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Coin-sized iButton device and 1-wire device programmer. The maximum diameter of an iButton device is 17.35 mm, the maximum height is 5.89 mm.
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Commercial, coin-sized iButton temperature logger devices are well-suited for densely instrumenting large outdoor areas. An efficient workflow for deploying and maintaining those devices is necessary when striving to deploy and operate several hundreds of data logger devices. Additionally, a sophisticated data management is required for handling th...
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... coin-sized iButton temperature logger devices are well-suited for densely instrumenting large outdoor areas. An efficient workflow for deploying and maintaining those devices is necessary when striving to deploy and oper- ate several hundreds of data logger devices. Additionally, a sophisticated data management is required for handling the emerging, large amounts of meta and measurement data. Therefore, we developed iAssist , a solution that integrates the handling of iButton data logger devices together with a GPS receiver and a digital camera for gathering accurate location information. iAssist efficiently supports the whole workflow consisting of deploying, relocating and reading tiny sensing systems. iAssist is especially tailored for outdoor operation asking for as little user interaction as possible. Dense instrumentations for environmental monitoring ask for cheap and easily installable sensing systems. For in- R stance, a Maxim iButton DS1923 [1] is a coin-sized, com- mercial device that integrates a micro-controller, 8 kB stor- age, a real-time clock, a temperature sensor, and a battery in a single package (see Figure 1). The lifetime of this low- power data logger is mainly determined by its configurable sampling interval, the device’s data sheet lists more than 7 years of operation when hourly sampling data. An iButton can be programmed and read out by connecting the device to a PC by using a 1-wire interface. Without limiting the application area of these devices and also our presented management tool, this paper focuses on the deployment of iButton temperature loggers for densely instrumenting high-alpine locations. The overall goal of this project is to obtain data for geophysical research. Within a first campaign, we have installed several hundreds of iButton devices in the Swiss Alps. At the beginning of a campaign, each device must be initially setup by up- loading a set of mission parameters such as the sampling interval, the starting time of the measurement and the desired measurement resolution. As the data loggers are installed outdoors within rough terrains, it is crucial to have accurate information about the deployment location. Here, we use both assisted GPS as well as pictures of the location. This information is used to relocate the iButton devices during the campaign when data is sporadically read out. It becomes apparent, that running a campaign with hundreds of devices firstly asks for as much as automation as possible, and secondly also generates a huge amount of data that must be handled properly. In this paper, we present the iAssist management tool for the deployment, the localiza- tion and the maintenance of tiny iButton data loggers. Concretely, iAssist integrates an iButton programmer interface, a digital camera, and a GPS receiver into a single application. All data is stored in a relational DBMS, the current version of the software runs on an Intel Atom netbook running Linux. iAssist is tailored for the rapid deployment and maintenance of tiny iButton data loggers in the field. Each iButton device comes with a unique device identifier that is read when an iButton is inserted into the device programmer hardware. The overall area covered by a measurement campaign can span many square kilometers. While it is not possible to fully cover such large areas, the measurement area is divided into several patches of dense instrumentation. Deploying sensors starts with registering a patch and configuring the mission parameters that are identical for a batch of devices. This allows to quickly program many devices without any further user interaction but only insertion and removal of devices from the device programmer hardware. GPS coordinates are automatically recorded by the software, optional pictures can be taken within the software by pressing a single button. For relocating iButton devices, the connected GPS receiver is used for guiding the user to the location of deployed data loggers. Here, distance and direction to a particular device are given. This is sufficient since the user has to move within rough terrain without fixed routes. Additionally, a user can also access captured photos by employing the in- tegrated picture viewer that is part of the software. When a deployed iButton is inserted into the device programmer hardware, all data is immediately read out. Reading out data loggers is also done in batches and can include the immedi- ate reprogramming of a data logger after the stored data has been read out. In this section, we give a brief overview of the most im- portant aspects of our solution. Several hundreds of iButton devices are deployed to gather timestamped temperature measurements. For a higher data quality, it is desirable that all data loggers periodically sample data at the same time instant. Firstly, the real-time clock of each data logger is synchronized with the PC when the iButton device is programmed. In turn, the local clock of the PC is synchronized by GPS or external NTP servers. Sec- ondly, all data loggers are programmed for a delayed start of the measurement at a pre-defined time instant, i. e. the beginning of the next day. Thirdly, the timestamp of the last sampling point is compared with the time on the synchronized clock of the PC when data is read out. This information is used to (linearly) account for the drift of the real-time clock of the data logger. In general, all data is annotated with the unique device identifier of the corresponding iButton device. Stored meta- information includes the mission parameters of each deployed data logger, the time when a data logger was programmed, the time when a data logger was read out, information about available pictures and detailed location information. Additionally, measurement data consisting of a timestamp and a temperature measurement are stored for each sampling point. While pictures are stored in the file system, all other information are stored in a relational DBMS. iAssist is implemented in C++ using the Qt4 GUI toolkit [4]. The SQLite [5] database engine is used for storing data. Gphoto2 [2] is used for interfacing a digital camera that is connected to a USB port, location and time from a GPS receiver are accessed via gpsd [3]. Our demo setup consists of the system that we actually use in the field. Concretely, this includes an Asus EeePC netbook, an external u-blox GPS receiver, a digital camera and the iButton device programmer. Additionally, our setup includes a bunch of Maxim DS1923 iButton devices that can be programmed and read out during the demonstration. We will demonstrate the whole workflow within the iAssist software plus visualizations of the measured data. While we sample with lower rates in the field, the demo becomes very interactive when setting the sampling interval of a logger to the smallest value of 1 second. For instance, we will encour- age visitors of our demo to measure their (approximate) body temperature by holding an iButton for a while. The work presented was supported by NCCR-MICS, a center supported by the Swiss National Science Foundation under grant number 5005-67322 as well as by the project CRYOSUB supported by the Swiss National Science Foundation under grant number ...
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... For D. octopetala, we additionally mapped its cover outlines in the grid cells. Subsequently, we created detailed The iAssist software 38 was used for logger programming and data read out, while data analysis was carried out in R (R Core Development Team). The temperature loggers recorded soil temperatures at 5 cm depth in 3-hr intervals with an accuracy of ±0.25 C. Temperature data accuracy was improved using the zero-curtain period as a 0 C reference. ...
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Abstract
Solifluction is one of the most widespread periglacial processes with low annual movement rates in the range of —millimeters to centimeters. Traditional methods to assess solifluction movement usually have low spatial resolution, which hampers our understanding of spatial movement patterns and the factors controlling them. In this study, we (a) test the applicability of unmanned aerial vehicle (UAV)‐based structure‐from‐motion photogrammetry in comparison to a traditional total station survey to map surface movement of a turf‐banked solifluction lobe (TBL) in the Turtmann Valley (Switzerland). We then (b) relate the detected movement patterns to potential geomorphometric, material, thermal and vegetation controls, which we assessed using geomorphic and vegetation mapping, electrical resistivity surveys and temperature loggers. Our results show that (a) UAV‐based mapping can detect solifluction movement with high spatial resolution (one point per m2, total > 900 points) and rates and patterns consistent with a total station survey, but requires careful measurement set‐up and analysis; and (b) movement rates differ between lobe tread, riser and a ridge feature. Differences can be explained by heterogeneous material, geomorphometric, thermal and vegetation properties of the TBL, which promote different solifluction processes. Our study demonstrates the applicability of UAV‐based mapping in solifluction research and improves our understanding of solifluction processes and landform development.
... Maxim iButton miniature temperature loggers were used to assess thermal and snow properties at a depth of 5 cm between August 2014 and August 2015. Logger programming and data read out was performed using iAssist (Keller et al., 2010). Prior to data analysis using the R software environment (R Core Team 2018), iButton data accuracy (given manufacturer value ±0.5 °C) was improved by using the zero-curtain period as 0° C reference (cf. ...
Many retreating Alpine valley glaciers leave large lateral moraines behind. Reworking of these landforms by geomorphic processes is one of the most important paraglacial process in many alpine environments. While several studies investigated reworking by gullying processes, it is not well known what happens when gullying ceases and why and when lateral moraine slopes become stable. This study improves the understanding of the paraglacial transition from active to stable alpine lateral moraine slopes by assessing potential influencing factors, indicators for completed paraglacial adjustment and its spatiotemporal patterns using a combination of geomorphic and ecologic data. A geomorphic and ecologic permanent plot survey and geomorphic mapping were carried out on three lateral moraine complexes in the Turtmann glacier foreland (Switzerland). Subsequently, permanent plot data were analysed using multivariate statistics. Our study suggests that ecosystem engineering by colonizing plant species, slope geomorphometry and material properties are important factors influencing the paraglacial transition from active to stable slopes. Geomorphic processes are often absent once vertical vegetation layers and soil horizons develop, showing that mature vegetation and advanced soil development are valuable indicators for slope stability and completed paraglacial adjustment. In a conceptual model, we describe the paraglacial transition of alpine lateral moraine slopes as a temporal sequence in which gullying (Stage I), solifluction (Stage II) and finally stabilisation (Stage III) follow one after another. In space, paraglacial adjustment is heterogeneous and resulting patterns can be explained by the identified influencing factors.
... MTLs recorded NSRT over three hour intervals with an accuracy of around ±0.1°C (calibrated). To program the mission settings and to download data we used the smart phone "iAssist" software of Keller et al. (2010) allowing very fast data management (< 15 minute data gap) in steep terrain. ...
Both from a systemic and natural hazard perspective, it is essential to understand the causes and frequency of rockfalls in mountain terrain and to predict the block sizes deposited at specific locations. Commonly, rockfalls are studied either retrospectively, using talus slopes, or directly by rockwall surveys. Nevertheless, our understanding of rockfall activity, particularly at the lower magnitude spectrum, is still incomplete. Moreover, the explanatory framework is rarely addressed explicitly. In this study, we investigate two rockwall–talus systems in the Swiss Alps to estimate the rockfall frequency–magnitude pattern and their key controls. We present a holistic approach that integrates deductive geotechnical and thermal investigations of the source rockwalls with abductive talus‐based explanations of rockfall volume and frequency.
The rockwalls' three‐dimensional (3D) joint pattern indicates that 75% of the blocks may be released as debris fall (< 14 m ³ ) and boulder falls (14–61 m ³ ), which is mirrored in the corresponding talus material. Using two‐year records of near‐surface rockwall temperatures as input for a 1D heat conduction model underlines the destabilizing role of seasonal ice segregation. Deepest frost cracking of 300 cm may occur on the north‐northeast (NNE)‐exposed, snow‐rich rockwall, with peaks at the outermost surface. The synthesis of all data suggests that infrequent, large planar slides (approximately every 250 years) overlain by smaller, more frequent wedge and toppling failures (approximately every 17–50 years) as well as high‐frequency flake‐like clasts (3–6 events/year) characterize the rockfall frequency–magnitude pattern at Hungerli Peak.
Here, we argue that small‐size rockfalls need more scientific attention, particularly in discontinuous permafrost zones. Our study emphasizes that future frequency–magnitude research should ideally incorporate site‐specific structural and thermal properties, rather than just focusing on climatic or meteorological triggers. We discuss how holistic rockwall–talus approaches, as proposed here, could help to increase our process understanding of rockfalls in mountain environments. Copyright © 2017 John Wiley & Sons, Ltd.
... The loggers were aligned along the longitudinal axis of the lobe ( Figure 1C) to assess thermal differences. Logger programming and data read out was performed using iAssist (Keller et al., 2010), afterwards, data was processed in R. The data accuracy according to the manufacturer is AE0.5°C and could be improved by using the zerocurtain period as 0°reference, which resulted in a temperature correction ranging from À0.13 to À0.37°C. ...
Vegetation is an important factor influencing solifluction processes, while at the same time, solifluction processes and landforms influence species composition, fine-scale distribution and corresponding ecosystem functioning. However, how feedbacks between plants and solifluction processes influence the development of turf-banked solifluction lobes (TBLs) and their geomorphic and vegetation patterns is still poorly understood. We addressed this knowledge gap in a detailed biogeomorphic investigation in the Turtmann glacier foreland (Switzerland). Methods employed include geomorphic and vegetation mapping, terrain assessment with unmanned aerial vehicle (UAV) and temperature logging. Results were subsequently integrated with knowledge from previous geomorphic and ecologic studies into a conceptual model. Our results show that geomorphic and vegetation patterns at TBLs are closely linked through the lobe elements tread, risers and ridge. A conceptual four-stage biogeomorphic model of TBL development with ecosystem engineering by the dwarf shrub Dryas octopetala as the dominant process can explain these interlinked patterns. Based on this model, we demonstrate that TBLs are biogeomorphic structures and follow a cyclic development, during which the role of their components for engineer and non-engineer species changes. Our study presents the first biogeomorphic model of TBL development and highlights the applicability and necessity of biogeomorphic approaches and research in periglacial environments.
... Typically, rock glacier flow velocities correlate with slope angle (Francou and Reynaud, 1992;Sloan and Dyke, 1998;Konrad et al., 1999). Movement observed at the rock glacier surface is in general due to deformation of the frozen rock glacier material; however, the magnitude of deformation is not necessarily uniform with depth ( Fig. 1). ...
... Typically, rock glacier flow velocities correlate with slope angle (Francou and Reynaud, 1992;Sloan and Dyke, 1998;Konrad et al., 1999). Movement observed at the rock glacier surface is in general due to deformation of the frozen rock glacier material; however, the magnitude of deformation is not necessarily uniform with depth ( Fig. 1). ...
In recent years,
strong variations in the speed of rock glaciers have been detected, raising
questions about their stability under changing climatic conditions. In this
study, we present continuous time series of surface velocities over 3 years
of six GPS stations located on three rock glaciers in Switzerland.
Intra-annual velocity variations are analysed in relation to local
meteorological factors, such as precipitation, snow(melt), and air and ground
surface temperatures. The main focus of this study lies on the abrupt
velocity peaks, which have been detected at two steep and fast-moving rock
glacier tongues ( ≥ 5 m a−1), and relationships to external
meteorological forcing are statistically tested.The continuous measurements with high temporal resolution allowed us to
detect short-term velocity peaks, which occur outside cold winter conditions,
at these two rock glacier tongues. Our measurements further revealed that all
rock glaciers experience clear intra-annual variations in movement in which
the timing and the amplitude is reasonably similar in individual years. The
seasonal decrease in velocity was typically smooth, starting 1–3 months
after the seasonal decrease in temperatures, and was stronger in years with
colder temperatures in mid winter. Seasonal acceleration was mostly abrupt
and rapid compared to the winter deceleration, always starting during the
zero curtain period. We found a statistically significant relationship
between the occurrence of short-term velocity peaks and water input from
heavy precipitation or snowmelt, while no velocity peak could be attributed
solely to high temperatures. The findings of this study further suggest that,
in addition to the short-term velocity peaks, the seasonal acceleration is
also influenced by water infiltration, causing thermal advection and an
increase in pore water pressure. In contrast, the amount of deceleration in
winter seems to be mainly controlled by winter temperatures.
... This study would not have been possible without the collaboration with colleagues from the project X − Sense, notably B. Buchli (Computer Engineering and Networks Lab of ETH Zurich), who contributed significantly to the design of the GPS stations, P. Limpach (Geodesy and Geodynamics Lab of ETH Zurich), who processed the daily GPS solutions; S. Weber and T. Gsell (Computer Engineering and Networks Lab of ETH Zurich), who contributed significantly to the installation and maintenance of the field site; and H. Raetzo (Federal Office for the Environment), who provided valuable insights and discussion concerning placement of GPS stations. The software iAssist ( Keller et al., 2010) was used to program and read out the iButtons. ...
In recent years, strong variations in the speed of rock glaciers have been detected, raising questions about their stability under changing climatic conditions. In this study, we present continuous time series of surface velocities over 3 years of six GPS stations located on three rock glaciers in Switzerland. Intra-annual velocity variations are analysed in relation to local meteorological factors, such as precipitation, snow(melt), and air and ground surface temperatures. The main focus of this study lies on the abrupt velocity peaks, which have been detected at two steep and fast-moving rock glacier tongues ( ≥ 5 m a−1), and relationships to external meteorological forcing are statistically tested.
The continuous measurements with high temporal resolution allowed us to detect short-term velocity peaks, which occur outside cold winter conditions, at these two rock glacier tongues. Our measurements further revealed that all rock glaciers experience clear intra-annual variations in movement in which the timing and the amplitude is reasonably similar in individual years. The seasonal decrease in velocity was typically smooth, starting 1–3 months after the seasonal decrease in temperatures, and was stronger in years with colder temperatures in mid winter. Seasonal acceleration was mostly abrupt and rapid compared to the winter deceleration, always starting during the zero curtain period. We found a statistically significant relationship between the occurrence of short-term velocity peaks and water input from heavy precipitation or snowmelt, while no velocity peak could be attributed solely to high temperatures. The findings of this study further suggest that, in addition to the short-term velocity peaks, the seasonal acceleration is also influenced by water infiltration, causing thermal advection and an increase in pore water pressure. In contrast, the amount of deceleration in winter seems to be mainly controlled by winter temperatures.
... The contact between the capsule and the rock was improved by the use of thermally conductive paste. To deploy, read out and maintain iButtons and their data, the open access software iAssist was used (Keller et al. 2010). To study the spatial variability of the rock slopes 30 iButtons were installed in a linear layout in 0.1 m deep horizontal boreholes over the N and S facing rock walls with a 3 m vertical spacing, to measure NSRT at 2 h intervals. ...
Snow cover influences the thermal regime and stability of frozen rock walls. In this study, we investigate and model the impact of the spatially variable snow cover on the thermal regime of steep permafrost rock walls. This is necessary for a more detailed understanding of the thermal and mechanical processes causing changes in rock temperature and in the ice and water contents of frozen rock, which possibly lead to rock wall instability. To assess the temporal and spatial evolution and influence of the snow, detailed measurements have been carried out at two selected points in steep north- and south-facing rock walls since 2012. In parallel, the one-dimensional energy balance model SNOWPACK is used to simulate the effects of snow cover on the thermal regime of the rock walls. For this, a multi-method approach with high temporal resolution is applied, combining meteorological, borehole rock temperature and terrain parameter measurements. To validate the results obtained for the ground thermal regime and the seasonally varying snowpack, the model output is compared with near-surface rock temperature measurements and remote snow cover observations.No decrease of snow depth at slope angles up to 70° was observed in rough terrain due to micro-topographic structures. Strong contrasts in rock temperatures between north- and south-facing slopes are due to differences in solar radiation, slope angle and the timing and depth of the snow cover.SNOWPACK proved to be useful for modelling snow cover–rock interactions in smooth, homogenous rock slopes.
... We thank Reynald Delaloye (Physical Geography at the University of Fribourg) and Andreas Vieli (3G, Department of Geography of the University of Zurich) for valuable comments on the manuscript. The software iAssist (Keller et al. 2010) was used to program and read-out the iButtons. ...
In this study, high resolution surface measurements of diverse slope movements are compared to environmental factors such as ground surface temperature (GST) and snow cover, in order to reveal and compare velocity fluctuations caused by changing environmental conditions. The data cover 2 years (2011–2013) of Global Positioning System (GPS) and GST measurements at 18 locations on various slope movement types within an alpine study site in permafrost (Mattertal, Switzerland). Velocities have been estimated based on accurate daily GPS solutions. The mean annual velocities (MAV) observed at all GPS stations varied between 0.006 and 6.3 ma−1. MAV were higher in the period 2013 compared to 2012 at all stations. The acceleration in 2013 was accompanied by a longer duration of the snow cover and zero curtain and slightly lower GST. The amplitude (0–600 %) and the timing of the intra-annual variability were generally similar in both periods. At most stations, an annual cycle in the movement signal was observed, with a phase lag of 1–4 months to GST. Maximum velocity typically occurred in late summer and autumn, and minimum velocity in late winter and beginning of spring. The onset of acceleration always started in spring during the snowmelt period. At two stations located on steep rock glacier tongues, overprinted on the annual cycle, short-term peaks of velocity increase, occurred during the snowmelt period, indicating a strong influence of meltwater.
Data from 27 snow profiles taken in frozen rock walls at two sites in the Swiss Alps reveal that steep slopes have distinctive snowpack characteristics. Snow pits were dug in 50–65° slopes at elevations between 2900 and 3600 m asl on north- and south-facing slopes at Gemsstock and Jungfraujoch Sphinx in the winters 2012–2013 and 2013–2014. There were marked contrasts in snow characteristics between the two aspects, yet strong inter-site similarities. Under the influence of intense solar radiation, basal ice layers and multiple hard melt-freeze crusts formed on the south-facing slopes. Soft layers of facets and depth hoar developed between the crusts. On the shady north-facing slopes, thick basal melt-freeze crusts formed when snow persisted during stable weather periods in autumn. The dominant snow grain types in winter were facets and depth hoar. When solar elevation exceeded slope angle from mid-April onwards, gravity-driven percolation of melt water flowing parallel to the frozen rock surface from areas with warm protruding rocks led to the formation of thick basal ice layers in the north-facing slopes. Windward slopes were covered with rime and glaze during storms, regardless of aspect and season. Despite widespread snowpack instability, the formation of large slab avalanches was hindered by the pronounced roughness of the rock surfaces. The main drivers contributing to the distinctive character of snow covers in frozen rock walls are the negative rock surface temperatures, enhanced/minimized solar radiation and multidirectional fluxes of water, vapour and heat induced by the steepness of the rock slopes.
