Dagrun Vikhamar-Schuler

• PhD
• Senior hydrologist at Statkraft

A linear regression model is developed to link anomalies of streamflow to anomalies of precipitation amounts and temperature with the goal of making multi-decadal streamflow projections based on CMIP6 multi-model simulations. Regression coefficients estimated separately for each catchment and each month show physically implausible spatial patterns...

In Finnmark, average winter (Dec-Jan-Feb) temperatures in the period 1961–1990 were about −5 °C at the coast, slightly lower in the fjords, and typically 10 °C lower inland. In the Yamal Nenets Autonomous Okrug (YNAO) average winter temperatures were even lower, ranging from −20 to −25 °C. Temperatures are presently increasing in the area, and towa...

Precipitation plays an important role in the Arctic hydrological cycle, affecting different areas like the surface energy budget and the mass balance of glaciers. Thus, accurate measurements of precipitation are crucial for physical process studies; but gauge measurements in the Arctic are sparse and subject to relocations and several gauge issues....

This chapter is based on outcomes of the working group 3 Questionnaire of the COST Action ES1404 (www.harmosnow.eu) and provides a discussion of snow data assimilation in research and operational applications, which will be presented in detail in a manuscript (Helmert et al., 2018).

This report was commissioned by the Norwegian Environment Agency in order to provide basic information for use in climate change adaptation in Svalbard. It includes descriptions of historical, as well as projections for the future climate development in the atmosphere, hydrosphere, cryosphere and ocean, and it includes effects on the physical natur...

In the Norwegian Centre for Climate Service (NCCS) report "Climate in Svalbard 2100", two data sets based on reanalysis were used as supplement to observations in order to describe past and present climate in Svalbard. For temperature and precipitation, the present report provides an evaluation of these two data sets, as well as maps and climate st...

In the Norwegian Centre for Climate Service (NCCS) report "Climate in Svalbard 2100", two data sets based on reanalysis were used as supplement to observations in order to describe past and present climate in Svalbard. For temperature and precipitation, the present report provides an evaluation of these two data sets, as well as maps and climate st...

The European Cooperation in Science and Technology (COST) Action ES1404 “HarmoSnow”, entitled, “A European network for a harmonized monitoring of snow for the benefit of climate change scenarios, hydrology and numerical weather prediction” (2014-2018) aims to coordinate efforts in Europe to harmonize approaches to validation, and methodologies of s...

Cambridge Core - Climatology and Climate Change - Indigenous Knowledge for Climate Change Assessment and Adaptation - edited by Douglas Nakashima

In Norway, 30 % of the annual precipitation falls as snow. Knowledge of the snow reservoir is therefore important for energy production and water resource management. The land surface model SURFEX with the detailed snowpack scheme Crocus (SURFEX/Crocus) has been run with a grid spacing of 1 km over an area in southern Norway for 2 years (1 Septembe...

In order to use the best suited snow models to investigate snow conditions at ungauged sites and for a changed climate, we have tested four snow models for 17 catchments in Norway. The Crocus and seNorge models are gridded whereas the Distance Distribution Dynamics (DDD) model with its two versions, DDD_CX and DDD_EB, is catchment based. Crocus and...

The exact cause of population dieback in nature is often challenging to identify retrospectively. Plant research in northern regions has in recent decades been largely focussed on the opposite trend, namely increasing populations and higher productivity. However, a recent unexpected decline in remotely-sensed estimates of terrestrial Arctic primary...

In recent years extreme winter warming events have been reported in arctic areas. These events are characterized as extraordinarily warm weather episodes, occasionally combined with intense rainfall, causing ecological disturbance and challenges for arctic societies and infrastructure. Ground-ice formation due to winter rain or melting prevents ung...

Snow is a critically important and rapidly changing feature of the Arctic. However, snow-cover and snowpack conditions change through time pose challenges for measuring and prediction of snow. Plausible scenarios of how Arctic snow cover will respond to changing Arctic climate are important for impact assessments and adaptation strategies. Although...

During the winter 2013/2014 we conducted frequent fieldwork, collecting snowpack prop-erty and stability data from five monitoring sites along a vertical transect. This transect stretched from 250 m to 750 m a.s.l. on a mountain in the southern part of the forecasting region "Tromsø", located in the county of Troms, Northern Norway. At these five s...

The release of cold temperature constraints on photosynthesis has led to increased productivity (greening) in significant parts (32–39%) of the Arctic, but much of the Arctic shows stable (57–64%) or reduced productivity (browning, <4%). Summer drought and wildfires are the best-documented drivers causing browning of continental areas, but factors...

High-density snow layers deteriorate grazing conditions for reindeer during winter. We compare two different methods for identifying past winters with difficult grazing conditions for reindeer in Kautokeino, northern Norway. A long-term climate analysis based on monthly values of precipitation and temperature (1900–2011) demonstrated that the repor...

Predictions of the future climate are generally based on atmospheric models operating on coarse spatial scales. However, the impact of a changing climate on most elements of the cryosphere becomes manifest on much smaller scales, which complicates sound predictions e.g. on glacier and permafrost development. CryoMET is a collaborative project betwe...

The Arctic land areas have experienced greater warming over the last three decades than elsewhere in the world. In Europe the Svalbard archipelago (located in the North Atlantic sector of the Arctic Ocean from 74° to 81°N and 10° to 35°E) have experienced the greatest temperature change during this period. At Svalbard airport the mean annual air te...

Humans describe the natural environment on the basis of their local experience and their interactions with nature in terms of its relevance to their daily lives. These descriptions are incorporated into local languages and form a specialized terminology that is unique and specifically applicable to needs and practices. In Guovdageaidnu (Kautokeino)...

In this study we have evaluated the JULES (Joint UK Land Environment Simulator) multi-layer snow-scheme at 18 weather stations in Norway. The stations are mainly located close to or within forested areas, but some are also located at exposed high-mountain areas. JULES has been run for single points (1D study), using forcing data which combines both...

In 2010 a research project was initiated with the aim to investigate methods to establish a regional snow avalanche forecasting system for Norway. A part of this project concerns snow models that simulate snow stratigraphy and physical parameters in the snow pack. For this purpose we have used the CROCUS snow scheme within the land surface model SU...

NVE 1 was in 2009 appointed the national authority responsible for avalanches and landslides. A project was initiated, aiming to test and develop methods for avalanche forecasting on a national/regional scale in Norway. The project focuses on developing methods and assembling data for the avalanche forecasting service. It also has a component on da...

Hard snow layers deteriorate the grazing situation for reindeers during winter. By modelling the snowpack evolution in Kautokeino over the period 1966-2009, we analyse the weather situations that favor the formation of high-density snow. This work is part of the IPY project EALAT (http://icr.arcticportal.org/en/ealat). We used daily meteorological...

The catchment of Øvre Heimdalsvatn and the surrounding area was established as a site for snow remote sensing algorithm development, calibration and validation in 1997. Information on snow cover and snowmelt are important for understanding the timing and scale of many lake ecosystem processes. Field campaigns combined with data from airborne sensor...

In this study trends and variability of temperature, precipitation and snow at four stations of theYamalo-Nenets AO, Russia (Mare-Sale, Tarko-Sale, Salekhard and Nadym) were examined along asimulated migration gradient used by nomadic reindeer herders where Mare-Sale represents pasturesused in summer and the Nadym region is used during winter. Migr...

Various types of slope processes, mainly landslides and avalanches (snow, rock, clay and debris) pose together with floods the main geohazards in Norway. Landslides and avalanches have caused more than 2000 casualties and considerable damage to infrastructure over the last 150 years. The interdisciplinary research project "GeoExtreme" focuses on in...

Avalanches pose one of the most serious problems to infrastructure and people in the mountains in Norway. Processes leading to avalanche release are deterministic but the time and place of avalanche release is notoriously difficult to predict. Statistical approaches using meteorological parameters to predict the probability of natural avalanche rel...

Geohazards are events related to geological features and processes that cause loss of life and severe damage to property and the natural and built environment. The most common and destructive geohazards in Norway are snow avalanches, clay-, debris- and rock slides, and floods, which together caused more than 2000 deaths during the last 150 years. S...

The main aim of this study is to investigate the suitability of 1) combining map data derived from the Landsat satellite and other sources with statistical methods for analyzing habitat selection and making probability maps for large areas, and 2) testing a sampling design where volunteers arbitrarily select a walking route within specific areas fo...

Ground cover classification based on a single satellite image can be challenging. The work reported here concerns the use of multitemporal satellite image data in order to alleviate this problem. We consider the problem of vegetation mapping and model the phenological evolution of the vegetation using a Hidden Markov Model (HMM). The different vege...

Not Available

Existing map databases contains valuable and accurate information that can be used as reference data for land cover classification with remotely sensed data. However, several problems occur when we try to use reference data that has been collected for a different purpose than satellite image classification. Differences in scale, legend, elapsed tim...

Forest parameters are mapped using decision trees and Landsat ETM+ data. Reference data consist of forest stand registrations. The mapped parameters are tree species, age groups, wood volume per hectare and productivity classes. Accuracy assessment is carried out using national forest inventory data. The study area for the project is Ostfold County...

Seasonal snow covers large land areas of the Earth. Information about the snow extent in these regions is important for climate studies and water resource management. A linear spectral mixture model for snow-covered forests (the SnowFor model) has previously been developed for flat terrain. The SnowFor model includes reflectance components for snow...

Land cover mapping. Test of a decision-tree method in Østfold county

Mapping winter pasture for reindeer

A snow-cover mapping method accounting for forests (SnowFrac) is presented. SnowFrac uses spectral unmixing and endmember constraints to estimate the snow-cover fraction of a pixel. The unmixing is based on a linear spectral mixture model, which includes endmembers for snow, conifer, branches of leafless deciduous trees and snow-free ground. Model...

A snow-cover mapping method accounting for forests (SnowFrac) is presented. SnowFrac uses spectral unmixing and endmember constraints to estimate the snow-cover fraction of a pixel. The unmixing is based on a linear spectral mixture model, which includes endmembers for snow, coniferous trees, branches of leafless deciduous trees and snow-free groun...

Forest represents a challenging problem for snow-cover mapping by optical satellite remote sensing. To investigate reflectance variability and to improve the mapping of snow in forested areas, a method for subpixel mapping of snow cover in forests (SnowFrac) has been developed. The SnowFrac method is based on linear spectral mixing modelling of sno...

A snow-cover mapping method for sparse forest by optical remote sensing is proposed. The method is based on linear sub-pixel reflectance modeling of the surface components snow, individual tree species, tree shadows and bare ground. Experiments are performed using a 100% snow-covered Landsat TM scene and aerial photos covering spruce, pine and birc...

A snow-covered forest mapping method for optical remote sensing is proposed. The method is based on linear sub-pixel reflectance modelling of the surface components snow, individual tree species and bare ground. Experiments are performed using a 100% snow-covered Landsat TM scene and aerial photos covering spruce, pine and birch forest in the Jotun...