Suretta Sud Glacier - Servizio Glaciologico Lombardo
Suretta Sud Glacier - Servizio Glaciologico Lombardo
Suretta Sud Glacier - Servizio Glaciologico Lombardo
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
mass balance<br />
•<br />
•<br />
•<br />
•<br />
processed with a specific, commercial<br />
software;<br />
production of a terrain digital model<br />
through a mesh of irregular triangles<br />
(TIN, Triangulated Irregular Network),<br />
starting from the quoted points of the<br />
previous step, using the 3D Analyst<br />
module of ArcView;<br />
calculation of a square-mesh elevation<br />
model with a 5 m cell side (GRID) starting<br />
from the TIN. The raster model is a<br />
mandatory step if the different surfaces<br />
have to be compared to identify the variations<br />
among two successive periods.<br />
The 2004 surface GRID is represented<br />
in Fig. 4;<br />
elaboration of the net mass balance of<br />
the glaciological year 2003-2004, using<br />
the Map Algebra functions implemented<br />
in the Spatial Analyst module of<br />
ArcView,<br />
production of the map of positive or<br />
- 54 -<br />
Fig. 6: <strong>Suretta</strong> <strong>Sud</strong> <strong>Glacier</strong>:<br />
the position of the ablation<br />
measurements stakes installed<br />
in September 2003.<br />
negative altitude variations (Fig. 5), as<br />
a result of the comparisons between the<br />
2003 and the 2004 GRIDS;<br />
• calculation of the altitude variations<br />
GRID (Fig. 6), by subtracting the corresponding<br />
cells of both overlapped matrixes<br />
(2003 GRID minus 2004 GRID).<br />
For a better interpretation of the figures, it is<br />
worth to remind that the altitude variations in<br />
the considered period are the combined result<br />
of two different phenomena, both acting<br />
at the same time: the accumulation/ablation<br />
processes and the mass transfer from the accumulation<br />
area to the ablation one.<br />
The comparison between the two surfaces<br />
has allowed the calculation of the glacier’s net<br />
mass balance during the 2003-2004 season<br />
(September 14, 2003 –September 5, 2004).<br />
The net mass balance was – 86.000 m3 water<br />
equivalent (w.e.), i.e. a loss of 0,52 m w.e. for<br />
the entire surface. This figure is then compared<br />
with the readings of the ablation stakes