Browsing by Author "Hendrikx, Jordy"

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Autonomous Aerial Vehicles (AAVs) as a Tool for Improving the Spatial Resolution of Snow Albedo Measurements in Mountainous Regions
(MDPI, 2020-07) Sproles, Eric A.; Mullen, Andrew; Hendrikx, Jordy; Gatebe, Charles; Taylor, Suzi
We present technical advances and methods to measure effective broadband physical albedo in snowy mountain headwaters using a prototype dual-sensor pyranometer mounted on an Autonomous Aerial Vehicle (an AAV). Our test flights over snowy meadows and forested areas performed well during both clear sky and snowy/windy conditions at an elevation of ~2650 m above mean sea level (MSL). Our AAV-pyranometer platform provided high spatial (m) and temporal resolution (sec) measurements of effective broadband (310–2700 nm) surface albedo. The AAV-based measurements reveal spatially explicit changes in landscape albedo that are not present in concurrent satellite measurements from Landsat and MODIS due to a higher spatial resolution. This AAV capability is needed for validation of satellite snow albedo products, especially over variable montane landscapes at spatial scales of critical importance to hydrological applications. Effectively measuring albedo is important, as annually the seasonal accumulation and melt of mountain snowpack represent a dramatic transformation of Earth’s albedo, which directly affects headwaters’ water and energy cycles.
Climate drivers of large magnitude snow avalanche years in the U.S. northern Rocky Mountains
(Springer Science and Business Media LLC, 2021-05) Peitzsch, Erich H.; Pederson, Gregory T.; Birkeland, Karl W.; Hendrikx, Jordy; Fagre, Daniel B.
Large magnitude snow avalanches pose a hazard to humans and infrastructure worldwide. Analyzing the spatiotemporal behavior of avalanches and the contributory climate factors is important for understanding historical variability in climate-avalanche relationships as well as improving avalanche forecasting. We used established dendrochronological methods to develop a long-term (1867–2019) regional avalanche chronology for the Rocky Mountains of northwest Montana using tree-rings from 647 trees exhibiting 2134 avalanche-related growth disturbances. We then used principal component analysis and a generalized linear autoregressive moving average model to examine avalanche-climate relationships. Historically, large magnitude regional avalanche years were characterized by stormy winters with positive snowpack anomalies, with avalanche years over recent decades increasingly influenced by warmer temperatures and a shallow snowpack. The amount of snowpack across the region, represented by the first principal component, is shown to be directly related to avalanche probability. Coincident with warming and regional snowpack reductions, a decline of ~ 14% (~ 2% per decade) in overall large magnitude avalanche probability is apparent through the period 1950–2017. As continued climate warming drives further regional snowpack reductions in the study region our results suggest a decreased probability of regional large magnitude avalanche frequency associated with winters characterized by large snowpacks and a potential increase in large magnitude events driven by warming temperatures and spring precipitation.
Colours and maps for communicating natural hazards to users with and without colour vision deficiency
(Elsevier BV, 2022-06) Engeset, Rune Verpe; Pfuhl, Gerit; Orten, Camilla; Hendrikx, Jordy; Hetland, Audun
Natural hazards are often communicated visually using colours and maps. However, users' ability to read and understand these products may be hampered by e.g., colour vision deficiency, potentially rendering the products less effective or even counter effective. To study these effects, we conducted two web-based surveys and analysed how to improve visual communication of avalanches, floods, landslides, and dangerous weather hazards. In survey 1 (n = 79), we tested four traffic light colour palettes, three map legends, and three map patterns used for communicating danger levels on the Norwegian website Varsom.no, to improve accessibility for individuals with and without colour vision deficiency (CVD). In survey 2 (n = 960), we tested four versions of traffic light colour palettes on a larger and international population. Survey 2 also tested six versions of Avalanche terrain exposure scale (ATES) maps on individuals with and without CVD varying in nationality, avalanche education and familiarity with ATES. Results suggest that the colours, legends, and maps used on Varsom should be improved, and that danger levels are best communicated with the colour palette used by Meteoalarm.info – in combination with symbols to help users with CVD. This study found that the colour scheme used for ski run difficulty in Europe was efficient for use with ATES maps for participants with and without CVD and is recommended as a worldwide standard for ATES. Further studies and testing of users’ understanding are recommended to improve clarity of danger level maps and to improve visualization of ATES classes 0 and 1 on maps. Our studies show the hidden potential for efficient and inclusive communication of natural hazards and highlights the importance of including the needs of CVD users in standardisation efforts.
Combining GPS tracking and survey data to better understand travel behavior of out-of-bounds skiers
(2020-09) Sykes, John M.; Hendrikx, Jordy; Johnson, Jerry; Birkeland, Karl W.
Our research seeks to expand existing knowledge of travel behavior and decision-making in avalanche terrain. We have done this by using GPS tracking to observe the travel behavior of out-of-bounds (OB) skiers and collecting survey data to investigate their terrain choices. We sampled participants in the field by distributing hand-held GPS units and surveys along the southern boundary of Bridger Bowl Ski Area, Southwest Montana, USA. In total, we used data from 136 participants that volunteered over the course of 19 field days, from February 2017 to February 2018. We analyzed the resulting GPS data using a GIS, and we derived terrain metrics from elevation and land cover data. We fit a multiple linear regression model using GPS track downhill starting distance from the ski area boundary as the response variable and survey responses, interaction with complex avalanche terrain (as defined using the Avalanche Terrain Exposure Scale), weather conditions, and avalanche hazard level as explanatory variables. This approach evaluates travel behavior as a function of human factors, terrain, weather, and snowpack, providing a holistic perspective on decision-making drivers. Our results show that gender (female), formal avalanche education, and perception of avalanche mitigation are statistically significant (p < 0.05) survey responses which indicate that participants travel further from the ski area boundary before descending Saddle Peak, which effects individuals avalanche terrain exposure. Downhill starting distance is also significantly correlated with time and distance in complex avalanche terrain (p < 0.05). Our results provide a case study of the terrain preferences and avalanche awareness of OB skiers and highlight specific “human factors” that are correlated with terrain selection. Two practical applications of this research are: 1) tailoring of targeted avalanche education outreach based on our results specific to the OB setting, and 2) designing new signage to illustrate the avalanche terrain near the ski area boundary for skiers who are inexperienced in the backcountry or unfamiliar with the specific area.
Combining high spatial resolution snow mapping and meteorological analyses to improve forecasting of destructive avalanches in Longyearbyen, Svalbard
(Elsevier BV, 2018-10) Hancock, Holt; Prokop, Alexander; Eckerstorfer, Markus; Hendrikx, Jordy
Two naturally triggered snow avalanches occurred on 19 December 2015 and 21 February 2017 in the town of Longyearbyen, Svalbard in the Norwegian high-Arctic. These events resulted in two fatalities, numerous injuries, and rendered fourteen residential buildings uninhabitable. Both avalanches occurred on the west-facing slope of the Sukkertoppen Mountain and were preconditioned by similar meteorological conditions. We investigate these two events by combining traditional weather and snowpack analyses with snow distribution data acquired via terrestrial laser scanning (TLS). As limited snow data exists on Svalbard, the TLS-derived snow depth and differential snow depth maps are the primary viable method for the description and analysis of destructive avalanche activity in this location. These TLS-derived surfaces permit detailed assessment of slope-scale snow distribution patterns both prior to and following avalanche activity. We identify strong easterly winds and moderate to heavy snowfall as precursors to destructive avalanche activity on this slope. The results of our investigation help clarify the relationship between winter storm characteristics and avalanche activity in high-Arctic environments and demonstrate the importance of scale-appropriate snow data for avalanche forecasting with increased precision at finer spatial scales. These results have implications for avalanche forecasting in this setting and other data sparse, high-relief Arctic settings where snow distribution patterns are controlled by wind.
Developing nationwide avalanche terrain maps for Norway
(2020-06) Larsen, Havard T.; Hendrikx, Jordy; Slatten, Martine S.; Engeset, Rune V.
Snow avalanches are a significant natural hazard in Norway. One method to manage the backcountry avalanche hazard is through detailed mapping of avalanche terrain. Avalanche terrain can be mapped using a variety of methods, including using the Avalanche Terrain Exposure Scale (ATES); however, manual classification of terrain using ATES is time consuming. This study has developed and compared a fully automated algorithm to provide ATES mapping for all of Norway. Our new algorithm is based on the technical model for ATES mapping. This model has specific terrain-based thresholds that can be applied for automated terrain-based modeling. Our algorithm expands on prior work by including the potential release area (PRA) model to identify and calculate the likelihood of an avalanche releasing from a start zone. We also use the raster-based TauDEM-model to determine the avalanche runout length. The final product is a 10-m resolution ATES map. We compared this nationwide ATES map with areas that have been manually mapped by avalanche experts, and find that the automated approach yields similar and reliable results. In addition to comparing mapped areas, we also examine manually mapped linear routes and compare these with the automated mapped ATES areas. Our results suggest that for open terrain, the vast majority of the manually classified tracks are predominantly in the same ATES class as our algorithm. For forested areas, we get mixed results, which can be attributed to a lack of suitable vegetation data at an appropriate scale. Despite this limitation, the current ATES algorithm and resulting spatial data are already valuable as a large portion (~ 70%) of the Norwegian backcountry terrain is above tree line. The automated algorithm is also useful to ensure consistent manual classification across different regions in Norway, or globally, and will permit greater reproducibility and easier updating of mapping for the future.
Perceptions Among Backcountry Skiers During the COVID-19 Pandemic: Avalanche Safety and Backcountry Habits of New and Established Skiers
(Elsevier BV, 2022-12) Valle, Esteban A.; Cobourn, Andrew P.; Trivitt, Spencer JH.; Hendrikx, Jordy; Johnson, Jerry D.; Fiore, David C.
Introduction. The coronavirus disease 2019 (COVID-19) pandemic impacted the ski industry worldwide by closing or limiting access to ski resorts. Subsequently, anecdotal reports of increased backcountry use emerged in the press, with concerns of inexperienced skiers causing or having problems in the backcountry. This study attempted to quantify this and identify motivations for new backcountry skiers. Methods. Self-identified backcountry skiers and snowboarders (aged ≥18 y) in the United States and Canada completed an anonymous29-question online survey distributed by regional avalanche centers, education providers, and skiing organizations (n=4792). Respondents were stratified by backcountry experience, defining “newcomers” who began backcountry skiing from 2019 to 2021, coincident with the COVID-19 pandemic. Percentages of ski days spent in the backcountry were compared before and during the COVID-19 pandemic using paired t-tests and across cohorts using repeated-measures analysis of variance. Avalanche education was compared using unpaired χ2 tests. Results. Of established skiers, 81% noticed more people in the backcountry and 27% reported increasing their own use. Participants reported spending 17% (95% CI, 15.8–17.9) more of their days in the backcountry during the COVID-19 pandemic, with newcomers increasing their time spent by 36% and established skiers increasing their time spent by 13% (P<0.0001). Of newcomers, 27% cited the COVID-19 pandemic as motivation to enter the backcountry and 24% lacked formal avalanche education, which is significantly higher than the 14% of established skiers (P<0.0001). Conclusions. Influenced by factors related to COVID-19, reported backcountry use increased during the pandemic. Newcomers had a lower level of avalanche education and less confidence in evaluating terrain. Because 80% of participants were recruited from avalanche safety or education websites, this likely underestimates skiers lacking avalanche awareness or education and is further limited by the nature of online surveys.
Perceptions Among Backcountry Skiers During the COVID-19 Pandemic: Avalanche Safety and Backcountry Habits of New and Established Skiers
(Elsevier BV, 2022-12) Valle, Esteban A.; Cobourn, Andrew P.; Trivitt, Spencer JH.; Hendrikx, Jordy; Johnson, Jerry D.; Fiore, David C.
Introduction.The coronavirus disease 2019 (COVID-19) pandemic impacted the ski industry worldwide by closing or limiting access to ski resorts. Subsequently, anecdotal reports of increased backcountry use emerged in the press, with concerns of inexperienced skiers causing or having problems in the backcountry. This study attempted to quantify this and identify motivations for new backcountry skiers. Methods. Self-identified backcountry skiers and snowboarders (aged ≥18 y) in the United States and Canada completed an anonymous 29-question online survey distributed by regional avalanche centers, education providers, and skiing organizations (n=4792). Respondents were stratified by backcountry experience, defining “newcomers” who began backcountry skiing from 2019 to 2021, coincident with the COVID-19 pandemic. Percentages of ski days spent in the backcountry were compared before and during the COVID-19 pandemic using paired t-tests and across cohorts using repeated-measures analysis of variance. Avalanche education was compared using unpaired χ2 tests. Results. Of established skiers, 81% noticed more people in the backcountry and 27% reported increasing their own use. Participants reported spending 17% (95% CI, 15.8–17.9) more of their days in the backcountry during the COVID-19 pandemic, with newcomers increasing their time spent by 36% and established skiers increasing their time spent by 13% (P<0.0001). Of newcomers, 27% cited the COVID-19 pandemic as motivation to enter the backcountry and 24% lacked formal avalanche education, which is significantly higher than the 14% of established skiers (P<0.0001). Conclusions. Influenced by factors related to COVID-19, reported backcountry use increased during the pandemic. Newcomers had a lower level of avalanche education and less confidence in evaluating terrain. Because 80% of participants were recruited from avalanche safety or education websites, this likely underestimates skiers lacking avalanche awareness or education and is further limited by the nature of online surveys.
Powder Fever and Its Impact on Decision-Making in Avalanche Terrain
(MDPI AG, 2021-09) Mannberg, Andrea; Hendrikx, Jordy; Johnson, Jerry; Hetland, Audun
We examined the effect of emotions, associated with “powder fever”, on decision-making in avalanche terrain. Background: Skiing in avalanche terrain is a voluntary activity that exposes the participant to potentially fatal risk. Impaired decision-making in this context can therefore have devastating results, often with limited prior corrective feedback and learning opportunities. Previous research has suggested that arousal caused by emotions affects risk assessment and intentions to engage in risky behavior. We propose that powder fever may induce similar responses. Methods: We used the following two experimental methods: laboratory studies with visual visceral stimuli (ski movies) and a field study with real stimuli (skiing exciting terrain). We evaluated the effect of emotions on attention, risk assessment, and willingness to expose oneself and others to risk. Results: Both the laboratory studies and the field study showed that skiing-related stimuli had a relatively strong effect on reported emotions. However, we found very few significant effects on decision-making or assessment of risk. Conclusions: Skiing activities make people happier. However, despite the clear parallels to sexual arousal, powder fever does not appear to significantly impair decision-making in our study. More research on the effects of powder fewer on milder forms of risk-taking behavior is needed.
Quantifying seasonal cornice dynamics using a terrestrial laser scanner in Svalbard, Norway
(2020-02) Hancock, Holt; Eckerstorfer, Markus; Prokop, Alexander; Hendrikx, Jordy
Snow cornices develop along mountain ridges, edges of plateaus, and marked inflections in topography throughout regions with seasonal and permanent snow cover. Despite the recognized hazard posed by cornices in mountainous locations, limited modern research on cornice dynamics exists and accurately forecasting cornice failure continues to be problematic. Cornice failures and associated cornice fall avalanches comprise a majority of observed avalanche activity and endanger human life and infrastructure annually near Longyearbyen in central Svalbard, Norway. In this work, we monitored the seasonal development of the cornices along the plateaus near Longyearbyen with a terrestrial laser scanner (TLS) during the 2016–2017 and 2017–2018 winter seasons. The spatial resolution at which we acquired snow surface data with TLS enabled us to observe and quantify changes to the cornice systems in detail not previously achieved. We focused primarily on the evolution and failure of the lower cornice surfaces where accessibility has precluded previous research. We measured cornice accretion rates in excess of 10 mm h−1 during several accretion events coinciding with winter storms. We observed five cornice fall avalanche events following periods of cornice accretion and one event following a warm period with midwinter rain. The results of our investigation provide quantitative reinforcement to existing conceptual models of cornice dynamics and illustrate cornice response to specific meteorological events. Our results demonstrate the utility of TLS for monitoring cornice processes and as a viable method for quantitative cornice studies in this and other locations where cornices are of scientific or operational interest.
A regional spatiotemporal analysis of large magnitude snow avalanches using tree rings
(Copernicus GmbH, 2021-02) Peitzsch, Erich H.; Hendrikx, Jordy; Stahle, Daniel; Pederson, Gregory; Birkeland, Karl; Fagre, Daniel
Snow avalanches affect transportation corridors and settlements worldwide. In many mountainous regions, robust records of avalanche frequency and magnitude are sparse or non-existent. However, dendrochronological methods can be used to fill this gap and infer historical avalanche patterns. In this study, we developed a tree-ring-based avalanche chronology for large magnitude avalanche events (size ≥∼D3) using dendrochronological techniques for a portion of the US northern Rocky Mountains. We used a strategic sampling design to examine avalanche activity through time and across nested spatial scales (i.e., from individual paths, four distinct subregions, and the region). We analyzed 673 samples in total from 647 suitable trees collected from 12 avalanche paths from which 2134 growth disturbances were identified over the years 1636 to 2017 CE. Using existing indexing approaches, we developed a regional avalanche activity index to discriminate avalanche events from noise in the tree-ring record. Large magnitude avalanches, common across the region, occurred in 30 individual years and exhibited a median return interval of approximately 3 years (mean = 5.21 years). The median large magnitude avalanche return interval (3–8 years) and the total number of avalanche years (12–18) varies throughout the four subregions, suggesting the important influence of local terrain and weather factors. We tested subsampling routines for regional representation, finding that sampling 8 random paths out of a total of 12 avalanche paths in the region captures up to 83 % of the regional chronology, whereas four paths capture only 43 % to 73 %. The greatest value probability of detection for any given path in our dataset is 40 %, suggesting that sampling a single path would capture no more than 40 % of the regional avalanche activity. Results emphasize the importance of sample size, scale, and spatial extent when attempting to derive a regional large magnitude avalanche event chronology from tree-ring records.
Rethinking the heuristic traps paradigm in avalanche education: Past, present and future
(2020-08) Johnson, Jerry; Mannberg, Andrea; Hendrikx, Jordy; Hetland, Audun; Stephensen, Matthew
This paper will review the emergence and adoption of decision heuristics as a conceptual framework within the avalanche research and education community and demonstrate how this emphasis on the heuristic decision framework has anchored and was critical in redefining the discussion around avalanche accidents. This paradigm has been a critical and meaningful step in recognizing the importance of decision making in avalanche accidents. However, in an attempt to reduce the incidence of fatal accidents, the adoption of these ideas within the wider avalanche community has overlooked some clearly stated limitations within the foundational work of the heuristic decision frame. With respect to the concept of heuristic traps in conventional avalanche education, the concepts are poorly operationalized to the extent that they are vague about what exactly they describe. The result is that as presently framed, they are of negligible value to avalanche education that seeks its basis on the best available information. We end with a discussion, and a call to action to the avalanche research community, of how we could move towards resolution of these weaknesses and add value to prior work on human factor research. Our aim is not to disparage the seminal, paradigm shifting work by McCammon, but rather draw attention to how it has been operationalized and how the industry needs to move beyond this paradigm to see further gains in our understanding of avalanche fatalities.
Risky positioning – social aspirations and risk-taking behaviour in avalanche terrain
(Informa UK Limited, 2020-10) Mannberg, Andrea; Hendrikx, Jordy; Johnson, Jerry
We test if positionality, i.e., the desire to gain social status, is associated with an increased willingness to take risk among backcountry riders. If positional preferences drive risk-taking behaviour in avalanche terrain, this is especially problematic because the stakes are high and can be fatal. Our analysis is based on data for hypothetical choices from an online survey (N = 648) in North America. We find that positional riders are significantly more likely to boast about riding bold lines, more likely to associate steep riding with social respect, and more likely to say that they would accept to ride a potentially risky line. The positionality effect is present regardless of level of avalanche training. We discuss implications for avalanche training and education.
Satellite detection of snow avalanches using Sentinel-1 in a transitional snow climate
(Elsevier BV, 2022-07) Keskinen, Zachary; Hendrikx, Jordy; Eckerstorfer, Markus
Snow avalanches endanger lives and infrastructure in mountainous regions worldwide. Consistent and accurate datasets of avalanche events are critical for improving hazard forecasting and understanding the spatial and temporal patterns of avalanche activity. Remote sensing-based identification of avalanche debris allow for the acquisition of continuous and spatially consistent avalanches datasets. This study utilizes expert manual interpretations of Sentinel-1 synthetic aperture radar (SAR) satellite backscatter images to identify avalanche debris and compares those detections against historical field records of observed avalanches in the transitional snow climates of Wyoming and Utah, USA. We explore and quantify the ability of an expert using Sentinel-1 (a SAR satellite) images to detect avalanche debris on a dataset comprised exclusively of dry slab avalanches. This research utilized four avalanche cycles with 258 field reported avalanches. Due to individual avalanches appearing in multiple overlapping Sentinel-1 images this resulted in 506 potential detections of avalanches in our SAR images, representing the possibility of multiple detections of a single avalanche event in different images. The overall probability of detection (POD) for avalanches large enough to destroy trees or bury a car (i.e., ≥D3 on the destructive size scale) was 65%. There was a significant variance in the POD among the 13 individual SAR image pairs considered (15–86%). Additionally, this study investigated the connection between successful avalanche detections and SAR-specific, topographic, and avalanche type variables. The most correlated variables with higher detection rates were avalanche path lengths, destructive size of the avalanche, incidence angles for the incoming microwaves, average path slope angle, and elapsed time between the avalanche and a Sentinel-1 satellite image acquisition. This study provides a quantification of the controlling variables in the likelihood of detecting avalanches using Sentinel-1 backscatter temporal change detection techniques, as specifically applied to a transitional snow climate.
Should I judge safety or danger? Perceived risk depends on the question frame.
(American Psychological Association, 2021-04) Stephensen, Matthew B.; Schulze, Christin; Landrø, Markus; Hendrikx, Jordy; Hetland, Audun
Linguistic polarity is a natural characteristic of judgments: Is that situation safe/dangerous? How difficult/easy was the task? Is that politician honest/dishonest? Across six studies (N = 1599), we tested how the qualitative frame of the question eliciting a risk judgment influenced risk perception and behavior intention. Using a series of hypothetical scenarios of skiing in avalanche terrain, experienced backcountry skiers judged either how safe or how dangerous each scenario was and indicated whether they would ski the scenario. Phrasing risk judgments in terms of safety elicited lower judged safety values, which in turn resulted in a lower likelihood of intending to ski the slope. The frame “safe” did not evoke a more positive assessment than the frame “danger” as might be expected under a valence-consistent or communication-driven framing effect. This seemingly paradoxical direction of the effect suggests that the question frame directed attention in a way that guided selective information sampling. Uncertainty was not required for this effect as it was observed when judging objectively safe, uncertain, and dangerous scenarios. These findings advance our theoretical understanding of framing effects and can inform the development of practices that harness question framing for applied risk perception and communication.
Synoptic atmospheric circulation patterns associated with deep persistent slab avalanches in the western United States
(Copernicus GmbH, 2021-02) Schauer, Andrea R.; Hendrikx, Jordy; Birkeland, Karl W.; Mock, Carly J.
Deep persistent slab avalanches are capable of destroying infrastructure and are usually unsurvivable for those who are caught. Formation of a snowpack conducive to deep persistent slab avalanches is typically driven by meteorological conditions occurring in the beginning weeks to months of the winter season, and yet the avalanche event may not occur for several weeks to months later. While predicting the exact timing of the release of deep persistent slab avalanches is difficult, onset of avalanche activity is commonly preceded by rapid warming, heavy precipitation, or high winds. This work investigates the synoptic drivers of deep persistent slab avalanches at three sites in the western USA with long records: Bridger Bowl, Montana; Jackson, Wyoming; and Mammoth Mountain, California. We use self-organizing maps to generate 20 synoptic types that summarize 5899 daily 500 mbar geopotential height maps for the winters (November–March) of 1979/80–2017/18. For each of the three locations, we identify major and minor deep persistent slab avalanche seasons and analyze the number of days represented by each synoptic type during the beginning (November–January) of the major and minor seasons. We also examine the number of days assigned to each synoptic type during the 72 h preceding deep persistent slab avalanche activity for both dry and wet slab events. Each of the three sites exhibits a unique distribution of the number of days assigned to each synoptic type during November–January of major and minor seasons and for the 72 h period preceding deep persistent slab avalanche activity. This work identifies the synoptic-scale atmospheric circulation patterns contributing to deep persistent slab instabilities and the patterns that commonly precede deep persistent slab avalanche activity. By identifying these patterns, we provide an improved understanding of deep persistent slab avalanches and an additional tool to anticipate the timing of these difficult-to-predict events.
Synoptic control on snow avalanche activity in central Spitsbergen
(Copernicus GmbH, 2021-08) Hancock, Holt; Hendrikx, Jordy; Eckerstorfer, Markus; Wickström, Siiri
Atmospheric circulation exerts an important control on a region's snow avalanche activity by broadly determining the mountain weather patterns that influence snowpack development and avalanche release. In central Spitsbergen, the largest island in the High Arctic Svalbard archipelago, avalanches are a common natural hazard throughout the winter months. Previous work has identified a unique snow climate reflecting the region's climatically dynamic environmental setting but has not specifically addressed the synoptic-scale control of atmospheric circulation on avalanche activity here. In this work, we investigate atmospheric circulation's control on snow avalanching in the Nordenskiöld Land region of central Spitsbergen by first constructing a four-season (2016/2017–2019/2020) regional avalanche activity record using observations available on a database used by the Norwegian Water Resources and Energy Directorate (NVE). We then analyze the synoptic atmospheric conditions on days with differing avalanche activity situations. Our results show atmospheric circulation conducive to elevated precipitation, wind speeds, and air temperatures near Svalbard are associated with increased avalanche activity in Nordenskiöld Land, but different synoptic signals exist for days characterized by dry, mixed, and wet avalanche activity. Differing upwind conditions help further explain differences in the frequency and nature of avalanche activity resulting from these various atmospheric circulation patterns. We further employ a daily atmospheric circulation calendar to help contextualize our results in the growing body of literature related to climate change in this location. This work helps expand our understanding of snow avalanches in Svalbard to a broader spatial scale and provides a basis for future work investigating the impacts of climate change on avalanche activity in Svalbard and other locations where avalanche regimes are impacted by changing climatic and synoptic conditions.
Tracking decision-making of backcountry users using GPS tracks and participant surveys
(Elsevier BV, 2022-07) Hendrikx, Jordy; Johnson, Jerry; Mannberg, Andrea
Snow avalanches are a significant natural hazard representing the primary risk of death to backcountry travelers in many alpine countries. Careful use of backcountry terrain through effective decision making can mitigate the risk of dangerous snowpack conditions, but requires relevant knowledge and experience. We present the results from a large-scale crowd sourced data collection method from backcountry users. Using GPS tracking via a smartphone application, coupled with online surveys, we investigate the intersection of geographical complexity, backcountry experience, demographics and behavioral biases on decision-making while navigating hazardous winter terrain. We use data from 770 GPS tracks, representing almost 1.3 million GPS points, as a geographic expression of a group's resulting decisions, and use them to quantify and understand their decision-making process. Our analysis focuses on the change in terrain use as quantified using the Avalanche Terrain Exposure Scale (ATES), and time spent in avalanche terrain, as a function of experience, avalanche hazard and other group factors. We show that self-identified experts rate themselves as significantly more skilled and also had higher levels of avalanche education. Experts also had an increased exposure to avalanche terrain overall, and also more severe terrain, as represented by median time in class 3 ATES terrain.
Using Citizen Science to Document Terrain Use and Decision-Making of Backcountry Users
(Ubiquity Press, Ltd., 2021-03) Johnson, Jerry; Hendrikx, Jordy
Avalanches represent the primary risk of death to backcountry skiers and snowmobilers in North American and European alpine countries. The best strategy for evading dangerous snowpack conditions that may result in an avalanche event requires skiers and snowmobilers to avoid or mitigate their use of hazardous terrain. Therefore, understanding terrain use is critical to understanding the causes of avalanche accidents. Secondary, post-event examination of accident data is inadequate for this understanding, and the logistical costs of user intercept surveys are problematic. Learning more about the behaviors and practices skiers and snowmobilers use to avoid avalanche fatalities or near misses is the primary concern of the avalanche education and research community. However, the topographical data required for analysis of skier and snowmobiler behavior with respect to terrain use is beyond the capacity of most backcountry skiers to provide via traditional surveys. This paper presents the use of a novel combination of user surveys and Global Positioning System (GPS) tracking to collect detailed terrain-use data from recreationists who voluntarily engage with researchers via active participation in citizen science research projects. We describe the methodology for these observations and present why they represent an effective approach to understand avalanche accidents.
Using time lapse photography to document terrain preferences of backcountry skiers
(2020-04) Saly, Diana; Hendrikx, Jordy; Birkeland, Karl W.; Challender, Stuart; Johnson, Jerry
Travel in avalanche terrain requires considered and careful selection of appropriate terrain to reduce exposure to avalanche danger. In many parts of the world, recreational backcountry skiers in avalanche terrain are aided by a regional avalanche forecast. The overall aim of an avalanche forecast is for users to adjust their terrain choices in response to the avalanche danger rating and avalanche problem, thereby reducing their risk of an avalanche involvement. In this paper we present a novel passive observation technique to assess how lift assisted backcountry skiers adjust their terrain use in response to the avalanche danger rating. This paper develops and demonstrates a method to record the terrain metrics of all skiers on an avalanche-prone backcountry slope. Using a remote time-lapse camera focused on a high skier-use backcountry slope, we anonymously recorded the descent route of skiers in ten-second increments. Using 31,966 images over 13 days and 7499 skier point locations, skier locations were digitized from the images, then transformed onto a geo-referenced digital elevation model (DEM) such that terrain metrics could be extracted for each anonymous skier location. When these location points are compared to simultaneous GPS measurements, the horizontal accuracy was estimated to be within a 49-m horizontal accuracy, with a 95% confidence interval. Analysis of the terrain metrics for each skier point compared slope, profile curvature (downslope), and plan curvature (cross slope) over days with different forecasted avalanche danger ratings. This statistical analysis was qualitatively supported by a review of the spatial patterns of the terrain choices on these days. Furthermore, we used this technique to estimate group size, and found a surprising number of solo skiers, even on Considerable avalanche danger days. By remotely photographing all skiers on a slope, the data collected provides a large and diverse data set of the terrain preferences of backcountry skiers under varying avalanche conditions, with limited bias. These results have implications for avalanche education by enhancing our understanding of specific terrain management skills by backcountry skiers.