Search

In this final chapter, we present how the different forms of data assimilation presented in this book are used in the geosciences. We shall attempt to represent as many of the geoscience disciplines as possible, but acknowledge we cannot cover all of them.

This study provides the first contemporaneous measurements of the concentration and speciation of dissolved nitrogen (N) in snow, meltwater and ice during the onset of the ablation season at a site within the Dark Zone of the Greenland Ice Sheet. The decaying, partially leached snow pack near S6 in south-west Greenland produced meltwater with relatively constant nitrate (NO3−) concentrations, approximating the snow pack average (1.1 µM). By contrast, ammonium (NH4+) (0–∼ 4 µM) and dissolved organic nitrogen (DON) (0–∼ 3 µM) concentrations were more variable, and sometimes higher than the average snow pack concentrations of 1.0 and 0.4 µM, respectively. This variability could be the result of microbial uptake and production within the melting snow pack. We observed pooled meltwater at the snow-ice interface that appeared to scavenge DON (∼1–8 µM) and possibly NO3− (∼1–2 µM) from the underlying ice, whose initial surface was a continuum of superimposed ice and weathering crust from the previous season. The shallow meteoric ice (∼10 cm–1 m) beneath the snow pack had high concentrations of DON and NH4+(6.5 and 2.6 µM, respectively), while NO3− concentrations were similar to the snow pack (1.1 µM). The absence of NH4+ in the snowmelt traversing the snow-ice interface may also point to microbial activity occurring at this boundary layer. Melt modelling indicated the presence of liquid meltwater at the snow-ice interface and that at least 10 cm of the surface ice below the snow pack was at 0°C. Solar radiation transmitted through the thin snow pack to the ice surface is absorbed by pigmented glacier algae causing melt of the surrounding ice, allowing the possibly of photosynthesis to begin under the thinning snowpack in these micro-melt environments. Hence, we conjecture that glacier algal blooms can commence before the snow pack has completely melted, occuring at a time when meltwaters are enhanced in nutrients scavenged from the snowpack, superimposed ice and the remnants of the weathering crust from the previous year.

Research on solid precipitation and snow cover, especially in mountainous areas, suffers from problems related to the lack of on-site observations and the low reliability of measurements, which is often due to instruments that are not suitable for the environmental conditions. In this context, the study area is the Monti Sibillini National Park, and it is no exception, as it is a mountainous area located in central Italy, where the measurements are scarce and fragmented. The purpose of this research is to provide a characterization of the snow cover with regard to maximum annual snow depth, average snow depth during the snowy period, and days with snow cover on the ground in the Monti Sibillini National Park area, by means of ground weather stations, and also analyzing any trends over the last 30 years. For this research, in order to obtain reliable snow cover data, only data from weather stations equipped with a sonar system and manual weather stations, where the surveyor goes to the site each morning and checks the thickness of the snowpack and records, it were collected. The data were collected from 1 November to 30 April each year for 30 years, from 1991 to 2020; six weather stations were taken into account, while four more were added as of 1 January 2010. The longer period was used to assess possible ongoing trends, which proved to be very heterogeneous in the results, predominantly negative in the case of days with snow cover on the ground, while trends were predominantly positive for maximum annual snow depth and distributed between positive and negative for the average annual snow depth. The shorter period, 2010–2022, on the other hand, ensured the presence of a larger number of weather stations and was used to assess the correlation and presence of clusters between the various weather stations and, consequently, in the study area. Furthermore, in this way, an up-to-date nivometric classification of the study area was obtained (in terms of days with snow on the ground, maximum height of snowpack, and average height of snowpack), filling a gap where there had been no nivometric study in the aforementioned area. The interpolations were processed using geostatistical techniques such as co-kriging with altitude as an independent variable, allowing fairly precise spatialization, analyzing the results of cross-validation. This analysis could be a useful tool for hydrological modeling of the area, as well as having a clear use related to tourism and vegetation, which is extremely influenced by the nivometric variables in its phenology. In addition, this analysis could also be considered a starting point for the calibration of more recent satellite products dedicated to snow cover detection, in order to further improve the compiled climate characterization.

This article presents a short-range, bistatic radar system for in situ , long-term snow monitoring. The proposed system is capable of autonomously capturing time-lapsed, 2-D images of the snow cover. In this article, we report on system concept and initial results for average snow-water-equivalent (SWE) assessment. Average SWE of dry snow is estimated based on two-way-travel time, bistatic radar measurements and compared to observed snow pit data as well as monostatic radar estimates. Although current empirical results are limited, measurements are indicating good performance. The bistatic radar instrument is capable of 2-D imaging and wet snow assessment, but empirical validation is required.

International audience; The presence of a snowpack, which may last up to 9 months in the Arctic, can provide insulation from the cold winter temperature for small mammals living beneath it, such as lemmings. Since lemmings have to move through the snowpack during that period, it is important to better understand how the physical properties of snow affect the way they dig tunnels. Here, we tested 1) whether lemmings systematically dig in the snowpack at the ground level where they can find their food plants, and 2) whether they choose the softest snow layer in which to dig, which is usually the depth hoar layer in the arctic snowpack. We found 33 lemming tunnels in 2017 and 2018 by digging through the snow at the sites of arctic fox attacks on lemmings. Contrary to our expectation, almost all the tunnels (32/33) were found to be higher than ground level, probably because of the presence of obstacles (i.e., melt-freeze crusts or hummocks) at the base of the snowpack. As predicted, all tunnels were dug in the soft depth hoar layer, which had a lower density than snow layers below and above it. Lemmings also showed a preference to dig their tunnels at the top of the depth hoar, just below a hard snow layer. Systematically digging their tunnels in the lowest-density snow layer, regardless of its height in the snow pack, could be a strategy for lemmings to minimize energy expenditure, which could improve their survival and chances of reproducing in winter. La présence d'un manteau neigeux, qui peut durer jusqu'à 9 mois en Arctique, assure une protection contre le froid pour certains petits mammifères qui s'y abritent pendant l'hiver, tels les lemmings. Cette neige est également susceptible d'affecter leurs mouvements, mais l'endroit exact où les lemmings creusent dans la neige pour se déplacer demeure peu connu. Nous avons donc testé 1) si les lemmings creusent toujours au niveau du sol, près de la végétation dont ils se nourrissent, et 2) s'ils choisissent la couche la plus molle pour creuser, généralement le givre de profondeur dans le manteau neigeux arctique. Nous avons trouvé 33 tunnels de lemmings en 2017 et 2018 en creusant dans la neige à des sites d'attaques de renards sur des lemmings. Nos résultats contredisent notre première hypothèse car presque tous les tunnels étaient plus haut que le niveau du sol (32/33), probablement en raison de la présence d'obstacles (c.-à-d. couches de fonte-regel et hummocks) dans les couches basales du manteau neigeux. En revanche, nos résultats supportent notre deuxième hypothèse puisque les tunnels étaient tous creusés dans le givre de profondeur qui avait une densité plus faible que les couches supérieures et inférieures. Les tunnels de lemmings étaient aussi souvent creusés à la limite supérieure du givre de profondeur, tout juste sous une couche plus dure. Creuser dans la couche de neige la moins dense pourrait être une stratégie des lemmings pour minimiser leurs dépenses énergétiques, ce qui pourrait augmenter leurs chances de survie et de reproduction en hiver.

Snow avalanche can be triggered by different mechanisms including metrological conditions, snow pack stability together with external factor such as seismic tremor and explosions. The snow avalanche triggered by seismic event is very important hazard phenomena in the snow covered region. In the present paper, investigation of earthquake-induced snow avalanches is introduced in Nubra–Shyok region of Western Himalaya, India. Compilation of seismogenic snow avalanche and earthquakes occurred in the Nubra–Shyok region during the period of 2010–2012 is made, which reveals that out of 393 natural avalanches, 81 avalanches was triggered due to the earthquake during this period. The local earthquakes occurred in Nubra–Shyok region, recorded by a local seismic network, are utilized for this work. The same date of occurrence of earthquakes and snow avalanches confirm seismogenic snow avalanche in this region. In the present work, avalanches triggered due to natural seismicity during the period of 2010–2012 related with earthquakes of magnitude 1.7 ≤ Mw ≤ 4.4 and distance of induced snow avalanche from epicenter of earthquakes, i.e., 4–92 km. In this study, lower bound limits of earthquake magnitudes, which cause avalanches, are established up to the distance of 92 km. Relation between earthquake magnitude and distance of induced snow avalanche from epicenter reveals that an earthquake of magnitude 1.4 (Mw) can trigger a snow avalanche as distance approaches to zero from earthquake epicenter. The comparison of obtained relation with other similar types of studies, i.e., Keefer (Geol Soc Am Bull 95:406–421, 1984), Podolskiy et al. (J Glaciol 56(197):431–446, 2010a) confirms the reliability of the present work.

Studies of ground freezing on the North-Eastern slope of the Aibga ridge (Western Caucasus) were conducted based on observations of the course of meteorological elements at three automated weather stations. Weather stations are located above the Rosa Khutor plateau at absolute elevations from 2130 to 1580 m. For the territory of the Rosa Khutor ski resort in the village. Krasnaya Polyana problems associated with the freezing of the soil, are not relevant. It is established that there is no ground freezing on the North-Eastern slope of the Aibga ridge. This allows you to significantly reduce the cost of construction of the foundation part of buildings and structures, but does not allow you to carry out early (on calendar dates) snowmaking of ski slopes. Artificial snowmaking of slopes (spraying snow on bare ground) in the fall is very problematic due to the large influx of heat from the soil of the mountain range. It is advisable to carry out snowmaking operations on the slopes after the establishment of a stable snow cover. Its minimum thickness should be 25 cm. Frequent thaws and associated precipitation in the liquid phase can form moisture-saturated layers in the snow cover that form a thermocline. This contributes to the formation of spring avalanches of wet snow. At all snow weather stations during the period of their observation, the average monthly temperature at the contact of the snow pack with the ground surface was always positive throughout the cold period. Studies have shown that before the establishment of a stable snow pack, the ground surface temperature fluctuates in a fairly large range. Since the establishment of a stable snow cover, the ground surface temperature begins to gradually increase, and by January 1 next year it already reaches +0.2°C. In the spring of 2010, snow avalanches descended on the Rosa Khutor ski complex (Krasnaya Polyana), destroying the underlying soil layer. The reason for the destruction of the soil layer was the thawed state of the soil under the snow cover. Such avalanches are random and extremely rare., Исследования промерзания грунта на северо-восточном склоне хребта Аибга проводились по материалам натурных наблюдений за ходом метеорологических элементов, наблюдавшимся на трёх автоматизированных метеостанциях, располагающихся выше плато Роза Хутор на абсолютных отметках от 2130 до 1580 м. Для территории горнолыжного комплекса «Роза Хутор» (посёлок Красная Поляна) проблемы, связанные с промерзанием грунта, не являются актуальными. Установлено, что промерзание грунта на северо-восточном склоне хребта Аибга отсутствует, что, с одной стороны, позволяет значительно удешевить строительства фундаментной части зданий и сооружений, но, с другой стороны, не даёт возможности проводить раннее (по календарным датам) оснежение горнолыжных трасс. Искусственное оснежение склонов (напыление снега на голый грунт) осенью является весьма проблематичным из-за большого притока тепла от грунтов горного массива. Работы по оснежению склонов целесообразно производить после установления устойчивого снежного покрова, причём его минимальная толщина должна составлять 25 см. Частые оттепели и связанные с ними осадки в жидкой фазе способны сформировать в толще снежного покрова влагонасыщенные пласты, образующие термоклин, способствующий образованию весенних лавин влажного и мокрого снега. На всех снеговых метеостанциях за период их наблюдения среднемесячная температура на контакте снежного покрова с поверхностью грунта была всегда положительна на протяжении всего холодного периода. Исследования показали, что до установления устойчивого снежного покрова температура поверхности грунта колеблется в достаточно большом диапазоне. С момента установления устойчивого снежного покрова температура поверхности грунта начинает постепенно расти и к 1 января следующего года уже достигает +0,2°С. Весной 2010 года на горнолыжном комплексе «Роза Хутор» сошли снежные лавины, разрушившие подстилающий почвенный слой. Причиной разрушения почвенного слоя явилось талое состояние грунтов под снежным покровом. Подобные снежные лавины случайны и происходят крайне редко. ЛитератураГОСТ 16350-80. Климат СССР районирование и статистические параметры климатических факторов для технических целей. М.: Государственный комитет СССР по стандартам, 1981. 150 с.

International audience; Snow packs cover large expanses of Earth’s land surface, making them integral components of the cryosphere in terms of past climate and atmospheric proxies, surface albedo regulators, insulators for other Arctic environments and habitats for diverse microbial communities such as algae, bacteria and fungi. Yet, most of our current understanding of snow pack environments, specifically microbial activity and community interaction, is limited to the main microbial growing season during spring ablation. At present, little is known about microbial activity and its influence on nutrient cycling during the subfreezing temperatures and 24-h darkness of the polar winter. Here, we examined microbial dynamics in a simulated cold (−5°C), dark snow pack to determine polar winter season microbial activity and its dependence on critical nutrients. Snow collected from Ny-Ålesund, Svalbard was incubated in the dark over a 5-week period with four different nutrient additions, including glacial mineral particles, dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP) and a combined treatment of DIN plus DIP. Data indicate a consumption of dissolved inorganic nutrients, particularly DIN, by heterotrophic communities, suggesting a potential nitrogen limitation, contradictory to phosphorus limitations found in most aquatic environments. 16S amplicon sequencing also reveal a clear difference in microbial community composition in the particulate mineral treatment compared to dissolved nutrient treatments and controls, suggesting that certain species of heterotrophs living within the snow pack are more likely to associate with particulates. Particulate phosphorus analyses indicate a potential ability of heterotrophic communities to access particulate sources of phosphorous, possibly explaining the lack of phosphorus limitation. These findings have importance for understanding microbial activity during the polar winter season and its potential influences on the abundance and bioavailability of nutrients released to surface ice and downstream environments during the ablation season.

Understanding the deposition history and signal formation in ice cores from polar ice sheets is fundamental for the interpretation of paleoclimate reconstruction based on climate proxies. Polar surface snow responds to environmental changes on a seasonal time scale by snow metamorphism, displayed in the snow microstructure and archived in the snowpack. However, the seasonality of snow metamorphism and its link to the deposited signal in isotopes and impurity load is poorly known.Here, we apply core-scale microfocus X-ray computer tomography to continuously measure snow microstructure of four snow cores from Greenlandic (Renland ice cap-drill site (2m), EASTGRIP drill site (5m)) and Antarctic sites (EDML-drill site (3m), COFI7/Plateau station (4m)) covering a wide range of annual temperatures from -18°C down to -56°C. In our multi-parameter approach we compare the derived microstructural properties on the mm- to cm-scale to discretely measured trace components and stable water isotopes, commonly used as climate proxies. We will show how ice and pore intercepts, the geometrical anisotropy, specific surface area, crusts anomalies and small-scale density distributions are represented under different climate conditions. Their profiles will be discussed in the context of snow metamorphism and deposition history using trace components and isotopes as additional constraints on timing.

Seasonal snow cover is a crucial resource for hydropower in Norway. Understanding water sources and processes related to inter-annual snow cover variability is therefore of fundamental societal relevance. The stable water isotope composition of precipitation provides a natural, integrated tracer of the condensation history during atmospheric water transport. The main parameters dD and d18O along with the secondary quantity d-excess give information about the origin and transport history of moisture from its source to its sink. When snow falls and deposits on the ground as a sediment, it creates a record in the form of the seasonal snow pack.Here we utilize data acquired during a field campaign in the winter season of 2018-2019 at the Finse Alpine Research Station Center (1222m, 60.6N, 7.5E) in Norway, in order to investigate the transfer of the isotopic signal of source and transport conditions from vapour to snowfall, and to the snow pack.Over a main period of two months, snowfall was sampled daily, while the water vapour was continuously measured from ambient air guided through a heated inlet to a Picarro L2130i infrared spectrometer, with daily calibration runs. During five periods with intense snowfall, we carried out higher frequency sampling down to 15 minute intervals. Covering the entire winter season, five snowpits were sampled for isotopic analysis as well as detailed stratigraphy. In total more than 400 snow samples where taken and analysed for their isotopic composition, accompanied by routine meteorological observations over the winter season at the site. In addition, we compare the variations in the observed isotope signal at Finse with one derived from moisture source analysis using the Lagrangian diagnostic WaterSip, based on the FLEXPART model and ERA Interim reanalysis data.To investigate to what degree moisture source information is archived in the snow pack, and how it evolves during the season, we compare snow observations at different time resolution (daily and high frequency snowfall samples) with the record of the snow pack, aided by the snow model CROCUS. The meteorological observations supply context for understanding the snow formation conditions. In particular, deviations from isotopic equilibrium between vapour and precipitation at ambient temperature conditions provide insight into the dominant condensation regime during different intense observation periods.

As a result of climate change, California is experiencing the impact of more extreme weather patterns including longer drought periods and atmospheric rivers resulting in extreme snow pack and heav...

Исследования промерзания грунта на северо-восточном склоне хребта Аибга проводились по материалам натурных наблюдений за ходом метеорологических элементов, наблюдавшимся на трёх автоматизированных метеостанциях, располагающихся выше плато Роза Хутор на абсолютных отметках от 2130 до 1580 м. Для территории горнолыжного комплекса «Роза Хутор» (посёлок Красная Поляна) проблемы, связанные с промерзанием грунта, не являются актуальными. Установлено, что промерзание грунта на северо-восточном склоне хребта Аибга отсутствует, что, с одной стороны, позволяет значительно удешевить строительства фундаментной части зданий и сооружений, но, с другой стороны, не даёт возможности проводить раннее (по календарным датам) оснежение горнолыжных трасс. Искусственное оснежение склонов (напыление снега на голый грунт) осенью является весьма проблематичным из-за большого притока тепла от грунтов горного массива. Работы по оснежению склонов целесообразно производить после установления устойчивого снежного покрова, причём его минимальная толщина должна составлять 25 см. Частые оттепели и связанные с ними осадки в жидкой фазе способны сформировать в толще снежного покрова влагонасыщенные пласты, образующие термоклин, способствующий образованию весенних лавин влажного и мокрого снега. На всех снеговых метеостанциях за период их наблюдения среднемесячная температура на контакте снежного покрова с поверхностью грунта была всегда положительна на протяжении всего холодного периода. Исследования показали, что до установления устойчивого снежного покрова температура поверхности грунта колеблется в достаточно большом диапазоне. С момента установления устойчивого снежного покрова температура поверхности грунта начинает постепенно расти и к 1 января следующего года уже достигает +0,2°С. Весной 2010 года на горнолыжном комплексе «Роза Хутор» сошли снежные лавины, разрушившие подстилающий почвенный слой. Причиной разрушения почвенного слоя явилось талое состояние грунтов под снежным покровом. Подобные снежные лавины случайны и происходят крайне редко., Studies of ground freezing on the North-Eastern slope of the Aibga ridge (Western Caucasus) were conducted based on observations of the course of meteorological elements at three automated weather stations. Weather stations are located above the Rosa Khutor plateau at absolute elevations from 2130 to 1580 m. For the territory of the Rosa Khutor ski resort in the village. Krasnaya Polyana problems associated with the freezing of the soil, are not relevant. It is established that there is no ground freezing on the North-Eastern slope of the Aibga ridge. This allows you to significantly reduce the cost of construction of the foundation part of buildings and structures, but does not allow you to carry out early (on calendar dates) snowmaking of ski slopes. Artificial snowmaking of slopes (spraying snow on bare ground) in the fall is very problematic due to the large influx of heat from the soil of the mountain range. It is advisable to carry out snowmaking operations on the slopes after the establishment of a stable snow cover. Its minimum thickness should be 25 cm. Frequent thaws and associated precipitation in the liquid phase can form moisture-saturated layers in the snow cover that form a thermocline. This contributes to the formation of spring avalanches of wet snow. At all snow weather stations during the period of their observation, the average monthly temperature at the contact of the snow pack with the ground surface was always positive throughout the cold period. Studies have shown that before the establishment of a stable snow pack, the ground surface temperature fluctuates in a fairly large range. Since the establishment of a stable snow cover, the ground surface temperature begins to gradually increase, and by January 1 next year it already reaches +0.2°C. In the spring of 2010, snow avalanches descended on the Rosa Khutor ski complex (Krasnaya Polyana), destroying the underlying soil layer. The reason for the destruction of the soil layer was the thawed state of the soil under the snow cover. Such avalanches are random and extremely rare., Гидросфера. Опасные процессы и явления, Выпуск 3 2020, Pages 246-259

The techniques and software presented in the article are to be used for taking into account the solid precipitation (in the form of snow deposits) effect on the seasonal changes in the Earth’s gravitational field. The combined gravitational effect of the snow cover is similar in value with the gravity measurements accuracy. Special program has been developed which makes it possible to assess the snow pack effect on the gravity changes. The map presented here shows gravitational field changes due to solid precipitation.

Interpretation of the physical and mechanical characteristic measurements of the snowpack is a base for avalanche release prediction. The spatial variability of the measured characteristics and measurement errors can affect the quality of the initial data for assessing the snowpack stability on a slope and results of this assessment. The work describes principles of rationalization for the measurements of the characteristics that influence on snow stability on a slope. The fields of these characteristics and errors of their measurements were considered as random. A few quality criteria for networks measuring snow characteristics on a slope are used. The study includes estimates of the parameters of the spatial statistical structure (variances and autocorrelation functions) for the fields of thickness, density, shear strength and temperature of snowpack on slopes in various mountain regions. Errors of methods for measuring snow characteristics were estimated. It is shown that in different landscapes, spatial patterns of the point measurements should be different. The influence of spatial measurement schemes on the quality of snowpack stability interpretation is analyzed for different parameters of spatial statistical structure of the snow characteristics and accuracy their measurements. The use of conventional deterministic methods for interpretation of point measurements of snowpack characteristics to assess its stability on the slope can and does lead to incorrect conclusions. The way out of this situation can be the use of statistical simulation based on deterministic models of mechanical stability of snowpack, the input data for which are generated on the basis of point measurements of snow characteristics and previously obtained parameters of their spatial statistical structure. Probabilistic estimates obtained with statistical simulation reflect the uncertainty of the input information in the probabilistic conclusion about the snowpack stability., Прогнозирование возникновения лавин в отдельно взятом лавинном очаге, как правило, основывается на интерпретации физико-механических характеристик снежного покрова. Обычно это достаточно грубые измерения, выполненные в отдельных точках склона. Пространственная изменчивость измеряемых характеристик и ошибки измерений могут существенно влиять на качество исходных данных для оценки устойчивости снега на склоне и на результаты такой оценки. Используемые в настоящее время системы пространственного мониторинга характеристик снега, определяющих его устойчивость на склоне, не имеют под собой рациональной основы. В работе рассмотрены принципы рационализации измерений характеристик снежного покрова, определяющих его устойчивость на склоне. При этом поля этих характеристик и ошибки методов их измерений рассматривались, как случайные. Определены критерии качества сети измерений характеристик снега на склоне. Даны оценки параметров пространственной статистической структуры (дисперсий и автокорреляционных функций) для полей толщины, плотности, температуры и сцепления снежного покрова на склонах в различных горных районах. Оценены ошибки методов измерений характеристик снега, в том числе с помощью экстраполяции эмпирической автокорреляционной функции в ноль. Показано, что в различных ландшафтах пространственные схемы измерений должны быть различными. Проанализировано влияние различных схем измерений на качество интерпретации получаемых с их помощью данных с целью оценки возможности возникновения лавин. Использование существующих детерминированных методов интерпретации точечных измерений характеристик снега, выполненных традиционными методами для оценки его устойчивости на склоне, приводит к неправильным заключениям о лавинной опасности. Для оценки устойчивости снега на склоне предлагается использование методов статистического моделирования, основанных на детерминированных моделях механической устойчивости снега, входные данные для которых генерируются на основе точечных измерений характеристик снега и ранее полученных параметрах их пространственной статистической структуры. Вероятностные оценки, полученные с помощью статистического моделирования, отражают неопределенность входной информации в вероятностном заключении об устойчивости снега. Литература Алексеев Г.А. Методы оценки случайных погрешностей гидрометеорологической информации. Л.:Гидрометеоиздат, 1975. 96 с. Божинский А.Н., Черноус П.А. Вероятностная модель устойчивости снега на склонах гор // Материалы гляциологических исследований. 1986. Вып. 55. С. 53-60. Бойко Е.С., Погорелов А.В. Применение лазерного сканирования в исследованиях рельефа и снежного покрова. Морфометрический аспект. Новосибирск: Академическое изд-во «Гео», 2012. 147 с. Войтковский К.Ф., Голубев В.Н. Войтковский В.К. Пространственная изменчивость строения и свойств снежного покрова на склонах гор // Вестник МГУ. Серия V. География. 1986. № 1. С. 80-86. Дроздов О.А., Шепелевский А.А. Теория интерполяции в стохастическом поле метеорологических элементов и ее применение к вопросам метеорологических карт и рационализации сети // ТрудыНИУГУГМС. 1946. Вып. 13. Серия1. С. 65-115. Жуковский Е.Б., Киселева Е.Л., Мандельштам С.М. Статистический анализ случайных процессов. Л.: Гидрометеоиздат, 1978. 408 с. Казакевич Д.И. Основы теории случайных функций и ее применение в гидрометеорологии. Л.: Гидрометеоиздат, 1977. 320 с. Канаев Л.А. Об изменчивости свойств снега // Тр. САРНИГМИ. 1969. Вып. 44 (59). С. 25–42. Москалев Ю.Д., Канаев Л.А. Практическое пособие по прогнозированию лавинной опасности. Л.: Гидрометеоиздат, 1979. 200 с. Соловьев В.А., Яхонтова В.Е. Элементарные методы обработки результатов измерений. Л.: Изд-во Ленинградского университета, 1977. 73 с. Черноус П.А., Барашев Н.В., Федоренко Ю.В. Изменчивость характеристик снега и образование лавин // Лёд и снег. 2010. № 3 (111). С. 27-36 Черноус П.А., Осокин Н.И., ЧерновР.А. Пространственная изменчивость толщины снежного покрова на горном склоне (архипелаг Шпицберген) // Лёд и Снег. 2018. №58(3). С.353-358. DOI:10.15356/2076-6734-2018-3-353-358 Черноус П.А., Селиверстов Ю.Г., Сучков В.Е. Влияние характеристик снега на лавинообразование // Лёд и Снег. 2015. № 55 (2). С. 53–59. DOI:10.15356/2076-6734-2015-2-53-59 Черноус П.А., Христоев Ю.В. Оценка точности данных о толщине снега в лавиносборах // Материалы гляциологических исследований. 1986. Вып. 55. С. 201–206. Чиркова А.А. Особенности структурных функций глубины снежного покрова в зависимости от характера рельефа лавинных очагов // Труды САРНИГМИ, 1977a, вып. 37 (118). С. 43-50. Чиркова А.А. Статистический анализ распределения глубины снежного покрова на малых площадях в горах // Тр. САРНИГМИ. 1977b. Вып. 32 (113). С. 40-54. Chernouss P.A., Fedorenko Yu.V. Probabilistic evaluation of snow-slab stability on mountain slopes // Annals Glaciology. 1998. Vol. 26. P. 303-306. DOI:10.3189/1998aog26-1-303-306 Chernous P., Barashev N., FedorenkoYu. Spatial variability of snow characteristics and snow stability // Proceedings of “International Snow Science Workshop 2008” (September 21st – September 27th, 2008, Whistler, British Columbia, Canada). Whistler. 2008. P. 948-949 Chernous P., Fedorenko Yu., Barashev N. Spatial variability of some snow characteristics on a slope and interpretation of measurements for snow stability assessment // Proceedings of “International Snow Science Workshop 2006” (October 1 - 6, 2006, Telluride, CO). Telluride. 2006. P.339-348

Here, we present the first detailed analysis of processes by which various current use pesticides (CUPs) and legacy organochlorine pesticides (OCPs) are concentrated in melt ponds that form on Arctic sea ice in the summer, when surface snow is melting and ice eventually breaks up. Four current use pesticides (dacthal, chlorpyrifos, trifiuralin, and pentachloronitrobenzene) and one legacy organochlorine pesticide (a-hexachlorocyclohexane) were detected in ponds in Resolute Passage, Canadian Arctic, in 2012. Melt-pond concentrations changed over time as a function of gas exchange, precipitation, and dilution with melting sea ice. Observed increases in melt-pond concentrations for all detected pesticides were associated with precipitation events. Dacthal reached the highest concentration of all current use pesticides in ponds (95 +/- 71 pg L-1), a value exceeding measured concentrations in the under-ice (0 m) and 5 m seawater by >10 and >16 times, respectively. Drainage of dacthal-enriched pond water to the ocean during ice break-up provides an important ice-mediated annual delivery route, adding-30% of inventory in the summer Mixed Layer (ML; 10 m) in the Resolute Passage, and a concentrating mechanism with potential implications for exposures to organisms such as ice algae, and phytoplankton. Crown Copyright (C) 2016 Published by Elsevier B.V. All rights reserved.

Snow avalanches in mountainous areas pose a significant threat to infrastructure (roads, railways, energy transmission corridors), personal property (homes) and recreational areas as well as for lives of people living and moving in alpine terrain. The impacts of snow avalanches range from delays and financial loss through road and railway closures, destruction of property and infrastructure, to loss of life. Avalanche warnings today are mainly based on meteorological information, snow pack information, field observations, historically recorded avalanche events as well as experience and expert knowledge. The ability to automatically identify snow avalanches using Very High Resolution (VHR) optical remote sensing imagery has the potential to assist in the development of accurate, spatially widespread, detailed maps of zones prone to avalanches as well as to build up data bases of past avalanche events in poorly accessible regions. This would provide decision makers with improved knowledge of the frequency and size distributions of avalanches in such areas. We used an object–oriented image interpretation approach, which employs segmentation and classification methodologies, to detect recent snow avalanche deposits within VHR panchromatic optical remote sensing imagery. This produces avalanche deposit maps, which can be integrated with other spatial mapping and terrain data. The object-oriented approach has been tested and validated against manually generated maps in which avalanches are visually recognized and digitized. The accuracy (both users and producers) are over 0.9 with errors of commission less than 0.05. Future research is directed to widespread testing of the algorithm on data generated by various sensors and improvement of the algorithm in high noise regions as well as the mapping of avalanche paths alongside their deposits.

Controls of stream water NO3 in mountainous and forested catchments are not thoroughly understood. Long-term trends in stream water NO3 are positive, neutral and negative, often apparently independent of trends in N deposition. Here, time series of NO3 in four small acid-sensitive catchments in southern Norway were analysed in order to identify likely drivers of long-term changes in NO3. In two sites, stream water NO3 export declined ca 50% over a period of 25 years while in the other sites NO3 export increased with roughly 20%. Discharge and N deposition alone were poor predictors of these trends. The most distinct trends in NO3 were found in winter and spring. Empirical models explained between 45% and 61% of the variation in weekly concentrations of NO3, and described both upward and downward seasonal trends tolerably well. Key explaining variables were snow depth, discharge, temperature and N deposition. All catchments showed reductions in snow depth and increases in winter discharge. In two inland catchments, located in moderate N deposition areas, these climatic changes appeared to drive the distinct decreases in winter and spring concentrations and fluxes of NO3. In a coast-near mountainous catchment in a low N deposition area, these climatic changes appeared to have the opposite effect, i.e. lead to increases in especially winter NO3. This suggests that the effect of a reduced snow pack may result in both decreased and increased catchment N leaching depending on interactions with N deposition, soil temperature regime and winter discharge.

This article provides an overview on active microwave methods for remote sensing of water equivalent (SWE). Technical concepts and applications for SWE sensing are presented based on the following principles: (1) measurement of backscatter intensity of the snow volume; (2) measurement of interferometric phase delay caused by signal propagation in the snow pack; and (3) measurement of reflecting layers to retrieve snow depth and infer SWE by means of radar altimetry.

On 19 January 2012, a large D3 avalanche (approximately 10 3 t) was recorded with an infrasound array ideally situated for observing the avalanche velocity. The avalanche crossed Highway 21 in Central Idaho during the largest avalanche cycle in the 15 years of recorded history and deposited approximately 8 m of snow on the roadway. Possible source locations along the avalanche path were estimated at 0.5 s intervals and were used to calculate the avalanche velocity during the 64 s event. Approximately 10 s prior to the main avalanche signal, a small infrasound signal originated from the direction of the start zone. We infer this to be the initial snow pack failure, a precursory signal to the impending avalanche. The avalanche accelerated to a maximum velocity of 35.9 ± 7.6 ms −1 within 30 s before impacting the highway. We present a new technique to obtain high spatial and temporal resolution velocity estimates not previously demonstrated with infrasound for avalanches and other mass wasting events.

Every year a large number of avalanches are triggered by anthropogenic activities. This study examines the occurrence of snow avalanches from 1940 to 2011 in the Fagaraș massif and Bâlea glacial area in the eastern region of the Southern Carpathian Mountains, Romania. We focused our attention on the relationship between anthropogenically triggered avalanches and terrain factors (including elevation, aspect and slope angle), snow depth and snow pack characteristics. We also examined the influence of issuing snow avalanche danger-level alerts to the public by the Bâlea Work Nivology Laboratory on the number of accidents since 2005. Most avalanche accidents occurred in the alpine and subalpine areas. The majority of avalanche fatalities occurred at high danger levels, while avalanche burials and injuries occurred at all danger levels (low–very high). Since the establishment of the National Administration of Meteorology and the Bâlea Work Nivology Laboratory, a marked reduction in accidents has occurred because of better education regarding avalanche hazards and the regular issuing of avalanche danger-level alerts to the public and authorities.

The current (2005–2011) status of the chemical composition of snow cover and rain collected at a height of 1.5 m above ground was studied within 11 km around the Severonikel industrial complex, one of the largest SO2 and metal contamination sources in N Europe. In spite of a significant decrease in emissions during the past 20 years, Ni and Cu concentrations in snow remain extremely high near the source (2500 and 1500 times background values, respectively). Although showing a five- to six-fold decrease in Ni and Cu concentrations since 1994, rain water currently still has concentrations 150 and 80 times background, respectively. Differences in the chemical composition of snow pack and rain collected at a height of 1.5 m above ground in this case are not caused by seasonal effects, but rather by the height of precipitation sampling relative to the ground.

To determine the transport processes of water vapor and aerosols over the northwestern Greenland ice sheet, we undertook a glaciological observation at a coastal site on the northwestern part of the ice sheet and revealed spatial variations in δ 18 O and in the concentrations of chemical substances in surface snow and the snowpack. On the outlet glacier (the Meehan glacier), water vapor and sea salt were transported from the coast. On the inland ice sheet in northwestern Greenland, water vapor, mineral dust, anthropogenic substances such as NO 3 - and SO4 2- , and CH3SO3 - from marine phytoplankton were transported from the west coast of Greenland via the central part of the Greenland ice sheet. 18 O, ion species

© 2017 by the authors. Monitoring the snow pack is crucial for many stakeholders, whether for hydro-power optimization, water management or flood control. Traditional forecasting relies on regression methods, which often results in snow melt runoff predictions of low accuracy in non-average years. Existing ground-based real-time measurement systems do not cover enough physiographic variability and are mostly installed at low elevations. We present the hardware and software design of a state-of-the-art distributedWireless Sensor Network (WSN)-based autonomous measurement system with real-time remote data transmission that gathers data of snow depth, air temperature, air relative humidity, soil moisture, soil temperature, and solar radiation in physiographically representative locations. Elevation, aspect, slope and vegetation are used to select network locations, and distribute sensors throughout a given network location, since they govern snow pack variability at various scales. Three WSNs were installed in the Sierra Nevada of Northern California throughout the North Fork of the Feather River, upstream of the Oroville dam and multiple powerhouses along the river. The WSNs gathered hydrologic variables and network health statistics throughout the 2017 water year, one of northern Sierra’s wettest years on record. These networks leverage an ultra-low-power wireless technology to interconnect their components and offer recovery features, resilience to data loss due to weather and wildlife disturbances and real-time topological visualizations of the network health. Data show considerable spatial variability of snow depth, even within a 1 km2network location. Combined with existing systems, these WSNs can better detect precipitation timing and phase in, monitor sub-daily dynamics of infiltration and surface runoff during precipitation or snow melt, and inform hydro power managers about actual ablation and end-of-season date across the landscape.

We present a climate analysis of nine unique Swiss Alpine new snow series that have been newly digitized. The stations cover different altitudes (450–1860 m asl) and all time series cover more than 100 years (one from 1864 to 2009). In addition, data from 71 stations for the last 50–80 years for new snow and snow depth are analysed to get a more complete picture of the Swiss Alpine snow variability. Important snow climate indicators such as new snow sums (NSS), maximum new snow (MAXNS) and days with snowfall (DWSF) are calculated and variability and trends analysed. Series of days with snow pack (DWSP) ≥ 1 cm are reconstructed with useful quality for six stations using the daily new snow, local temperature and precipitation data. Our results reveal large decadal variability with phases of low and high values for NSS, DWSF and DWSP. For most stations NSS, DWSF and DWSP show the lowest values recorded and unprecedented negative trends in the late 1980s and 1990s. For MAXNS, however, no clear trends and smaller decadal variability are found but very large MAXNS values (>60 cm) are missing since the year 2000. The fraction of NSS and DWSP in different seasons (autumn, winter and spring) has changed only slightly over the ∼150 year record. Some decreases most likely attributable to temperature changes in the last 50 years are found for spring, especially for NSS at low stations. Both the NSS and DWSP snow indicators show a trend reversal in most recent years (since 2000), especially at low and medium altitudes. This is consistent with the recent ‘plateauing’ (i.e. slight relative decrease) of mean winter temperature in Switzerland and illustrates how important decadal variability is in understanding the trends in key snow indicators.

Initial densities of deposited snows mainly depend on hydrometeors types of snowfalls. Some previous researchers qualitatively indicated their relations. However a quantitative relationship between snowfall densities and hydrometeors types had not been established because of difficulty in parameterizing varieties of types of hydrometeors in a snowfall event. Thus in a previous study, we introduced a new variable, CMF (Center of Mass Flux distribution), which described the hydrometeors mainly contributing to a snowfall. The CMF is a set of the averages of the size and the fall speed weighted by the mass flux estimated from all measured hydrometeors in a snowfall. It represents the predominant type of hydrometeors of the snowfall quantitatively. In this study, we examined the relationships between the densities of newly fallen snows and their predominant snow types as indicated by the CMFs. We measured the snowfall densities, simultaneously observing the size and the fall speed of the hydrometeors of the snowfalls and deduced the predominant hydrometeor types of each snowfall event from their CMFs. The measurements of snow densities were carried out for short periods, 1 or 2 h, during which the densification of the deposited snows was negligible. We also selected cases when snowfalls contained basically the same type of hydrometeors. As a result, we could obtain the relationships between the main snow types and the snowfall densities not only qualitatively reported by previous researchers but also the quantitative relationships between snowfall densities and the CMF-densities, which were a presumed density derived from the size and mass components of the CMFs. This suggests the possibility of estimating snowfall densities, which reflected snow types (the main types of hydrometeors), directly from the measured size and the fall speed data, and using them as the initial densities for a snow pack in a numerical model, even though difficult issues remain in parameterization for a plactical use. Our results might be applicable only to temperate snow at our observation site, Nagaoka, 37°N, where riming and aggregation are predominant. However the methodology in this study would be useful for other kinds of snow.

From 10 May through 17 June 2007 and 6 June through 9 July 2008 intensive sampling campaigns at Summit, Greenland confirmed that active bromine chemistry is occurring in and above the snow pack at the highest part of the Greenland ice sheet (72°36´ N, 38°25´ W and 3.2 km above sea level). Direct measurements found BrO and soluble gas phase Br− mixing ratios in the low pptv range on many days (maxima < 10 pptv). Conversion of up to 200 pg m−3 of gaseous elemental mercury (GEM) to reactive gaseous mercury (RGM) and enhanced OH relative to HO2 plus RO2 confirm that active bromine chemistry is impacting chemical cycles even at such low abundances of reactive bromine species. However, it does not appear that Bry chemistry can fully account for observed perturbations to HOx partitioning, suggesting unknown additional chemical processes may be important in this unique environment, or that our understanding of coupled NOx-HOx-Bry chemistry above sunlit polar snow is incomplete. Rapid transport from the north Atlantic marine boundary layer occasionally caused enhanced BrO at Summit (just two such events observed during the 12 weeks of sampling over the two seasons). In general observed reactive bromine was linked to activation of bromide (Br−) in, and release of reactive bromine from, the snowpack. A coupled snow-atmosphere model simulated observed NO and BrO at Summit during a three day interval when winds were weak. The source of Br− in surface and near surface snow at Summit is not entirely clear, but concentrations were observed to increase when stronger vertical mixing brought free tropospheric air to the surface. Reactive Bry mixing ratios above the snow often increased in the day or two following increases in snow concentration, but this response was not consistent. On seasonal time scales concentrations of Br− in snow and reactive bromine in the air were directly related.

We quantify the effect of the snow-albedo feedback on Swiss spring temperature trends using daily temperature and snow depth measurements from six station pairs for the period 1961–2011. We show that the daily mean 2-m temperature of a spring day without snow cover is on average 0.4 °C warmer than one with snow cover at the same location. This estimate is comparable with estimates from climate modelling studies. Caused by the decreases in snow pack, the snow-albedo feedback amplifies observed temperature trends in spring. The influence is small and confined to areas around the upward-moving snow line in spring and early summer. For the 1961–2011 period, the related temperature trend increases are in the order of 3–7 % of the total observed trend.

The temperature of snow at 10 discrete vertical levels in the snow pack was measured using automatic temperature recorders at 10 min intervals following 5 snowfalls between January and March 2009 at the Tianshan Station for Snow Cover and Avalanche Research. The amplitude of the diurnal fluctuation in the temperature during the measurement run of 10 March 2009, when the snow was melting, was 1.85 times greater than during the measurement run of 15 February, when snow was accumulating. Analysis of the vertical temperature gradient for all five measurement runs shows that the temperature gradient of the snow was at a maximum value at the snow surface. The maximum snow temperature gradient was measured during the run of 21 January and was 4.46 times greater than during the run of 15 February. The temperature gradient was approximately zero 30 cm below the snow surface. Analysis of the characteristics of the snow temperature and the daily mean volumetric moisture content of the snow leads to the conclusion that the snow cover in the western Tianshan Mountains can be divided into stable, interim, and melting stages. A critical snow volumetric moisture content of 0.1% separates the stable and interim stages, while a volumetric moisture content of 0.3% separates the interim and melting stages.

A multilayered backscattering model for a lossy medium has been presented in this paper. This multilayered model has been used to calculate the total surface re∞ection coe-cients of a snow pack for both horizontal and vertical co-polarizations. The total surface re∞ection coe-cients include contributions from both surface and volumetric backscattering. The backscattering coe-cients calculated by this model were compared with in situ measurements on dry and wet snow. Results show that good agreements are obtained between the model and measurements for the co-polarization modes, especially for the snow with less liquid water content.

Summary This paper presents that a simple regional regression-based approach with readily available geographic and meteorological parameters as predictors could be a viable method for mapping snow water equivalent (SWE) climatology in the mountainous areas of the western United States. Such climatological information is potentially useful for several hydrologic applications, including estimation of real-time SWE grids and calibration and evaluation of SWE estimates obtained from remote sensing or through various snow models. Regional delineation for the mountainous regions of the western United States was done through cluster analysis in consideration of the characteristics of seasonal snow pack accumulation and ablation processes. Various geographic and meteorological parameters were further investigated through stepwise regression as potential predictors of monthly changes in climatological SWE in each delineated region. In-situ measurements of SWE, obtained from the Natural Resources Conservation Service’s Snow Telemetry network for the period from 1980 to 2004, were used to calibrate regional equations. The spatial and temporal resolution of the analysis was based on the resolution of available meteorological data – 4 km and 1 month, respectively. For a monthly time step, the reliability of the SWE estimates did not significantly increase when the number of regions was more than five. The performance of the developed regional equations was evaluated via a jack-knife technique. The regional equations developed using monthly resolution and large regions provided reliable estimates for the majority of regions from October to March, but not in April, especially in the North Pacific and Southwest regions. Sub-regionalization, a finer time step for the analysis and/or inclusion of additional SWE predictor variables may increase the reliability of SWE climatological estimates for warmer months.

Seasonal snow cover is an important source of melt water for irrigation and hydropower production in many regions of the world, but can also be a cause of disasters, such as avalanches and floods. In the remote Himalayan environment there is a great demand for up-to-date information on the snow conditions for the purposes of planned hydropower development and disaster risk reduction initiatives. We describe and evaluate a snow mapping setup for the remote Langtang Valley in the Nepal Himalayas, which can deliver data for snow and water availability mapping all year round. The setup utilizes (1) robust and almost maintenance-free in-situ instrumentation with satellite transmission, (2) a freely available numerical snow model, and (3) estimation of model key parameters from local meteorological and snow observations as well as from freely available climatological data. Novel features in the model include the estimation of melt parameters and solid precipitation from passive gamma-radiation based snow sensor data, as well as improved parameterization and estimation of melt water refreezing (36% of total melt) within, and sublimation/evaporation (57 mm yr−1) from the snow pack. Evaluation of the model results show a reasonable fit with snow cover data from satellite images. As many of the high-mountain regions in central and eastern Nepal show high correlation (>0.8) with the estimated snow line elevation in the Langtang catchment, the results may provide a first-order approximation of the snow conditions for these areas too.

Migration can enhance survival and recruitment of mammals by increasing access to higher-quality forage or reducing predation risk, or both. We used telemetry locations collected from 140 adult female elk during 2000– 2003 and 2007–2008 to identify factors influencing the migration of northern Yellowstone elk. Elk wintered in 2 semidistinct herd segments and migrated 10–140 km to at least 12 summer areas in Yellowstone National Park (YNP) and nearby areas of Montana. Spring migrations were delayed after winters with increased snow pack, with earlier migration in years with earlier vegetation green-up. Elk wintering at lower elevations outside YNP migrated an average of 13 days earlier than elk at higher elevations. The timing of autumn migrations varied annually, but elk left their summer ranges at about the same time regardless of elevation, wolf numbers, or distance to their wintering areas. Elk monitored for multiple years typically returned to the same summer (96% fidelity, n 5 52) and winter (61% fidelity, n 5 41) ranges. Elk that wintered at lower elevations in or near the northwestern portion of the park tended to summer in the western part of YNP (56%), and elk that wintered at higher elevations spent summer primarily in the eastern and northern parts of the park (82%). Elk did not grossly modify their migration timing, routes, or use areas after wolf restoration. Elk mortality was low during summer and migration (8 of 225 elk-summers). However, spatial segregation and differential mortality and recruitment between herd segments on the northern winter range apparently contributed to a higher proportion of the elk population wintering outside the northwestern portion of YNP and summering in the western portion of the park. This change could shift wolf spatial dynamics more outside YNP and increase the risk of transmission of brucellosis from elk to cattle north of the park. DOI: 10.1644/08-MAMM-A-252.1.

Understanding and quantifying satellite-based remotely sensed snow cover errors are critical for successful utilization of snow cover products. The Moderate Resolution Imaging Spectroradiometer (MODIS) Snow Covered Area (SCA) product errors have been previously recognized to be associated with factors such as cloud contamination, snow pack particles, vegetation cover, and topography; however, the quantitative relationship between the retrieval errors and these factors remains elusive. Joint analysis of MODIS SCA and land surface temperature (LST) products, and in-situ air temperature and snow water equivalent (SWE) measurements provides a unique look at the error structure of the recently developed MODIS SCA products. Analysis of the MODIS SCA data set over the period from 2000 to 2005 was undertaken for the California/Nevada and Colorado regions of the western United States. Both regions have extensive observational networks. For this study area, the MODIS SCA product demonstrates strong ability in detecting the presence of snow cover (80%). However, significant spatial and temporal variations in accuracy (from 75% in high roughness to 86% in low roughness regions and 45% in October to 94% in February) suggest that a proxy is required to adequately predict the MODIS SCA product errors. For the first time, we demonstrate a relationship between the errors in the MODIS SCA products and temperature in the western United States, and find that this relationship is well-represented by the cumulative double exponential distribution function. We have performed a fitting and validation experiment by deriving the relationship between temperature and the errors in the MODIS SCA product from 2000-2004 period and using 2005 to independently test our method. This relationship is shown to hold for both in-situ daily mean air temperature and MODIS LST. Both of them are useful indices in quantifying the errors in MODIS product for various hydrological applications.

This paper presents results of two experiments on snow stress measurements under vehicles running over snow pack. In the experiments, a 5.6 T 4 × 4 military truck and a grooming machine were used. The military truck was driven over a 30-cm shallow snow pack in which a stress state transducer (SST) was installed. The grooming machine was driven over a 170-cm deep snow pack, in which four pressure sensors were installed at four different depths: 10, 20, 30, and 40 cm. Stress state in snow under the military truck was determined for rolling and for driving (pulling tests at high slip) modes and also for multiple passes. Stresses under the grooming machine were measured during low-speed rolling mode and multiple passes.

For the development of passive microwave remote sensing techniques, brightness temperature information on the medium covering the Earth's surface under different conditions is required. An emission model is a useful tool for the estimation of the brightness temperature of the medium. If the medium is a snow pack, the microwave radiation emitted will depend on the physical temperature, crystal characteristics, stratification and density of the snow. The parameters of microwave emission models available for the retrieval of snow characteristics are highly dependent on local environmental and climatological conditions. The aim of this study was to compare the empirical Chang model with the semiempirical radiative transfer model of snow developed at Helsinki University of Technology (HUT) for snow depth (SD) retrieval for UK snow packs. In the first step we used the HUT model. The root mean square error (RMSE) was used to validate the accuracy of model estimates. The snow events from different days in 1995, 1...

In the development of integrated pest management (IPM) plans for the control of sea lice there are some components that are common to many areas. However, effective plans must be tailored to regionally varying environmental and biological factors affecting the severity of sea lice infections. This paper describes factors that would be involved in the development of an IPM plan for sea lice in the Broughton Archipelago, British Columbia. Temperature, salinity and currents affect the production, dispersion and competence of larvae of sea lice, Lepeophtheirus salmonis (Krøyer), as they develop to the infective copepodid stage. This information can be coupled with oceanographic conditions in the Broughton Archipelago and emerging computer models to define zones of infection where infections of new hosts are most likely. Salinity and temperature depend, in part, on river discharge in estuarine systems. River discharge depends on precipitation, snow pack and ambient temperatures, which can be monitored to help forecast the intensity of sea lice infections associated with both farmed and wild hosts. One of the goals of IPM planning is to reduce reliance on pesticides to avoid development of resistance in targeted parasites and to minimize environmental residues. Recommendations for developing an IPM plan specific to the Broughton Archipelago are provided along with a discussion of the additional information needed to refine IPM plans in this and other areas.

A 2460-year-long hydroclimatic record for Crevice Lake, Yellowstone National Park, Montana was constructed from the δ 18 O values of endogenic carbonates. The δ 18 O record is compared to the Palmer Hydrologic Drought Index (PHDI) and Pacific Decadal Oscillation (PDO) indices, as well as inferred discharge of the Yellowstone River. During the last century, high δ 18 O values coincide with drought conditions and the warm phase of the PDO index. Low δ 18 O values coincide with wet years and a negative PDO index. Comparison of tree-ring inferred discharge of the Yellowstone River with the δ 18 O record over the last 300 years indicates that periods of high discharge (i.e., wet winters with significant snow pack) correspond with low δ 18 O values. Extrapolating this relationship we infer wet winters and high river discharge for the periods of 1090–1030, 970–870, 670–620, and 500–430 cal years BP. The wet intervals at 670 and 500 cal BP are synchronous with similar events in Banff, Canada and Walker Lake, Nevada. The wet intervals at 970 and 670 cal BP overlap with wet intervals at Walker Lake and major drought events identified in the western Great Basin. These results suggest that the northern border of Yellowstone National Park straddles the boundary between Northern Rocky Mountains and Great Basin climate regimes.

This paper presents the estimation of snow depth over north-western Indian Himalaya using the 18.7H and 36.5H GHz channels of Advanced Microwave Scanning Radiometer-EOS (AMSR-E). The Microwave Emission Model of Layered Snowpacks (MEMLS) was used along with AMSR-E to understand the difference in the snow pack emitted and sensor received signals due to the prevailing topography. The study shows that the brightness temperature of AMSR-E and MEMLS are comparable at 18.7 GHz with some differences in their values at 36.5 GHz showing the sensitivity of this channel to the prevailing topography. Three years of AMSR-E data were used to modify the 1.59 algorithm to suit the terrain and snow conditions of the north-western Indian Himalayas. The retrieved snow depth is then compared with ground observations. Data from December to February 2003-2006 were used for the study of snow depths less than 1 m. The modified algorithm estimates the snow depth better than the old algorithm over the mountainous terrains of the north-western Himalayas.

To make snow from treated municipal wastewater is one possible polishing treatment method that can be used in cold climates. In this study, the behavior of an artificial snow pile made from treated wastewater was studied. The primary focus of the study was the release of residual contaminants into the meltwaters. It was found that the first meltwaters of the snow pack are the most concentrated with contaminants. The first 30% of the meltwaters from the snow storage area included 50% of all the impurities held in the snow pack.

Temporal variation in the abundance of the encephalitis virus vector mosquito, Culex tarsalis Coquillet, was linked significantly with coincident and antecedent measures of regional climate, including temperature, precipitation, snow pack, and the El Niño/Southern Oscillation anomaly. Although variable among traps, historical records that spanned two to five decades revealed climate influences on spring and summer mosquito abundance as early as the previous fall through early summer. Correlations between winter and spring precipitation and snow pack and spring Cx. tarsalis abundance were stronger than correlations with summer abundance. Spring abundance was also correlated positively with winter and spring temperature, whereas summer abundance correlated negatively with spring temperature and not significantly with summer temperature. Correlations with antecedent climate provide the opportunity to forecast vector abundance and therefore encephalitis virus risk, a capability useful in intervention decision support systems at local and state levels.

Frequency Modulated Continuous Wave (FMCW) radars have been used by snow scientists for the past 30 years. This radar technology provides a promising alternative to point measurements, as properties such as snow depth can be measured quickly and non-destructively. Recent advances in microwave FMCW radar technology have resulted in lightweight, portable instrumentation. This is in contrast to the early FMCW radar systems which were often too heavy to cover large distances efficiently. These advanced FMCW radars provide snow scientists and hydrologists with the ability to map snow pack properties, such as depth, snow water equivalent (SWE) and stratigraphy, rapidly over large distances, at high resolution. We discuss the development of FMCW radar over the past 30 years and review the diverse applications of these radars by snow scientists.

It was discovered in 1995 that, during the spring time, unexpectedly low concentrations of gaseous elemental mercury (GEM) occurred in the Arctic air. This was surprising for a pollutant known to have a long residence time in the atmosphere; however conditions appeared to exist in the Arctic that promoted this depletion of mercury (Hg). This phenomenon is termed atmospheric mercury depletion events (AMDEs) and its discovery has revolutionized our understanding of the cycling of Hg in Polar Regions while stimulating a significant amount of research to understand its impact to this fragile ecosystem. Shortly after the discovery was made in Canada, AMDEs were confirmed to occur throughout the Arctic, sub-Artic and Antarctic coasts. It is now known that, through a series of photochemically initiated reactions involving halogens, GEM is converted to a more reactive species and is subsequently associated to particles in the air and/or deposited to the polar environment. AMDEs are a means by which Hg is transferred from the atmosphere to the environment that was previously unknown. In this article we review Hg research taken place in Polar Regions pertaining to AMDEs, the methods used to collect Hg in different environmental media, research results of the current understanding of AMDEs from field, laboratory and modeling work, how Hg cycles around the environment after AMDEs, gaps in our current knowledge and the future impacts that AMDEs may have on polar environments. The research presented has shown that while considerable improvements in methodology to measure Hg have been made but the main limitation remains knowing the speciation of Hg in the various media. The processes that drive AMDEs and how they occur are discussed. As well, the role that the snow pack and the sea ice play in the cycling of Hg is presented. It has been found that deposition of Hg from AMDEs occurs at marine coasts and not far inland and that a fraction of the deposited Hg does not remain in the same form in the snow. Kinetic studies undertaken have demonstrated that bromine is the major oxidant depleting Hg in the atmosphere. Modeling results demonstrate that there is a significant deposition of Hg to Polar Regions as a result of AMDEs. Models have also shown that Hg is readily transported to the Arctic from source regions, at times during springtime when this environment is actively transforming Hg from the atmosphere to the snow and ice surfaces. The presence of significant amounts of methyl Hg in snow in the Arctic surrounding AMDEs is important because this species is the link between the environment and impacts to wildlife and humans. Further, much work on methylation and demethylation processes has occurred but these processes are not yet fully understood. Recent changes in the climate and sea ice cover in Polar Regions are likely to have strong effects on the cycling of Hg in this environment; however more research is needed to understand Hg processes in order to formulate meaningful predictions of these changes. It was discovered in 1995 that, during the spring time, unexpectedly low concentrations of gaseous elemental mercury (GEM) occurred in the Arctic air. This was surprising for a pollutant known to have a long residence time in the atmosphere; however conditions appeared to exist in the Arctic that promoted this depletion of mercury (Hg). This phenomenon is termed atmospheric mercury depletion events (AMDEs) and its discovery has revolutionized our understanding of the cycling of Hg in Polar Regions while stimulating a significant amount of research to understand its impact to this fragile ecosystem. Shortly after the discovery was made in Canada, AMDEs were confirmed to occur throughout the Arctic, sub-Artic and Antarctic coasts. It is now known that, through a series of photochemically initiated reactions involving halogens, GEM is converted to a more reactive species and is subsequently associated to particles in the air and/or deposited to the polar environment. AMDEs are a means by which Hg is transferred from the atmosphere to the environment that was previously unknown. In this article we review Hg research taken place in Polar Regions pertaining to AMDEs, the methods used to collect Hg in different environmental media, research results of the current understanding of AMDEs from field, laboratory and modeling work, how Hg cycles around the environment after AMDEs, gaps in our current knowledge and the future impacts that AMDEs may have on polar environments. The research presented has shown that while considerable improvements in methodology to measure Hg have been made but the main limitation remains knowing the speciation of Hg in the various media. The processes that drive AMDEs and how they occur are discussed. As well, the role that the snow pack and the sea ice play in the cycling of Hg is presented. It has been found that deposition of Hg from AMDEs occurs at marine coasts and not far inland and that a fraction of the deposited Hg does not remain in the same form in the snow. Kinetic studies undertaken have demonstrated that bromine is the major oxidant depleting Hg in the atmosphere. Modeling results demonstrate that there is a significant deposition of Hg to Polar Regions as a result of AMDEs. Models have also shown that Hg is readily transported to the Arctic from source regions, at times during springtime when this environment is actively transforming Hg from the atmosphere to the snow and ice surfaces. The presence of significant amounts of methyl Hg in snow in the Arctic surrounding AMDEs is important because this species is the link between the environment and impacts to wildlife and humans. Further, much work on methylation and demethylation processes has occurred but these processes are not yet fully understood. Recent changes in the climate and sea ice cover in Polar Regions are likely to have strong effects on the cycling of Hg in this environment; however more research is needed to understand Hg processes in order to formulate meaningful predictions of these changes.

Many arctic ecological processes are regulated by soil temperature that is tightly interconnected with snow cover distribution and persistence. Recently, various climate-induced changes have been observed in arctic tundra ecosystems, e.g. shrub expansion, resulting in reduction in albedo and greater C fixation in aboveground vegetation as well as increased rates of soil C mobilization by microbes. Importantly, the net effects of these shifts are unknown, in part because our understanding of belowground processes is limited. Here, we focus on the effects of increased snow depth, and as a consequence, increased winter soil temperature on ectomycorrhizal (ECM) fungal communities in dry and moist tundra. We analyzed deep DNA sequence data from soil samples taken at a long-term snow fence experiment in Northern Alaska. Our results indicate that, in contrast with previously observed responses of plants to increased snow depth at the same experimental site, the ECM fungal community of the dry tundra was more affected by deeper snow than the moist tundra community. In the dry tundra, both community richness and composition were significantly altered while in the moist tundra, only community composition changed significantly while richness did not. We observed a decrease in richness of Tomentella, Inocybe and other taxa adapted to scavenge the soil for labile N forms. On the other hand, richness of Cortinarius, and species with the ability to scavenge the soil for recalcitrant N forms, did not change. We further link ECM fungal traits with C soil pools. If future warmer atmospheric conditions lead to greater winter snow fall, changes in the ECM fungal community will likely influence C emissions and C fixation through altering N plant availability, fungal biomass and soil-plant C-N dynamics, ultimately determining important future interactions between the tundra biosphere and atmosphere. ispartof: Global Change Biology vol:22 issue:9 pages:3080-3096 ispartof: location:England status: published

Snow avalanche studies require different snow-meteorological parameters for avalanche forecasting. Snow surface temperature is one of the major parameters, which is responsible for the evolution of snow pack characteristics. In the present paper, the snow surface temperature was estimated using TERRA satellite based — Moderate resolution imaging spectroradiometer (MODIS) sensor for NW-Himalayas. Ground data observed by automatic weather stations (AWS) was used to calibrate the brightness temperature obtained by MODIS thermal bands data into the actual snow surface temperature data through regression analysis. A split window technique has been implemented for the estimation of snow surface temperature. The multi-date satellite derived snow surface temperature was validated with ground data of winter 2004–05 and 2005–06 collected at various observation stations located in different ranges of NW-Himalaya. Good correlations were observed for Upper Himalaya (0.98, 0.98), Middle Himalaya (0.92, 0.96) and Lower Himalaya (0.88, 0.82) for 2004–05 and 2005–06 winter respectively. Further, estimated snow surface temperature was also verified with snow-cover information collected by manned observatories and area delineated by thematic maps of snow surface temperature was validated with the different snow climatic zones of NW-Himalaya.

A hydrologic model was driven by the climate projected by 11 GCMs under two emissions scenarios (the higher emission SRES A2 and the lower emission SRES B1) to investigate whether the projected hydrologic changes by 2071–2100 have a high statistical confidence, and to determine the confidence level that the A2 and B1 emissions scenarios produce differing impacts. There are highly significant average temperature increases by 2071–2100 of 3.7°C under A2 and 2.4°C under B1; July increases are 5°C for A2 and 3°C for B1. Two high confidence hydrologic impacts are increasing winter streamflow and decreasing late spring and summer flow. Less snow at the end of winter is a confident projection, as is earlier arrival of the annual flow volume, which has important implications on California water management. The two emissions pathways show some differing impacts with high confidence: the degree of warming expected, the amount of decline in summer low flows, the shift to earlier streamflow timing, and the decline in end-of-winter snow pack, with more extreme impacts under higher emissions in all cases. This indicates that future emissions scenarios play a significant role in the degree of impacts to water resources in California.

長野県白馬村周辺の山岳地において発生した5つの雪崩の破断面での積雪断面観測と1999/00～2003/04冬期に実施した6つの定点での積雪断面観測結果(140ピット)を基に対象地の雪崩発生に関わる積雪特性について考察した.破断面の観測によると,雪崩の発生原因は,新雪の弱層(2例),表層付近に形成されたこしもざらめの弱層(1例),凍結したざらめと新雪との弱い層境界(1例),地面付近に形成されたこしも・しもざらめ(1例)によるものであった.定点での断面観測により新雪,表層のこしもざらめによる弱層および弱い層境界は対象地内の広域で観測された.新雪による弱層は観測期間において最も高頻度で年により較差なく観測されたのに対し,表層のこしもざらめによる弱層および弱い層境界は観測される頻度が低く,年により較差もみられた.一方,地面付近に形成されたこしも・しもざらめは吹き払い地において局所的に形成されるが,高頻度で年により較差なく観測された.過去10冬期の気象データから北米において使用されている雪崩気候区分を試みたところCoastalに区分され,観測結果を支持する結果となり,この区分が日本の山岳地にも適用できる可能性があることが示唆された.

Snow quality and its variations due to distance from the road were studied. Also, how the snow quality changes over time during the melting period was discussed. Snow samples were collected at three occasions during the winter of 2004. The samples were taken along a highway in the Luleå region, Sweden, with an average daily traffic load of 9,200 vehicles. Snow samples were taken perpendicular to the road and at different distances. The snow samples were analysed for metals and polycyclic aromatic hydrocarbons (PAH). Also, weather parameters such as temperature, precipitation, and wind speed and wind direction were measured. The highest total metal and PAH concentrations were found at the sample site closest to the road and at the end of the season. Before the melting period started, 42–57% of the total amount of metals and PAH were found in the first 1 m of the snow pack. This information could be valuable when one is discussing how to achieve sustainable snow-handling management.