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Permanent URL to this publication: http://dx.doi.org/10.5167/uzh-30684

Delaloye, R; Frei, C; Gärtner-Roer, I; Gruber, S; Hauck, C; Hilbich, C; Lambiel, C; Noetzli, J; Phillips, M; Stucki, T; Vonder Mühll, D (2009). Permafrost in Switzerland 2004/2005 and 2005/2006. Zürich.

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Abstract

The present report covers the period from October 2004 to September 2006. It is the last report of
the pilot phase 2000–2006 of the network for permafrost monitoring in Switzerland (PERMOS). At
this point, PERMOS includes (a) 11 drill sites (including 22 boreholes and geophysical monitoring at
4 of the sites), (b) 11 surface temperature sites (including measurements in loose debris at 9 sites, in
bedrock at 5 sites, and at the bottom of the snow cover (BTS) at 3 sites), and (c) aerial photographs
taken by Swisstopo.
Winter 2004/2005 was characterized by an early and thin snow cover in the higher alpine regions
and an early snow melt in spring. A long phase of above average air temperatures followed, which
lasted until July and made summer 2005 the second warmest on record. Winter 2005/2006 started
late, had a long lasting thick snow cover, and was followed by a warm summer with the hottest July
ever measured.
Active layer thicknesses in summer 2004 were similar to those before 2003 at most sites. Hence,
thermal changes in the subsurface from the 2003 heat wave were not sustained, although the ice
content at the permafrost table may have been permanently modified. The active layer deepened
again in several boreholes in summer 2005, reaching values similar to 2003, and remained more
or less stable in summer 2006. At ca. 10 m depth, ground temperatures at the drill sites displayed
a warming until the beginning of 2005, which results from the preceding heat period in summer
2003. Then, mainly as a result of the snow conditions in winter, a cooling period followed. Since
2005, temperature observations are complemented by electrical resistivity tomography (ERT) measurements
at 4 drill sites to monitor physical properties of the ground (e.g., ice content or unfrozen
water content). The ERT monitoring strategy is outlined and discussed in this report.
Ground surface temperatures (GST) were low in both years of the reporting period, especially during
winter. In 2005, GST temporarily dropped to new minima and reached about mean values of the
past decade at the end of the reporting period. Rock surface temperatures (RST) were integrated
into PERMOS in summer 2004 and are presented and discussed in detail in this report. Temperature
values in steep rock clearly display the cold conditions in winter 2004/2005 as well as the warm
summer 2006.
The chapter on special aspects of permafrost monitoring is dedicated to the observed acceleration of
rock glaciers in the past two decades. The destabilization of several landforms shows that permafrost
creep conditions in the Alps are changing.
In general, both, surface temperatures and ground temperatures in the uppermost meters decreased
to pre-2003 conditions at all sites during the reporting period, which is mainly a result of the snow
conditions.

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Additional indexing

Other titles:PERMOS 2009
Item Type:Monograph
Communities & Collections:07 Faculty of Science > Institute of Geography
DDC:910 Geography & travel
Language:English
Date:2009
Deposited On:19 Feb 2010 14:06
Last Modified:28 Apr 2013 12:22
Publisher:Cryospheric Commission
Series Name:Glaciological Report (Permafrost)
Volume:6/7
Number of Pages:100
Official URL:http://www.permos.ch/publications.html
Related URLs:https://biblio.unizh.ch/F/?local_base=UZH01&con_lng=GER&func=find-b&find_code=SYS&request=001834437

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