Winter Severity Index Research Articles

Problems and opportunities for biometeorological assessment of conditions cold season

The article is devoted to a discussion of the possibilities of biometeorological assessment of the severity of weather conditions during the cold season. The relevance of the study is ensured not only by the fact that residents of a number of states, whose total number is more than 27 million people, live in these extreme climatic conditions, but also by the need to improve biometeorological approaches to assessing the impact of these conditions on the body and health of the population. This study examined biometeorological characteristics that illustrate a measure of cold stress. These include the Siple wind-chill index; Bodman winter severity index; Arnoldi weather hardness coefficient; Mountain wind chill index; weather hardness coefficient according to I.M. Osokin. The results of a comparison of winter severity assessments based on the values of the calculated Siple and Bodman indices made it possible to establish that the Bodman index is more acceptable when assessing mildly severe winters. The most adequate for assessing the "severity" of the cold period against the background of a decrease in air temperature and an increase in wind speed is the Siple index. The need to provide the countries of the world with high-quality hydrometeorological and biometeorological forecast information is justified and relevant. In this regard, these studies are very promising.

Black Sea Freezing and Relation to the Winter Conditions in 2006–2021

Black Sea freezing in winter is observed regularly in its northern parts and near the Kerch Strait. The reason for this is the relatively shallow northwestern shelf part and the river inflow of the three major European rivers Danube, Dnieper, and Dniester, as well as Don through the Azov Sea, carrying a large amount of fresh water to this part of the Black Sea. The global warming that has been observed in recent decades has made these episodes less intense; nevertheless, they exist and impact people who live n the area. The aim of this study is to analyze the extent of sea-ice variability in the last 15 years, observed by satellite observations, and to describe the weather conditions favorable for freezing to occur. It is found that, in 2006, 2012 and 2017, sea ice extended unusually southward, which is related to the unusually cold winter and weather conditions in these years. The weather patterns associated with the periods of maximal sea ice in the Black Sea are discussed. In addition, we analyze how the winter conditions change in the period 1926–2021 by combining different data sources. The winter is classified as cold, moderate or mild through the Winter Severity Index following a previously published methodology. The findings in our paper could help to monitor and predict these events and to inform the interested end-users.

A Jet-Centered Framework for Investigating High Plains Winter Storm Severity

Abstract This study utilizes a winter severity index (WSI) to characterize the impacts of High (Great) Plains winter storms during the 2006/07–2018/19 winter seasons across Nebraska and the Colorado Front Range. Winter storms are specifically defined based on the severity of their meteorological impacts and are required to influence a majority of Department of Transportation (DOT) districts within both states. Following their identification, winter storms are examined using a jet-centered framework based on the two leading modes of North Pacific jet (NPJ) and North Atlantic jet (NAJ) variability. The analysis reveals that a retracted or equatorward-shifted NPJ establishes a highly amplified flow pattern conducive to cyclogenesis over the central United States, while a poleward- or equatorward-shifted NAJ favors the development of a strongly baroclinic environment across the study region that serves as a focal region for cyclogenesis and precipitation. Composite analyses of winter storms that rank in the top 25% and bottom 25% in terms of their aggregate WSI are also performed to identify characteristics of the synoptic-scale evolution that discriminate between “high impact” and “low impact” events, respectively. High-impact events are found to feature a more amplified upper-tropospheric flow pattern over the eastern North Pacific and western United States relative to low-impact events, which subsequently favors stronger cyclogenesis over the southern plains. The integration of jet regimes with winter storm severity metrics as part of this study offers the potential to enhance impact-based decision support services and provide the weather enterprise, and its stakeholders, with critical life-saving information.

Changes in snow cover occurrence and the atmospheric circulation impact in Pozna\u0144 (Poland)

The variability of occurrence of snow cover and the impact of atmospheric circulation on the snow cover occurrence in the period 1966/1967–2019/2020 in Poznań (Poland) have been examined. The implementation of the primary study objective covers the comprehensive analysis of the winter snow and thermal conditions using various indicators. This paper is based on daily data from the years 1966–2020 concerning the winter period. Winters in Poznań are highly variable and differentiated, considering the duration of particular seasons, number of days with snow cover, mean snow cover thickness, winter snowiness coefficient, or winter severity index. Negative trends concerning days with snow cover total snow cover depth winter snowiness coefficient and winter severity index in Poznań prove statistically significant. A higher probability of occurrence of snow cover was determined during cyclonic than anticyclonic circulation. The westerly and northerly types especially favoured the occurrence of days with snow cover. The increase of snow cover was associated with the northerly inflow mainly. Westerly types of circulation caused the decrease of snow cover predominantly.

White‐Tailed Deer, Weather and Predation: a New Understanding of Winter Severity for Predicting Deer Mortality

ABSTRACTVariation in white‐tailed deer (Odocoileus virginianus) mortality during winter affects population growth in cold climates. Across the northern extent of their range, mortality increases with colder temperatures and snow. Few studies have examined the relationships between winter conditions and deer mortality, and no studies have concurrently studied this relationship for different ages of deer across multiple years and landscapes. We used recently developed cause‐specific mortality models to evaluate temporal and age‐class variation in deer mortality in farmland areas and compared to published results from forest areas in Wisconsin, USA, from 2011–2014. We then used temporally varying snow and temperature covariates to predict mortality trends using telemetry information from 860 deer. Cause‐specific mortality in the farmland varied by age and year, similar to results from previous research in the forest. Human‐related mortality was the leading cause of mortality in the farmland during most years and ranged from 4.3% to 10.3% for juveniles and 3.6% to 9.1% for adults from 2011–2014. Very little predation occurred in the farmland, and this differed from previous research in the forest where predation was the leading cause of mortality. During more severe winters (2013 and 2014), other mortality, usually associated with starvation, was the leading cause of mortality for juveniles in the farmland but not adults. In the forest, we found support for saturating effects of accumulated snow depth days >30.5 cm and accumulated temperature days >0°C on mortality. We also found support for the relationship of mortality with accumulated temperature days >0°C in the farmland but no relationship with snow depth. Deer tolerate sustained cold temperatures, but the timing of winter to spring transition is more important for deer survival in both forested and agricultural areas. In the absence of empirical survival information, managers can use our model to predict annual winter effects on deer survival, which can provide improved inference compared to traditional winter severity indices. Our results suggest changes in predator abundance may have minor influence on overwinter survival compared to winter weather. Based on mortality estimates from previous research, the highest predation rates on juvenile deer in the forest occurred when wolf (Canis lupus) counts were lowest and when wolf abundance was highest, juvenile deer predation rates were lowest. © 2021 The Wildlife Society.

The development of climate services to inform decisions about winter maintenance at different timescales

Snow and ice control programs are critical for the efficiency and safety of transportation systems in all winter climates. Tools that help road authorities plan for, assess, and communicate the relationship between climate and winter road maintenance (WRM) activities are needed. There is increasing evidence that the development of such Climate Services (CS) tools is an iterative, evolving, and long-term process between the producers and users of this climate information, which increases the usability and application of climate science. This paper presents a case study describing the co-production of a climate translation service for a Canadian road authority. The purpose of this study is to: 1) refine an existing Winter Severity Index (WSI) to better understand how winter weather translates into inter-annual variations in WRM activities using publicly available data; 2) apply the index to historical weather observations to assess the magnitude and significance of historical winter weather trends, and 3) apply the index to modelled climate data to project the impacts of climate change on WRM operations in Ontario, Canada. Results indicate that the WSI for Ontario highways has strong fit with maintenance activity, when measured as equipment-hours. Analysis of WRM trends over more than three decades shows that winter severity has increased in some areas and decreased in others. The climate change analysis reveals that winters will experience a reduction in winter severity into the coming century.

Canada Goose Survival and Recovery Rates in Urban and Rural Areas of Iowa, USA

ABSTRACTOnce extirpated from much of their North American range, temperate‐breeding Canada geese (Branta canadensis maxima) have reached high abundance. As a result, focus has shifted from restoration to managing harvest and addressing human‐goose conflict. Conflict persists or is increasing in urban areas throughout the Mississippi Flyway. Managers need more information regarding demographic rates to determine how hunting affects geese breeding in urban areas and what management actions may be required to achieve management goals. We estimated survival, dead recovery, live recapture, and fidelity probabilities using data from 77,872 Canada geese banded in Iowa, USA, during 1999–2019 using Burnham joint live‐dead band recovery models. Factors predicted to affect parameters in candidate models included age (juvenile, subadult, adult), banding site (urban, rural), time, trend, harvest regulation index, and winter severity index. We predicted Canada geese banded in urban areas would have higher survival and lower dead recovery rates than geese banded at rural sites. The top model indicated support for age and banding site effects, and trends in survival and recovery rate (Brownie parameterization). Adult survival was similar for urban (0.75; range = 0.60–0.92) and rural (0.75; range = 0.66–0.82) geese and relatively constant across years. Mean juvenile survival was lower in urban (0.74; range = 0.48–0.93) than rural (0.85; range = 0.68–0.92) areas. Survival increased for urban‐banded juveniles and recovery rates increased during liberalization of harvest regulations and decreased after regulations stabilized. Recovery rates of subadults increased for the urban and rural groups. Our results suggest Canada geese breeding in urban areas contribute to harvest and specialized regulations can affect these populations. Harvest regulations in place during our analysis may not have reached a threshold required to observe substantial changes in survival. Current human‐goose conflict in urban areas suggests survival has not decreased to a level required to completely address conflict via reduction in goose abundance. Managers may consider additional liberalization of harvest regulations and monitoring via banding to determine to what degree hunter harvest contributes to reducing human‐goose conflict and what additional management actions will be required to achieve goals. © 2020 The Wildlife Society.

Influence of body mass and environmental conditions on winter mortality risk of a northern ungulate: Evidence for a late-winter survival bottleneck.

A relationship between winter weather and survival of northern ungulates has long been established, yet the possible roles of biological (e.g., nutritional status) and environmental (e.g., weather) conditions make it important to determine which potential limiting factors are most influential.Our objective was to examine the potential effects of individual (body mass and age) and extrinsic (winter severity and snowmelt conditions) factors on the magnitude and timing of mortality for adult (>2.5 years old) female white‐tailed deer (Odocoileus virginianus [Zimmerman, 1780]) during February–May in the Upper Peninsula of Michigan, USA.One hundred and fifty deer were captured and monitored during 2009–2015 in two areas with varying snowfall. February–May survival ranged from 0.24 to 0.89 (mean = 0.69) across years. Mortality risk increased 1.9% with each unit increase in cumulative winter severity index, decreased 8.2% with each cumulative snow‐free day, and decreased 4.3% with each kg increase in body mass. Age and weekly snow depth did not influence weekly deer survival. Predation, primarily from coyote (Canis latrans [Say, 1823]) and wolves (Canis lupus [L., 1758]), accounted for 78% of known‐cause mortalities.Our results suggest that cumulative winter severity, and possibly to a lesser degree deer condition entering winter, impacted deer winter survival. However, the timing of spring snowmelt appeared to be the most influential factor determining late‐winter mortality of deer in our study. This supports the hypothesis that nutrition and energetic demands from weather conditions are both important to northern ungulate winter ecology. Under this model, a delay of several weeks in the timing of spring snowmelt could exert a large influence on deer survival, resulting in a survival bottleneck.

Developing a Department of Transportation Winter Severity Index

AbstractAdverse weather conditions are responsible for millions of vehicular crashes, thousands of deaths, and billions of dollars per year in economic and congestion costs. Many transportation agencies utilize a performance or mobility metric to assess how well they maintain road access; however, there is only limited consideration of meteorological impacts to the success of their operations. This research develops the Nebraska winter severity index (NEWINS), which is a daily event-driven index derived for the Nebraska Department of Transportation (NDOT). The NEWINS includes a categorical storm classification framework to capture atmospheric conditions and possible road impacts across diverse spatial regions of Nebraska. A 10-yr (2006–16) winter season database of meteorological variables for Nebraska was obtained from the National Centers for Environmental Information. The NEWINS is based on a weighted linear combination applied to the collected storm classification database to measure severity. The NEWINS results were compared to other meteorological variables, many used in other agencies’ winter severity indices. This comparison verified the NEWINS robustness for the observed events for the 10-yr period. An assessment of the difference between days with observed snow versus days with accumulated snow revealed 39% fewer snow-accumulated days than snow-observed days. Furthermore, the NEWINS results highlighted the greater number of events during the 2009/10 winter season and the lack of events during the 2011/12 winter season. It is expected that the NEWINS could help transportation personnel allocate efficiently resources during adverse weather events. Moreover, the NEWINS framework can be used by other agencies to assess their weather sensitivity.

WINTER HARDINESS OF REPRESENTATIVES OF THE GENUS Allium L. IN THE MOSCOW REGION, DEPENDING ON THE SEVERITY OF THE WINTER PERIOD

In the Moscow region, for a long-term species of bows in winter, a complex of limiting factors determines their winter hardiness. To characterize the period from November to March 2014-2017. The winter severity index (Woz) was calculated on a scale from 0 to 10 points (0 very soft, 10 very severe). The severity of winter in 2014-2015 was 2.91 points, 20152016 3.14 points, 2016-2017 4.75 points. The average percentage of overwintered plants for each sample was determined by the ratio of the number of living plants to the number of dead. Many varieties of welch onion were not sufficiently winter-hardy, including Red, Snowdrop, Russian size, Handsome, April, Russian winter. Stable high 100% winter hardiness showed a variety of welch onion Green feathers. From the studied 71 species and 194 samples of bows of perennial different ecological and geographical origin under the conditions of the Moscow region in the subgenus Amerallium plants A. neapolitanum Cirillo (Molium section) and A. ursinum L. (section Arctoprasum), and also in the subgenus Nectaroscordum A. bulgaricum plants (Janka) Prodбn (section Nectaroscordum (Lindl.) Gren. & Godr.) in the winter of 2014-2015 died completely. Winter in 2016-2017 years in the subgenus Rhizirideum, section Rhizirideum G. Don ex Koch A. senescens L. plants overwintered 75%, A. nutans L. – 90-95% depending on the sample, A. stellarianum Willd. 15 %. In subgenus Melanocrommyum, section Melanocrommyum Webb & Berthel. s.s. plants A. cyrillii Ten. overwintered 75%. In the subgenus Butomissa, sections Butomissa (Salisb.) Kamelin plants Allium odorum L. overwintered 86-93% depending on the sample. In the subgenus Cepa, the section Schoenoprasum Dum. plants A. ledebourianum Schult. & Schult. f. overwintered 75%. The remaining species overwintered 100%.

Winter severity and snowiness and their multiannual variability in the Karkonosze Mountains and Jizera Mountains

This paper analyses winter severity and snow conditions in the Karkonosze Mountains and Jizera Mountains and examines their long-term trends. The analysis used modified comprehensive winter snowiness (WSW) and winter severity (WOW) indices as defined by Paczos (1982). An attempt was also made to determine the relationship between the WSW and WOW indices. Measurement data were obtained from eight stations operated by the Institute of Meteorology and Water Management – National Research Institute (IMGW–PIB), from eight stations operated by the Czech Hydrological and Meteorological Institute (CHMI) and also from the Meteorological Observatory of the University of Wrocław (UWr) on Mount Szrenica. Essentially, the study covered the period from 1961 to 2015. In some cases, however, the period analysed was shorter due to the limited availability of data, which was conditioned, inter alia, by the period of operation of the station in question, and its type.Viewed on a macroscale, snow conditions in the Karkonosze Mountains and Jizera Mountains (in similar altitude zones) are clearly more favourable on southern slopes than on northern ones. In the study area, negative trends have been observed with respect to both the WSW and WOW indices—winters have become less snowy and warmer. The correlation between the WOW and WSW indices is positive. At stations with northern macroexposure, WOW and WSW show greater correlation than at ones with southern macroexposure. This relationship is the weakest for stations that are situated in the upper ranges (Mount Śnieżka and Mount Szrenica).

Planning for Winter Road Maintenance in the Context of Climate Change

Abstract Winter weather creates mobility challenges for most northern jurisdictions, leading to significant expenditures on winter road maintenance (WRM) activities. While the science and practice of snow and ice control is continually evolving, climate change presents particular challenges for the strategic planning of WRM. The purpose of this study is 1) to develop a winter severity index (WSI) to better understand how winter weather translates into interannual variations in WRM activities and 2) to apply the WSI to future climate change projections to assist a northern community in preparing for climate change. A new method for creating a WSI model is explored, using readily available data from maintenance records and meteorological stations. The WSI is created by optimizing values for three levels of snowfall as well as potential icing events and is shown to have high predictive accuracy for WRM (coefficient of determination R2 of 0.93). The WSI is then applied to historic and future climate data in a municipality located in central British Columbia, Canada. Findings reveal that much of the variability in WRM can be attributed to weather. The results of the climate change analysis show that winter precipitation in the region is expected to increase by 5.2%–12.3%, and winter average temperatures are projected to increase by 1.5°–2.8°C in the 2050s, compared to the 1976–2000 baseline based on 65 GCMs. Based on the midrange (25th to 75th percentiles) of the 65 GCM projections, annual demand for WRM activities is estimated to decrease by 13.0%–22.0%.

Development of a Flexible Winter Severity Index for Snow and Ice Control

AbstractSnow removal and ice control are critical to the safe and efficient use of roadways in much of the world. Tools that help road authorities plan for, assess, and communicate about winter mai...

Long-term changes of the ice regime of rivers in Latvia

The ice regime of rivers is considered a sensitive indicator of climate change. This paper summarises the results of research on the long-term changes in the ice regime parameters under changing climate conditions and their regional peculiarities in Latvia from 1945 to 2012. The ice cover duration on Latvian rivers has decreased during recent decades. The research results demonstrated that there is a positive trend as regards the formation of the ice cover and in 31.8% of the cases the trend is statistically significant at p < 0.05. As regards the breaking up of ice, there is a statistically significant negative trend in 93.2% of the cases at p < 0.05. This indicates an earlier ice break-up date, which in turn, displays a strong correlation with the increase of the air temperature. The same pattern applies to the reduction of the length of ice cover (a statistically significant trend in 86.4% of the cases at p < 0.05). In approximately 60% of the cases, there is a statistically significant reduction of the ice thickness. The estimated winter severity index indicates warmer winters over the last 20 years as well as regional differences in the west–east direction.

Born to be wild? Response of an urban exploiter to human-modified environment and fluctuating weather conditions

Human-driven environmental changes affect behavior, morphology, life history, and population dynamics of wild species. Artificial food sources in anthropogenic environments benefit some species and may lead to faster somatic growth and larger body size, which affects survival and reproduction, thus contributing to a species’ success in modified environments. Using raccoons (Procyon lotor (L., 1758)) as a model, we documented age-specific body-mass pattern and evaluated the influence of human activities (human density, area with artificial food sources, edges of forested area bordering corn (Zea mays L.) fields) and weather (index of winter severity and mean annual precipitation) on body-mass variation at multiple spatial scales. The effect of human-driven changes on raccoon mass varied with age, sex, and spatial scale, suggesting that anthropogenic changes affect raccoons differentially according to gender and life stages. Human activity had consistently opposing effects between the sexes. Weather covariates represented >50% of the total variance in body mass explained by our models. Previous winter severity and mean annual precipitation affected body mass negatively and positively, respectively. Our results emphasize the importance of multiscale, sex- and age-specific analyses when studying influences of human activity on wildlife.

Twenty-First-Century Projections of Snowfall and Winter Severity across Central-Eastern North America*,+

Abstract Statistically downscaled climate projections from nine global climate models (GCMs) are used to force a snow accumulation and ablation model (SNOW-17) across the central-eastern North American Landscape Conservation Cooperatives (LCCs) to develop high-resolution projections of snowfall, snow depth, and winter severity index (WSI) by the middle and late twenty-first century. Here, projections of a cumulative WSI (CWSI) known to influence autumn–winter waterfowl migration are used to demonstrate the utility of SNOW-17 results. The application of statistically downscaled climate data and a snow model leads to a better representation of lake processes in the Great Lakes basin, topographic effects in the Appalachian Mountains, and spatial patterns of climatological snowfall, compared to the original GCMs. Annual mean snowfall is simulated to decline across the region, particularly in early winter (December–January), leading to a delay in the mean onset of the snow season. Because of a warming-induced acceleration of snowmelt, the percentage loss in snow depth exceeds that of snowfall. Across the Plains and Prairie Potholes LCC and the Upper Midwest and Great Lakes LCC, daily snowfall events are projected to become less common but more intense. The greatest reductions in the number of days per year with a present snowpack are expected close to the historical position of the −5°C isotherm in December–March, around 44°N. The CWSI is projected to decline substantially during December–January, leading to increased likelihood of delays in timing and intensity of autumn–winter waterfowl migrations.

Thermal and snow conditions of winters and winter floods on example of Zagożdżonka River

Abstract Thermal and snow conditions of winters and winter floods on example of Zagożdżonka River. Thermal and snowy conditions in Zagożdżonka River catchment during hydrological years 2003-2013 and winter floods are presented in paper. The meteorological and hydrological data, such as maximum, minimum, mean diurnal air temperatures, daily snow cover depth, and water discharge, collected at Czarna station (WULS-SGGW) have been used. Meteorological conditions were analyzed using indexes proposed by Paczos. Temperate cold and extraordinarily low snowy winters has dominated in Zagożdżonka catchment in presented period of time. Winter floods as a result of snowmelt have been observed almost each year, except 2008 when winter was mild and extremely low snowy. The relation between winter severity index (WOz) and winter snowiness index (WSn) has been estimated, as well as the relation between winter snowiness index and maximum discharge (Qmax).

A hidden Markov model to identify and adjust for selection bias: an example involving mixed migration strategies.

An important assumption in observational studies is that sampled individuals are representative of some larger study population. Yet, this assumption is often unrealistic. Notable examples include online public-opinion polls, publication biases associated with statistically significant results, and in ecology, telemetry studies with significant habitat-induced probabilities of missed locations. This problem can be overcome by modeling selection probabilities simultaneously with other predictor–response relationships or by weighting observations by inverse selection probabilities. We illustrate the problem and a solution when modeling mixed migration strategies of northern white-tailed deer (Odocoileus virginianus). Captures occur on winter yards where deer migrate in response to changing environmental conditions. Yet, not all deer migrate in all years, and captures during mild years are more likely to target deer that migrate every year (i.e., obligate migrators). Characterizing deer as conditional or obligate migrators is also challenging unless deer are observed for many years and under a variety of winter conditions. We developed a hidden Markov model where the probability of capture depends on each individual's migration strategy (conditional versus obligate migrator), a partially latent variable that depends on winter severity in the year of capture. In a 15-year study, involving 168 white-tailed deer, the estimated probability of migrating for conditional migrators increased nonlinearly with an index of winter severity. We estimated a higher proportion of obligates in the study cohort than in the population, except during a span of 3 years surrounding back-to-back severe winters. These results support the hypothesis that selection biases occur as a result of capturing deer on winter yards, with the magnitude of bias depending on the severity of winter weather. Hidden Markov models offer an attractive framework for addressing selection biases due to their ability to incorporate latent variables and model direct and indirect links between state variables and capture probabilities.

Influence of climate and human land use on the distribution of white-tailed deer (Odocoileusvirginianus) in the western boreal forest

Understanding the factors that drive species distributions is emerging as an important tool in wildlife management, under unprecedented changes in species ranges. While invasion ecologists have long studied the impact of human land use on species’ distributions, and models developed more recently to explain changes in species range boundaries have been largely parameterized by climate variables, few authors have considered climate and land-use factors together to explain species distribution. The purpose of this study was to test two main competing hypotheses involving human land use and climate effects on white-tailed deer (Odocoileus virginianus (Zimmermann, 1780)) distribution, which has expanded into the boreal ecosystem in recent decades. Using a species distribution modeling approach with data from boreal Alberta, we found that climate, as measured by an index of winter severity, was the most important individual factor determining current white-tailed deer distribution in boreal Alberta. Human land use (as measured by total land-use footprint) acted to substantially increase white-tailed deer presence but only in areas with more severe winter conditions. We use our findings to recommend where limiting or reclaiming the industrial footprint may be most beneficial to limiting white-tailed deer distribution.

Reconstructed river ice extent on the River Mersey, UK, an index of winter severity since 1500

Reconstructed river ice extent on the River Mersey, UK, an index of winter severity since 1500