The influence of drifting snow on the location of glaciers on western Spitsbergen, Svalbard

On western Spitsbergen, Svalbard, the amount of winter precipitation is insufficient to maintain the present-day mass balance of the local glaciers. Additional snow mass must be added to the precipitation to reach the observed accumulation rates of the glaciers. It was assumed in previous work that this additional mass is transported onto the glaciers by drifting snow and snow avalanches. This study is a first attempt to quantify the amount of snow mass added to the glacier mass balance by wind-transported snow. The wind field over an area of 60 × 50 km2 on western Spitsbergen was simulated for 24 idealized weather types by a mesoscale meteorological model on a 750 m grid. The resulting wind velocities and directions were coupled to a two-level snowdrift model. The model output clearly shows erosion and accumulation areas in the terrain. Comparison with the present glacier locations suggests that the glacier accumulation areas coincide with low wind speeds. Moreover, exposed areas with high wind speeds are mostly glacier-free in reality. Thus, the wind field and corresponding snowdrift gives an indication of the location of the present glaciers on western Spitsbergen

Longyearbyen, Svalbard - Vulnerability and risk management of an arctic settlement under changing climate - a challenge to authorities and experts

Longyearbyen, the administrative centre of the Svalbard archipelago, is facing most types of natural hazards under a changing Arctic climate. The catastrophic avalanche in December 2015 led NGI to review our professional work during 30 years of research and consulting in the community. Hazard zonation in Longyearbyen has been a tool in area planning, not for hazard assessment of developed areas, and mainly done during the early 1990s based on current knowledge and methods. The procedures for avalanche warning in Longyearbyen reflect that avalanche release is primarily a consequence of drifting snow, embedded surface snow and collapse of cornices. The first indication in meteorological data of a change in climate was a heavy rainfall midwinter 1995/96, years before global warming of the Arctic was documented. Field research in the 1990s documented that runout in terms of α-angle is longer in cold regions than in other areas. NGI has advised the local administration to revise the old hazard zones taking changing climate and up-dated knowledge and methods into account. The worst-case scenario in Longyearbyen will be a change towards present-day Norwegian Coastal climate with corresponding large avalanches, as well as increasing depth of the active layer and ditto potential for larger and more frequent debris flows and rockslides. Authorities and experts are facing challenging and difficult decisions concerning hazard zoning in a changing climate, design of mitigative measures, removal of exposed houses and extensive costs

Fonnbu, a new (old) platform for snow and avalanche research.

One of the first tasks of the newly established avalanche group at the NGI in 1973 was the selection of a suitable location for an avalanche research station. The choice was on Grasdalen, north of the Jotunheimen mountains, 1000 m asl., in a valley well known for its avalanche activity and high amounts of snow. The station was ready for use in 1973 and intensive research has been made for more than 20 years before budget constraints decreased the activity in the late 80ies. Main research interest was on snow properties, weather and avalanche relations, avalanche dynamics and snow creep in steep slopes. In connection to the research station the Ryggfonn test site was established in 1979. Two years after the 30 years anniversary party, the station burned down completely in February 2005 due to an electrical failure. Scientific data and results were safe in the NGI archive, but lots of old memorials and instruments were lost. Already on the day after the fire, it was decided to build up a new modern station on the same location. Work started the same summer and in August 2006, the new station was officially opened. The new station features accommodation for up to 15 persons, a combined seminar and living room, offices, workshop and of course a sauna. The station is equipped with a modern weather station that also measures snow temperatures and radiation balance. It is now used for NGI research in connection with the Ryggfonn test site, for avalanche courses and courses arranged by the Norwegian School of Winter Warfare and Norwegian Universities. We would like by this presentation inform about the station and invite international researchers to use the station for their research in Norway

GIS aided avalanche warning in Norway.

By 2008 detailed avalanche warning for the entire Norway is not available. The Norwegian Meteorological Institute only issues a general warning for large regions of the country for danger level 4 or 5, mainly based on automatic indexes integrated in the meteorological forecasting models. Regional and local avalanche warning are issued by the NGI on request of customers such as the railway or road administration and local communities. The NGI warning projects cover vast areas of several 1000 sq km with a very limited budget, approx. 2 man hours a day. Therefore the workflow has to be extremely efficient from acquiring observation data, evaluation of the situation and sending out the new forecast. It has been an aim to include the entire workflow in an all in one web application. A GIS solution was chosen to integrate all data needed by the forecaster for the avalanche danger evaluation. This interactive system of maps features background information for the entire country such as topographic maps, slope steepness, aspect and hill shade to give a 3D impression of the terrain. In each avalanche warning area, all active avalanche paths are plotted including information on the most wind exposed direction. Each avalanche path is linked to a database generated webpage, which will inform the user on more details on the path, such as fall height, release area elevation, pictures etc. In this way the forecaster easily can get an overview over large areas and can give detailed avalanche warnings to the customer. The system is under constant development and is planned to be completely available on web browser such that no special software is needed on local PCs. Future versions will include interactive access to weather data both as 2D fields as well as time series at selected stations

Integrated Database for Rapid Mass Movements in Norway

Rapid mass movements include all kinds of slides in geological material, snow or ice. Traditionally, information about such events is collected separately in different databases covering selected geographical regions and event types. In Norway the terrain is susceptible to all types of rapid mass movements ranging from single rocks hitting roads and houses to large avalanches and huge rock falls where entire mountainsides collapse into fjords creating flood waves and endangering large areas. In addition, quick clay slides occur in desalinated marine sediments in south eastern and mid Norway. For the authorities and inhabitants of endangered areas, the type of treat is of minor importance and mitigation measures have to consider all types of mass movements. This demand asks for a national overview over all registered slide events that allows fast and easy access to the available data. Therefore an integrated national database for all kind of rapid mass movements was developed. The database is built around the single slide event. Only three data entries are mandatory: Time, location and type of slide. The remaining optional information enables registration of detailed information about the terrain, involved materials and damages. Pictures, movies and other documentation can be uploaded into the database. A web based graphical user interface was developed that allows entering new slides, editing and search for slide events. An integration of the database into a GIS system is currently under development. Datasets from various national sources like the road authorities and geological survey were imported into the database. Today, the database contains 21,000 slide events from the last 500 hundred years covering the entire country. A first analysis of the data shows that most slide registrations cover snow avalanche and rock fall events followed by debris slide events. Most events are registered in the steep fjord terrain of the Norwegian west coast, but major slides are registered all over the country. Avalanches clearly account for most fatalities, while large rock avalanche events causing flood waves are the most severe single events. The data is strongly influenced by the personal engagement of local observers and varying observation routines. This database gives a unique source for statistical analysis of slide events, risk analysis and the relation between slides and climate

Identification of slushflow situations from regional weather models

Slushflows are known phenomena that cause significant problems for settlements and infrastructure in Norway. Even though single events in the same location are rather rare compared to avalanches, slushflows do occur annually on a national scale. Both intensive snowmelt events as well as high amounts of rain on the snow cover can cause slushflows during the whole winter season. In recent years eight fatalities and widespread problems for infrastructure in Norway have increased the focus on slushflows. Early warning criteria based on readily available meteorological, hydrological and snow data need to be identified to allow a nationwide monitoring of potentially critical situations and corresponding locations that might lead to slushflow events. Earlier work focused on input data from meteorological stations. These stations are often located at sea level and give little information on the meteorological conditions in the release and drainage areas in the mountains. During the last decade, regional weather models have been developed that deliver weather prognosis every hour with up to 4 km grid resolution. In Norway, observed precipitation and temperature are interpolated to a one-kilometre grid and used to model snow conditions and snowmelt. This study aims at analysing the available data to identify critical meteorological elements and their thresholds for the release of slushflows. Examples from recent years will be studied also taking into account the development of the snow cover prior to the slushflow events. The results indicate that the available data has a promising ability to identify critical situations on a regional level

Forecasting the fatal Longyearbyen avalanche. Possibilities and challenges

One of the main questions after the fatal avalanche in Longyearbyen in December 2015, where two persons perished and eleven houses were destroyed, was whether an active avalanche warning system would have identified the upcoming danger. At the time of the catastrophe, no avalanche warning was in operation. Observation routines established in the early 90ties were discontinued. The forecasted and observed weather is compared with 42 years of meteorological data from Longyearbyen airport. Similar weather conditions are identified and corresponding records of avalanche events clearly states that alarm bells should have sounded. The analysis showed that heavy snowstorms usually occur with westerly winds, while avalanches on the hillside leading to the fatal avalanche are associated with winds from Southeast. Minor precipitation and critical wind causes minor avalanches almost annually, while the fatal event in 2015 occurred due to a rare combination of intense precipitation and wind from Southeast. After the fatal avalanche on Saturday morning, larger parts of the settlements below west facing mountain sides were evacuated. Norwegian Geotechnical Institute managed to establish a fully manned avalanche warning service within Tuesday evening. A month later replaced by regional forecasts. The lessons learned from this work will be helpful in future local avalanche warning for settlements

The avalanche situation in a special winter. Review of the 09/10 season in Norway.

The 2009/10 season featured significantly different snow conditions compared to the usually maritime snow pack in most of Norway. A stable high-pressure system over large parts of Europe led to low temperatures and limited precipitation in the country. Along the coast a continuous snow cover was observed for several weeks while the mountains received down to 20% of the 1971-2000 normal precipitation values. The snowpack had several weeks to develop extensive layers of depth hoar also in areas where this is usually not observed. The weather situation promoted the development of surface hoar in many locations as well, especially on the eastern side of the mountains. Still, the danger level was moderate most days of the winter. Similar conditions lead to the catastrophic avalanche winter in 1979. Based on that experience awareness was high and both road closures and evacuations were implemented in several occasions when heavy snowfalls were to load the weak base of the well established persistent weak layers. The observed avalanches were often hard slab avalanches of medium size occurring on slopes where avalanches are not observed in normal winters. The five registered fatalities during the past season were all back country skiing accidents and most of the avalanches were at least partly released in the week base of the depth hoar layers. The daily presence of avalanche observations caused intensive media coverage of the special snow situation. Journalists and the public soon adopted the international danger scale and communication between avalanche experts and the media improved significantly as a result of this season