (SP2). Beside the previously applied ultrasonic (CETAC) and Collison-type nebulizers we introduce a jet (Apex Q) nebulizer to aerosolize the aqueous sample for SP2 analysis. Both CETAC and Apex Q require small sample volumes (a few milliliters) which makes them suitable for ice core analysis. The Apex Q shows the least size-dependent nebulizing efficiency in the BC particle diameter range of 100–1000 nm. The CETAC has the advantage that air and liquid flows can be monitored …
Seasonal And Elevational Variations Of Black Carbon And Dust In Snow And Ice In The Solu-Khumbu, Nepal And Estimated Radiative Forcings, Susan Kaspari, T. H. Painter, M. Gysel, S. M. Skiles, M. Schwikowski
Seasonal And Elevational Variations Of Black Carbon And Dust In Snow And Ice In The Solu-Khumbu, Nepal And Estimated Radiative Forcings, Susan Kaspari, T. H. Painter, M. Gysel, S. M. Skiles, M. Schwikowski
All Faculty Scholarship for the College of the Sciences
Black carbon (BC) and dust deposited on snow and glacier surfaces can reduce the surface albedo, accelerate snow and ice melt, and trigger albedo feedback. Assessing BC and dust concentrations in snow and ice in the Himalaya is of interest because this region borders large BC and dust sources, and seasonal snow and glacier ice in this region are an important source of water resources. Snow and ice samples were collected from crevasse profiles and snow pits at elevations between 5400 and 6400 m a.s.l. from Mera glacier located in the Solu-Khumbu region of Nepal during spring and fall 2009, …
Influence Of Regional Precipitation Patterns On Stable Isotopes In Ice Cores From The Central Himalayas, H. Pang, S. Hou, Susan Kaspari, P. A. Mayewski
Influence Of Regional Precipitation Patterns On Stable Isotopes In Ice Cores From The Central Himalayas, H. Pang, S. Hou, Susan Kaspari, P. A. Mayewski
All Faculty Scholarship for the College of the Sciences
Several ice cores have been recovered from the Dasuopu (DSP) Glacier and the East Rongbuk (ER) Glacier in the central Himalayas since the 1990s. Although the distance between the DSP and the ER ice core drilling sites is only 125 km, the stable isotopic record (18O or D) of the DSP core is interpreted in previous studies as a temperature proxy, while the ER core is interpreted as a precipitation proxy. Thus, the climatological significance of the stable isotopic records of these Himalayan ice cores remains a subject of debate. Based on analysis of regional precipitation patterns over the region, …
Black Carbon Measurements Of Snow And Ice Using The Single Particle Soot Photometer: Method Development And An Ad 1852-1999 Record Of Atmospheric Black Carbon From A Mount Logan Ice Core, James Andrew Menking
Black Carbon Measurements Of Snow And Ice Using The Single Particle Soot Photometer: Method Development And An Ad 1852-1999 Record Of Atmospheric Black Carbon From A Mount Logan Ice Core, James Andrew Menking
All Master's Theses
Black carbon (BC), produced by the combustion of fossil and biofuels, warms the climate by absorbing solar radiation when in the atmosphere and by reducing the albedo of snow and ice when deposited. Measuring BC in snow and ice is important for estimating albedo reduction and developing historical records of BC concentration. Experiments were conducted to further develop a method for measuring BC in snow and ice using the Single Particle Soot Photometer (SP2). Results suggest the optimal procedures for sample storage, treatment, and nebulization, and analysis and calibration of BC concentrations measured using the SP2 coupled to a CETAC …
Assessment Of Black Carbon In Snow And Ice From The Tibetan Plateau And Pacific Northwest, Matthew Glen Jenkins
Assessment Of Black Carbon In Snow And Ice From The Tibetan Plateau And Pacific Northwest, Matthew Glen Jenkins
All Master's Theses
An ice core from Mt. Geladandong, Tibetan Plateau, spanning 1853-1983, and snow samples collected over two winters from the Cascade Mountains were analyzed for concentrations of black carbon (BC) using a Single Particle Soot Photometer (SP2). From the ice core, the high-resolution BC record displayed substantial variability, a 2-fold increase in peak concentrations from 1853-1930 to 1930-1983, and a 1.6-fold increase in average concentrations from 1853-1975 to 1975-1983. Concentrations were also higher than at two areas closer to BC sources and analyzed by the same method. In the Pacific Northwest, BC concentrations varied seasonally and annually, with the highest concentrations …
Post-Coring Entrapment Of Modern Air In Some Shallow Ice Cores Collected Near The Firn-Ice Transition: Evidence From Cfc-12 Measurements In Antarctic Firn Air And Ice Cores, Murat Aydin, S. A. Montzka, M. O. Battle, M. B. Williams, Warren J. De Bruyn, J. H. Butler, K. R. Verhulst, C. Tatum, B. K. Gun, D. A. Plotkin, B. D. Hall, Eric S. Saltzman
Post-Coring Entrapment Of Modern Air In Some Shallow Ice Cores Collected Near The Firn-Ice Transition: Evidence From Cfc-12 Measurements In Antarctic Firn Air And Ice Cores, Murat Aydin, S. A. Montzka, M. O. Battle, M. B. Williams, Warren J. De Bruyn, J. H. Butler, K. R. Verhulst, C. Tatum, B. K. Gun, D. A. Plotkin, B. D. Hall, Eric S. Saltzman
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
In this study, we report measurements of CFC-12 (CCl2F2) in firn air and in air extracted from shallow ice cores from three Antarctic sites. The firn air data are consistent with the known atmospheric history of CFC-12. In contrast, some of the ice core samples collected near the firn-ice transition exhibit anomalously high CFC-12 levels. Together, the ice core and firn air data provide evidence for the presence of modern air entrapped in the shallow ice core samples that likely contained open pores at the time of collection. We propose that this is due to closure of the open pores …
Atmospheric Soluble Dust Records From A Tibetan Ice Core: Possible Climate Proxies And Teleconnection With The Pacific Decadal Oscillation, B. Grigholm, P. A. Mayewski, S. Kang, Y. Zhang, Susan Kaspari, S. B. Sneed, Q. Zhang
Atmospheric Soluble Dust Records From A Tibetan Ice Core: Possible Climate Proxies And Teleconnection With The Pacific Decadal Oscillation, B. Grigholm, P. A. Mayewski, S. Kang, Y. Zhang, Susan Kaspari, S. B. Sneed, Q. Zhang
Geological Sciences Faculty Scholarship
In autumn 2005, a joint expedition between the University of Maine and the Institute of Tibetan Plateau Research recovered three ice cores from Guoqu Glacier (33°34′37.8″N, 91°10′35.3″E, 5720 m above sea level) on the northern side of Mt. Geladaindong, central Tibetan Plateau. Isotopes (δ18O), major soluble ions (Na+, K+, Mg2+, Ca2+, Cl−, NO3−, SO42−), and radionuclide (β‐activity) measurements from one of the cores revealed a 70‐year record (1935–2005). Statistical analysis of major ion time series suggests that atmospheric soluble …
Iron In Ice Cores From Law Dome: A Record Of Atmospheric Iron Deposition For Maritime East Antarctica During The Holocene And Last Glacial Maximum, Ross Edwards, Peter N. Sedwick, Vin Morgan, Claude Boutron
Iron In Ice Cores From Law Dome: A Record Of Atmospheric Iron Deposition For Maritime East Antarctica During The Holocene And Last Glacial Maximum, Ross Edwards, Peter N. Sedwick, Vin Morgan, Claude Boutron
OES Faculty Publications
Total dissolvable iron (TDFe) was measured in sections of ice cores recovered from Law Dome on the coast of Wilkes Land, East Antarctica. These samples include ice dating from the Last Glacial Maximum (LGM), the Last Deglaciation, and the early and mid Holocene as well as samples from the Anthropocene that have been dated with seasonal to annual resolution. Combining our TDFe concentration data with estimates of the ice accumulation rate, we estimate the atmospheric iron deposition for Law Dome and the adjacent Southern Ocean during these periods. Our results indicate that the atmospheric iron deposition flux to this region …
A 700 Year Record Of Southern Hemisphere Extratropical Climate Variability, Paul A. Mayewski, Kirk A. Maasch, James W.C. White, Eric J. Steig, E A. Meyerson, Ian D. Goodwin, Vin Morgan, Tas D. Van Ommen, Mark Aj Curran, Joseph M. Souney Jr, K Kreutz
A 700 Year Record Of Southern Hemisphere Extratropical Climate Variability, Paul A. Mayewski, Kirk A. Maasch, James W.C. White, Eric J. Steig, E A. Meyerson, Ian D. Goodwin, Vin Morgan, Tas D. Van Ommen, Mark Aj Curran, Joseph M. Souney Jr, K Kreutz
All Materials
Annually dated ice cores from West and East Antarctica provide proxies for past changes in atmospheric circulation over Antarctica and portions of the Southern Ocean, temperature in coastal West and East Antarctica, and the frequency of South Polar penetration of El Niño events. During the period AD 1700–1850, atmospheric circulation over the Antarctic and at least portions of the Southern Hemisphere underwent a mode switch departing from the out-of-phase alternation of multi-decadal long phases of EOF1 and EOF2 modes of the 850 hPa field over the Southern Hemisphere (as defined in the recent record by Thompson and Wallace, 2000; Thompson …
Atmospheric Variability Of Methyl Chloride During The Last 300 Years From An Antarctic Ice Core And Firn Air, M. Aydin, Eric S. Saltzman, Warren J. De Bruyn, S. A. Montzka, J. H. Butler, M. Battle
Atmospheric Variability Of Methyl Chloride During The Last 300 Years From An Antarctic Ice Core And Firn Air, M. Aydin, Eric S. Saltzman, Warren J. De Bruyn, S. A. Montzka, J. H. Butler, M. Battle
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
Measurements of methyl chloride (CH3Cl) in Antarctic polar ice and firn air are used to describe the variability of atmospheric CH3Cl during the past 300 years. Firn air results from South Pole and Siple Dome suggest that the atmospheric abundance of CH3Cl increased by about 10% in the 50 years prior to 1990. Ice core measurements from Siple Dome provide evidence for a cyclic natural variability on the order of 10%, with a period of about 110 years in phase with the 20th century rise inferred from firn air. Thus, the CH3Cl increase measured in firn air may largely be …
A 700-Year Record Of Atmospheric Circulation Developed From The Law Dome Ice Core, East Antarctica, Joseph M. Souney Jr, Paul A. Mayewski, Ian D. Goodwin, David Meeker, Vin Morgan, Mark Aj Curran, Tas D. Van Ommen, Anne S. Palmer
A 700-Year Record Of Atmospheric Circulation Developed From The Law Dome Ice Core, East Antarctica, Joseph M. Souney Jr, Paul A. Mayewski, Ian D. Goodwin, David Meeker, Vin Morgan, Mark Aj Curran, Tas D. Van Ommen, Anne S. Palmer
All Materials
A 700-year, high-resolution, multivariate ice core record from Dome Summit South (DSS) (66°46′S, 112°48′E; 1370 m), Law Dome, is used to investigate sea level pressure (SLP) variability in the region of East Antarctica. Empirical orthogonal function (EOF) analysis reveals that the first EOF (LDEOF1) of the combined glaciochemical, oxygen isotope ratio, and accumulation rate record from DSS represents most of the variability in sea salt seen in the record. LDEOF1 is positively correlated (at least 95% confidence level) to instrumental June mean SLP across most of East Antarctica. Over the last 700 years, LDEOF1 levels at Law Dome were the …