Introduction
Avalanches can exhibit many different flow regimes
depending on (1) the released and entrained amount of snow, (2) the properties
of the snow and (3) the topography (slope, curvature) .
Studies showed that avalanches can increase their mass due to entrainment by
multiple factors which in turn influences the
run-out distance. Even though important, the amount of snow entrained is not
the main controlling factor that determines the flow form of the avalanche
. The flow regimes and in turn mobility are strongly
influenced by the properties of the entrained snow .
Data on front velocities, run out, flow regimes and powder clouds revealed
that different avalanches can form with similar release conditions and on the
same avalanche path depending on the inherent snow cover properties.
Advancements in avalanche dynamics models allow to account for the properties
of the flowing snow with more and more detail .
Recently, it has been shown that snow temperature inside an avalanche can
significantly change its flow dynamics ,
mainly by changing the granular structure of the flow
. Laboratory studies on the granulation of snow
showed a distinct dependency on snow temperatures with a fundamental change
in snow structure at a threshold of -1 ∘C. Therefore, significant changes in
flow dynamics can be expected with relatively small changes in temperature
around this threshold.
Avalanches at the Flüelapass field site released by artificial
triggering of the cornices on the ridge. Avalanche #1a and #1b (a)
were released on 23 January 2013, #2 (b) on 5 February 2013 and
#3 (c) on 31 January 2014. Note the significant secondary release
and entrainment of deeper layers below the rock face for
(b) avalanche #2 and (c) avalanche #3.
Measuring temperature inside a flowing avalanche or in its deposit with
traditional methods has proven to be difficult due to technical constraints
or because measurements cannot be conducted due to safety reasons. In
addition to manual snow profiles we therefore investigate the application
potential of infrared radiation thermography (IRT) technologies. IRT is a
non-contact, non-intrusive technique, which enables us to see surface
temperature in a visible image. give an overview on
existing work and describe the most relevant industrial and research
applications of IRT.
The emissivity of a surface is a function of many factors, including water
content, chemical composition, structure and roughness as
well as the viewing angle between observer and measurement object. Even
though many technical challenges and shortcomings of IRT are known, possible
applications on the field of snow science have recently been discussed
. and applied IRT to
measure spatial snow surface temperatures on snow pit walls. It was found
that fast and large temperature changes resulting from surface energy balance
processes must be expected . These energy balance
processes between air and snow are particularly important during windy
conditions, clear skies and large temperature differences between air and
snow. These findings indicate that measuring the snow surface temperature of
avalanche deposits or erosion layers along the track must be carried out as
fast as possible. If IRT can therefore be seen as a useful qualitative or
quantitative tool for snow applications still needs further verification.
The aim of this study is to identify the spatial temperature distribution in
an avalanche and to quantify potential sources of thermal energy in an order
of magnitude estimation. This is achieved by field measurements and the
application of an IRT camera. A secondary aim is to evaluate the application
of the IRT technique to get deeper insights into the thermal state of an avalanche.
Methods and data
The Flüelapass field site
Multiple dry avalanches were artificially released during winters 2012–13 and
2013–14 at the Flüelapass field site above Davos (Switzerland). Here we
will discuss three avalanches, #1 (23 January 2013), #2 (5 February 2013)
and #3 (31 January 2014), out of this data base (Fig. ).
The avalanche path is a north-east facing slope covering 600 vertical metres.
Deposits of larger avalanches typically reach a lake located at 2374 m a.s.l. at
the bottom of the slope (Fig. ). Observations and remote
measurements can safely be conducted from the road at the pass which is
approximately 800 m away from the avalanche. The slope angle ranges from
50∘ in the rock face in the upper part to 20∘ at the beginning of the run-out
zone with an average of 30∘ of the open slope around 2600 m a.s.l.
Flüelapass field site close to Davos (Switzerland). Outlines of
avalanche #1a and #1b (green), #2 (red) and #3 (blue). The colour bar shows
differences between terrestrial laser scans before and after the individual
avalanches. Prelease and Ptrack indicate locations of
snow profile in the release and along the path, respectively. Red and blue
lines indicate positions of lateral investigations and deposition snow
profile Pdepo.
Snow profiles
To assess the properties of the released and entrained snow, manual snow
profiles according to were conducted in the
release zone (Prelease), i.e. just below the rock face, along the track
(Ptrack), in the deposition zone (Pdepo) and in the undisturbed
snow cover in the run out zone (Prunout) (Fig. ). The
profile location of the initially released cornice is refereed to as
Pcornice. In combination with release and erosion depths, the acquired
snow profiles allowed to identify which layers were entrained into the avalanche.
All profiles were conducted as fast as possible after the avalanche stopped.
Yet, especially for the profiles in the release area and the track, it took
around 30 min to reach the profile locations. The temperature
measurements close to the surface must therefore be interpreted carefully due
to a rapid adaptation to the ambient conditions.
In addition to the acquired video and pictures of the powder cloud the
deposits of the avalanche were investigated for indications of different flow
regimes according to the observation criteria of .
Lateral temperature profiles
In addition to the regular snow profiles, trenches were dug in the deposition
zone and modified avalanche probes were used to measure lateral temperature
gradients. The modified temperature probes (BTS probes) are regular avalanche
probes for which the tip was replaced by a thermistor. BTS probes are usually
used for permafrost applications to
measure the temperature at the interface between soil and snow. Their
application allowed to measure the temperature of snow layers without
exposing them to the ambient air temperature. As for the thermometers used
for regular snow profiles (Sect. ) they measure the snow
temperature with an accuracy of ±0.1 ∘C. As for the regular snow
profiles the upper most layers need to be interpreted carefully in this
investigation due to an expected change in temperature over time. The lateral
temperature measurements were conducted from the left and right side towards
the snow profile Pdepo, which was situated in the centre of the
deposition zone (Fig. ), simultaneously. The BTS probe
measurements were conducted with a vertical resolution of typically 30 cm and
each individual measurement took around 3–5 min, giving the thermistor
sufficient time to adapt to the snow temperature. In total these measurements
took 1–2 h. Additionally, the snow depth of the deposits was determined
by regularly spaced pits along the transect after the temperature
measurements for avalanche #3. For avalanche #2 a full trench was dug were
the measurements were performed.
Infrared radiation thermography (IRT) camera
The snow temperature measurements acquired from profiles where supplemented
with an infrared radiation thermography (IRT) camera which allowed to record
snow surface temperatures before, during and after the avalanche (Figs.
and ). Time-lapse measurements after the
avalanche stopped allowed to follow the temporal evolution of surface
temperatures (Fig. ) and videos of the moving avalanche
provided a qualitative yet illustrative point of view (provided as
Supplement). The first pictures were recorded as fast as possible
(usually less than 1 min) after the powder cloud disappeared and the video
recording was stopped.
We used an InfraTec VarioCAM hr 384 sl and a VarioCAM HD 980 s that both
operate in the long wave infrared spectral range (LWIR) covering 7.5 to
14 µm. According to the manufacturer the cameras measure with an absolute
accuracy of ±1.5 ∘C and a resolution of 0.05 ∘C. The measurements were
either conducted with a 15 or 30 mm lens. With the used IRT cameras and
lenses the pixel size of the footprint is approximately 1 m with the old
camera and 0.5 m with the newer model. Since cold and dry atmospheric
(determined by an automatic weather station close by) and snow conditions
prevailed during avalanche experiments #1 and #2 an emissivity value of 1
has been chosen for all post-processing operations.
Even though in our study we use the IRT measurements mainly in a qualitative
way, a basic verification was conducted.
Screenshot of IRT camera videos for avalanche #1a and #1b. The
first picture was taken 12 s after the avalanche
released.
Temporal evolution and comparison of snow temperatures of
avalanche #2 using an IRT camera and manually measured data. Solid lines
represent IRT measurements in the release (blue line) and track (orange line)
sliding surfaces. Dashed lines represent IRT measurements performed in the
undisturbed snow cover close to the release (blue) and close to the avalanche
path (orange). Small dots on the orange dashed line correspond to the time
resolution of all IRT measurements. Data from IRT are compared with manual
measurements performed at the corresponding layer (filled diamonds) and at
the snow surface (empty diamonds) at the closest snow
profile.
The surface temperatures measured with the IRT camera (lines in
Fig. ) were compared to the corresponding manually measured
temperatures (diamonds in Fig. ) at the snow profile
locations (Fig. ). The release sliding surface temperature
measured with the IRT camera (IRTrelease_sliding, blue continuous line
in Fig. ) has been compared with the corresponding layer in
the manual profile performed close to the release zone
(T_Prelease_sliding, blue full diamond at 0 min). The avalanche
sliding surface temperature measured with the IRT camera in the upper part of
the track (IRTtrack_sliding, orange continuous line in
Fig. ) has been compared with the corresponding layer in the
manual profile performed close to the flowing zone (T_Ptrack_sliding,
orange full diamond). Further, the surface temperature of the undisturbed
snow close to the snow profile location in the release and in the track
(IRTrelease_undisturbed and IRTtrack_undisturbed, blue and orange
dashed lines) have been compared to snow surface temperature measurements at
the profiles (T_Prelease_undisturbed and T_Ptrack_undisturbed,
empty diamonds). Measurements are in fairly good agreement with an absolute
difference of about ±1.5 ∘C (except for T_Ptrack_sliding).
This accuracy suggests that the data cannot be used to quantify precise
absolute temperature values, but to get an order of magnitude between
relative differences.
Terrestrial laser scan (TLS) and mass balance
A terrestrial laser scanner (Riegl LPM-321) was operated from the
Flüelapass road (Fig. ) to acquire digital surface models
before and after the avalanche releases. These measurements facilitated the
calculation of the release, entrainment and deposition area. Furthermore, the
difference between the two laser scans allowed to calculate the spatially
averaged release and erosion depth along the path. The combination of area,
release/erosion depth and depth-averaged snow density from the manually
created snow profiles (Sect. ) allowed to calculate the
corresponding mass. Adding release and entrained mass results in the
deposited mass. This procedure is common practice and was applied in multiple
other studies .
A complete set of terrestrial laser scans is available for avalanche #3
only. For avalanche #2 the scan before the avalanche is only available for
the release zone (Fig. ). No information from terrestrial laser
scanning was available for avalanche #1. Avalanche boundaries and field
measurement locations were recorded by GPS allowing spatial referencing with
the TLS data. A summer digital elevation model (DEM) was available from an
airborne digital photogrammetry campaign with 1 m
spatial resolution. It was mainly used to georeference our data and allow
consequent processing in a GIS system. Furthermore, the summer DEM allowed to
determine the topography below the lateral transects in the avalanche
deposits (Sect. ).
Investigated avalanches
This section summarizes the key characteristics and available data
(Table ) of the avalanches. All avalanches were released after a
snow storm by triggering the cornices at the ridge at 2900 m a.s.l. with
explosives. Therefore, most of the released snow was new snow. Yet, two of
the avalanches, avalanche #2 and #3 (Fig. b and c),
entrained significant amounts of snow from deeper layers due to a secondary
release in a deeper weak layer, below the rock face. Since the main mass
contribution can be assumed to be defined by the secondary releases and the
entrainment along the path, we focused our investigations on these snow
masses. Mass contributions by the cornices are usually relatively small
compared to entrained snow on the open slope below. Furthermore, entrainment
of snow in the gullies of the rock face is not assumed to contribute a
significant amount since regularly occurring (small) avalanches and slides
continuously erode the snow cover. In this study we use the word release to
refer to profile locations at the secondary release below the rock face (Fig. ).
Avalanche #1a and #1b (23 January 2013)
In the days previous to the avalanche experiment 10 cm of new snow were
recorded and snow drift accumulations formed due to strong southerly winds.
The national avalanche bulletin reported a moderate avalanche danger (level 2)
and identified the fresh snow drift accumulations as the main danger.
During the experiment clear sky conditions prevailed and the automatic
weather station (AWS) at the Flüelapass (FLU2) measured an air
temperature of -10 ∘C. Multiple charges were exploded on the ridge to the
left (south) side, facing uphill, of the summit, resulting in two independent small powder
avalanches which followed the gullies (Figs. a and ).
Due to the relatively small release mass and no
significant entrainment, both avalanches, #1a and #1b, stopped halfway down
the open slope. Even though the avalanches were small and a full data set of
field measurements is not available, they are retained in this study since
they provide good quality IRT data (Fig. ). We excluded the
snow profile measurements from the analysis since the erosion and deposition
depths were very small, around 0.1 m, and the manual measurements were
conducted more than 1 h after the release. The deposition zone was not
accessible before due to safety reasons. The TLS could not be completed due
to technical problems.
Summary of measurements for the investigated
avalanches.
Avalanche
#1a
#2
#3
Date
23 Jan 2013
5 Feb 2013
31 Jan 2014
IRT camera model
h 384 sl
h 384 sl
HD 980 s
Terrestrial laser scan
no
partly
yes
Snow profiles lateral
–*
yes
yes
Snow profiles track
–*
yes
yes
IRT video
yes
yes
no
IRT pictures
yes
yes
yes
Released mass mr(t)
–
502
818
Entrained mass me(t)
–
1857
1302
Deposited mass md(t)
–
2359
2120
Growth index Ig
–
3.7
1.6
* indicate that erosion and deposition depths were too
small. Growth index Ig is defined as
Ig = me/mr.
Screenshot of IRT camera videos for avalanche #2. The first picture
was taken 3 s after the avalanche released. Note that the temperature scale
was changed by 0.5 ∘C for the last shown image
(82 s).
Avalanche #2 (5 February 2013)
20 cm of fresh snow that covered older snow drift accumulations resulted in a
considerable (level 3) avalanche danger. Furthermore, the bulletin noted that
avalanches in isolated cases could be released deeper within the snowpack.
The AWS at Flüelapass measured -12 ∘C and a partly cloudy sky prevailed
during the experiment.
Explosions along the ridge and to the observer's left (South) side of the summit
only produced small avalanches that stopped shortly below the rock face. A
single explosion that triggered the cornice to the right side of the summit
caused another small powder avalanche that followed the gully and triggered a
secondary release at the start of the open slope (Fig. b).
Even though the avalanche almost stopped after entering the open slope, the
additional mass which was entrained resulted in an re-acceleration resulting
in a long running medium-sized avalanche (deposition mass 2357 t) which only
stopped in the flat part close to the lake. Average snow density of the
release was 170 and 210 kg m-3 for the entrained snow.
No full TLS was available before the avalanche release. Nevertheless,
in-field observations showed the surface before the release and the
entrainment depth to be rather homogenous along the slope which allowed to
extrapolate the upper entrainment area, in combination with the envelope of
the avalanche acquired with GPS, and thus to calculate the entire entrained mass.
Avalanche #3 (31 January 2014)
Multiple consecutive smaller snowfalls and strong southerly winds created
snow accumulations close to ridges. The national avalanche bulletin issued a
considerable (level 3) danger level and that the weak, old snowpack could
cause avalanches to be released in near-ground layers. Moderate winds with
gusts up to 60 km h-1 from the South and cloudy to overcast conditions
prevailed during the experiment. The automatic weather station FLU2 recorded
-6 ∘C with steadily increasing temperatures during the experiment.
Two small spontaneous avalanches already released before the experiment.
Initial bombing of the main gully and to the observer's left (south) of the
summit did not produce any significant avalanches. Yet, the bombing of the
cornice to the observer's right (north) of the summit resulted in a small powder
avalanche which triggered a second slide at the lower end of the rock face
(similar to avalanche #2). Consequently a significant amount of snow was
eroded and resulted in a medium-sized avalanche (deposition mass 2120 t) that
stopped in the flat run out zone (Fig. c). The secondary
release nearly entrained all layers to the bottom of the snowpack (1.6 m).
Average snow density of the release was 270 and 310 kg m-3
for the entrained snow. For avalanche #3 snow temperature
measurements were also available for the cornice at the ridge.
IRT camera images for avalanches (a) #1a and #1b and
(b) #2. Note the different temperature scales amongst the
avalanches. Black lines indicate positions of lateral snow temperature
transects.
Discussion
It has been noted in other studies that potential sources
of thermal energy in snow avalanches are friction processes or entrainment of
snow with differing temperatures. The investigated avalanches in this study
indicate that the thermal energy increase was mainly defined by frictional
heating, which in turn depends only on the effective elevation drop
(Sect. ). Yet, it is well known that avalanches can
significantly increase their mass along the path via entrainment
. Also for the investigated avalanches the growth index
were Ig of 3.7 and 1.6 for avalanche #2 and #3, respectively. Therefore,
the calculated (maximum) value of approximately 0.46 ∘C per 100 altitudinal
metres (Eq. ) has to be adapted to consider the actual
mass that enters the avalanche at a certain point along the track
(Sect. ). For dry and cold snow avalanches far away from
the melting point, the warming due to friction alone is not expected to have
a substantial influence on flow dynamics. Yet, if the overall avalanche
temperature is already close to the critical temperature threshold of -1 ∘C
the warming by frictional processes can cause
drastic changes of the granular structure inside the avalanche and
consequently affect flow behaviour.
Contrarily, the warming due to entrainment varied for the individual
avalanches. These variations depend on the temperature of the snow and the
erosion depth as shown in the profiles along the avalanche track
(Fig. ) and the IRT pictures (Fig. ).
Typically, the alpine snow cover shows a positive temperature gradient
towards the ground . Except for areas with
permanent permafrost, the temperature at the soil–snow interface can be
assumed to be approximately 0 ∘C if there has been a significant snow cover
for several weeks. Consequently, the erosion of deeper snow layers leads to
warmer snow temperatures (Fig. ). Also changes of snow
temperature due to elevation gradients have been proven to be quite variable
and directly influence flow dynamics . As in the
case of avalanche #2 even a cooling of an avalanche is possible when the
avalanche released into deep layers but entrained only superficial (cold)
layers of snow, e.g. blue and orange lines in Fig. .
Overall, the contribution of the temperature of the entrained snow to the
temperature change was smaller than by friction for the investigated
avalanches (Table ).
Our temperature measurements on the surface (Fig. ) and in
depth (Fig. ) of the deposit indicate that the
highest temperatures are located in the dense core of the avalanche. The
interface between the bottom of the avalanche deposits and the subjacent
undisturbed snow cover featured a very clear and sharp transition (violet
lines in Fig. ). The shape of the temperature curve
indicates the warmest temperatures in the lower parts of the deposits profile
(-0.4 to -0.8 m and -1.2 to -1.9 m for avalanches #2 and #3, respectively)
and close to the sliding surface. This would support the expectation of the
most pronounced friction at the bottom of the flow, typical for this kind of
avalanche. Unfortunately, a cooling of the lowest deposition layers to the
temperature of the subjacent undisturbed snow cover has to be expected and
thus prevents a definite conclusion on this observation. Also, whether the
small temperature variations in the upper part of the deposition profile
between 0 and -1 m of avalanche #3 (violet line in Fig. )
are a result of a mixture of broken parts of the eroded snow cover, with
varying temperatures, and formed granules could not be fully answered. Yet,
granules embedded in fine grained snow were still clearly observable in this
area of the deposition.
It is without question that reaching the deposits after an avalanche release
to measure the snow surface temperature with traditional methods,
e.g. thermometers, takes too long and the surface as well as the upper most layers
would have changed their temperature already. It could be observed in the
video of avalanche #1 (see Supplement) that right after the
dense core stopped it started to cool. In all those cases for which a
real-time measurement is necessary, IRT technology provides a valuable
addition to traditional measurements. Even though in our study we only
applied the IRT camera in a qualitative way, the presented basic verification
(Fig. ) with manually measured snow surface temperatures
showed a fairly good agreement with an accuracy of about ±1.5 ∘C.
Although further investigations are necessary to define whether absolute
values of surface temperature can be acquired without significant
uncertainties, the relative accuracy of the IRT cameras are usually high,
around 0.05 ∘C in our case as specified by the manufacturer. This facilitates tracking relative changes in temperatures even if the absolute value might
not be accurate.
Recently IRT was mainly tested and evaluated for snow profile applications at
short distances . investigated the
effect of viewing angle on the infrared brightness temperature of snow and
found differences of up to 3 ∘C. Similar values have been found by
, yet they concluded that for viewing angles less than
40∘ from the nadir, the error in temperature is less than -0.8 ∘C. The effect of
moisture has been studied extensively and references
therein, basically concluding that the presence of water causes a
strong absorbance and consequently a decrease in reflectance in the
near-infrared spectra of soils. In general, low signal attenuation can be
expected for (peak) winter month atmospheres, especially for clear sky
conditions, due to relatively low humidity levels. An effect that still
illustrates challenges for the interpretation of IRT images is due to the
roughness of the investigated surface . In most studies, it is assumed that the scene elements are isothermal, smooth and homogenous . Consequently supposing that the object of
interest is Lambertian, i.e. behaves as a perfect diffuser and emits and
reflects radiation isotropically. observed that the
effective emissivity spectra of rough surfaces are different from those of
perfectly smooth surfaces of the same composition due to multiple scattering
among roughness elements. Yet, they only found an up to 3 % reduction in the
spectral contrast due to sub-pixel surface roughness variations. This might
also be the case for situations similar to the presented application as size
of the granules, i.e. the sub pixel structures, are much smaller than the
pixel size (0.5 to 1 m).
Also whether the surface temperature, and possibly even the composition, of
the aerosol mixture of the powder cloud can be measured is an open question.
Visualization of air flows on the qualitative level is common practice for
various applications and, as presented
in this study, provides impressive footage of powder snow avalanches. Usually
a tracer is injected into the flow field. In our case the tracer is already
present by snow particles of the entrained snow which are transported into
the powder cloud.
A possible further application of IRT could be the differentiation of flow
regimes in the deposition area. As shown earlier the warmest part of an
avalanche is located in the dense core, e.g. center (red and pink) of
avalanche #2 in Fig. b, whereas layers with less mass or where
less friction occurred are cooler (yellow and orange areas in
Fig. b). Especially the observer's left (south) side thin-deposit
area in Fig. b might be associated with the deposits of a
fluidized layer . The IRT observations of this
thin-deposit area are in agreement with the field observation criteria for
fluidized layers as described by : (1) rapid decrease of
deposit thickness, (2) snowballs of various sizes embedded in a matrix of
compacted fine-grained snow, (3) large snowballs lying on top of the deposit
and (4) fewer snowballs per unit area than on the dense deposit.
The powder clouds of the investigated avalanches (see Figs.
and and corresponding videos) had consistently lower
temperatures than the warm dense core despite the fact that the powder cloud
(at least from one avalanche) travelled as far downhill as the dense core. Two
distinct processes may contribute to this fact: (i) a preferential ejection
of colder and lighter surface with colder snow while the dense core may have
a higher fraction of snow from lower layers in the profile and therefore with
a higher temperature. (ii) The particle concentration in the suspension layer
is low and therefore molecular dissipation of kinetic energy and exchange of
sensible and latent heat happens largely between air and snow and not between
snow and snow particles as in the dense core. This leads to a rapid adoption
of temperatures close to the air temperature for the suspended snow.
Furthermore, the IRT results can be qualitatively interpreted in a similar
way as a laser scan to identify areas where deeper or shallower erosion
occurred, e.g. see entrainment by secondary release below the rock face for
avalanche #2 (Fig. b). For this avalanche, we (for the sake of example) calculated the release mass solely by using information from the IRT pictures
and manually measured snow profiles in the release. Therefore, the IRT
picture was georeferenced in a GIS software and shallower and deeper release
layers were identified. The (IRT) surface temperature of these layers were
combined with the snow height of the corresponding temperature in the
conducted snow profile in the release. This resulted in a calculated release
mass of 457 t, which is similar to the mass measured with the terrestrial
laser scan (502 t). This depicts a rough yet quick and efficient method to
estimate the release mass of an avalanche. As shown in this study, the
release and entrainment depth does not only define the overall mass of snow
but equally important its temperature. IRT pictures and videos provide an
intuitive and easy way to identify these relevant erosion processes (Fig. ).
Conclusions
We conducted full-scale avalanche experiments at the Flüelapass field
site above Davos (Switzerland) to investigate the distribution of snow
temperatures in avalanche deposits and identify the sources of thermal energy
in dry avalanches. A further goal was to test the usability of infrared
radiation thermography (IRT) in this context.
For the investigated similar avalanches the temperature increase due to
friction has been shown to dependent on the effective elevation the mass
inside the avalanche dropped. The contribution to the total temperature
increase by erosion processes was shown to be quite variable, depending on
the release depth and snow temperatures of the entrained snow. The warmest
temperatures were observed in the centre of the avalanche deposits and thus
represented the dense core of the flowing avalanche.
The IRT camera allowed to observe the avalanche phenomenon “with different
eyes” and provides a lot of potential for more detailed research in the
field of avalanche dynamics, both quantitative and qualitative. It is still
necessary to further verify the measurements and define to which extent
absolute snow surface temperatures can be measured. Then, the spatial
distribution of surface temperatures can help in the interpolation of profile
temperatures measured by hand.
Our results allow for a more comprehensive understanding of snow temperatures
in avalanche flow and their consequences on flow regimes. This information
can directly be used to verify and enhance the performance of avalanche
dynamics models and is thus of great interest for practitioners.