Prediction of slushflow hazard. Objectives and procedures of an ongoing research project in Rana, North Norway

Objective criteria for slushflow prediction and warning are sought. Central objectives are deduction of texture and structure of snowpack from meteoroligical data and estimation of critical water influx to various snowpack properties and ground conditions. Two study sites are each monitored by an automatic weather station, precipitation gauge, snow depth sensor and pressure transmitters which record the water level in the snowpack and adjacent brook. The instruments are logged every 10 minutes. Fiels work is carried out every third week and during extraordinary weather conditions. The local Road Department is using the data for supervision of slushflow hazard. / Des critères objectifs sont requis pour la prédiction des écoulements de neige saturée. Les objectifs principaux sont la détermination de la structure et de la texture de la couverture neigeuse d'après les données météorologiques et l'estimation des flux d'eau critique pour différentes propriétés de la neige et du sol. Deux sites d'étude sont contrôlés par une station météorologique automatique équipée d'une jauge de précipitations, d'une mesure d'épaisseur de la couche de neige, et de capteurs de pression donnant le niveau d'eau dans la couche de neige et le ruisseau voisin. Les capteurs sont interrogés toutes les dix minutes. Des mesures sur site sont effectuées toutes les trois semaines et en cas de conditions météorologiques extraordinaires. Les services de voirie locaux utilisent les données pour la surveillance du danger d'écoulement de neige saturée

Calculation methods for avalanche run-out distance for the Austrian Alps

Runout distance for the flowing component of 80 extreme avalanches in Austria is calculated based on topographical parameters from the avalanche paths. The results are compared with calculations performed by dynamic models. Eleven terrain parameters are studied, applying 21 independent combinations of these parameters as variables. / Les courses de la portion en mouvement dans le cas de 80 avalanches extrèmes en Autriche ont été calculées à partir des paramètres topographiques le long du parcours des avalanches. Les résultats ont été comparés aux calculs faits avec des modèles dynamiques. Onze paramètres de terrain ont été considérés, appliquant 21 permutations de ces paramètres comme variables

Diurnal cycle of precipitation amount and frequency in Sweden : observation versus model simulation

This study investigated the diurnal cycle of precipitation in Sweden using hourly ground observations for 1996-2008. General characteristics of phase and amplitude for the diurnal cycle of precipitation, both in amount and frequency, were identified. In the warm season (April-September), the 'typical' afternoon (14-16 LST) peaks are dominant over inland Sweden, whereas late night to early morning (04-06 LST) peaks with relatively weak amplitude are discernable in the east coast along the Baltic Sea. The diurnal variation is almost negligible in the cold season (October-March), due to the weak solar radiation at high latitudes. The variations of convective activity forced by solar heating and modulated by geographical characteristics were suggested as primarily factors to invoke the cycles and spatial variation identified. The observed cycle was compared with the cycle simulated by a regional climate model. The model fairly well captures the spatial pattern of the phase of the diurnal cycle. However, the warm season afternoon peak is simulated too early and too uniformly across the stations, associated with too frequent occurrences of convective rainfall events with relatively light intensity. These discrepancies point to the need to improve the convection parametrization and geographic representation of the model

Permafrost in Svalbard: a review of research history, climatic background and engineering challenges

This paper reviews permafrost in High Arctic Svalbard, including past and current research, climatic background, how permafrost is affected by climatic change, typical permafrost landforms and how changes in Svalbard permafrost may impact natural and human systems. Information on active layer dynamics, permafrost and ground ice characteristics and selected periglacial features is summarized from the recent literature and from unpublished data by the authors. Permafrost thickness ranges from less than 100 m near the coasts to more than 500 m in the highlands. Ground ice is present as rock glaciers, as ice-cored moraines, buried glacial ice, and in pingos and ice wedges in major valleys. Engineering problems of thaw-settlement and frost-heave are described, and the implications for road design and construction in Svalbard permafrost areas are discussed