Andreas Wiesmann

GAMMA Remote Sensing Research and Consulting AG

Knowledge on ice surface velocity of glaciers and ice caps contributes to a better understanding of a wide range of processes related to glacier dynamics, mass change and response to climate. Based on the recent release of historical SAR data from various space agencies we compiled nearly complete mosaics of winter ice surface velocities for the 19...

The modular Snow Microwave Radiative Transfer (SMRT) model simulates microwave scattering behavior in snow via different selectable theories and snow microstructure representations, which is well suited to intercomparisons analyses. Here, five microstructure models were parameterized from X-ray tomography and thin-section images of snow samples and...

The WBSCAT microwave scatterometer operates between 1 and 40 GHz, is fully coherent and polarimeteric for ground-based measurements of radar backscatter.

Ice marginal lakes are a dynamic component of terrestrial meltwater storage at the margin of the Greenland Ice Sheet. Despite their significance to the sea level budget, local flood hazards and bigeochemical fluxes, there is a lack of Greenland-wide research into ice marginal lakes. Here, a detailed multi-sensor inventory of Greenland’s ice margina...

Current methods for retrieving SWE (snow water equivalent) from space rely on passive microwave sensors. Observations are limited by poor spatial resolution, ambiguities related to separation of snow microstructural properties from the total snow mass, and signal saturation when snow is deep (~>80 cm). The use of SAR (Synthetic Aperture Radar) at s...

We computed circum-Arctic surface velocity maps of glaciers and ice caps over the Canadian Arctic, Svalbard and the Russian Arctic for at least two times between the 1990s and 2017 using satellite SAR data. Our analyses are mainly performed with offset-tracking of ALOS-1 PALSAR-1 (2007–2011) and Sentinel-1 (2015–2017) data. In certain cases JERS-1...

First results using the new Sentinel-1 SAR look very promising but the special interferometric wide-swath data acquired in the TOPS mode makes InSAR processing more challenging than for normal stripmap mode data. The steep azimuth spectra ramp in each burst results in very stringent co-registration requirements. Combining the data of the individual...

The objective of the Nordic Snow Radar Experiment (NoSREx) campaign was to provide a continuous time series of active and passive microwave observations of snow cover at a representative location of the Arctic boreal forest area, covering a whole winter season. The activity was a part of Phase A studies for the ESA Earth Explorer 7 candidate missio...

The snow microstructure, i.e., the spatial distribution of ice and pores, generally shows an anisotropy which is driven by gravity and temperature gradients and commonly determined from stereology or computer tomography. This structural anisotropy induces anisotropic mechanical, thermal, and dielectric properties. We present a method based on radio...

The GlobPermafrost project develops, validates and implements Earth Observation (EO) products to support research communities and international organisations in their work on better understanding permafrost characteristics and dynamics. To facilitate usability of these products by the target audience, user requirements with respect to the planned p...

European Space Agency's SnowScat instrument is a real aperture scatterometer which was developed by Gamma Remote Sensing AG. It operates in a continuous-wave mode, covers a frequency range of 9.15–17.9 GHz in a user-defined frequency-step and has a full polarimetric capability. The measurement campaigns were started first in February 2009 at Weissf...

Snowpack displacement and resulting full depth gliding snow avalanches are a widespread problem in alpine regions during springtime after snow-rich winters. This is a major threat for infrastructures nearby. Today field observers detect gliding snow visually. However, they can only detect suspicious snowpack displacement after gliding cracks opened...

The Glaciers_cci project is developing algorithms and creating products for the ECV ‘Glaciers and Ice caps’ using satellite data. From the wide range of glacier related variables that can be observed from space, we have selected glacier outlines, elevation changes (from altimetry and DEM differencing) and ice velocity (from optical and microwave se...

The study of soil moisture is a scientific challenge. Not only because of large diversity of soils and differences in their water content, but also due to the difficulty of measuring, especially in large scale. On this field of interest sev- eral methods to determine the content of water in soil exists. The basic and referential is gravimetric meth...

The objective of the Nordic Snow Radar Experiment (NoSREx) campaign was to provide a continuous time series of active and passive microwave observations of snow cover in a representative location of the Arctic boreal forest area, covering a whole winter season. The activity was a part of Phase A studies for the ESA Earth Explorer 7 candidate missio...

A prototype algorithm for hemispheric scale detection of autumn soil freezing using space-borne L-band passive microwave observations is presented. The methodology is based on earlier empirical and theoretical studies of L-band emission properties of freezing and thawing soils. We expand a method originally developed for soil freeze–thaw (F/T) stat...

errestrial radar interferometry is used in geotechnical applications for monitoring hazardous Earth or rock movements. In this study, we use it to continuously monitor snowpack displacements. As test site, the Dorfberg slope at Davos, Switzerland, was measured continuously during March 2014. The line of sight displacement was retrieved at a spatial...

In this chapter, we present the significant contribution of Synthetic Aperture Radar (SAR) based techniques in measuring surface displacements. Specifically, two main well-established SAR techniques, namely Differential Synthetic Aperture Radar Interferometry (DInSAR) and Persistent Scatterer Interferometry (PSI) are described. A review for both ex...

Snow settles under the force of gravity and recrystallizes by vertical temperature gradients. Both effects are assumed to form oriented ice crystals which induce an anisotropy in mechanical, thermal, and dielectric properties of the snow pack. On microscopic scales, the anisotropy could be hitherto determined only from stereology or computer tomogr...

The SnowScat device, a fully-polarimetric scatterometer originally designed to measure the radar cross-section of snow at a frequency range from 9.2 to 17.8 GHz (X-band to Ku-band), has recently been extended towards a high-resolution tomographic measurement mode. Such tomographic profiling observations provide further insights into the complex ele...

First results using the new Sentinel-1 SAR look very promising, but the special interferometrie wide-swath (IWS) data acquired in the FOPS mode makes InSAR processing challenging. Fhe steep azimuth spectra ramp in each burst results in very stringent co-registration requirements. Combining the data of the individual bursts and sub-swaths into consi...

C-band observations of the SAR backscatter from the Envisat ASAR (2005–2012) and Sentinel-1 (2014-ongoing) instruments are reviewed to understand their suitability to detect of open water bodies. The temporal variability (TV) and the minimum backscatter (MB) of ASAR backscatter were fed to a simple algorithm based on thresholds to obtain an indicat...

The Microwave Emission Model of Layered Snowpacks (MEMLS) was originally developed for microwave emissions of snowpacks in the frequency range 5–100 GHz. It is based on six-flux theory to describe radiative transfer in snow including absorption, multiple volume scattering, radiation trapping due to internal reflection and a combination of coherent...

A synthetic study was performed to determine the potential to retrieve dry-snow density and ground permittivity from multiangular L-band brightness temperatures. The thereto employed emission model was developed from parts of the “microwave emission model of layered snowpacks” (MEMLS) coupled with components adopted from the “L-band microwave emiss...

Large scale mapping of snow water equivalent (SWE) is a long-lasting request in many scientific and economical fields. Active and passive microwave remote sensing methods are explored, as local methods cannot be generalized due to the spatial inhomogeneity of the snow pack. Microwaves interact with snow by absorption, scattering, and refraction. Fo...

Synergistic use of satellite and terrestrial radar interferometry was considered for the measurement of slope deformation in the Mattervalley (Canton of Valais, Switzerland). Highest rates of movement of more than 1cm/day were measured only with terrestrial radar interferometry, because of the large time interval between satellite SAR observations....

Remote sensing of snow with active and passive microwaves on terrestrial, aerial, and satellite platforms has a long tradition. However, the observation of dynamic processes on alpine slopes is difficult due to fixed satellite orbits and consequently given observation geometry and interval and in some cases, also the lack of spatial resolution. Fur...

CryoLand (2011–2015) is a project carried out within the 7th Framework of the European Commission aimed at developing downstream services for monitoring seasonal snow, glaciers and lake/river ice primarily based on satellite remote sensing. The services target private and public users from a wide variety of application areas, and aim to develop sus...

CryoLand (2011–2015) is a project carried out within the 7th Framework of the European Commission aimed at developing downstream services for monitoring seasonal snow, glaciers and lake/river ice primarily based on satellite remote sensing. The services target private and public users from a wide variety of application areas, and aim to develop sus...

The Microwave Emission Model of Layered Snowpacks (MEMLS) was originally developed for microwave emissions of snowpacks in the frequency range 5–100 GHz. It is based on six-flux theory to describe radiative transfer in snow including absorption, 5 multiple volume scattering, radiation trapping due to internal reflection and a combination of coheren...

Terrestrial radar interferometry is used in geotechnical applications for monitoring hazardous earth or rock movements. In this study, we use it to continuously monitor snowpack displacements. As testsite, the Dorfberg slope at Davos, Switzerland was measured continuously during March 2014. The line of sight displacement was retrieved at a spatial...

This paper presents a review of the current state of the art in the use of terrestrial radar interferometry for the detection of surface changes related to mass movement. Different hardware-types and acquisition concepts are described, which use either real or synthetic aperture for radar image formation. We then present approaches for data process...

The European Space Agency's Data User Element (DUE) project GlobSnow was established to create a global database of Snow Extent and Snow Water Equivalent. The Snow Extent (SE) product portfolio provided within ESA DUE GlobSnow (2008–2014) is introduced and described, with a special focus on the Daily Fractional Snow Cover (DFSC) of the SE version 2...

Microwaves interact with snow on a wide variety of effects. The specific effect of interaction depends mainly on liquid water content which determines the penetration depth. The penetration depth changes by orders of magnitude at the transition from dry snow to wet snow. Further affects appear due to roughness of the boundary layers soil-snow and s...

The “Improved Alpine Avalanche Forecast Service” (AAF) study was a one-year feasibility study funded by the Integrated Application Program (IAP) of the European Space Agency (ESA). The project consortium consisted of four partners: the WSL Institute for Snow and Avalanche Research SLF (CH), the Norwegian Geotechnical Institute NGI (NO), GAMMA Remot...

Information on avalanche activity or non-activity on local and regional scale is of great value for avalanche warning services, traffic authorities and experts responsible for safety in communities or ski resorts. In particular during bad weather condition, such information is available only very limited or not at all. The aim of the ESA IAP feasib...

Synthetic Aperture Radar Interferometric (InSAR) techniques are widely applied to detect ground displacements caused by both natural and anthropogenic effects. Such techniques are a powerful tool for monitoring the ground motion, however, they have limitations such as temporal and geometrical decorrelation. Persistent Scatterer Interferometry (PSI)...

Results from an experimental campaign, providing measurements of snow microwave backscatter over four winter seasons, are presented. The main dataset consists of tower-based scatterometer observations and coinciding measurements of snow, soil and atmospheric properties. In situ data includes measurements of snow SSA and snow microstructure using co...

We describe a method for rapid identification and precise quantification of slope deformation using a portable radar interferometer. A rockslide with creep-like behavior was identified in the rugged and inaccessible headwaters of the Illgraben debris-flow catchment, located in the Central Swiss Alps. The estimated volume of the moving rock mass was...

Terrestrial radar interferometry allows precise detection and measurement of surface deformation related to mass movements. One of the known limitations of this technology is temporal decorrelation, affecting in particular its application in heavily vegetated areas. Based on the exceptional landslide activity in the area of Hintergraben (OWl in the...

In this contribution, a car-borne SAR and InSAR experiment is described. The slope of a valley was imaged by means of a single-pass InSAR system mounted on a car driving on roads along the bottom of the valley. The GAMMA portable radar interferometer GPRIII hardware with a modified antenna configuration was used for data acquisition. The experiment...

The Nordic Snow Radar Experiment (NoSREx) was initiated in November 2009 and has been running for three winter seasons. The objective of the campaign was to provide a continuous time series of active and passive microwave observations of snow cover in a representative location of the Arctic boreal forest area, covering a whole winter season. The ac...

Methods for the estimation of forest growing stock volume (GSV) are a major topic of investigation in the remote sensing community. The boreal zone contains almost 30% of global forest by area but measurements of forest resources are often outdated. Although past and current spaceborne synthetic aperture radar (SAR) backscatter data are not optimal...

ESA's SnowScat instrument is a real aperture scatterometer which was developed by Gamma Remote Sensing AG (CH). It operates in a continuous wave mode, covers a frequency range of 9.15 (X-band) to 17.9 GHz (Ku-band) in a user-defined frequency-step and have a po-larimetric capability. The measurement campaigns were started first in Feb. 2009 at Weis...

The possibility of high-resolution SAR imagery to derive information on the Snow Water Equivalent (SWE) of seasonal snow cover is one of the main goals of the proposed CoReH2O (Cold Regions Hydrology High-Resolution Observatory) mission. CoReH2O is a candidate 7th Earth Explorer Core mission by the European Space Agency (ESA), currently in Phase A....

Soil freezing and thawing, including the winter-time evolution of soil frost, are important characteristics influencing hydrological and climate processes at the regions of seasonal frost and permafrost, which include major land areas of North America and northern Eurasia. Changes in the seasonal behaviour of soil frost have a major effect on the s...