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SCIENTIFIC RESEARCHES (English version)

VERIFICATION OF THE EUROPEAN AVALANCHE HAZARD SCALE (Verifica della scala europea del pericolo di valanghe)

Research Responsable:Dott. Bernhard Brabec, Swiss Federal Institute for Snow and AvalancheResearch (SLF), Fluelastrasse 11, CH-7260 Davos Dorf, e-mail: brabec@slf.ch)

The aim of this project is todeveloping a scheme for verifying the European Avalanche Hazard Scalein the field. Both aspects, the necessary theoretical foundation aswell as the application in the field in different alpine countries(Austria, Italy and Switzerland) will be addressed. The result will beof particular significance to improve the European avalanche warningand therefore the safety of habitation, roads and tourist activities inthe participating countries. A major contribution to the cooperation ofEuropean avalanche warning services is also expected.

Estimations of the forecastedavalanche hazard levels are published every day by the Europeanavalanche warning services in their bulletins during winter time. In1993 the European Avalanche Hazard Scale has been introduced and is inuse since then. Nevertheless there still exists no internationallyaccepted method to measure or objectively construct the hazard levelfrom field measurements or observations for a certain day and area.Such a method would be of great importance for:

  • consistent use of the European Avalanche Hazard Scale in different countries,
  • quality control of the avalanche bulletins and
  • development of statistical models based on verified hazard judgements.

First, a decision tree for theunambiguous construction of a hazard level assigned a posteriori to ahomegeneous area will be theoretically constructed. This tree will bebased on different information sources such as the measureddistribution of the snow-pack stability, observed avalanche activityand the personal judgment of people in the field. Based on the threethe actual hazard level can be assigned or additional information hasto be collected, e.g. if there is no ski-touring or avalanche activityin a area snow-pack stability tests have to be performed. The necessaryamount and possible layout of the tests will be described.

Second, a statistically basedtest-scheme for a whole winter and a region consisting of homogeneoussubareas will be developed. A random sampling procedure to determinethe time and place of the application will be used. The conclusion thatcan be theoretically drawn from this kind of camparison will bediscussed in detail.

Third, the method and test schemewill be applied in the field in different alpine countries. Theindividual results will be input of a common database andInternet-based visualization tool. This tool will allow cooperatingpartners to observe the progress of the practical application duringwinter and will provide intermediate results.

Partners of project

  • WSL: Swiss federal Institute for Snow and Avalanche Research, Davos, Switzerland (Tom Russi, Bernhard Brabec)
  • ETHZ: Department of Computer Science, Institute for Information Systems, Zurich, Zwitzerland (Moira Norrie)
  • ETHZ: Department of Mathematics, Statistics Seminar of ETH Zurich, Zurich, Switzerland (Martin Machler)
  • BOKU: Universität für Bodenkultur Wien, Institut für Wildbach und Lawinenschutz, Wien, Osterreich (Karl Kleemayr)
  • CVA: Regione del Veneto ARPAV, Centro Valanghe di Arabba, Arabba, Italia (Anselmo Cagnati, Mauro Valt cva@arpa.veneto.it)

This project is supported by Swiss Federal Insitute for Snow and Avalanche Research (SLF)

PERMAFROST AND GLOBAL CHANGE IN ANTARCTICA (Permafrost e cambiamenti climatici globali in Antartide)

Research Responsable: Prof. Francesco Dramis; Earth Sciencies Dept., Third University of Rome, Largo L. San Murialdo 1, Roma, e-mail: dramis@unirom3.it

Principal Investigator: Dott. Mauro Guglielmin; Earth Sciencies Dept., Third University of Rome, Largo L. San Murialdo 1, Roma, e-mail: cannone.guglielmin@galactica.it

The research represents a continuation and deepeningof the previous one started in 1996 and still in progress. This projectaims to contribute to the study of Global Change in Antarctica, andsubordinately in Arctic areas (Svalbard Islands), through the analysisof permafrost and ground ice. The distribution of permafrost, as wellas its thickness and that of active layer, are determined by thesuperficial energy balance, which in turn mostly depends upon climaticparameters (air temperature, sun radiation, snow cover) and, wherepresent, vegetal cover (Williams and Smith, 1989).

The sensitivity of the permafrost system to thosedifferent factors allows to approach the knowledge of global climaticchanges (Lachenbruch et al., 1988; Osterkamp and Gosink, 1991).Variations of the active layer, mostly in sub-Antarctic and arcticareas, strongly influence the amount of gaseous exchanges between CO2and CH4 (deriving from both photosynthetic activity and organic matterdecomposition), thus contributing to the greenhouse effect.

Permafrost also represents an important data baseuseful to know the geoenvironmental evolution of the studied areasDenton et al., 1991; Sudgen et al., 1995; Guglielmin et al., 1997 a,b). In fact, being a practically closed and conservative system, itallows the preservation of climatic testimonies recorded in the varioustypes of ground ice. Studying the genesis and age of the latter it istherefore possible to obtain useful information on both sea levelchanges and the position of the Antarctica ice-cap during the differentphases of maximum glaciation.

For the same motivations, thermal profiles ofpermafrost represent a testimony of climatic evolution in the studyareas, not as mere variations of air temperature but as changes ofenergy balance caused by noteworthy and long-lasting climaticvariations (precipitation, cloudiness and temperature). They also havea natural low-pass filter effect on the oscillations, thus favoring themodeling of climatic dynamics. Multidisciplinary monitoring ofvariations in both permafrost and related ecosystems, as well as theircomparing with the same system in Arctic areas, allows also to evaluateboth direct and indirect anthropic impact in the two hemispheres,, thusgiving an important contribution to environmental conservation andprotection (Young, 1991).

The project could contribute to fill the almosttotal lack of data on permafrost in Antarctica (Beckeinm, 1995), ashoped by international research programs, such as PAGES and CLIMEX.Anyhow, it will mostly be a part of a wider international programcalled CIRCUMANTARCTIC PERMAFROST MONITORING PROJECT. The latter willbe based upon the construction of a network of monitoring stationsaround Antarctica (including Antarctic and sub-Antarctic islands).

This project will be supported by the IPA(International Permafrost Association) and will be coordinated withsimilar projects for the northern hemisphere, such as CALM, ITEX andEU-PACE.

Partners of project

  • TerzaUniversità degli studi di Roma, Dipartimento di Scienze geologiche,Largo San LeonardoMurialdo 1, 00196 Roma, (Francesco Dramis, e-mail: dramis@uniroma3.it)
  • Universitàdegli studi di Ferrara, Dipartimento di Biologia, Sezione di Botanica,Corso Porta Mare 2, 44100 Ferrara (Renato Gerdol, e-mail: grn@dns.unife.it)
  • ConsiglioNazionale delle Ricerche, Istituto di ricerca sulle Acque, RepartoSperimentale di Idrobiologia, via della Mornera 25, 20047 Brugherio MI(Marina Camusso, e-mail: camusso@server-mi.irsa.rm.cnr.it)
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  • Regione del Veneto-ARPAV, Centro Valanghe di Arabba, via Pradat 5, 32020 Arabba BL (Anselmo Cagnati, e-mail: cva@arpa.veneto.it)

International cooperations

  • University of Ottawa (Canada): cooperation for the studies about the paleoclimatic reconstruction and net energy balance of soil surface of Canadian Arctic areas and North Victoria Land (Responsable Prof. Hugh French)
  • Swiss Federal Institute for Snow and Avalanche Research (Switzerland):cooperation for developing models of temporal evolution of snow cover (Responsable Dott. Walter Amman)

This project is supported by Italian Programme for Antarctic Research (PNRA)

 

THE SNOW NET MONITORING SYSTEM OF MOUNT CHERZ (Il sistema di monitoraggio di reti fermaneve)

Research Responsable:Francesco Sommavilla,ARPAV Avalanches Centre of Arabba, Pradat street,5 - 32020 Arabba di Livinallongo (BL)- ITALY

Principal Investigator: Betty Sovilla, ARPAV Avalanches Centre of Arabba,

Pradat street,5 - 32020 Arabba di Livinallongo (BL)- ITALY

 

The snow net monitoring system of Mount Cherz has been created in 1998 by the Avalanche Centre of Arabba in order to determine the real tensions that the snowpack produces in each part constituent this particular avalanches active defence.

One tract of net of about 8 m have been monitored with laboratory manufactured devices built using Strain Gauge sensors.

The system records and transmits, by radio, to the Centre, one measure for each sensor every 30 minutes; particularly these parts of net have been monitored:

  • Two swivel posts having different diameter (pressure)
  • Three upper anchors connecting the net to the ground (tension forces)
  • Four perimetral net ropes (tension forces)
  • Two lower anchors (tension forces)

There is also one measure station that records the height of snow over the net.

This project is supported by the Avalanche Centre of Arabba

 

THE AVALANCHE MONITORING SYSTEM OF MOUNT PIZZAC (Il sistema di monitoraggio del monte Pizzac)

Research Responsable:Francesco Sommavilla,ARPAV Avalanches Centre of Arabba, Pradat street,5 - 32020 Arabba di Livinallongo (BL)- ITALY

Principal Investigator: Betty Sovilla, ARPAV Avalanches Centre of Arabba, Pradat street,5 - 32020 Arabba di Livinallongo (BL)- ITALY

The monitoring system of Mount Pizzac has been created in order to study the avalanche dynamics and the effect of its impact on the structures.

In its extreme dimensions the monitored avalanche gets off at 2200 meters and stops at 1745 meters, thus following a trajectory of 836 meters with an average gradient of 31°.

The necessary structures for monitoring have been installed in the track of the gully between the above limit of the flowing zone and the central track of the accumulation zone, for a whole length of 418 meters. They allow us to observe the development of the event, thus recording continuously: pressures, speed and geometric variations of the body of the avalanche.

In particular six steel poles, each one fitted out with n. 8 pressure measuring devices (each one with an area of 7850 mm²) allow us to determine the profile of the pressures continually with a resolution of 50 cm up to a maximum height of 5 m. Moreover, five of the six poles placed along the flowing zone of the avalanche are fitted out with measuring devices able to check the flow height, allowing the recreation both in time and space. A small-sized wedge-shaped obstacle (area 1 m²) allows us to estimate the influence of the form and area over the power of the avalanche impact.

Furthermore, knowing the time when the avalanche flow passes by means of sections placed at known distances, it is possible to determine the average speed of the front in 14 tracks of the flow line.

The monitoring system has three cameras which permit us to record the event automatically.

15 events have been recorded since 1993, when the monitoring system was first installed. The avalanches which occured most frequently were wet snow flowing avalanches in springtime and dry snow flowing avalanches in wintertime, with average volumes of 2000 m³. Particularly for average speeds of the avalanche front ranging from 2.5 to 23 m/s, the pressures have recorded variable readings going from 5 to 175 kPa.

This project is supported by the Avalanche Centre of Arabba

 

STUDY OF CHANGES IN SNOW/ICE SURFACES BY SPECTRORADIOMETRIC SURVEYS AND REMOTE SENSING DATA (Studio delle variazioni delle coperture nivo/glaciali mediante rilievi spettroradiometrici e dati telerilevati)

Responsable of project: Dott. Ruggero Casacchia, Consiglio Nazionale delle Ricerche, Progetto Antartide, viale Marx 15, 00137 Roma, e-mail rosas@gioconda.polar.rm.cnr.it

This research proposal is a contribution tomonitoring programmes of environmental changes that occur in the polarregions. The study of the physical characteristics of natural surfacesbased on the reflection of electromagnetic energy represents one of themost relevant issues in many programmes of environmental monitoring.

The snow/ice covers undergo periodic changes both instructure (i.e. grain size and water content) and in areal extent dueto seasonal cycles. The amount of these changes is determined by theclimatic conditions and, in particular, by the annual thermal trends.The distribution and the physical characteristics of the snow coverscan be retrieved by the albedo values as detected by remote sensorsthat acquire data in the visible, infrared and microwave wavelengthintervals. The proper use of satellite data requires ground truthmeasurements, necessary to understand the interaction mechanismsbetween snow structure and electromagnetic radiation. It is thereforenecessary to improve the knowledge of these mechanisms at differentwavelength in order to detect the correlation between radiance and snowphysical condition at different state of metamorphism.

It is known that in the visible (VIS) and in thenear infrared (NIR) wavelengths snow reflectivity depends on the sizeand the geometry of the ice grains, on liquid water inclusions and onsolid and soluble impurities. The albedo, defined as the total amountof the reflected radiation, decreases as the grain size increases;grain size variation is related to density and to water content of thesnow cover. In the microwave spectral band emission and diffusion arestrongly correlated to the thickness and to the water content of thesnow cover.

Ice, in the VIS, weakly absorbs the electromagneticradiation with a minimum value at 460 nm; ice absorption increases withwavelengths. In the microwave range the dishomogeneity of the snow packdetermines diffusion - that increases with frequency - of theradiation; the presence of liquid water causes absorption.

The experiments carried out on snow reflectivityboth in the field and in laboratory, show that the most suited spectralregion to investigate the different snow surfaces, according to theirmetamorphic state and their age is that between 500 and 2500 nm; atthis spectral range also most of the satellite sensors operate.

Remote sensing provides a synoptic view of theglacial surfaces and of the outcropping rock materials and permits tomonitor sea ice. Passive sensors in the VIS and NIR (SPOT/HRV andLandsat/TM) are characterised by a good spatial resolution (20 - 30 m)and their spectral channels allow to discriminate among the differentsnow surfaces according to the albedo characteristics. The SpecialSensor Microwave Scanning Radiometer allows a good discriminationbetween dry and wet snow on the basis of microwave spectral indexes.The performance of this instrument will be improved with the AdvancedMicrowave Scanning Radiometer on board of the japanese satelliteADEOS-II.

The proposed research, focused on the simultaneousacquisition of data concerning the nivologic and radiometriccharacteristics of the snow covers, both by ground and satellitemeasurements, will complete some of the results obtained in theframework of the 96-98 scientific plan.

Partners of project

  • Consiglio Nazionale delle Ricerche, Progetto Antartide, viale Marx 15, 00137 Roma, (Ruggero Casacchia, e-mail rosas@gioconda.polar.rm.cnr.it)
  • Consiglio Nazionale delle Ricerche, Istituto Ricerca Rischio Sismico, via Bassini 15, 20133 Milano (Massimo Antoninetti, e-mail massimo@irrs.mi.cnr.it)
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  • Regione del Veneto-ARPAV, Centro Valanghe di Arabba, Pradat 5, 32020 Arabba BL (Anselmo Cagnati, e-mail: cva@arpa.veneto.it)

International cooperations

Norwegian Polar Institute, 90005 Tromso, Norway (Responsable Dott. Jan-Gunnar Winther)

This project was submitted to Italian Programme for Antarctic Research (PNRA)

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16-09-2022 09:05

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