16 Sep 2025

Standard Operating Procedures for the Design, Maintenance, and Operation of Arctic and Subarctic Winter Roads

Abstract: Operations in cold regions require vehicular maneuvering across snowpacks or frozen surfaces. Winter roads and their route determination, construction, and monitoring are widely studied. This report analyzes historical and current literature on winter road construction and operations, reviews risk assessment techniques, examines the impact of uncertain weather on road reliability, and provides a standard operating procedure for design, maintenance, and use. Winter roads, snow roads, ice roads, and ice bridges enable seasonal access in Arctic and Subarctic regions. They allow cross-country maneuverability over terrain like wetlands and bogs, which are impassable in summer. These roads are critical for training, logistics, and construction in areas without all-season access. When combined with ice bridges they can provide near-unlimited travel. Effectiveness depends on proper planning, construction, and monitoring. Snow roads require controlled compaction for strength, while ice roads require sufficient ice thickness to support loads. Both rely on tools like visual inspections, ground-penetrating radar, and unmanned aerial systems to ensure safety. With extreme seasonal variability, adaptive strategies are essential. Shortened seasons and unpredictable freeze–thaw cycles demand modern technologies, predictive weather modeling, and improved reinforcement. This report integrates historical knowledge with engineering advancements to improve winter road durability, reduce risks, and support cold-region operations.

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.

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.

6 May 2025

Applications of the CRREL–-Geometric Optics Snow Radiative Transfer (GOSRT) Model: Incorporating Diffraction and Simulating Detection of Buried Targets

Abstract: Radiative transfer through a snow surface within the visible and near infrared (NIR) spectra is complicated by the shape, size, and configuration of the snow grains that comprise the snow surface. Ray-tracing and photon-tracking techniques combined with 3D renderings of snow resolved at the microscale have shown promise as a means to directly simulate radiative transfer through snow with no restrictions on the snow grain configuration. This report describes and evaluates the US Army Cold Regions Research and Engineering Laboratory (CRREL) Geometric Optics Snow Radiative Transfer (GOSRT) model. In particular, we describe the incorporation of the diffraction process into the photon-tracking framework and evaluate how accurately the model simulates the spectral albedo of targets buried within the snow. We find that the model simulated spectral albedo is little affected by the incorporation of diffraction for most applications. However, there are nonnegligible impacts on simulated albedo for small grains in the NIR due to a reduction in forward scattering. We conclude by recommending that diffraction is neglected in CRREL–GOSRT for most cases, as including it substantially increases the computational expense with minimal impacts on the result. Finally, we show that buried targets are only distinguishable for very shallow snowpacks.

14 May 2024

Snow-Impacted National Inventory of Dams by GAGESII Watershed

Abstract: This Engineering Research and Development Center (ERDC) Technical Note describes the development of a set of locations within the contiguous United States (CONUS) where snowmelt is a component of the annual streamflow. The locations are selected from the US Geological Survey (USGS) Geospatial Attributes of Gages for Evaluating Streamflow II (GAGESII) and National Inventory of Dams (NID) data sets. The 30-year normal snow regimes were used to identify all GAGESII watersheds that have any of the basin delineated as transitional (rain/snow), snow dominated, or perennial snow zones. NID dams that are within snow affected GAGESII watersheds are included in the data set. The purpose of this ERDC Technical Note is to describe the development of a comprehensive data set of CONUS GAGESII and dam infrastructure affected by snow changing regimes.

29 Sep 2023

Microbial Activity in Dust-Contaminated Antarctic Snow

Abstract: During weather events, particles can accumulate on the snow near the Pegasus ice and Phoenix compacted-snow Runways at the US McMurdo Station in Antarctica. The deposited particles melt into the surface, initially forming steep-sided holes, which can widen into patches of weak and rotten snow and ice. These changes negatively impact the ice and snow runways and snow roads trafficked by vehicles. To understand the importance of microbes on this process, we examined deposited dust particles and their microbial communities in snow samples collected near the runways. Snow samples were analyzed at the Cold Regions Research and Engineering Laboratory where we performed a respiration study to measure the microbial activity during a simulated melt, isolated microorganisms, examined particle-size distribution, and performed 16S rRNA gene sequencing. We measured higher levels of carbon dioxide production from a sample containing more dust than from a sample containing less dust, a finding consistent with viable dust-associated microbial communities. Additionally, eleven microorganisms were isolated and cultured from snow samples containing dust particles. While wind patterns and satellite images suggest that the deposited particles originate from nearby Black Island, comparisons of the particle size and chemical composition were inconclusive.

28 Sep 2023

Incorporating Advanced Snow Microphysics and Lateral Transport into the Noah-Multiparameterization (Noah-MP) Land Surface Model

Abstract: The dynamic state of the land surface presents challenges and opportunities for military and civil operations in extreme cold environments. In particular, the effects of snow and frozen ground on Soldier and vehicle mobility are hard to overstate. Current authoritative weather and land models are run at global scales (i.e., dx > 10 km) and are of limited use at the Soldier scale (dx < 100 m). Here, we describe several snow physics upgrades made to the Noah-Multiparameterization (Noah-MP) community land surface model (LSM). These upgrades include a blowing snow overlay to simulate the lateral redistribution of snow by the wind and the addition of new prognostic snow microstructure variables, namely grain size and bond radius. These additions represent major upgrades to the snow component of the Noah-MP LSM because they incorporate processes and methods used in more specialized snow modeling frameworks. These upgrades are demonstrated in idealized and real-world applications. The test simulations were promising and show that the newly added snow physics replicate observed behavior with reasonable accuracy. We hope these upgrades facilitate ongoing and future research on characterizing the effects of the integrated snow and soil land surface in extreme cold environments at the tactical scale.

7 Apr 2023

Upper basin runoff forecast improves with spring precipitation

The latest 2023 calendar year runoff forecast for the Missouri River Basin above Sioux City, Iowa is showing improvement. The 2023 calendar year runoff forecast above Sioux City is 26.4 million acre-feet (MAF), 103% of average. The runoff forecast is based on current soil moisture conditions, plains snowpack, mountain snowpack, and long-term precipitation and temperature outlooks. March runoff in the Missouri River Basin above Sioux City was 1.7 MAF, 57% of average.    

7 Sep 2022

Extracting Sintered Snow Properties from MicroCT Imagery to Initialize a Discrete Element Method Model

Abstract: Modeling snow’s mechanical behavior is important for many cold regions engineering problems. Because snow’s microstructure plays a significant role in its mechanical response, it is imperative to initialize models with accurate bond characteristics and realistic snow-grain geometries to precisely capture the microstructure interactions. Previous studies have processed microcomputed tomography scans of snow samples with a watershed method to extract grain geometries. This approach relies on identification of seed points to segment each grain. Our new methodology, called the “moving window method,” does not require prior knowledge of the snow-grain-size distribution to identify seed points. We use the interconnectivity of the segmented grains to identify bond characteristics. We compare the resultant grain-size and bond-size distributions to the known grain sizes of the laboratory-made snow samples. The grain-size distributions from the moving window method closely match the known grain sizes, while both results from the traditional method produce grains that are too large. We propose that the bond net-work identified using the traditional method underestimates the number of bonds and overestimates bond radii. Our method allows us to segment realistic snow grains and their associated bonds, without prior knowledge of the samples, from which we can initialize numerical models of the snow.

5 Aug 2022

SAGE-PEDD Theory Manual: Modeling Windblown Snow Deposition around Buildings

Abstract: Numerical modeling of snowdrifting is a useful tool for assessing the im-pact of building design on operations and facility maintenance. Here we outline the theory for the SAGE-PEDD snowdrift model that has applica-tion for determining snowdrift accumulation around buildings. This model uses the SAGE computational fluid dynamics code to determine the flow field in the computational domain. A particle entrainment, dis-persion, and deposition (PEDD) model is coupled to SAGE to simulate the movement and deposition of the snow within the computational do-main. The report also outlines areas of future development that upgrades to the SAGE-PEDD model should address.