I n s t r u m e n t s

a n d

M e t h o d s

Fig. 5. Melting in the surface layerand refreezingafter a sudden decrease ofcloudiness and nebulosity.The thick bars

in the snow profile show the wetting front. The sudden drop of surface temperature because of increased net outward IR-

radiation of the snow surface causes the fast refreezing.

Sofar5warningstationshavebeeninstalled.Each
stationconsistsoftworemotedataacquisitionsystems,
oneforwindandadditionalmeteorologicalparameters
located on aridgecrest, thesecond for snow measurements
at a location that represents the snow coverdevelopment
oftheregion.Eleven morestationsare currently putin
placefortheSwissAvalancheandSnowInformation
Network IMIS coordinated by SFISAR.Twoalarm systems
are operational since 1 year, one to close a road in case of a
mud flow, the second to stop trains in caseof avalanches.
Twomore alarm stations to protect roads will beoperational

thiswinter.Two profileradarare operationalsince two
years.At least twomore willbe installed forthe coming
winter.SofartwoGAZ-EXcontrolsystemshavebeen
installed, athird oneis underconstruction. Experiencewith
thetraditionalsensorswasgood,someminorproblems
have already been mentioned. Fig. 4 shows a typical plot
ofdata.Thesnowprofilersturnedouttobeespecially
helpful to assess snow accumulation and fracture heights
below GAZ-EX installations (Fig .4) and to predict spring
type surface slides (Fig 5).

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