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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 Avalanche Research (SLF), Fluelastrasse 11, CH-7260 Davos Dorf, e-mail: brabec@slf.ch)

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

Estimations of the forecasted avalanche hazard levels are published every day by the European avalanche warning services in their bulletins during winter time. In 1993 the European Avalanche Hazard Scale has been introduced and is in use since then. Nevertheless there still exists no internationally accepted method to measure or objectively construct the hazard level from 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 the unambiguous construction of a hazard level assigned a posteriori to a homegeneous area will be theoretically constructed. This tree will be based on different information sources such as the measured distribution of the snow-pack stability, observed avalanche activity and the personal judgment of people in the field. Based on the three the actual hazard level can be assigned or additional information has to be collected, e.g. if there is no ski-touring or avalanche activity in a area snow-pack stability tests have to be performed. The necessary amount and possible layout of the tests will be described.

Second, a statistically based test-scheme for a whole winter and a region consisting of homogeneous subareas will be developed. A random sampling procedure to determine the time and place of the application will be used. The conclusion that can be theoretically drawn from this kind of camparison will be discussed in detail.

Third, the method and test scheme will be applied in the field in different alpine countries. The individual results will be input of a common database and Internet-based visualization tool. This tool will allow cooperating partners to observe the progress of the practical application during winter 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 deepening of the previous one started in 1996 and still in progress. This project aims to contribute to the study of Global Change in Antarctica, and subordinately in Arctic areas (Svalbard Islands), through the analysis of permafrost and ground ice. The distribution of permafrost, as well as its thickness and that of active layer, are determined by the superficial energy balance, which in turn mostly depends upon climatic parameters (air temperature, sun radiation, snow cover) and, where present, vegetal cover (Williams and Smith, 1989).

The sensitivity of the permafrost system to those different factors allows to approach the knowledge of global climatic changes (Lachenbruch et al., 1988; Osterkamp and Gosink, 1991). Variations of the active layer, mostly in sub-Antarctic and arctic areas, strongly influence the amount of gaseous exchanges between CO2 and CH4 (deriving from both photosynthetic activity and organic matter decomposition), thus contributing to the greenhouse effect.

Permafrost also represents an important data base useful to know the geoenvironmental evolution of the studied areas Denton et al., 1991; Sudgen et al., 1995; Guglielmin et al., 1997 a, b). In fact, being a practically closed and conservative system, it allows the preservation of climatic testimonies recorded in the various types of ground ice. Studying the genesis and age of the latter it is therefore possible to obtain useful information on both sea level changes and the position of the Antarctica ice-cap during the different phases of maximum glaciation.

For the same motivations, thermal profiles of permafrost represent a testimony of climatic evolution in the study areas, not as mere variations of air temperature but as changes of energy balance caused by noteworthy and long-lasting climatic variations (precipitation, cloudiness and temperature). They also have a natural low-pass filter effect on the oscillations, thus favoring the modeling of climatic dynamics. Multidisciplinary monitoring of variations in both permafrost and related ecosystems, as well as their comparing with the same system in Arctic areas, allows also to evaluate both direct and indirect anthropic impact in the two hemispheres,, thus giving an important contribution to environmental conservation and protection (Young, 1991).

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

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

Partners of project

  • Terza Università degli studi di Roma, Dipartimento di Scienze geologiche, Largo San LeonardoMurialdo 1, 00196 Roma, (Francesco Dramis, e-mail: dramis@uniroma3.it)
  • Università degli studi di Ferrara, Dipartimento di Biologia, Sezione di Botanica, Corso Porta Mare 2, 44100 Ferrara (Renato Gerdol, e-mail: grn@dns.unife.it)
  • Consiglio Nazionale delle Ricerche, Istituto di ricerca sulle Acque, Reparto Sperimentale 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 to monitoring programmes of environmental changes that occur in the polar regions. The study of the physical characteristics of natural surfaces based on the reflection of electromagnetic energy represents one of the most relevant issues in many programmes of environmental monitoring.

The snow/ice covers undergo periodic changes both in structure (i.e. grain size and water content) and in areal extent due to seasonal cycles. The amount of these changes is determined by the climatic conditions and, in particular, by the annual thermal trends. The distribution and the physical characteristics of the snow covers can be retrieved by the albedo values as detected by remote sensors that acquire data in the visible, infrared and microwave wavelength intervals. The proper use of satellite data requires ground truth measurements, necessary to understand the interaction mechanisms between snow structure and electromagnetic radiation. It is therefore necessary to improve the knowledge of these mechanisms at different wavelength in order to detect the correlation between radiance and snow physical condition at different state of metamorphism.

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

Ice, in the VIS, weakly absorbs the electromagnetic radiation with a minimum value at 460 nm; ice absorption increases with wavelengths. In the microwave range the dishomogeneity of the snow pack determines diffusion - that increases with frequency - of the radiation; the presence of liquid water causes absorption.

The experiments carried out on snow reflectivity both in the field and in laboratory, show that the most suited spectral region to investigate the different snow surfaces, according to their metamorphic state and their age is that between 500 and 2500 nm; at this spectral range also most of the satellite sensors operate.

Remote sensing provides a synoptic view of the glacial surfaces and of the outcropping rock materials and permits to monitor sea ice. Passive sensors in the VIS and NIR (SPOT/HRV and Landsat/TM) are characterised by a good spatial resolution (20 - 30 m) and their spectral channels allow to discriminate among the different snow surfaces according to the albedo characteristics. The Special Sensor Microwave Scanning Radiometer allows a good discrimination between dry and wet snow on the basis of microwave spectral indexes. The performance of this instrument will be improved with the Advanced Microwave Scanning Radiometer on board of the japanese satellite ADEOS-II.

The proposed research, focused on the simultaneous acquisition of data concerning the nivologic and radiometric characteristics of the snow covers, both by ground and satellite measurements, will complete some of the results obtained in the framework 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)

Azioni sul documento

ultima modifica 20/05/2010 11:56