15 Sep 2025

Standard Operating Procedures for the Design, Construction, and Maintenance of Linear Infrastructure in Fens in Cold Regions

Abstract: In Alaska and across the Arctic and Subarctic, winter conditions can enable the expansion of linear infrastructure across the frozen landscape of fen wetlands. This expands military training opportunities into lowland wet, boggy, mostly impassable terrain. However, there are personnel, civilian, and environmental risks from using fens as travel corridors and drop zones. The effective design, construction, operation, and maintenance of such infrastructure on fens supports the dual mandate of troop training to fulfill the mission and protect the environment. This Technical Report (TR) addresses the risks of the establishment and use of linear infrastructure on the DoD lands in Alaska and in other austere cold environments where the DoD operates. This TR is founded on a review of methods used by US Army Installations, focusing primarily on Fort Wainwright in Interior Alaska. It establishes basic standard operating procedures (SOPs) by drawing on federal agency and international best practices and emerging research in circumpolar regions and beyond. This TR serves as a reference document for military land and infrastructure planners and unit leadership to create and maintain linear infrastructure on fens as environmental challenges evolve and opportunities develop to further the Army mission in high latitude environments.

15 Sep 2025

Standard Operating Procedures for the Design, Maintenance, and Operation of Freshwater Ice Bridges

Abstract: Operations in cold regions inevitably require maneuvering across, through, or atop frozen surfaces. Ice bridges are special components of winter linear infrastructure that can have significant impacts on mission targets. Proper siting, design, monitoring, and operation of ice bridges reduces potential environmental impacts and decreases risks to personnel and equipment. The US Army operates multiple ice bridge crossings on training lands in Alaska and collaborates with other countries in training events that use them. They are a likely means of travel for potential operations in cold regions. However, the US Army lacks up to date guidance on the design, maintenance, and operation of ice bridges. This report addresses this need by providing a set of standard operating procedures that have been developed from a broad synthesis of ice bridge usage in northern regions. In addition, it reviews all relevant historic and current literature regarding ice bridges, describes risk assessment and mitigation techniques for ice bridge operations, discusses specific considerations for US Army training areas in Alaska, and briefly describes important ramifications of changing weather conditions and increasing uncertainty as they relate to ice bridge life span.

11 Sep 2025

A Calibration Method for Projecting Future Extremes via a Linear Mapping of Parameters

Abstract: In order to study potential impacts arising from climate change, future projections of numerical model output often must be calibrated to be comparable to observations. Rather than calibrating the data values themselves, we propose a novel statistical calibration method for extremes that assumes there exists a linear relationship between parameters associated with model output and parameters associated with observations. This approach allows us to capture uncertainty in both parameter estimates and the linear calibration, which we achieve via bootstrap. To focus on extreme behavior, we assume both model output and observations have distributions composed of a mixture model combining a Weibull distribution with a generalized Pareto distribution for the tail. A simulation study shows good coverage rates. We apply the method to project future daily-averaged river runoff at the Purgatoire River in southeastern Colorado.

11 Sep 2025

Effect of Gypsum on Transport of IMX-104 Constituents in Overland Flow Under Simulated Rainfall

Abstract: Residue of energetic formulations, deposited on military training grounds following incomplete detonation, poses biotic hazards. This residue can be transported off-site, adsorb to soil clays and organic matter, transform or degrade, or taken up by plants and animals. Its harmful effects can be mitigated by localizing the energetics at the initial deposition using soil amendments and allowing them to bio- and photodegrade in situ. Small plots with coarse loamy soil were used to study the effect of gypsum on transport and redistribution under simulated rainfall of various sizes of insensitive munition explosive IMX-104 particles. The addition of gypsum more than doubled infiltration and decreased sediment loss by 16%. The post-rainfall mass balance of IMX-104 in the order from greater to smaller pools was: (1) soil surface retention, (2) off-site loss to overland flow, and (3) sub-surface infiltration. The application of gypsum decreased concentration and the total mass loss of dissolved DNAN, RDX, and HMX in surface runoff. In addition, gypsum significantly decreased or delayed the peak discharge of <2mm particulate energetics. Gypsum shifted the total mass balance of energetics toward subsurface flow. This study indicates gypsum may decrease off-site transport of energetic constituents in the soils subject to surface sealing.

10 Sep 2025

Snow Depth Measurements from Arctic Tundra and Boreal Forest Collected During NASA SnowEx Alaska Campaign

Abstract: Boreal forest and Arctic tundra environments collectively hold the largest percentage of global terrestrial seasonal snow cover. Тhe in-situ snow measurement network is sparse and costly in these remote northern regions. Here, we complement existing snow depth monitoring in Arctic tundra and boreal forest by presenting an extensive (64°N–70°N) snow depth dataset and description of ground-based snow depth measurements collected during the NASA SnowEx Alaska intensive field campaign, March 7–16, 2023. We also report the accuracy of snow depth measurements in shallow boreal forest and Arctic tundra snowpack and share considerations in developing the consistent and repeatable snow depth data collection procedures. Snow depth measurements and technical validation described in this paper can serve as a robust product for testing snow remote sensing techniques, and for providing a reference dataset for climatological and hydrological studies.

10 Sep 2025

Mapping the Vulnerability of Boreal Permafrost in Central Alaska in Relation to Thaw Rate, Ground Ice, and Thermokarst Development

Abstract: Permafrost roughly affects half the boreal region in Alaska and varies greatly in its thermophysical properties and genesis. In boreal ecosystems, permafrost formation and degradation respond to complex interactions among climate, topography, hydrology, soils, vegetation, and disturbance. We synthesized data on soil thermal conditions and permafrost characteristics to assess current permafrost conditions in central Alaska, and classified and mapped soil landscapes vulnerable to future thaw and thermokarst development. Permafrost soil properties at 160 sites ranged from rocky soils in hillslope colluvium and glacial till, to silty loess, to thick peats on abandoned floodplains and bogs, across 64 geomorphic units. To assess the vulnerability of permafrost to climate variability and disturbance, we differentiated permafrost responses in terms of rate of thaw, potential thaw settlement, and thermokarst development. Using a rule-based model that uses geomorphic units for spatial extrapolation at the landscape scale, we mapped 10 vulnerability classes across three areas ranging from high potential settlement/low thaw rate in extremely ice-rich loess to low potential settlement/high thaw rate in rocky hillslope colluvium. Vulnerability classes corresponded to thermokarst features developed in response to past climates. Differing patterns in permafrost vulnerability have large implications for ecosystem trajectories, land use, and infrastructure damage from thaw.

10 Sep 2025

Detachment and Transport of Composition B Detonation Particles in Rills

Abstract: The partial detonation of munitions used in military exercises leaves behind energetic particles on the surface of soil. Energetic particles deposited by incomplete detonations can then dissolve and be transported by overland flow and potentially contaminate ground and surface waters. The objective of this study was to evaluate the mechanisms of transport of Composition B, a formulation that includes TNT and RDX during overland flow. The transport of Composition B was examined using a rill flume with three flow rates and four energetic particle sizes. After each erosion simulation, energetic particles remaining on the soil surface were measured along with energetics dissolved in runoff, in suspended sediment, and in infiltration. Smaller particle sizes led to greater transport in both solution and sediment. The properties of the energetic compounds also influenced transport. More TNT was transported in runoff than RDX, likely due to TNT’s higher solubility and dissolution rates, however, overall, dissolved energetics in runoff and infiltration accounted for very little of the total transport. Most transport of Composition B was the result of the physical movement of energetic particles and flakes by erosion forces. This study’s results allow for improved prediction of Composition B transport during overland flow.

10 Sep 2025

Cellulose Nanofibers Impart Melt Resistance to Ice Through Optical and Thermal Mechanisms

Abstract: Ice is ubiquitous in cold regions with historical significance as a key structural material. Contemporary efforts to leverage ice for the construction of large structures have incorporated cellulose-based reinforcing materials to increase strength. While an increased resistance to melting has been observed, it has not been investigated. Herein, we provide evidence that cellulose nanofibers (CNFs), as a heterogeneous component to synthetic ices, increase melt resistance through optical and thermal mechanisms. Specifically, we investigated the effect of 0.1−1.0 wt % CNFs on the reflectance, thermal conductivity, and melt rate of ice. The presence of CNFs increased reflectance of ice from 20 to 70% at 640 nm. Thermophysical measurements revealed that CNFs both slow melting and facilitate freezing and do not statistically affect the specific heat capacity of ice. Measurements with light flash analysis revealed that CNFs reduce thermal conductivity up to 10%. Overall CNFs reduced the melt rate of ice by 10× with only 1.0 wt % CNF. These results demonstrate that insoluble CNFs impart melt resistance to ice by both optical and thermal mechanisms, results that provide an interesting combination of controls for ice stability and formation to optimize ice material properties for high performance applications in cold regions.

9 Sep 2025

Active Layer and Permafrost Microbial Community Coalescence Increases Soil Activity and Diversity in Mixed Communities Compared to Permafrost Alone

Abstract: Permafrost is experiencing rapid degradation due to climate warming. Dispersal of microbial communities from the seasonally-thawed active layer soil into newly thawed permafrost may influence community assembly and increase carbon release from soils. We conducted a laboratory soil mixing study to understand how carbon utilization, heterotrophic respiration, and microbial community structure were affected when active layer and permafrost soils were mixed in varying proportions. Active layer soil and permafrost collected from two sites in Alaska were mixed in five different ratios and incubated for 100 days at 10°C. Respiration rates were highest in the 100% active layer soils, averaging 19.8 µg C-CO2 g−1 dry soil d−1 across both sites, and decreased linearly as the ratio of permafrost increased. Mixing of the two soil layers resulted in utilization of a more diverse group of carbon substrates compared to permafrost alone. Additionally, combining active layer and permafrost soils increased microbial diversity and resulted in communities resembling those from the active layer when soils were mixed in equal ratios. Understanding the effects of active layer-permafrost mixing on functional potential and soil organic matter decomposition will improve predictions of carbon-climate feedbacks as permafrost thaws in these regions.

2 Sep 2025

Airborne Bacteria over Thawing Permafrost Landscapes in the Arctic

Abstract: Rapid warming in the Arctic, outpacing global rates, is driving significant changes in cryospheric landscapes, including the release of long-preserved microorganisms. This study focuses on thawing permafrost in Northern Alaska, where microbes previously preserved in frozen soils are introduced into thermokarst lakes, rivers, and coastal waters and may also become airborne as bioaerosols. We present the first microbial composition measurements of bioaerosols in Alaska, identifying their local sources, such as soils, water bodies, and vegetation. Although sea/brackish water is the dominant bioaerosol contributor, we provide the first evidence of permafrost microbial signatures in bioaerosols from permafrost-laden regions. Permafrost is highly enriched with ice nucleating particles (INPs), which play a crucial role in cloud formation, precipitation processes, and radiation budget despite their relatively low atmospheric concentrations. With rising Arctic temperatures, increased permafrost thaw could result in higher levels of airborne permafrost-derived microbes and biological INPs active at warmer subzero temperatures. This, in turn, could enhance precipitation, further accelerating the permafrost thaw. Our findings emphasize the complex interactions between terrestrial changes and atmospheric processes, revealing a potential feedback loop that could intensify permafrost thaw and its broader environmental impacts.