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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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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.

Snow depth is one of the most important parameters for water resource management in those areas where snowfall is significant. Two different methods are applied here for snow monitoring using passive microwave data retrieved from the Special Sensor Microwave Imager (SSM/I). Since microwave sensors are least attenuated by the cloud cover, they have been widely used to retrieve snow cover data in a timely way. Passive microwave studies have shown that dry snow cover as well as mixed snow packs that contain free liquid water, affect naturally up-welling microwave radiation through forward scattering. In the first approach, brightness temperature (Tb) values at 18.7, 36.5 and 90 GHz vertical and horizontal frequencies for various snow packs are measured. In the second approach, the passive microwave response from snow packs of different physical conditions at 19, 37 and 85 GHz vertical and horizontal frequencies are modelled. Thus, various snow pack characteristics were estimated, the results indicat...

A multipurpose hydrological and statistical analysis of long-term changes in suspended sediment yield has been made for large Russian rivers discharging to the Arctic Ocean. Factors affecting sediment yield formation, e.g., snow pack duration, mean air temperature and mean water discharge, have been analyzed as well. The duration of observations at 13 selected meteorological stations varies from 56 to 113 years and covers the period from 1883 to 1995. The duration of water discharge measurements at 22 hydrological stations varies from 20 to 120 years; measurements were made from 1881 to 2000. The duration of sediment yield observations is shorter (from 1936 to 2000) and varies from 14 to 62 years. The air temperature rise is evident for 10 stations while temperature fall is observed at 3 stations (Dickson Island, Narjan Mar, Kiusiur). These three stations are established in the coastal area of the Arctic Ocean. The most impressive coincidence of trends towards an increase of mean air temperature and mean annual water discharge is observed in the Pechora, Angara, Lena, Aldan, Yana and Indugirka river basins, and in the lower reaches of the Ob and Yenisei river basins. A decrease of water discharge is observed in the Severnaya Dvina river, probably refracting by the effect of cut forest on water availability in the river. The decrease of water discharges in the upper parts of the Ob and Yenisei river basins refracts reservoirs. Changes in suspended sediment yield depend more on man's activity than on climate change. Construction of reservoirs in the upper reaches of the Ob and Yenisei rivers explains the decreased sediment yield. An increase of sediment yield in the Kolyma river basin has been observed due to the gold mining there.

in California and end in Nevada. The Truckee River originates at Lake Tahoe and is fed below the lake by Prosser Creek, Martis Creek, Independence Creek, and the Little Truckee River. After crossing the border into Nevada, the Truckee flows east through Reno and Sparks, then turns north and ends at Pyramid Lake, "a natural sink or basin, from which water can only leave by evaporation." The headwaters of the Carson River originate in east and west forks in Alpine County, California. As it flows eastward the Carson River is impounded by the Lahontan Reservoir, part of the Newlands Project. After it is used for irrigation purposes on the Newlands Project, the water terminates in the Carson's sink, a "wetland which fluctuates in size depending on the extent of the winter's snow pack in the Sierra Nevada Mountains."1 This article examines the changing political fortunes of the Newlands Project irrigators and their governing entity, the Truckee-Carson Irrigation District (TCID). The TCID is controlled by an elected board of directors cho

The regional distribution of ion concentration and ionic load along a meridional transect in the Eastern Alps was investigated in 1993 and 1994 taking samples of the high alpine snow pack at six sites. High concentrations of atmospheric trace substances seemed to be related to high rates of snow accumulation. Zugspitze at the northern, and Careser Glacier at the southern margin of the Alps and Hintereisferner at the main divide had higher concentrations of sulfate and nitrate than adjacent sites. The pattern found in the ion concentrations was accentuated in the deposition rates with maximum ionic loads up to three times higher than the minima at the dry sites. Sulfate concentrations and sulfate to nitrate ratios were higher in the southern part of the transect.

International audience; A small-size meteorological mast, BEAR (Budget of Energy for Arctic regions) has been developed as a part of a new autonomous buoy for monitoring the sea ice mass balance. BEAR complements observations of the thickness and thermodynamic properties of the ice/snow pack determined by the so-called Ice-T (Ice-Thickness) buoy, giving access to bulk fluxes and energy budget at the surface, using meteorological measurements. The BEAR mast has been tested with success during ten days in April-May 2010 at Ny Alesund, in the Svalbard archipelago (Norway) showing that meteorological data were close to measurements at the same level of the Italian Climate Change Tower (CCT) from the ISAC-CNR. A discussion is undertaken on bulk fluxes determination and uncertainties. Particularly, the strategy to systematically use different relevant fluxes parameterizations is pointed out to explore flux range uncertainty before to analyze energy budget. Net radiation, bulk fluxes and energy budget are estimated using as average 10 minutes, 24 hours and the ten days of the experiment. The observation period was very short, but we observe a spring transition when the net radiation begins to warm the surface while the very small turbulent heat flux cools the surface.

12 páginas, 5 figuras, 6 tablas., Large areas in the Spanish Pyrenees are covered by snow between December and April, especially above 1650 m a.s.l., the location of the cold season 0°C isotherm. However, a significant negative trend in Pyrenean snow pack was detected during the second half of the 20th century. This paper analyses the interannual evolution of snow accumulation in these mountains in relation to the variability of atmospheric circulation. The study considers two spatial scales, from weather types over the Iberian Peninsula to hemispheric atmospheric patterns. The results show strong relationships between the annual occurrence of several weather types and spring snow accumulation. Changes in the frequency of several weather types are explained by the evolution of large scale hemispheric circulation patterns, especially the North Atlantic Oscillation (NAO). Thus, the positive trend observed in the NAO index leads to a decrease in the occurrence of types that favour snow accumulation and an increase in unfavourable conditions for snow pack during the second half of the 20th century., This study was supported by the following research projects: PIRIHEROS, REN 2003- 08678/HID, CGL2005-04508/BOS and CANOA, CGL 2004-04919-c02-01, all funded by the CICYT, Spanish Ministry of Science and Technology. The research of the authors was supported by postdoctoral fellowships from the Spanish Ministry of Education, Culture and Sports, Spain.

Theme Ecological processes are strongly influenced by climate drivers as well as by the landscape in which they are embedded, with the interactions between these influences resulting in complex phenomena. It is imperative to have a strong understanding of these attributes of an ecosystem as a foundation for ecological investigations. In mid- to high-latitude environments snow pack may be present for five to eight months each year and represents an abiotic attribute of fundamental importance to large mammal ecology. Capturing the dynamic heterogeneity of snow pack at temporal and spatial scales relevant to large mammal communities is extremely challenging. Thus, most studies of large mammal ecology have either ignored snow pack dynamics or used surrogates for snow pack such as elevation and aspect. However, snow pack attributes are determined by many influences. The large-scale orographic influence of mountain ranges and valleys determines the overall distribution of precipitation and, hence, snow water equivalent. But many influences such as solar radiation, dense forest cover, and exposure to high winds act at highly localized scales to reduce snow pack accumulation. The Madison headwaters system of central Yellowstone National Park provides a good template for evaluating these interactions, as it is a highly heterogeneous landscape experiencing heavy snow pack (Figure 6.1) and is strongly influenced by geothermals and high winds. We described the integration of climate and landscape databases, as well as rigorous field sampling of snow pack, to develop and validate a spatially distributed, physically-based snow pack simulation model. We used this model to provide a variety of snow pack metrics for 16 of the Chapters in this book ( Chapter 8–11, 13, 16–17, 18–23, and 27–29 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Chapter 13 Chapter 16 Chapter 17 Chapter 18 Chapter 19 Chapter 20 Chapter 21 Chapter 22 Chapter 23 Chapter 27 Chapter 28 Chapter 29 ).

Theme Winter for ungulates in the northern Rocky Mountains is a period of chronic under‐nutrition and catabolism of lean muscle and body fat because forage availability and quality are low, while energetic demands are high (Moen 1976, Torbit et al. 1985, DelGuidice et al. 1990). The rate of ingestion of assimilable energy and nutrients, and the resulting state of body components, reflect the adequacy of forage quality and quantity to meet metabolic demands (Harder and Kirkpatrick 1994; Parker et al. 1999; Cook et al. 2004a,b). Furthermore, nutrition and nutritional condition strongly influence the probability of breeding, over‐winter survival, lactation yields, and susceptibility to predation (Loudon et al. 1983, Hobbs 1989, Kohlmann 1999, Mech et al. 2001, Bender et al. 2002, Cook 2002). The heterogeneous environment inhabited by elk (Cervus elaphus) wintering in the Madison headwaters area of Yellowstone National Park provides a diversity of potential foods for elk with quite divergent energy, protein, secondary compound, and toxin characteristics (Craighead et al. 1973). We characterized the composition and quality of elk diets prior to wolf (Canis lupus) recolonization, evaluated the effects of diet selection and snow pack on nutrition using an index of metabolizable energy intake, and related annual variability in winter nutrition to demographic vital rates.

Theme While the elk herd that winters on the northern range of Yellowstone National Park has been the subject of almost continuous investigations since the inception of the park, the elk herd that occupies the Madison headwaters area in the central portion of Yellowstone has received much less scientific attention. This is a particularly interesting population for the study of regulatory processes because the elk remain within the confines of the park year‐round and, thus, are not subjected to harvest by human hunters. Historic records also suggest that the herd was not targeted by market hunters during the 1800s nor managed by the National Park Service through intensive culling, as was common for ungulates occupying the northern range until 1968 when the Park Service adopted the natural regulation policy (Cole 1971, 1983). Hence, the dynamics of this herd have not been influenced to any appreciable extent by human manipulations other than the extirpation of wolves from the Park in the early 1900s. This portion of Yellowstone is also subjected to harsh winter conditions with periods of intense cold temperatures and deep snow pack in most years. These conditions provide an excellent opportunity to study the influence of density‐dependent and density‐independent factors and their interactions in regulating population processes in an ungulate herd. In this chapter, we present the results of an intensive demographic study of this population that was conducted just prior to the reestablishment of wolves.

Lack of a method to properly account for snowmelt runoff and erosion in the Revised Universal Soil Loss Equation Version 2 (RUSLE2) hampers its use in areas where there is a period of melting of snow accumulated during the winter. This also adversely affects the performance of other models that use RUSLE2 as the driver for hill slope erosion. Because RUSLE2 relies on input data sets to drive the erosion process, we sought models that could effectively estimate snow accumulation and melt and provide data from which snowmelt erosivity databases could be developed. The Soil-Plant-Air-Water (SPAW) model was tested for ability to simulate accumulation and melt of snow. Model tests were based on daily climate data collected over a forty-one-year period from selected weather stations in cold or high elevation cropland areas of the western U S, the Northern Great Plains, and the northeastern U S. Snow depths predicted with SPAW default parameters are generally less than observed and the snow pack is predicted to melt before observed records indicate. Adjusting the accumulation and melt temperatures allows for a better match to the observed data. Density of falling snow is an important issue that needs to be considered in snow depth prediction and snow accumulation because new snow density is highly variable. After converting observed snow density to the constant value used in SPAW, the model fitting evidently improved. The model performance also indicated that ET and air temperature need to be well handled to achieve better prediction. When RUSLE2 average climate data is used in SPAW, the model is insensitive to the input accumulation and melting temperature for stations with low winter temperature and heavy snow. However, the model is sensitive to these input temperatures for stations where winter temperature is high and snowfall is light. Here, snow accumulation is less likely to be a winter long event; rather, snow accumulates and melts frequently during the winter.

During the Winter Weddell Gyre Study 1989, the RV ”Polarstern“ transected the Weddell Sea West to East. Detailed snow pit studies which included the determination of the amount of free water within the snow pack were correlated with the brightness temperatures from the Special Sensor Microwave/Imager. The results indicate a steep increase in brightness temperatures with increasing free water content from 0 to 1% by volume.

Sampling for adult Kootenai River white sturgeon Acipenser transmontanus began in March and continued through April 1999. Forty-six adult sturgeon were captured with 4,091 hours of angling and set-lining effort, while an additional three adult sturgeon were captured during gillnetting for juveniles. Flows for Kootenai River white sturgeon spawning were expected to be high because the snow pack in the basin was estimated at 130% of normal, but runoff came very slowly. Discharge from Libby Dam from mid-March through mid-June was maintained at 113 m{sup 3}/s (4,000 cfs). Flows in the Kootenai River at Bonners Ferry during early April, including local inflow, were 227-255 m{sup 3}/s (8,000-9,000 cfs) but increased gradually in late April to a peak of 657 m{sup 3}/s (23,200 cfs). Flows subsided in early May to about 340 m{sup 3}/s (12,000 cfs), but rose to 1,031 m{sup 3}/s (36,370 cfs) by Mary 26 because of local runoff, and white sturgeon began spawning. However, flows subsided again to 373 m{sup 3}/s (13,200 cfs) June 11, 1999 and some female white sturgeon with transmitters began leaving the spawning reach. Water temperature ranged from about 8 C to 10 C (45 F to 50 F) during these two weeks. On June 13 (two weeks after sturgeon began spawning), spawning and incubation flows from Libby Dam began. The flow was brought up to 1,136 m{sup 3}/s (40,100 cfs) and temperature rose to about 11 C (52 F). They sampled for 3,387 mat days (one mat day is a single 24 h set) with artificial substrate mats and captured 184 white sturgeon eggs. The Middle Shorty's Island reach (river kilometer [rkm] 229.6-231.5) produced the most eggs (144), with 388 mat days of effort; the Refuge section (rkm 234.8 to 237.5) with 616 mat days of effort produced 23 eggs; and the Lower Shorty's section produced 19 eggs with 548 days of mat effort. No eggs were collected above the Refuge section (> rkm 240.5) with 988 mat days of effort. They do not believe flows for sturgeon spawning in 1999 were very time for adequate spawning. Most spawning is thought to have occurred before the spawning flows, when 66% of the spawning events and 87% of the eggs were collected. Recommendations for the 2000 spawning season are given.

Test flows for Kootenai River white sturgeon Acipenser transmontanus spawning, scheduled for June 1996, were postponed until July. However, an estimated 126% snow pack and unusually heavy precipitation created conditions for sturgeon spawning that were similar to those occurring before construction of Libby Dam. Discharge in the Kootenai River at Bonners Ferry rose to nearly 1,204 m{sup 3}/s (42,500 cfs) during May and water temperature ranged from 5.8 C to 8.4 C (42 F to 47 F). Migration of adult white sturgeon into spawning areas occurred in late May during a rising hydrograph. Discharge and water temperature were rising and had reached approximately 1,077 m{sup 3}/s (38,000 cfs) and 8 C (46 F). Discharge at Bonners Ferry peaked at about 1,397 m{sup 3}/s (49,300 cfs) on June 5. A total of 348 eggs (and one egg shell) were collected with 106,787 h of mat effort during the flow events. The first white sturgeon eggs were collected on June 8 and continued through June 30. Staging of eggs and back-calculating to spawning dates indicated there were at least 18 spawning episodes between June 6 and June 25. Discharge on June 6 was 1,196 m{sup 3}/s (42,200 cfs) and decreased steadily to 850 m{sup 3}/s (30,000 cfs) by June 26. Although sturgeon spawned in the same reach of river that they had during 1994 and 1995, the majority of eggs were found significantly (P = 0.0001) farther upstream than 1994 and 1995 and this in turn may be related to elevation of Kootenay Lake.

The Big Sioux River flows through Sioux Falls, located in Minnehaha County, South Dakota. A Reconnaissance Study completed in 1988 identified a Federal interest in upgrading the existing flood control project at Sioux Falls by raising the levees. A diversion channel bypasses the 25.7-km (16-mile) loop of the Big Sioux River, avoiding the populated downstream area and a 24-m (80-ft) drop at the natural falls downstream of the downtown area. The city of Sioux Falls requested U.S. Army Corps of Engineers assistance in 1969 because of a heavy snow pack and other conditions conducive to a major flood event. The levee across the channel from the diversion spillway chute stilling basin suffered erosion damage and was in danger of being breached. A 1993 Feasibility Report by the Omaha District examined deepening the stilling basin, raising the stilling basin walls, and raising the levees. The design of the chute stilling basin was based on sound engineering procedures; however, the need for a model study was necessary to optimize chute and stilling basin features to obtain the most economical design. The model verified that modifications to the stilling basin walls were necessary. While modifications to the stilling basin were not necessary, it was determined that channel realignment would increase energy dissipation. The following information was obtained from the model: flow characteristics and stilling basin performance, chute wall heights to prevent overtopping, downstream levee heights to prevent overtopping, riprap requirements for protection downstream of the structure, and wave heights of existing flow for design of riprap protection of the levees. The model study was used to determine the type of modifications to the basin. Serious consideration to lowering the basin was made.

In recent years the study of how atmospheric aerosols and gases are deposited in the snow pack of the interiors of the Greenland and Antarctic ice sheets has become a growing field, exemplified by the proceedings of this volume and the proceedings of the NATO ARW in Annecy in 1993 (Delmas, 1995). If the functions of transfer of various aerosols and gases from the atmosphere to snow/ice strata were known, then ice core data could be used to calculate past atmospheric compositions.

Ecology![Figure][1] CREDIT: WIKIPEDIA In the early 20th century, Joseph Grinnell, who cofounded the University of California's Museum of Vertebrate Zoology, initiated a series of biological surveys throughout the western United States. He and his colleagues could not have predicted the extent of climate change that we are experiencing in the 21st century, but their survey data have proven to be invaluable. Morelli et al. have used these data to determine how climate change has affected Belding's ground squirrel, a mountain meadow specialist. From resurveys of 74 of the same sites in California's Sierra Nevada Mountains, which were originally sampled between 1902 and 1966, they found that 31 of the ground squirrel populations have been extirpated; in addition, there was no evidence for their having colonized nearby suitable habitats. Next, the authors examined climate, landscape, and land-use data to identify causal factors for the observed range contraction and found that winter cold was the strongest positive predictor of population persistence: Both more frequent rain-on-snow events and a thinner insulating snow pack are known to harm montane mammals. Interestingly, they found a buffering effect of human activity, such as camping and agriculture, which locally increase food and water availability. Models based on these causal factors predict a continuing contraction of Belding's ground squirrel populations, with the most extreme outcome being a 99% loss of suitable habitat in California by 2080. Proc. R. Soc. London Ser. B. 279 , 10.1098/rspb.2012.1301 (2012). [1]: pending:yes

Ensembles of 21st century climate projections made using a state of the art global climate model are analyzed to explore possible changes in spring snow cover and summer air temperature in present-day wolverine habitats in the contiguous United States (US). Projected changes in both snow cover and temperature are presented for a range of future emissions scenarios, and implications for the continued survival of the wolverine in the contiguous US are discussed. It is shown that under a high or medium–low emissions scenario there are likely to be dramatic reductions in spring snow cover in present-day wolverine habitats. Under these scenarios there is also likely to be a concomitant increase in summer-time temperatures, with projected maximum daily August temperatures far above those currently tolerated by the wolverine. It is likely that the wolverine, with its many adaptations for cold weather and deep snow pack, would have great difficulty adapting to such changes. The results of the simulations presented here suggest that the very low numbers of wolverines currently living in the contiguous US will likely further decline in response to the deterioration of their habitat in coming decades.

Timberline, or the low-temperature limits of forest and tree growth, is one of the most fundamental ecological boundaries. Below timberline, foliage and reproductive structures are successfully produced at the height of tree canopies; above timberline, plants grow only in favoured environments close to the ground. Timberlines are also relatively well-defined, even where altitudinal environmental gradients are gradual. Most other sharp boundaries in nature reflect environmental discontinuities such as shore lines, or disturbances such as forest clearance.

Very small changes in the Earth's gravity field—which might result from shifts in deep ocean currents, melting of ice sheets in Antarctica, or accumulation of seasonal snow pack in the mountains—could be detected and mapped using newly developed instruments on future satellite missions. A new report from the National Research Council recommends the satellite missions, which would detect gravity changes that are 100 to 100,000 times smaller than those measured previously, to map the Earth's gravity field and provide new data for a variety of scientific fields.

The predictive snowmelt runoff model (SRM), previously suggested by other authors, is reliable and easy to use. Furthermore, the only parameters required are temperature and precipitation, and density and thickness of the snow pack. The literature available indicates that simulation results with this model are generally satisfactory. However, data on the extent of the snow cover are not always available; this means that the snow pack must be calculated before the SRM can be used. Our purpose herein is to develop a model to evaluate the snowpack, which is to be used in conjunction with the SRM. The SRM was modified in that maximum daily temperature was used instead of the number of degrees-days. The snowmelt and snow cover models were calibrated and tested along the drainage basin of the Eaton River, a tributary of the Saint-François River in the province of Quebec. Key words: snowmelt, prediction, flooding. [Journal translation]

Quantitative aspects of technogenic pollution of the snow cover are reported, based on field measurements made in the vicinity of the Barentsburg coalmine, Spitsbergen, in 1987. The mean total contamination of the snow cover with solid aerosols, based on cores through the total depth of the snow pack, reached levels of 300 t/ km2 for the immediate area of the settlement of Barentsburg and 30 t/km2 for the surrounding area. The rate of dustfall within the settlement is estimated to be 480 t/ km2 per year. The total amount of dust falling throughout the area of contamination which is 6 times larger than that of the settlement per se reaches 6001 per year. The data recorded on pollution of the snow cover at Barentsburg are comparable with those from the Vorkuta coalmining region. It is concluded that the pollution is local in nature. The importance of studies of snow pollution within the framework of a wider program of environmental protection of the archipelago of Svalbard is demonstrated.

The snow pack that accumulated in central Ontario in the winter of 1977–78 had a pH of 4.0–4.5. The resultant runoff in the following spring in three intensively studied watersheds was characterized by a 2–13-fold increase in H+ content. Between 36 and 77% of the year's export of H+ from the watersheds occurred in April. Similar pH depressions were observed in almost all of 17 other streams that were less frequently sampled and in the littoral zones, surface waters, and outflows of five lakes. Key words: acidification, snowmelt, hydrogen ion

Recent work on snow pack energy exchange has involved detailed investigations on snow albedo and attempts to integrate energy energy balance calculations over drainage basins. Along with our better understanding of the electromagnetic properties of snow, research in remote sensing has become more focused toward estimation of snow pack properties. In snow metamorphism, analyses of the physical processes must now be coupled to better descriptions of the geometry of the snow’s microstructure. The dilution method now appears to be the best direct technique for measuring the liquid water content of snow; work on electromagnetic methods continues. Increasing attention to the chemistry of the snow pack has come with the general focus on acid precipitation in hydrology. Copyright 1987 by the American Geophysical Union.

Eyewitness accounts, conventional and computer-assisted analysis of photographs, and sedimentological studies indicate the likely occurrence of a volcanic blast associated with the eruption of a dacite lava flow and the emplacement of a major lahar at Lassen Peak, California, on the night of 19 May 1915. Although early investigators arrived at this conclusion, it was subsequently abandoned in favor of an interpretation that stressed the generation of the lahar by heat exchange between a dacite lava flow and the residual snow pack. The existence of a deposit with many of the characteristics of those formed by volcanic blasts, including charred organic material, and the planimetric distribution of the effects of the eruption are the strongest evidence for a volcanic blast on the night of 19 May. The cause of the blast is, however, problematic. The preferred candidate mechanism involves the physical disruption and avalanching of the dacite lava down the steep eastern slope of Lassen Peak, with intimate mixing and heat exchange between snow and hot fragments of dacite causing an explosive production of steam and leading to a volcanic blast and a subsequent lahar.

This paper presents a method for evaluating maximum runoff from mountain snow melt in a large drainage basin and its application to studies for spillway design capacity of Garrison Dam on the Missouri River in North Dakota. The method involves consideration of degree-days and observed runoff for establishment of correlations between indicated heat supply, depth of snow pack, losses, and stream flow by double-mass curve plotting. The correlations thus obtained may be used to estimate floods from maximum probable hydrometeorologic conditions in the drainage basin.

Anderson's ideal snow-conservation forest and “Operation Snow Pack” (Western Water News, Aug. 1956) revive memories of Trans., AGU 1940, pp. 920–25, and Sci. Amer. Sup. Sep. 7, 1912 (Vol. 74, no. 1914). In 1912 while the Wagon Wheel Gap experiment was under way, I proposed the ‘honey-comb’ forest, timber screens on the lips of canyons and timber-line screens to accumulate and conserve the snow. In 1940 at Seattle, Charles A. Connaughton proposed a similar plan for the lodge-pole-pine forests of the Rocky Mountain Forest.

The relative severity of winter climate for white-tailed deer (Odocoileus virginianus) can be determined by using rather simple and inexpensive equipment to measure the principal stressors, air chill and snow hazard. A rating for air chill is derived with a specially designed chillometer described in this report. Depth of the snow pack and its supporting quality, obtained with a compaction gauge, yield the snow's hazard rating. Respective air chill and snow hazard ratings are summed to compute a weekly severity index. The cumulative total of these values constitutes the seasonal score. Trials with this system in Michigan's Upper Peninsula indicate that it provides a reliable means for judging the physical welfare of yarded deer; hence, their probable mortality rate can be predicted through inspec- tion of collected data as winter progresses. Moderate to heavy deer losses occurred during winters in which the season's severity index exceeded a value of 100 among the various stations across the peninsula.