Cold Regions Research And Engineering Laboratory Research Articles

Identifying ice wedges in ground-penetrating radar data from the Cold Regions Research and Engineering Laboratory permafrost tunnel, Fox, Alaska

The warming of Alaska’s permafrost has been leading to thawing within its discontinuous permafrost. This can cause ice wedges to melt, resulting in thermokarst formations such as sinkholes and landslides, which are causing damage to Alaskan infrastructure. To avoid developing further infrastructure in areas containing ice wedges, it is necessary to improve methods of detecting subsurface ground ice. Ground-penetrating radar (GPR) is a nonintrusive remote sensing method of locating and characterizing permafrost and other subsurface features that are not evident on a cut face or surface. When applied to the detection of ice wedges at the Cold Regions Research and Engineering Laboratory permafrost tunnel in Fox, Alaska, a few identifying features have been observed which corresponded with prior research. We first use GPR reflections of areas along the tunnel walls holding known ice wedges to verify the identifying features of an ice wedge within GPR data. We use these reflections as test data to identify possible ice wedges in locations where they were not observed on the tunnel walls.

An Improved Backscattering Theoretical Model for Snow Area

Remote sensing has been studied for a long time to monitor the earth terrain. Remote sensing technology has been used globally in many different fields and one of the most popular area of study that uses remote sensing technology is snow monitoring. In previous researches, remote sensing has been modelled on snow area to study the scattering mechanisms of various scattering processes. In this paper, surface volume second order term that was dropped in previous study is derived, included and studied to observe the improvement in the surface volume backscattering coefficient. This new model is applied on snow layer above ground and the snow layer is modelled as a volume of ice particles as the Mie scatterers that are closely packed and bounded by irregular boundaries. Various parameters are used to investigate the improvement of adding the new term. Results show improvement in cross-polarized return, for all the range of parameters studied. Comparison is made with the field measurement result from U.S. Army Cold Regions Research and Engineering Laboratory (CRREL) in 1990. Close agreement is shown between developed model and data field backscattering coefficient result.

Evaluation of 2-m Air Temperature and Surface Temperature from ERA5 and ERA-I Using Buoy Observations in the Arctic during 2010–2020

In data-sparse regions such as the Arctic, atmospheric reanalysis is one of the key tools for understanding rapid climate change at the regional and global scales. The utility of reanalysis datasets based on data assimilation is affected by their accuracy and biases. Therefore, it is important to evaluate their performance. Here, we conduct inter-comparisons of two temperature variables, namely, the 2-m air temperature (Ta) and the surface temperature (Ts), from the widely used ERA-I and ERA5 reanalysis datasets provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) against in situ observations from three international buoy programs (i.e., the International Arctic Buoy Programme (IABP), the Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC), and the Cold Regions Research and Engineering Laboratory (CRREL)) during 2010–2020 in the Arctic. Overall, the results show that both the ERA-I and ERA5 were well correlated with the buoy observations, with the highest correlation coefficient reaching 0.98. There were generally warm Ta biases for both ERA-I (2.27 ± 3.33 °C) and ERA5 (2.34 ± 3.22 °C) when compared with more than 3000 matching pairs of daily buoy observations. The warm Ta biases of both reanalysis datasets exhibited seasonal variations, reaching the maximum of 3.73 ± 2.84 °C in April and the minimum of 1.36 ± 2.51 °C in September. For Ts, both ERA-I and ERA5 exhibited good consistencies with the buoy observations, but have higher amplitude biases compared with those for Ta, with generally negative biases of −4.79 ± 4.86 °C for ERA-I and −4.11 ± 3.92 °C for ERA5. For both reanalysis datasets, the largest bias of Ts (−11.18 ± 3.08 °C) occurred in December, while the biases were rather small (less than −3 °C) in the warmer months (April to October). The cold Ts biases for ERA-I and ERA5 were probably overestimated due to the location of the surface temperature sensors on the buoys, which may have been affected by snow cover. Both the Ta and Ts biases varied for different buoy programs and different sea ice concentration conditions, yet they exhibited similar trends.

(Invited) Atmospheric Corrosion Monitoring in Cold Arctic Climate Using Modular Corrosion Test Racks

Atmospheric corrosion is a complex process, which involves chemical, electrochemical, and physical changes to the metal exposed. Atmospheric corrosion occurs when a metal surface is under a thin layer of moisture, but not completely immersed, and the metal surface corrodes while exposed to environmental factors. The arctic and sub-arctic region identified by the U.S. Army Cold Regions Research and Engineering Laboratory (CRREL) has an average temperature of -18oC or less during winter. It is commonly assumed that there is very little to no corrosion in cold environments. However, previous studies in the Antarctic and Arctic regions have shown significant corrosion damage when exposed to cold conditions. Studies in the sub-arctic region of Canada, Norway, and Russia show extensive atmospheric corrosion rates (when compared to Antarctica) due to human developments and the resulting increase in mining and metallurgical industries. Experimental and theoretical work has shown that the electrochemical process proceeds at temperatures as low as -25oC to -20oC . Moreover, very little corrosion data are available for metal alloys exposed to cold arctic and sub-arctic conditions. The two important factors that affect atmospheric corrosion rates are aerosol chlorides (or salt-laden snow from the marine environment or deicing salts on roads) and time of wetness (TOW) along with other climatic parameters such as rainfall, temperature, humidity. Factors that drive the atmospheric corrosion in cold climates are winds that can bring in salt-laden snow from the marine environment and the use of de-icing salts can also contribute to high levels of chlorides. The eutectic point or the freezing point of de-icing salts can be lowered to -50oC, melting the ice/snow layer on top of metal samples. This phenomenon keeps metal samples moist for much longer periods, thus increasing the TOW. In the presence of chlorides and moisture, extensive atmospheric corrosion damages can be observed on metal samples. Another contributing factor to high corrosion rates is low rainfall, which in turn cannot periodically wash off the deposited chlorides and SO2 on top of the samples. In addition, ever-increasing ambient temperatures due to climate change in recent years affect the snow presence on top of the metal samples. The temperature of the samples is not too high to evaporate the snow/ice deposited, but high enough to cause melt and sustain moisture for longer periods of time. This leads to the formation of varying thickness of wet ice/snow layers on the metal surface. Long hours of sunlight in the summer also increase the surface temperature of metal samples beyond the ambient temperatures, causing dew formation and condensation, which in turn results in higher TOW. The atmospheric corrosion damage in cold environments is close to the main human activity, which is concentrated near the coastal areas. The substantial human growth and climate change in the arctic and sub-arctic region pushes for a renewed better understanding of the atmospheric corrosion mechanisms that can lead to good choice of materials selection and better design practices for infrastructure and other applications. The combination of urbanization and proximity to marine environments make arctic and sub-arctic regions in North America, particularly Alaska, an important natural laboratory to study atmospheric corrosion in cold regions. Design and establishment of modular corrosion test racks equipped with weather stations will be discussed. The angle of exposure can be changed to 0, 30 and 45-degrees to the horizontal (see the attached figure). This will allow us to test the metals alloys exposed to different angles for the same exposure period and study the effect of snow/ice retention on top of the metal surface. Figure 1

Measurements of beryllium isotopes in ice wedges in Alaska

To explore the possibility of using ground ice archives for studies of the cosmogenic radionuclide 10Be, we analyzed the beryllium isotopes in ice wedges exposed in the Cold Regions Research and Engineering Laboratory (CRREL) Permafrost Tunnel and the Barrow Permafrost Tunnel in Alaska. We determined the concentrations of 10Be and 9Be in samples pretreated following two procedures: acidification before (procedure A) and after (procedure B) removal of particles. The 10Be and 9Be concentrations spanned wide ranges. Concentrations in procedure A samples were higher than those in procedure B samples. The 10Be/9Be ratios fell within a narrow range, and values from CRREL (about 8.5 × 10−9) and Barrow (about 7 × 10−9) were of the same order of magnitude. Further studies are needed to validate our findings and assess the feasibility of using the 10Be/9Be ratio of syngenetic ice wedges for reconstruction of 10Be variations due to cosmogenic and environmental changes, and radiometric dating of ice-wedge sequences that contain very old (beyond 1 Ma) ice.

UNMANNED AERIAL SYSTEM LIDAR SURVEY OF TWO BREAKWATERS IN THE HAWAIIAN ISLANDS

The U.S. Army Corps of Engineers (USACE), Honolulu District (POH) is responsible for the operation and maintenance of 26 navigation projects within the State of Hawaii and the U.S. Pacific territories. The majority of these deep-draft and small-boat harbors include breakwaters that are consistently exposed to a substantial and varied Pacific Ocean wave climate, requiring POH to maintain a rigorous structure condition inspection program to ensure safe and efficient operations at all of its navigation projects. As part of its constant efforts to improve the quality and efficiency of this inspection program, POH has joined with the USACE Cold Regions Research and Engineering Laboratory (CRREL) Remote Sensing and GIS Center of Expertise to utilize an Unmanned LiDAR Scanning (ULS) system to collect LiDAR (Light Detection and Ranging) spatial data and co-registered imagery of breakwaters at Hilo Deep Draft Harbor on the island of Hawaii, and Kaumalapau Deep Draft Harbor on the island of Lanai.

Hourly mass and snow energy balance measurements from Mammoth Mountain, CA USA, 2011–2017

Abstract. The mass and energy balance of the snowpack govern its evolution. Direct measurement of these fluxes is essential for modeling the snowpack, yet there are few sites where all the relevant measurements are taken. Mammoth Mountain, CA USA, is home to the Cold Regions Research and Engineering Laboratory and University of California – Santa Barbara Energy Site (CUES), one of five energy balance monitoring sites in the western US. There is a ski patrol study site on Mammoth Mountain, called the Sesame Street Snow Study Plot, with automated snow and meteorological instruments where new snow is hand-weighed to measure its water content. There is also a site at Mammoth Pass with automated precipitation instruments. For this dataset, we present a clean and continuous hourly record of selected measurements from the three sites covering the 2011–2017 water years. Then, we model the snow mass balance at CUES and compare model runs to snow pillow measurements. The 2011–2017 period was marked by exceptional variability in precipitation, even for an area that has high year-to-year variability. The driest year on record, and one of the wettest years, occurred during this time period, making it ideal for studying climatic extremes. This dataset complements a previously published dataset from CUES containing a smaller subset of daily measurements. In addition to the hand-weighed SWE, novel measurements include hourly broadband snow albedo corrected for terrain and other measurement biases. This dataset is available with a digital object identifier: https://doi.org/10.21424/R4159Q.

Remote Sensing of Oil In and Under Ice in a Climate-Controlled Test Basin

Abstract (2017-111) The ability to rapidly detect and delineate an oil spill in an Arctic environment is critical for efficient and effective response. The International Association of Oil and Gas Producers (IOSP), Arctic Oil Spill Response Technology – Joint Industry Programme (JIP) funded a novel controlled laboratory experiment to assess the relative efficacy of a variety of remote sensing instruments. This unbiased evaluation of existing and emerging technologies was recently conducted in the Ice Engineering Test Basin at the U.S. Army Engineer Research and Development Center’s Cold Regions Research and Engineering Laboratory (CRREL) in Hanover, New Hampshire, USA. CRREL provided the unique testing environment for sensor evaluation using the 120 ft. long by 30 ft. wide by 8 ft. deep Test Basin. The refrigerated Test Basin was filled with a manufactured saltwater solution and an 80 cm sea ice sheet was grown with fifteen individual containment hoops. Within the individual containment hoops, oil volumes were injected at predetermined ice thicknesses leading to oil encapsulation at differing ice depths. The Prince William Sound Oil Spill Recovery Institute assembled a team of remote sensing experts to select, operate and interpret sensors to examine and validate oil detection capabilities in level sea ice. Testing covered the full ice cycle from fresh oil and encapsulated oil in growing ice to migrating oil during ice melt out. Five aerial sensors were attached to a cantilevered boom on a motorized carriage operating above the ice surface, while at the bottom of the tank were nine subsea sensors installed on a computer-controlled traveling underwater platform Ice cores were obtained outside the hoops during ice growth and in designated hoops during the melt-out phase, with the objective of characterizing ice structure and oil migration using crystallography and CT scanning. Environmental measurements that would affect sensor performance such as resistivity, acoustics, air, ice and water temperatures were also recorded. This experiment provided a comprehensive side-by comparison of the sensors evaluated, while correlating measurements with the ice properties. The paper will provide a full description of the hoop layout plan, the oil injection process, and the measurements schedule that minimized sensor interference.

Investigations of skeletal layer microstructure in the context of remote sensing of oil in sea ice

ABSTRACT (2017-159)The Arctic Oil Spill Response Technology – Joint Industry Program (JIP) funded a controlled basin experiment in November 2014 to assess the relative capabilities of a variety of oil in ice remote sensing techniques. An 80-cm sheet of level salt-water ice was grown in the Test Basin facility at the US Army Corps of Engineers Cold Regions Research and Engineering Laboratory (CRREL) in Hanover, New Hampshire. The basin ice was representative of natural level sea ice grown under quiescent conditions. This created a controlled baseline environment to compare different sensors with a manageable number of variables. The sensor testing spanned a two-month ice growth phase and a one-month decay/melt period. The detailed physical and electrical properties of the lab-grown ice sheet were monitored over the course of the experiment.Analysis of preliminary sensor data revealed that the skeletal layer--the soft, porous band of new ice crystals at the growing ice water interface--plays a significant role in the process of incorporation of oil into the ice sheet, with oil infiltration occurring between the small lamellae structures. In addition, the underwater sensors, particularly acoustic sensors, appeared to be very sensitive to skeletal layer properties, especially the surface roughness of the ice/water interface and the density of the skeletal layer.Preliminary X-ray micro-computed tomography (micro-CT) data collected as part of the experiment demonstrated a qualitative scale dependence of sensor response to the skeletal layer microstructure. We used a cold-hardened Bruker SkyScan 1173 micro-CT scanner, housed in a −10 °C cold room, to generate full 3-dimensional x-ray images of the sea ice samples. We have demonstrated that the system is capable of distinguishing areas of void space, brine, ice, and oil at 40 micron resolution. The micro-CT scans were used to characterize the skeletal layer of the ice, including measuring density, thickness, orientation and spacing of the lamellae at 39 – 71 micron voxel resolution.Characterizing the ice structure with high resolution micro-CT imaging may resolve some of the ambiguity in the sensor measurements and lead to improved accuracy of the numerical models that predict sensor performance in different oil and ice scenarios.

Detection of oil in and under ice

ABSTRACT (2017-147) In 2014, researchers from ten organizations came to the U.S. Army Corps of Engineers, Cold Regions Research and Engineering Laboratory (CRREL) in New Hampshire to conduct a first of its kind large-scale experiment aimed at determining current sensor capabilities for detecting oil in and under sea ice. This project was the second phase of the Oil Spill Detection in Low Visibility and Ice research project of the International Association of Oil and Gas Producers (IOGP), Arctic Oil Spill Response Technology - Joint Industry Programme. The objectives of the project were to:Acquire acoustic, thermal, optical and radar signatures of oil on, within, and underneath a level sheet of laboratory sea ice.Determine the capabilities of various sensors to detect oil in specific ice environments created in a test tank, including freeze-up, growth and melt.Model the potential performance of the sensors under realistic field conditions using the test data for validation.Recommend the most effective sensor suite of existing sensors for detecting oil in the ice environment. The sensor testing spanned a two-month ice growth phase and a one-month decay/melt period. The growth phase produced an 80 centimeter thick level sheet of salt water ice representative of natural sea ice grown under quiescent conditions. Above-ice sensors included frequency modulated continuous wave radar, ground penetrating radar, laser fluorescence polarization sensor, spectral radiometer, visible and infrared cameras. Below-ice sensors included acoustics (broadband, narrowband, and multibeam sonars), spectral radiometers, cameras, and fluorescence polarization. Measurements of physical and electrical properties of the ice and oil within the ice were provided to optical, acoustic, and radar modelers as inputs into their models. The models were then used to extrapolate the sensors’ laboratory performance to potential performance over a range of field conditions. All selected sensors detected oil under some conditions. The radar systems were the only above-ice sensors capable of detecting oil below or trapped within the ice. Cameras below the ice detected oil at all stages of ice growth, and the acoustic and fluorescence systems detected encapsulated oil through limited amounts of new ice growth beneath the oil. No single sensor detected oil in and below ice under all conditions tested. However, we used the test results to identify suites of sensors that could be deployed today both above and below the ice to detect and map an oil spill within ice covered waters.

Ongoing Research on Herding Agents for In Situ Burning in Arctic Waters: Laboratory and Test Tank Studies on Windows-of-Opportunity

ABSTRACT Researching the use of herding agents to contain and thicken oil slicks for in situ burning in Arctic waters continues under the auspices of the International Association of Oil and Gas Producers (IOGP) Arctic Oil Spill Response Technology-Joint Industry Programme. In 2014/2015 laboratory and test tank studies were conducted on defining potentials for effective herder use. The objective of these experiments was to determine the window-of-opportunity for two commercially available herders (ThickSlick 6535 and OP 40) to contract slicks of weathered oils to ignitable thicknesses. The experiments involved a range of crude oils that were quantitatively evaporated and emulsified (ANS, Endicott, Grane and Terra Nova). Small and medium-scale herding experiments (1-m2 quiescent pans, Dynamic Film Performance tests on a Rocking Shaker, 10-m2 quiescent pools and tests in an indoor wind/wave tank) were carried out at the SL Ross laboratory in Ottawa, ON. Larger-scale tests were conducted in 28.5-m2 quiescent refrigerated pools at the US Army Corps of Engineers Cold Regions Research and Engineering Laboratory (CRREL) in Hanover, NH. The purpose of these experiments was to determine at what point (defined by oil type, evaporation and emulsion water) the herders could no longer contract the slicks to an ignitable thickness in cold ice-free water and slush ice. Some laboratory tests involved burning the herded slicks under a fume hood.

Oil in and under Ice Detection using Nuclear Magnetic Resonance

ABSTRACT (2017-387) The application of existing remote sensing sensors and technologies for the detection of oil in and under ice is an ongoing and active research area. Currently, the suite of sensors that have and are being tested include acoustic, radar, optical and fluorosensors. Another technology being tested is Nuclear Magnetic Resonance (NMR) in the earth’s magnetic field. NMR to detect oil in and under ice has undergone extensive testing since 2006 and results to date have been promising. Field tests performed using a prototype 1 × 1 m flat transmitting/receiving antenna coil have differentiated seawater and Crisco® oil, a crude-oil surrogate. Research has been focused on scaling-up the 1 m2 prototype to increase the signal-to-noise ratio (SNR) and allow the sensor to detect oil beneath ice that is up to 1 m thick. The coil currently being tested has a diameter of 6 m in a modified figure-8 pattern. This coil was being tested at Cold Regions Research and Engineering Laboratory (CRREL) in Hanover, New Hampshire, USA. The final phase of feasibility testing was completed in late 2016 with the use of a ruggedized NMR system flown under a helicopter over a pond. The ruggedized NMR system was able to detect a 1.0 cm thick layer of a crude oil surrogate under ~ 110 cm of simulated ice.

Advances in Remote Sensing Research on Oil and Ice from the IOGP Arctic Oil Spill Response Technology JIP

ABSTRACT (2017-044) The IOGP Arctic Oil Spill Response Technology Joint Industry Program’s Remote Sensing Technical Working Group was initiated in 2012 with the objective to expand the oil industry’s detection and monitoring capabilities for spills on, under, around or in ice. The first phase produced two state-of-knowledge reports assessing sensor capabilities above and below the ice. A key finding from these studies was that many existing remote sensing platforms and sensors originally developed for oil on open water can also provide effective sensing in a broad range of ice conditions. The second phase covered an integrated experiment that included sensor testing in a cold basin, followed by modeling to determine potential applicability of different sensors in a wider range of sea-ice conditions. Five above-ice (Frequency Modulated Continuous Wave Radar (FMCW), ground penetrating radar (GPR), visible and infrared cameras and laser fluorescence polarization [LP] sensor) and seven below-ice (high dynamic range optical camera, visible and infrared spectrometer, LP sensor, broadband and narrowband sonar and multibeam echo sounder) sensors were tested with varying ice thickness and oil concentrations at the US Army Corps of Engineers Cold Regions Research and Engineering Laboratory (CRREL) over a three-month period. All of the sensors used during this experiment showed some ability to detect oil on, in, or below ice under certain conditions and major advances in the knowledge of sensor applicability were made. Three follow-on projects (late 2016) include an operations guide providing a concise operationally oriented review of the different sensor technologies in key oil and ice scenarios, and additional field testing with medium to long-wave infrared, and the FMCW radar.

Empirical Models for Permanent Deformation of Subgrade Soils from the Data Collected at the Pavement Subgrade Performance Study

AbstractA national pooled-fund study supported by 19 states, the Federal Highway Administration, and the U.S. Army Corps of Engineers was conducted at the Cold Regions Research and Engineering Laboratory (CRREL) of the U.S. Army Corps of Engineers in Hanover, New Hampshire. The study, titled the Pavement Subgrade Performance Study (PSPS), aimed to develop failure criteria and prediction models for permanent deformation in the subgrade soil that incorporate the effects of soil type and moisture content. Full-scale pavement structures were built with the same crushed stone base and asphalt concrete surface layers on top of five subgrade soils. The soils were placed and compacted at three in situ moisture contents: the optimum and two other contents above the optimum. The pavements were subjected to full-scale accelerated pavement testing. An extensive volume of response and performance data was collected in the study. This paper presents the development of empirical models for permanent deformation of subgr...

Persistence-based temporal filtering for MODIS snow products

Abstract Single-day snow covered area (SCA) products are incomplete and often inadequate representations of ground conditions due to short term variation in cloud cover, snow cover, and sensor geometry. To mitigate these effects, we developed a by-pixel filtering algorithm to produce relatively cloud-free SCA products from 16 days of MODIS imagery. The algorithm uses previous days' data to estimate the current SCA value of each pixel and uses a simple persistence test to reduce the effects of spurious SCA/cloud classifications in the input products. To be positively identified as SCA, a pixel must be snow-covered in the two most recent, cloud-free scenes of the 16-day period. We applied this time-domain-filtering (TDF) methodology to two single-day MODIS fractional snow cover products (MOD10A1 and MODSCAG) over the MODIS period of record (2000-present) and compared the outputs to the unfiltered products, to filtered maps generated using the cloud-gap-filled algorithm (CGF, Hall et al., 2010), and to historical snow assessment reports from the U.S. Army Corps of Engineers, Cold Regions Research and Engineering Laboratory (CRREL). The CRREL reports were manually generated and quality-controlled by an analyst and are treated as ground truth. We find that, when applied to MODSCAG, the TDF algorithm successfully fills in gap pixels and limits the effects of snow/cloud confusion and produces a filtered product that is more consistent and accurate than the MODSCAG CGF product and comparable to the MOD10A1 CGF product.

Edgar “Ed” L Andreas 1946–2015

Edgar Andreas died on 30 September 2015 in Lebanon, New Hampshire, USA. Ed was born on 6 December 1946 in Sterling, Illinois, USA. Known as an independent thinker, he made important advances in the development of instrumentation and methods of data analysis and he contributed substantially to improved understanding of boundary-layer meteorology (Fig. 1). Ed worked in a variety of fields within boundary-layer meteorology, concentrating on fluxes from water, ice, and snow surfaces; but he also published work on fluxes from snow-free land surfaces and even on fluxes from the surface of the moon. He published many valuable papers in atmospheric and geophysical journals but additionally published in the American Journal of Physics, Physics Today, Applied Optics, Journal of the Optical Society of America, Radio Science, and Cold Regions Science and Technology. He received his Ph.D. in physical oceanography at Oregon State University in 1977 under the direction of Clayton Paulson where he studied internal boundary layers over Arctic leads and published a pioneering paper on this subject. For this work, Ed participated as a major contributor in the first of what would become a dozen field programs during his career. In 1978, Ed was hired as a research physicist at the US Army Cold Regions Research and Engineering Laboratory (CRREL) in Hanover, New Hampshire, USA. At CRREL, Ed had two notable Antarctic firsts. In 1981, he was a member of the Weddell Polynya Expedition, which made the first deep penetration into the Antarctic ice pack and was the first time that American and Russian scientists worked together on the Antarctic sea-ice. In 1992, Ed was the lead American meteorologist on the American and Russian ice station Weddell, the first research ice camp ever deployed on drifting Antarctic sea-ice. It floated northward for 4months, paralleling the track of Ernest Shackleton’s legendary Endurance, and was the first human visit to this remote area in the 75years since Shackleton’s epic adventure. Additionally, Ed participated in several expeditions to the Arctic. Whilst at CRREL, Ed worked on surface fluxes over snow, ice, marginal ice zones and water surfaces.He continuedwork on instrumentation issues includingwork on the ship boom assembly, calibration and interpretation of hot-film data, the effective averaging inherent in

CUES—a study site for measuring snowpack energy balance in the Sierra Nevada

Accurate measurement and modeling of the snowpack energy balance are critical to understanding the terrestrial water cycle. Most of the water resources in the western US come from snowmelt, yet statistical runoff models that rely on the historical record are becoming less reliable because of a changing climate. For physically based snow melt models that do not depend on past conditions, ground based measurements of the energy balance components are imperative for verification. For this purpose, the US Army Corps of Engineers Cold Regions Research and Engineering Laboratory (CRREL) and the University of California, Santa Barbara (UCSB) established the “CUES” snow study site (CRREL/UCSB Energy Site, http://www.snow.ucsb.edu/) at 2940 m elevation on Mammoth Mountain, California. We describe CUES, provide an overview of research, share our experience with scientific measurements, and encourage future collaborative research. Snow measurements began near the current CUES site for ski area operations in 1969. In the 1970s, researchers began taking scientific measurements. Today, CUES benefits from year round gondola access and a fiber optic internet connection. Data loggers and computers automatically record and store over 100 measurements from more than 50 instruments each minute. CUES is one of only five high altitude mountain sites in the Western US where a full suite of energy balance components are measured. In addition to measuring snow on the ground at multiple locations, extensive radiometric and meteorological measurements are recorded. Some of the more novel measurements include scans by an automated terrestrial LiDAR, passive and active microwave imaging of snow stratigraphy, microscopic imaging of snow grains, snowflake imaging with a multi-angle camera, fluxes from upward and downward looking radiometers, snow water equivalent from different types of snow pillows, snowmelt from lysimeters, and concentration of impurities in the snowpack. We give an example of terrain-corrected snow albedo measurements compared to several models and of sublimation measured from lysimeter and snow pillow melt. We conclude with some thoughts on the future of CUES.

Responding to Oil Spills Under Ice: Alaska Clean Seas' Cold Regions Research and Engineering Laboratory (CRREL) Training Course

The Alaska North Slope region is a demanding operating environment for oil exploration, production and transportation operations. The Arctic Ocean remains frozen for an average of nine months of the year, with only a limited open-water season in the summer. There are long periods of darkness, extremely harsh weather conditions, remote installations and limited infrastructure. As Arctic oil exploration, production and transportation activities expand, there is growing concern about the ability of public and private sector response organizations to effectively clean up oil spills under ice. Alaska Clean Seas (ACS) is the Alaska North Slope oil spill response cooperative based in Prudhoe Bay, AK. ACS oversees the training and coordination of the North Slope Spill Response Team (NSSRT), a volunteer-based organization consisting of personnel from the workforce of ACS' Member Companies and their support contractors. Beginning in January 2012, ACS partnered with the U.S. Army Corps of Engineers Cold Regions Research and Engineering Laboratory (CRREL) in Hanover, NH, to develop an Advanced Oil Spill Response in Ice Course. Now in its third year, this partnership has combined the unique facilities, capabilities and ice research history of CRREL with the Arctic response expertise and experience of Alaska Clean Seas to deliver realistic, one-of-a-kind training for recovering oil spilled under ice. Participants have included members of the NSSRT, several federal regulatory agencies and representatives from the Global Response Network. ACS provides response equipment from the North Slope and several vendors have demonstrated additional skimming and pumping systems specifically designed for recovery in ice. Central to the course is CRREL's outdoor saline test basin, a 60′ × 25′ × 7′ refrigerated in-ground tank equipped to grow and maintain a two-foot cover of sea ice. Approximately 600 gallons of Alaska North Slope crude oil are injected under the ice to provide a realistic field scenario to practice response tactics. These tactics include assessment and profiling techniques for safely working on the ice; employing underwater lights and ground penetrating radar for detection of oil under ice; use of augers and chainsaw sleds to cut holes and slots in the ice; deployment of recovery and storage systems to remove oil from an ice environment; and in-situ burning operations in slush and broken ice. This poster highlights the development of the CRREL Training Course and provides guidelines for course content, length, and special considerations for similar advanced field training courses.

Heave and Heaving Pressure in Freezing Soils: A Unifying Theory

A unifying theory is presented for the process of heave in freezing soils. Out of the Cold Regions Research and Engineering Laboratory (CRREL) school of D.M. Anderson came the concept of the segregation potential. Out of the Cornell school of R.D. Miller came the model for the heave rate. Here ideas from both schools are put on a fundamental thermodynamic footing, leading to the definition of a new heave index. Both schools use the temperature gradient in the frozen fringe as the driving force for heave. We argue and demonstrate that this choice leads to erratic results. The driving force should be the temperature gradient over the complete layer of soil that is at sub‐zero (°C) temperature, that is, the combined frozen zone plus the frozen fringe. The value of the heave index is completely dominated by the unsaturated hydraulic conductivity function of both the unfrozen soil below the frozen fringe and the soil layer at sub‐zero temperature.

Herding surfactants to contract and thicken oil spills in pack ice for in situ burning

Abstract In situ burning is an oil spill response option particularly suited to remote, ice-covered waters. The key to effective in situ burning is thick oil slicks. If ice concentrations are high, the ice can limit oil spreading and keep slicks thick enough to burn. In drift ice conditions and open water, oil spills can rapidly spread to become too thin to ignite. Fire-resistant booms can collect and keep slicks thick in open water; however, even light ice conditions make using booms challenging. A multi-year research project was initiated to study oil-herding surfactants as an alternative to booms for thickening slicks in light ice conditions for in situ burning. Small-scale laboratory experiments were completed in 2003 and 2005 to examine the idea of using herding agents to thicken oil slicks among loose pack ice for the purpose of in situ burning. Encouraging results prompted further mid-scale testing in 2006 and 2007 at the US Army Cold Regions Research and Engineering Laboratory (CRREL) in Hanover, NH; at Ohmsett, the National Oil Spill Response Research & Renewable Energy Test Facility in Leonardo, NJ; and, at the Fire Training Grounds in Prudhoe Bay, AK. The non-proprietary hydrocarbon-based herder formulation used in these experiments proved effective in considerably contracting oil slicks in brash and slush ice concentrations of up to 70% coverage. Slicks in excess of 3 mm thick, the minimum required for ignition of weathered crude oil on water, were routinely achieved. Herded slicks were ignited, and burned equally well in both brash and slush ice conditions at air temperatures as low as − 17 °C. The burn efficiencies measured for the herded slicks were only slightly less than the theoretical maximums achievable for equivalent-sized, physically contained slicks on open water. Successful meso-scale field trials of the technique were carried out in the Barents Sea off Svalbard in the spring of 2008 as one facet of a large joint industry project on oil spill response in ice co-ordinated by SINTEF. The larger field experiment involved the release of 630 L of fresh Heidrun crude onto water in a large lead. The free-drifting oil was allowed to spread for 15 min until it was far too thin to ignite (0.4 mm), and then the hydrocarbon-based herder was applied around the slick periphery. The slick contracted and thickened for approximately 10 min at which time the upwind end was ignited. A 9-minute long burn ensued that consumed an estimated 90% of the oil. From 2007 to 2009 experiments were carried out in the laboratory and at CRREL comparing the efficacy of herding agents formulated with silicone-based surfactants, herding agents formulated with second-generation fluorosurfactants, and the hydrocarbon-based herder. The results showed that the fluorosurfactant-based herders did not function better than the hydrocarbon-based herder; however, the new silicone surfactant formulations considerably outperformed the hydrocarbon-based herder. Most recently, experiments were conducted to determine if herding agents could: 1) improve skimming of spilled oil in drift ice; 2) clear oil from salt marshes; and, 3) improve the efficiency of dispersant application operations.