IEEE Geoscience and Remote Sensing Magazine - March 2020 - 63

SNOW COVER AREA
MONITORING
Snow depth and snow water equi-
valent (SWE), i.e., the snow mass
on the ground, are some of the key
MARCH 2020

Daily Velocity (meters per hour)

0.045
0.04
0.035
0.03
0.025
0.02
0.015
0.01
0.005
0

Z (m)

2,000
1,500
1,000
500
0
-3,000
-2,000
-1,000

0
50

00
-5

00
,0

-1

-2

-1

VOLCANO MONITORING
Sonia et al. utilized GB-DInSAR to monitor active volcanoes
with an analysis of the 12 January
2013 crater-wall collapse occurring at
the Stromboli volcano [93]. Figure 35
ago
Stromboli
presents the northeastern portion of
Calabria
the crater terrace of Stromboli and the
GB-DInSAR system located in a stable
area 1.5 km from the crater terrace.
Ionian Sea
Figure 36 shows the monitoring results from 8 December 2012 to 8 March
2013 using a thermal camera and GBDInSAR. The occurrence of overflows
is represented by red triangles, and the
12 January 2013 crater-wall collapse
is indicated with the black arrow that
was recorded by the thermal camera, as
shown in Figure 37.

parameters in the assessment of an avalanche hazard for
snow, snow drift, and avalanche modeling as well as model
verification. In [94], Schaffhauser et al. validated that GBDInSAR can, in principle, be used to retrieve snow depth
and SWE.
The test site for snow and avalanche observations is located in the Wattener Lizum province of Tyrol, Austria, a
training center of the Austrian Army. The remote monitoring instruments were installed in the valley's bottom at an
altitude of 2,040 m, sheltered by a wooden hut. The distance
to the boundary of the target area, the Tarntaler Köpfe (a
2,757-m peak), is roughly 1,900 m and within the range of
both remote monitoring instruments, as depicted in Figure 38. The spatial distribution of the snow-depth changes

GLACIER MONITORING
Luzi et al. monitored the Belvedere glacier [92], located
above the village of Macugnaga in the Italian Alps. The
photo shown in Figure 31 gives an overview of the monitored area and of the radar apparatus. The apparatus was
positioned at 2,254 m above sea-level altitude to monitor
the area just above the supraglacial lake.
The image displayed in Figure 32 reproduces the main geometrical features of the monitored slope, demonstrating that
the signal backscattered from the glacier is measurable using
a good signal-to-noise ratio. The pixels showing the highest
reflectivity values are those corresponding to rock or ice bulges.
Figure 33 depicts the coherence calculated for a one-day interval. High values are present, both in steady and moving areas.
For the interval between subsequent acquisitions, the melting
does not dramatically affect coherence for the retrieval of the
displacement from GB-SAR interferometric maps.
To obtain an estimate of the actual displacement, Luzi
et al. assumed that it occurred along the maximum-slope
direction. Data taken from the DEM were used to calculate
the angle between the LOS and the surface maximum-slope
direction. The actual displacement was found by dividing the
LOS values by the cosine of this angle. Figure 34 shows a daily
velocity map in meters per hour along the range direction obtained from the interferometric map collected from 30 August 2004 on 21 h and 00 min to 31 August 2004 on 21 h and
00 min. With respect to the coherent area, only two moving
areas can be identified: one in the upper part with a slower
motion and the second corresponding to a rectangular patch,
where the displacement is regular with a central part showing
the maximum value (red), corresponding to 30-40 mm/h.

Y (m)

FIGURE 34. The daily velocity map in meters per hour along a
range direction obtained from the GB-SAR interferometric map
-collected from 30 August 2004 at 21 h and 00 min to 31 August
2004 at 21 h and 00 min [92].

Pizzo

Ginostra
Village
Crater Terrace Area

Cameras
Field of View
GBInSAR
Field of View

Sciara del Fuoco
Cameras and
GBInSAR
Location

Stromboli Village

1 km

FIGURE 35. The location of the volcano and the GB-DInSAR system [93].

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IEEE Geoscience and Remote Sensing Magazine - March 2020

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