Field Sites
Currently, PermaSense has two field sites in the Swiss Alps, one on Jungfraujoch, the other one on the Hörnli ridge of Matterhorn. The Jungfraujoch site is accessible by the "Jungfraujoch railway" all around the year but the weather condition is limiting the direct access to the individual nodes. Consequently, this site was used to gather first technical experiences. The Matterhorn location is more remote requiring either a long climb or a helicopter and demonstrates the ful operation of the stand-alone system.
1st Deployment: Jungfraujoch since 2006/2007
The aim of our measurement site at Jungfraujoch is to quantify the spatial variability of thawing processes and heat transport in the near-surface layer.
The influence of surface characteristics, fracturing and melt water availability is measured by eight sensor rods in gently steep (40-70°) and fractured rock faces (general case in high alpine areas) around the Sphinx observatory at Jungfraujoch 3500m a.s.l. Additionally, two thermistor chains are installed into the bordering ice faces on the northern side.
The initial installation of the sensors took place in fall 2006. After a debugging and testing phase over winter 2006/2007 short intervals of valid data could be gathered in April 2007 with software version 1. Since February 2009 a new set up of the communication system is operational with the same software generation that runs successfully on Matterhorn since August 2008.
Deployment on Jungfraujoch (picture below) consisting of ten sensor nodes with network topology; the base station is mounted on the Sphinx observatory; each circle (picture left) depicts a network node with its corresponding number. Lines indicate good radio connectivity between nodes, dashed lines indicate unstable connectivity, dashed circles are hidden nodes, and bn is a bridge node introduced to provide stable connection to the base station; the network is divided into to two clusters on the north (left) and the south (right) facing slope of the ridge
2nd Deployment: Matterhorn, Hörnliridge since 2007
In contrast to the Jungfraujoch installation, the Matterhorn site aims to investigate the temperature evolution in singular clefts and the corresponding cleft dilatations. Thereto a combination of the PermaSense senorrods and commercial sensors are integrated in the system. These "multiple sensors" survey temperature, rock moisture, water pressure, cleft dilatation and ice strain at different positions. The installation containing 13 sensor nodes with the mentioned sensors types, two bridge nodes, and one basestation was made in October 2007.
The Matterhorn installation is on 3450 m a.s.l. on the north-east ridge called Hörnligrat (picture below). The sensor cloud is located around and within the detachment zone of the rock fall from July 2003 (left top). The close-up views on the left show the sensor nodes. Position 1 to 4 are instrumented with crackmeters (cleft dilatation) and temperature sensors in the cleft. Position 5 to 8 are equiped with similar sensors but have additionally a water pressure sensor and an ice strain sensor. Position 10 to 12 (as well as pos. 7) have sensor rods attached.
An information poster in german is available under the following link: Poster 2008
