Plants have an important role in the tundra carbon (C) cycle by storing C in primary production and thus potentially counteract the C released from thawing permafrost. Tundra vegetation is limited by nitrogen (N), which is predicted to increase with rising temperatures and increased snow depth. In permafrost systems, rooting depth will determine whether plants can access N in the deep soil which, with increasing snow depth, has the potential to turn into a significant N source. Increased plant-available N is thus expected to affect both plant productivity and vegetation composition. This study aims to investigate vegetation responses to increased temperature and snow depth in a permafrost system of moist tussock tundra by combining open-top chambers with a realistic snow manipulation (snowfences). The shallow-rooted shrubs, Betula nana and Rhododendron tomentosum, and the deep-rooted sedge Eriophorum vaginatum were analyzed for responses in growth and reproduction effort. Also, vegetation responses in terms of normalized difference vegetation index (NDVI) were investigated. Winter warming increased flower density of E. vaginatum while B. nana showed an increased shoot growth in response to winter warming, but only during mid-growing season. Although winter warming increased winter soil temperature and generated a trend of increased thaw depth, there were no responses in NDVI or further species-specific responses in reproduction effort, leaf and shoot growth, leaf production or leaf dry weight to warming treatments. These results indicate that E. vaginatum respond in reproduction effort while B. nana respond in (mid-season) growth to winter warming. In total, the warming treatments generated a weak response in tundra plants which indicate that tussock tundra might not be very responsive to short-term warming. These results suggest that tundra plants have a low ability to counteract increased releases of soil C in response to short-term warming.

Increased temperatures, changed snow conditions, increasing demand for skiing and other winter sports lead to increased demand and production of artificial snow. Besides the positive aspects of artificial snow, it is important to understand potentially negative effects of artificial snow on the environment and vegetation. This study investigated the differences between artificial snow and natural snow in two adjacent ski slopes. This was done by measuring and comparing the snow depth, duration of the snow cover, snow density, and ground vegetation between the slopes. Snow depth and density showed differences between artificial snow and natural snow. The artificial snow cover stayed about 11 days longer than the natural snow. A few variations in the vegetation were also found; earlier flowering and more species and colors in the natural snow slope compared to in the slope using artificial snow. Therefore, it is clear that there is a difference between artificial snow and natural snow, and that this results in effects on the environment, but it is difficult to assess to what extent and how large the negative impact is. For more general conclusions, I think it is important to study the vegetation under artificial snow during a longer period and in several areas.

I Sverige utförs dagligen observationer av snöns djup och utbredning under snösäsongen.Observationerna används till exempel för att årsvis avgöra maximalt snödjup, snötäckets första ochsista dag samt antal dygn med snötäcke på olika platser. Traditionellt utförs snödjupsmätningarmanuellt med en enkel mätpinne, men med ny teknik kommer nya möjligheter. Med enultraljudssnömätare kan automatiserade snödjupsmätningar utföras med bättre upplösning i bådetiden och rummet vilket därmed ger bättre uppfattning av snöns tillväxt, hopsjunkning samtsmältning och innebär att alla signifikanta förändringar i snötäcket garanterat kommer observeras. I denna utvärdering har en jämförelse gjorts av manuella och automatiska snödjupsmätningarutförda parallellt på samma plats men med olika frekvens. Instrumentet som utvärderats är enSR50A Sonic Ranging Sensor uppmonterad vid Institutionen för geovetenskapers mätstation vidUppsala universitet. Vid mätstationen görs även manuella snödjupsmätningar en gång per dag. Deautomatiska snödjupsmätningarna genomförs varje minut och medelvärdesbildas över ett 10minuters intervall. Utvärderingen visar att de båda metodernas mätresultat stämmer mycket väl överrens förutomen mer eller mindre systematisk skillnad. I medeltal ger Sonic Ranging Sensorn 1,6 cm större snödjup,något som till största del kommer av en osäkerhet vid kalibreringen av instrumentet. Resultaten visartydligt på en bättre upplösning hos de automatiska mätningarna men att de manuella mätningarnaändå fått med de stora förändringarna av snötäcket vad gäller tillväxt, minskning samt max‐ ochmindjup. Rådata från Sonic Ranging Sensorn visade på större och mindre fluktuationer som berodde påosäkra mätningar. Kvaliteten på mätningarna har avgjorts antingen med instrumentets inbyggdakvalitetsnummer eller utifrån max‐ och minvärden på snödjupet tagna under varje 10 minutersintervall. De faktorer som försämrade kvaliteten i mätningarna var först och främst snöfall, men ävenregndroppar eller snö som drev på grund av vinden gav försämrad kvalitet. Instrumentets känslighetför temperaturdifferensen i skiktet precis ovanför snöytan har också utvärderats vilket visade att detemperaturmätningar som görs i nuläget på 1,5 m höjd ger tillräckligt bra mätresultat. Det skildeendast 0,14 cm i medeltal om temperaturdifferensen togs med i beräkningarna av snödjupet. Förutom en systematisk skillnad visade sig drivbildning inom mätområdet vara den faktor som gavstörst skillnad mellan manuella och automatiska snödjupsmätningar. För att avgöra hurrepresentativa snödjupsmätningarna vid mätstationen är i jämförelse med närområdet och därmedockså eliminera påverkan av drivbildning genomfördes ytterligare manuella mätningar av snödjupetpå ett homogent fält i närheten. Resultaten visar att de manuella mätningarna vid mätstationen gerett för området representativt snödjup. / During the snow season, daily observations of snow depth and distribution are performed all aroundSweden. The observations are for example used to yearly determine maximum snow depth, first andlast day of snow coverage and number of days with snow coverage in different areas. Manual snowdepth measurements are traditionally performed with a simple measurement stick but with newtechnology new possibilities arise. With an ultrasonic snow depth sensor, automatic snow depthmeasurements can be performed with much better resolution in both time and space, thus give amore detailed picture of the growth, compaction and melting of the snow coverage. There is also norisk to miss out on any important changes in the snow coverage. In this evaluation, a comparison has been made between manual and automatic snow depthmeasurements performed parallel on the same place but with different frequency. The instrumentthat has been evaluated is a SR50A Sonic Ranging Sensor mounted at a measuring station near theDepartment of Earth Sciences, Uppsala University. At the measuring station manual snow depthmeasurements are made once a day. The automatic snow depth measurements are made everyminute and an average is taken over a 10 minute interval. The evaluation shows that the measuring results of both techniques follow each other very wellexcept for a more or less systematic difference. The Sonic Ranging Sensor gives in average 1.6 cmlarger snow depth which mostly is due to in uncertainty in the calibration of the instrument. Theresults clearly show a better resolution in the automatic snow depth measurements, although themanual measurements still show all significant changes of the snow coverage when it comes togrowth, compaction, maximum and minimum depth. Raw data from the Sonic Ranging Sensor showed some large amplitude and small amplitudefluctuations that were implemented by uncertainty in the measurements. The quality of themeasurements have been determined either with the built in quality number of the instrument orfrom maximum and minimum snow depth measurements during each 10 minute interval. The factorsthat reduced the quality of the measurements was mainly snow fall, but also rain drops or driftingsnow reduced the quality. The sensitivity of the instrument due to the temperature difference in thelayer just above the snow surface was also evaluated, showing that the temperature measurementsthat currently are performed at 1.5 m height give good enough measuring results. The difference wasonly 0.14 cm in average if the temperature difference was taken into account when calculating thesnow depth. Except for a systematic difference, drifting snow inside the measuring area was the factor givinglargest difference between manual and automatic snow depth measurements. To determine howrepresentative the snow coverage at the measuring station is compared to the local area, extramanual measurements were performed at a field near the station. The result shows that themeasuring station has a representative snow depth.

Recently, Hudson Bay experienced unidirectional trends in temperature, sea-ice extent, time of break-up, and length of the open-water season. Predicted impacts on population dynamics of ice-associated species include habitat loss and shift in prey availability. The ringed seal (Phoca hispida) depends on a stable ice platform with sufficient snow depth and a productive open-water season for reproduction and survival. Evidence of ringed seal sensitivity to environmental variations has been reported, but mechanisms involved were poorly understood. In western Hudson Bay, density, life-history traits, and diet of ringed seals were monitored over two decades, providing an opportunity to understand the effects of climatic variations on the population dynamics of this long-lived carnivore. Ringed seal density was estimated through strip-transect analyses after aerial surveys were flown in western Hudson Bay in late spring during the annual moult in the 1990s and 2000s. During these periods, ringed seals were also sampled from Inuit subsistence fall harvests In Arviat, NU, and ages, reproductive status, percentage of pups in the harvest, body condition, and diet were assessed. Strong inter-annual variations in these parameters were observed, and a decadal cycle was suggested and related to variations in the sea-ice regime. The cold and heavy ice conditions that prevailed in western Hudson Bay in 1991-92 likely induced a decrease in pelagic productivity, reducing the availability to ringed seals of sand lances (Ammodytes sp.), their major prey. The nutritional stress endured, combined with a strong predation pressure, led to a decrease in ringed seal reproductive performances, pup survival, and density during the 1990s. The recovery of ringed seal demographic parameters and number in the 2000s was associated with the immigration of pups, juveniles, and young adults into western Hudson Bay. Impact of current climatic trends on ringed seal population dynamics was not apparent, but considering the limited range of environmental variations tolerated by ringed seals, the response of this species to climate warming might be of a catastrophic type. Ringed seals were found to be good indicators of ecosystem changes, and long-term monitoring of the species in Hudson Bay should be a priority.

Recently, Hudson Bay experienced unidirectional trends in temperature, sea-ice extent, time of break-up, and length of the open-water season. Predicted impacts on population dynamics of ice-associated species include habitat loss and shift in prey availability. The ringed seal (Phoca hispida) depends on a stable ice platform with sufficient snow depth and a productive open-water season for reproduction and survival. Evidence of ringed seal sensitivity to environmental variations has been reported, but mechanisms involved were poorly understood. In western Hudson Bay, density, life-history traits, and diet of ringed seals were monitored over two decades, providing an opportunity to understand the effects of climatic variations on the population dynamics of this long-lived carnivore. Ringed seal density was estimated through strip-transect analyses after aerial surveys were flown in western Hudson Bay in late spring during the annual moult in the 1990s and 2000s. During these periods, ringed seals were also sampled from Inuit subsistence fall harvests In Arviat, NU, and ages, reproductive status, percentage of pups in the harvest, body condition, and diet were assessed. Strong inter-annual variations in these parameters were observed, and a decadal cycle was suggested and related to variations in the sea-ice regime. The cold and heavy ice conditions that prevailed in western Hudson Bay in 1991-92 likely induced a decrease in pelagic productivity, reducing the availability to ringed seals of sand lances (Ammodytes sp.), their major prey. The nutritional stress endured, combined with a strong predation pressure, led to a decrease in ringed seal reproductive performances, pup survival, and density during the 1990s. The recovery of ringed seal demographic parameters and number in the 2000s was associated with the immigration of pups, juveniles, and young adults into western Hudson Bay. Impact of current climatic trends on ringed seal population dynamics was not apparent, but considering the limited range of environmental variations tolerated by ringed seals, the response of this species to climate warming might be of a catastrophic type. Ringed seals were found to be good indicators of ecosystem changes, and long-term monitoring of the species in Hudson Bay should be a priority.

Due to the changing climate and inherent atypically occurring meteorological events in the Arctic regions, more accurate snow quality predictions are needed in order to support the Sámi reindeer herding communities in northern Sweden that struggle to adapt to the rapidly changing Arctic climate. Spatial snow depth distribution is a crucial parameter not only to assess snow quality but also for multiple environmental research and social land use purposes. This contrasts with the current availability of affordable and efficient snow monitoring methods to estimate such an extremely variable parameter in both space and time. In this thesis, a novel approach to determine spatial snow depth distribution in challenging alpine terrain is presented and tested during a field campaign performed in Tarfala, Sweden in April 2019. A multispectral camera capturing five spectral bands in wavelengths between 470 and 860 nanometers on board of a small Unmanned Aerial Vehicle is deployed to derive 3D snow surface models via photogrammetric image processing techniques. The main advantage over conventional photogrammetric surveys is the utilization of accurate RTK positioning technology that enables direct georeferencing of the images, and thus eliminates the need for ground control points and dangerous and time-consuming fieldwork. The continuous snow depth distribution is retrieved by differencing two digital surface models corresponding to the snow-free and snow-covered study areas. An extensive error assessment based on ground measurements is performed including an analysis of the impact of multispectral imagery. Uncertainties and non-transparencies due to a black-box environment in the photogrammetric processing are, however, present, but accounted for during the error source analysis. The results of this project demonstrate that the proposed methodology is capable of producing high-resolution 3D snow-covered surface models (< 7 cm/pixel) of alpine areas up to 8 hectares in a fast, reliable and cost-efficient way. The overall RMSE of the snow depth estimates is 7.5 cm for data acquired in ideal survey conditions. The proposed method furthermore assists in closing the scale gap between discrete point measurements and regional-scale remote sensing, and in complementing large-scale remote sensing data by providing an adequate validation source. As part of the Swedish cooperation project ’Snow4all’, the findings of this project are used to support and validate large-scale snow models for improved snow quality prediction in northern Sweden. / På grund av klimatförändringar och naturliga meteorologiska händelser i arktis behövs mer exakta snökvalitetsprognoser för att stödja samernas rensköttsamhällen i norra Sverige som har problem med att anpassa sig till det snabbt föränderliga arktiska klimatet. Rumslig snödjupsfördelning är en avgörande parameter för att inte bara bedöma snökvaliteten utan även för flera miljöforskning och sociala markanvändningsändamål. Detta står i motsats till den nuvarande tillgången till överkomliga och effektiva metoder för snöövervakning för att uppskatta sådan extremt varierande parameter i tid och rum. I detta arbete presenteras och testas en ny metod för att bestämma rumslig snödjupssdistribution i utmanande alpin terräng under en fältstudie som genomfördes i Tarfala i norra Sverige i april 2019. Via fotogrammetrisk bildbehandlingsteknik hämtades snöytemodeller i 3D med hjälp av en multispektral kamera monterad på en liten obemannad drönare. En viktig fördel, i jämförelse med konventionella fotogrammetriska undersökningar, är användningen av exakt RTK-positioneringsteknik som möjliggör direkt georeferencing och eliminerar behovet av markkontrollpunkter. Den kontinuerliga snödjupfördelningen hämtas genom att ytmodellerna delas upp i snöfria respektive snötäckta undersökningsområden. En omfattande felsökning som baseras på markmätningar utförs, inklusive en analys av effekten av multispektrala bilder. Resultaten från denna studie visar att den famtagna metoden kan producera högupplösta snötäckta höjdmodeller i 3D (< 7 cm/pixel) av alpina områden på upp till 8 hektar på ett snabbt, pålitligt och kostnadseffektivt sätt. Den övergripande RMSE för det beräknade snödjupet är 7,5 cm för data som förvärvats under idealiska undersökningsförhållanden. Som ett led i det svenska projektet “Snow4all” används resultaten från projektet för att förbättra och validera storskaliga snömodeller för att bättre förutse snökvaliteten i norra Sverige.

Plusieurs études récentes démontrent que la prolifération de la végétation dans le Nord a augmenté sous un climat en réchauffement lors des quatres dernières décennies, surtout dans la zone de transition entre toundra et taïga. L’accroissement des arbustes a un effet sur les propriétés de la neige et du bilan d’énergie de surface. L’objectif de cette recherche est d’améliorer la caractérisation de l’impact des arbustes sur l’évolution de la neige (accumulation et fonte) en utilisant des données terrains et la télédétection. La recherche a été réalisée sur le site d’Umiujaq, au Nunavik, représentatif de la zone de transition entre l’Arctique de basse latitude et les zones subarctiques. La profondeur de neige, mesurée le long de nombreux transects qui couvrent plusieurs types de végétation (toundra arbustive, toundra de lichen, forêt ouverte et forêt fermée d’épinettes) démontre l’effet d’emprisonnement de la neige dans la zone de transition entre une zone de toundra arbustive vers une zone de forêt d’épinettes. Cet effet est lié à la hauteur de la végétation et à la perte de densité (la profondeur de neige augmente par des facteurs de 2,5 à 3). De plus, des mesures de profondeur de neige en continue ont été prises par deux stations météorologiques situées l'une en zone de toundra arbustive et l'autre en zone de forêt. Les résultats montrent que la neige réagit de façons très différentes selon la couverture du sol, mais reste très dépendante des sites considérés. Des analyses spatiales à très haute résolution (Pléiades) et à moyenne résolution (Landsat et MODIS) suggèrent un délai dans la fonte entre les zones de forêts et les zones de toundra de lichen et arbustives. Une technique de mesure de profondeur de neige par télédétection à haute résolution est aussi discutée. / Abstract : Recent studies have shown that northern vegetation has been growing in relation to a warming climate over the last four decades, especially across the transition zone between tundra and taiga. Shrub growth affects snow properties and the surface energy budget, which must be better studied to quantify shrub-snow-climate feedbacks. The objective of this research is to improve the characterization of the impact of shrubs on snow evolution, from its accumulation to its melt, using in-situ and satellite measurements. The research is presented for the Umiujaq site, Nunavik, representative of the low Arctic – Subarctic transition zone. Snow depth, measured along numerous transects spanning different land cover types is found to increase by a factor 2.5 to 3 between tundra and forest, while snow density decreases. This illustrates the trapping effect of vegetation well. Complementary continuous snow depth measurements using weather stations from two sites (tundra with low shrubs and a small clearing with shrubs within the forest) show different site-dependent behaviors. Spatial analysis from high-resolution Pleiades images combined with Landsat (Normalized Difference Snow Index) and MODIS (Fractional Snow Cover) images suggest a slight delay in melt over open and dense forest areas compared to tundra and dense high shrubs. A technic to measure snow depth using high resolution is also discussed.

<p>Snö har en stor betydelse för oss inom hydrologin samt ekologin. Inom hydrologin har snön inverkan på våra vattendrag under vinter och vår dessutom har den en stor betydande roll för elektricitetsproduktionen via vattenkraft. För ekologin ger snön isolering för växter, marken och skydd för mindre djur arter. Snöförhållanden förklarar också ofta naturkatastrofer, så som lavinrisker och översvämningar i vattendragen. Ökad kunskap om snöegenskaper skulle kunna hjälpa oss att förstå alla ovan nämnda skeenden bättre.</p><p>På Abiskos naturvetenskapliga forskningsstation har det sedan år 1961 till nu gjorts snöprofilsmätningar, där snötäckets egenskaper, tjocklek, snölagrets täthet/hårdhet, snö kristallernas fasthet, snökornens storlek och snöns torrhet uppskattas. Dessa mätningar utgör grunden till denna studie där syftet är att klimatologiskt undersöka den inre snöstrukturen.</p><p>Undersökningen av snöns inre struktur ger oss en tydlig bild av att kategorin is förekommer mycket ofta i snötäcket och att dess tjocklek är mycket tunn. Under de senaste 15-åren (1993-2007) har kategorin is utgjorts till 25% av alla egenskaper i snötäckets översta lager. Vi kan även se att snön har blivit mycket blötare under våren för perioden 1993-2007 (senaste 15 åren) speciellt under maj månad. Att detta är klara och distinkta spår på den ökade lufttemperaturen är det inga tvivel på. Tydliga spår av metamorfosen i snötäcket ses när kategorin mycket lucker och lucker har ökat kraftigt i det understa lagret de senaste åren, något som även förklarar ökade lavinrisker i området.</p><p>Snödjupet har minskat under de senaste 15 åren (1993-2007) under hösten (oktober och november) i jämförelse med de andra två 15-års perioderna (1961-1992), men snölagrets tjocklek har däremot ökat under våren.</p> / <p>Snow is of great importance to our environment in ways such as hydrological and ecological. When speaking in terms of hydrology, snow affects our water streams and has a great influence on hydropower. In ecological purposes, snow is a good isolator for vegetation, soil and it also gives shelter for smaller animals. Snow conditions often explain natural disaster, such as risks for avalanches and submergence in the streams. Understanding the fundamentals of snow properties would give scientist a greater understanding of snow and its effects on our environment.</p><p>Snow profile measurements have been made in Abisko research centre since 1961 until present time. Measurements have been done on snow cover properties, such as the thickness of the snow layer, grain size, snow layer hardness, grain compactness and the dryness of the snow. Collected data from Abisko research centre is the foundation of this study where our objective is to analyze the inner snow structure. This will give us a greater understanding of how snow has been behaving historically.</p><p>Result of this study illustrates that category ice occurs very frequent in the snow cover and its thickness is very thin. During the last 15-years (1993-2007) has the category ice constitute up to 25% of all the properties in the snow cover in the upper layer. We can also see that the snow cover has drastically become more wet during spring specially for the month may and there is no doubt that the increased air temperature is behind it. There are also distinct signs of metamorphoses in the snow cover which can explain the increased risks for avalanches in the area.</p><p>Results also shows that the snow depth has decreased during the last 15 years (1993-2007) in autumn (October and November) in comparison with the other 15-year periods (1961-1992), but on the other hand the snow layer thickness has increased during the spring.</p>

Snö har en stor betydelse för oss inom hydrologin samt ekologin. Inom hydrologin har snön inverkan på våra vattendrag under vinter och vår dessutom har den en stor betydande roll för elektricitetsproduktionen via vattenkraft. För ekologin ger snön isolering för växter, marken och skydd för mindre djur arter. Snöförhållanden förklarar också ofta naturkatastrofer, så som lavinrisker och översvämningar i vattendragen. Ökad kunskap om snöegenskaper skulle kunna hjälpa oss att förstå alla ovan nämnda skeenden bättre. På Abiskos naturvetenskapliga forskningsstation har det sedan år 1961 till nu gjorts snöprofilsmätningar, där snötäckets egenskaper, tjocklek, snölagrets täthet/hårdhet, snö kristallernas fasthet, snökornens storlek och snöns torrhet uppskattas. Dessa mätningar utgör grunden till denna studie där syftet är att klimatologiskt undersöka den inre snöstrukturen. Undersökningen av snöns inre struktur ger oss en tydlig bild av att kategorin is förekommer mycket ofta i snötäcket och att dess tjocklek är mycket tunn. Under de senaste 15-åren (1993-2007) har kategorin is utgjorts till 25% av alla egenskaper i snötäckets översta lager. Vi kan även se att snön har blivit mycket blötare under våren för perioden 1993-2007 (senaste 15 åren) speciellt under maj månad. Att detta är klara och distinkta spår på den ökade lufttemperaturen är det inga tvivel på. Tydliga spår av metamorfosen i snötäcket ses när kategorin mycket lucker och lucker har ökat kraftigt i det understa lagret de senaste åren, något som även förklarar ökade lavinrisker i området. Snödjupet har minskat under de senaste 15 åren (1993-2007) under hösten (oktober och november) i jämförelse med de andra två 15-års perioderna (1961-1992), men snölagrets tjocklek har däremot ökat under våren. / Snow is of great importance to our environment in ways such as hydrological and ecological. When speaking in terms of hydrology, snow affects our water streams and has a great influence on hydropower. In ecological purposes, snow is a good isolator for vegetation, soil and it also gives shelter for smaller animals. Snow conditions often explain natural disaster, such as risks for avalanches and submergence in the streams. Understanding the fundamentals of snow properties would give scientist a greater understanding of snow and its effects on our environment. Snow profile measurements have been made in Abisko research centre since 1961 until present time. Measurements have been done on snow cover properties, such as the thickness of the snow layer, grain size, snow layer hardness, grain compactness and the dryness of the snow. Collected data from Abisko research centre is the foundation of this study where our objective is to analyze the inner snow structure. This will give us a greater understanding of how snow has been behaving historically. Result of this study illustrates that category ice occurs very frequent in the snow cover and its thickness is very thin. During the last 15-years (1993-2007) has the category ice constitute up to 25% of all the properties in the snow cover in the upper layer. We can also see that the snow cover has drastically become more wet during spring specially for the month may and there is no doubt that the increased air temperature is behind it. There are also distinct signs of metamorphoses in the snow cover which can explain the increased risks for avalanches in the area. Results also shows that the snow depth has decreased during the last 15 years (1993-2007) in autumn (October and November) in comparison with the other 15-year periods (1961-1992), but on the other hand the snow layer thickness has increased during the spring.

For the purpose of hydrological forecasting on mountains' and sub-mountains' rivers is important knowledge of distribution of snow water equivalent in the watershed. Submitted thesis therefore deals with comparison of 9 interpolation methods in terms of quality of their forecasting when predicting snow depth and snow water equivalent in watershed Bystřice (127,6 km2 ), which is situated in the northwest of Bohemia in the Ore mountains. Point data of snow depth and snow water equivalent used in interpolation were sampled during an off- road measuring in 17. 2. 2010 at the 14 snow sampling locations. The interpolation methods were: (1) Thiessen's polygons, (2) inverse distance weighting, (3) global polynomial (4) local polynomial (5) radial basis functions, (6) ordinary kriging, (7) cokriging, (8) residual kriging and (9) orographic interpolation. Independent variable-altitude used in the calculation of snow depth and snow water equivalent was used only in the last three listed methods. Predictive ability of interpolation methods was evaluated by using cross-validation and visual comparison of predicted maps. The best prediction ability was provided by residual kriging and orographic interpolation. The geostatistical methods were next in the order. The method of Thiessen's polygons and inverse distance...