Anna Wendleder

Anna Wendleder
German Aerospace Center (DLR) | DLR · German Remote Sensing Data Center (DFD)

Diplom

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86
Publications
8,426
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803
Citations

Publications

Publications (86)
Conference Paper
Polarimetric signatures in L-band data measured by the spaceborne SAR sensor ALOS-2 are correlated with typical forest parameters derived by airborne laser scanning via single-tree segmentation and classification over a test site within the Bavarian Forest National Park. Forest parameters like tree species, tree height, crown volume, or crown base...
Conference Paper
Polar ice masses play a crucial role in regulating regional and global climates and are sensitive indicators of climate change. However, due to their large area and their remoteness, the changes of the Canadian glaciers have been insufficiently observed. Remote sensing data could bridge this gap. This study uses a dense time series of TerraSAR-X an...
Article
Full-text available
Changes in snowpack associated with climatic warming has drastic impacts on surface energy balance in the cryosphere. Yet, traditional monitoring techniques, such as punctual measurements in the field, do not cover the full snowpack spatial and temporal variability, which hampers efforts to upscale measurements to the global scale. This variability...
Article
In recent years, there has been a strong upswing in the construction industry especially with respect to residential buildings. Due to the obligation to document changes in the building stock in Bavaria, this article presents a new method for the detection of construction activities from remote sensing data. The approach bases on time series from f...
Conference Paper
The current family of SAR products from Sentinel-1, TerraSAR-X, ERS-1/2 and ENVISAT, primarily contains Level-1 Single Look Complex, Ground Range Detected or ellipsoid and terrain corrected products [1] [2] [3] [4], which inherit their definition from the European heritage Synthetic Aperture Radar (SAR) satellite missions ERS-1/2 and ENVISAT. These...
Conference Paper
The existence of supraglacial lakes influences debris-covered glaciers in two ways. The absorption of solar radiation in the water leads to a higher ice ablation, and water draining through the glacier to its bed leads to a higher velocity. Rising air temperatures and changes in precipitation patterns provoke an increase in the supraglacial lakes i...
Conference Paper
The existence of supraglacial lakes influences debris-covered glaciers in two ways. The absorption of solar radiation in the water leads to a higher ice ablation, and water draining through the glacier to its bed leads to a higher velocity. Rising air temperatures and changes in precipitation patterns provoke an increase in the supraglacial lakes i...
Conference Paper
Today, several SAR missions provide valuable and extensive information for monitoring the Earth’s surface, for assessing the current state and to improve the understanding of ongoing changes. In the last decades the capabilities for data reception and storage have been continuously extended to allow routine operations of the growing amount of SAR d...
Article
BDVI Forum Zeitschrift des Bundes der Öffentlich bestellten Vermessungsingenieure e. V. Die Kryosphäre und insbesondere Gletscher und Eisschilde spielen eine fundamentale Rolle im globalen Klimasystem und werden durch Veränderungen im System selbst stark beeinflusst. Die Kryosphäre bezieht sich auf die gefrorenen Komponenten des Erdsystems, die si...
Conference Paper
The Canadian Arctic Archipelago (CAA) is undergoing rapid atmospheric warming at rates that are twice that of the global average and greater than at any other time in the past four millennia. Longer and more intense melt seasons, modifications in glacier motion, and persistent glacier mass loss are all changes in glacier behavior being experienced...
Conference Paper
Quantifying and characterizing variability in the motion of tidewater glaciers is important for calculating total mass loss (iceberg production) to the ocean, refining estimates of global sea level rise, identifying the processes that control ice motion at seasonal and multi-annual time scales and for creating datasets that can be used to calibrate...
Article
Full-text available
The existence of supraglacial lakes influences debris-covered glaciers in two ways. The absorption of solar radiation in the water leads to a higher ice ablation, and water draining through the glacier to its bed leads to a higher velocity. Rising air temperatures and changes in precipitation patterns provoke an increase in the supraglacial lakes i...
Article
Full-text available
Arctic tundra landscapes are highly complex and are rapidly changing due to the warming climate. Datasets which document the spatial and temporal variability of the landscape are needed to monitor the rapid changes. Synthetic Aperture Radar (SAR) imagery is specifically suitable for monitoring the Arctic, as SAR, unlike optical remote sensing, can...
Preprint
Full-text available
Changes in snowpack associated with climatic warming has drastic impacts on surface energy balance in the cryosphere. Yet, traditional monitoring techniques, such as punctual measurements in the field, do not cover the full snowpack spatial and temporal variability, which hampers efforts to upscale measurements to the global scale. This variability...
Article
Full-text available
The global digital elevation model (DEM) produced by the TanDEM-X (TerraSAR-X add-on for Digital Elevation Measurements) mission is an interferometric elevation model with unprecedented quality, accuracy, and coverage. It represents an unedited surface model and artifacts inherent to the interferometric Synthetic Aperture Radar (SAR) acquisition an...
Conference Paper
This paper reviews achievements with C-band SAR in general and specifically Sentinel-1 for Arctic land monitoring, the implications of the current acquisition strategy including the availability of certain polarizations and discusses differences to other wavelengths through the use of Kennaugh parameterization. Unfrozen as well as frozen season obs...
Conference Paper
Snow cover in the mountain ranges of Canada has great social economical and environmental impacts on Canadians. It is one of the main drivers for winter tourism, attracting tourists both nationwide, and internationally to ski resorts, visit National Parks, and snowmobile various areas. However, the mountains also include avalanche terrain, and if t...
Conference Paper
The cryosphere and particularly glaciers and ice sheets play a fundamental role in the global climate system and are strongly influenced by changes in the system itself. The cryosphere refers to frozen components of the Earth system that are at or below the land and ocean surface. These include snow, glaciers, ice sheets, ice shelves, icebergs, sea...
Conference Paper
Sea ice is an essential part of the Arctic Ocean and is extremely affected by the global warming. Over the past 30 years, the Arctic has warmed at roughly twice the rate as the entire globe. The Kangiqsujuammiut (people of Kangiqsujuaq, Nunavik, in Canada) observed a later sea ice freeze-up in the fall (Nickels et al., 2011), less snow on the groun...
Conference Paper
Polar Regions pass through dramatic changes caused by ongoing climate warming. In many areas, rapid glaciers surface velocity has been observed provoked by supraglacial lakes if their water is able to drain to the ground. This study analyses the evolution of supraglacial lakes on the western margin of Greenland near Kangerlussuaq based on a Sentine...
Conference Paper
Lac Bam is one of the most important water reservoirs and wetlands in the semi-arid Sahel zone of Burkina Faso. The natural lake fills up during the short rainy season and continuously dries out due to the long dry season without any rainfall and the extensive water abstraction by farmers. The present study classifies 119 dual-co-polarised TerraSAR...
Article
Full-text available
Radar penetration in brine-wetted snow-covered sea ice is almost nil, yet reports exist of a correlation between snow depth or ice thickness and SAR parameters. This article presents a description of snow depth and first-year sea ice thickness distributions in three fjords of the Hudson Strait and of their tenuous correlation with SAR backscatterin...
Conference Paper
This study investigates the seasonality of surface ice motion of Belcher and South Croker Bay Glaciers, two of the fastest flowing and highest discharging glaciers on Devon Ice Cap, Nunavut, Canada, from 2009 to 2021. We utilize a variety of remote sensing datasets (RADARSAT-2, TerraSAR-X imagery, ITS-Live) to map ice motion at 11-day to monthly ti...
Article
Full-text available
This article presents a case study for the combined use of TerraSAR-X and time-lapse photography time series in order to monitor seasonal sea ice processes in Nunavik's Deception Bay. This area is at the confluence of land use by local Inuit, ice-breaking transport by the mining industry, and climate change. Indeed, Inuit have reported greater inte...
Article
Full-text available
This article spanned a new, consistent framework for production, archiving, and provision of analysis ready data (ARD) from multi-source and multi-temporal satellite acquisitions and an subsequent image fusion. The core of the image fusion was an orthogonal transform of the reflectance channels from optical sensors on hypercomplex bases delivered i...
Conference Paper
Ongoing global warming causes dramatic changes globally, especially with respect to Polar Regions. In this context, digital elevation data is of high importance for most glaciological applications. In this paper, we investigate TanDEM-X penetration depth over snow and ice on the Devon Ice sheet. In particular, the relation of backscatter intensity...
Article
Full-text available
Accelerating melt on the Greenland ice sheet leads to dramatic changes at a global scale. Especially in the last decades, not only the monitoring, but also the quantification of these changes has gained considerably in importance. In this context, Interferometric Synthetic Aperture Radar (InSAR) systems complement existing data sources by their cap...
Poster
Full-text available
1 Why Should we care about snow ? The lack of in-situ data in the Arctic and the problem about accessibility to these region constraints the traditional sampling over a year. While thermodynamic models such as CROCUS or SNOWPACK worked well in alpine area, they still need further calibrations for polar applications 1. 2 How to proceed? First snow c...
Article
Full-text available
Inuit have reported greater inter-annual variability in seasonal sea ice conditions. For Deception Bay (Nunavik), an area prized for seal and caribou hunting, an increase in solid precipitation and a shorter snow cover period is expected in the near future. In this context, and considering ice-breaking transport in the fjord by mining companies, we...
Conference Paper
Snow is a crucial element within Arctic ecosystems that is undergoing rapid change in the context of Arctic warming. High spatial resolution synthetic aperture radar (SAR) systems have shown high potential to characterize changes in snow properties, such as depth, density, water equivalent and microstructure. However, distinguishing between the con...
Conference Paper
Mapping snow cover (SC) on glaciers at the end of the ablation period supports the comprehension how and in which rate a glacier accumulates and ablates, respectively, and which influence climate variabilities have. Furthermore, the SC can be used for the determination of the mass balance. Remote Sensing data are able to provide this information fo...
Conference Paper
The Baltoro Glacier is one of the largest glaciers in the Karakoram mountain range. Long-term monitoring of glacier dynamics provides key information on glacier evolution in a changing climate, which is essential for regional water resource and natural hazard management. On large glaciers, detailed field based mass balance is not feasible. Ice dyna...
Conference Paper
Full-text available
Arctic snow cover dynamics exhibit strong changes in terms of extent and duration due to recent climate changeconditions (Mudryk et al., 2018; Lemke & Jacobi, 2011). In this context, innovative observation methods arehelpful for a better comprehension of the role of the snow for climate research and hydrology. The spatialvariability of snow propert...
Article
Full-text available
Continuous monitoring of glacier changes supports our understanding of climate related glacier behavior. Remote sensing data offer the unique opportunity to observe individual glaciers as well as entire mountain ranges. In this study, we used synthetic aperture radar (SAR) data to monitor the recession of wet snow area extent per season for three d...
Conference Paper
Snow avalanches are natural hazards which cause damage to nature, persons, and property in mountainous terrain. But when and where happens avalanches and how large are they? A complete avalanche activity record over an entire winter season is important for the present avalanche research and forecasting which cannot be provided by traditional field...
Conference Paper
The lake of Bam, located in northern Burkina Faso, is one of the most important water reservoirs for agriculture of semi-arid Africa. The area is also important for the local flora and fauna. Due to the annual increase in water extraction, the lake continues to dry out. The lake is part of the Ramsar program and is referred to as a "Wetland of Inte...
Conference Paper
Monitoring sea ice in Deception Bay (Nunavik, Hudson Strait) is not only relevant for local community members who rely on the fjord's rich ecosystem for subsistence in a context of a changing climate - lessons learned from this work have the potential to be applied in similar contexts elsewhere in Inuit Nunangat, and by other researchers studying t...
Article
Full-text available
The Baltoro Glacier is one of the largest glaciers in the Karakoram mountain range. Long-term monitoring of glacier dynamics provides key information on glacier evolution in a changing climate, which is essential for regional water resource and natural hazard management. On large glaciers, detailed field based mass balance is not feasible. Ice dyna...
Article
Full-text available
The Kennaugh framework turned out to be a powerful tool for the preparation of multi-sensor SAR data during the last years. Using intensity-based (an-) isotropic diffusion algorithms like the Multi-scale Multi-looking or the Schmittlets, even robust pre-classification change detection from multi-polarized images is enabled. The only missing point s...
Conference Paper
Snow cover plays an important role both globally and regionally as it is fundamental for local water availability, river run-off, and groundwater recharge. Hence, the exact knowledge of extent and dynamic of the snow coverage is essential. This study combines synergetic optical and SAR data with the main object to map the snow cover extent. As the...
Article
Full-text available
Since its launch in 2007, TerraSAR-X observations have been widely used in a broad range of scientific applications. Particularly in wetland research, TerraSAR-X's shortwave X-band synthetic aperture radar (SAR) possesses unique capabilities, such as high spatial and temporal resolution, for delineating and characterizing the inherent spatially and...
Article
Die Erstellung einer täglichen aus Satellitendaten abgeleiteten, Wassermaske und deren Visualisierung rückt in der Wissenschaft immer mehr in den Fokus. In diesem Artikel wird am Beispiel des Forggensees, der als Stausee für seine starke Wasserflächenänderung bekannt ist, eine einfache und robuste Methode zur Erstellung einer täglichen Wassermaske...
Conference Paper
Full-text available
Arctic snow cover dynamics offer a changing face in terms of temporal duration and water equivalent, due to recent climate change conditions (Callaghan et al., 2011; Lemke & Jacobi, 2012). Indeed, the Arctic is now experiencing some of the most rapid and severe climate change on earth. In this context, innovative and improved methods are helpful to...
Conference Paper
Ground penetrating radar (GPR) provides relevant information about the stratigraphy of the snow pack. The elaborative pointwise measurements are only provided along tracks. Synthetic Aperture Radar (SAR) offers two-dimensional information about snow cover and snow type. Multi-frequency SAR data delivers information about the stratigraphy of a snow...
Conference Paper
During the past three decades, increases in mean summer air temperature over the Canadian Arctic have resulted in a longer melt season and intensified mass loss from ice caps and glaciers, mainly via supraglacial melt and meltwater runoff. However, the processes by which meltwater is delivered to the ocean have been little studied due to the lack o...
Conference Paper
The Kennaugh framework turned out to be a powerful tool for the preparation of multi-sensor SAR data during the last years. Using intensity-based (an-) isotropic diffusion algorithms like the Multi-scale Multi-looking or the Schmittlets, even robust pre-classification change detection from multi-polarized images is enabled. The only missing point s...
Article
Full-text available
Fresh water is a scarce resource in the West-African Sahel region, seasonally influenced by droughts and floods. Particularly in terms of climate change, the importance of wetlands increases for flora, fauna, human population, agriculture, livestock and fishery. Hence, access to open water is a key factor. Long-term monitoring of water dynamics is...
Article
Full-text available
Fresh water is a scarce resource in the West-African Sahel region, seasonally influenced by droughts and floods. Particularly in terms of climate change, the importance of wetlands increases for flora, fauna, human population, agriculture, livestock and fishery. Hence, access to open water is a key factor. Long-term monitoring of water dynamics is...
Article
Full-text available
Water scarcity is one of the main challenges posed by the changing climate. Especially in semi-arid regions where water reservoirs are filled during the very short rainy season, but have to store enough water for the extremely long dry season, the intelligent handling of water resources is vital. This study focusses on Lac Bam in Burkina Faso, whic...
Article
Full-text available
Water scarcity is one of the main challenges posed by the changing climate. Especially in semi-arid regions where water reservoirs are filled during the very short rainy season, but have to store enough water for the extremely long dry season, the intelligent handling of water resources is vital. This study focusses on Lac Bam in Burkina Faso, whic...
Conference Paper
The joint use of diverse sensors is of major interest in the remote sensing community. With view to the repeata-bility of acquisitions, todays satellite sensor systems provide a temporal resolution of about one month in the Shannon sense. Thus, the joint use of different sensor systems is unavoidable for monitoring purposes. This contribution desig...
Conference Paper
The joint use of diverse sensors is of major interest in the remote sensing community. As each sensor has its own characteristics in terms of geometric, radiometric and polarimetric resolution, it provides certain advantages and disadvantages for special applications. This contribution presents a way of image sharpening both in the geometric and po...
Conference Paper
Fresh water is a scarce resource in the West-African Sahel region, seasonally influenced by droughts and floods. Particularly in terms of climate change, the importance of wetlands increases for flora, fauna, human population, agriculture, livestock and fishery. Hence, access to open water is a key factor. Long-term monitoring of water dynamics is...
Conference Paper
Water scarcity is one of the main challenges posed by the changing climate. Especially in semi-arid regions where water reservoirs are filled during the very short rainy season, but have to store enough water for the extremely long dry season, the intelligent handling of water resources is vital. This study focusses on Lac Bam in Burkina Faso, whic...
Article
Full-text available
Wetlands in semi-arid Africa are vital as water resource for local inhabitants and for biodiversity, but they are prone to strong seasonal fluctuations. Lac Bam is the largest natural freshwater lake in Burkina Faso, its water is mixed with patches of floating or flooded vegetation, and very turbid and sediment-rich. These characteristics as well a...
Article
The digital elevation model (DEM) of the Shuttle Radar Topography Mission (SRTM) still has known long-wave height errors. These errors occur especially in the continent's interior with a spatial scale of hundreds to thousands of kilometers and a magnitude of several meters. In this letter, for the first time, a method for estimating those long-wave...
Conference Paper
The German Remote Sensing Data Center (DFD) of the German Aerospace Center (DLR) has gained a lot of experience in surface water extraction from Synthetic Aperture Radar (SAR) data for various application domains within the last years. In this context four operational approaches have been developed which jointly form the so called DFD Water Suite:...
Article
In recent years, the German Remote Sensing Data Center (DFD) of the German Aerospace Center (DLR) has gained a lot of experience in water surface extraction from synthetic aperture radar (SAR) data for various application domains. In this context, four approaches have been developed, which jointly form the so-called DFD Water Suite: The Water Mask...
Conference Paper
The digital elevation model (DEM) produced by TanDEM-X is an interferometric elevation model with global unprecedented quality, accuracy, and coverage. It represents an unedited surface model that means for example in case of water bodies it still contains noisy, random or void DEM values. For the most applications a DEM editing is crucial. After a...
Conference Paper
Full-text available
Lac Bam is the largest natural lake in Burkina Faso, and is of high importance for the local inhabitants for irrigated farming, animal watering, and extraction of water for drinking and sanitation. Wetlands in semi-arid African areas are prone to strong seasonal fluctuations and their waters are often covered by floating or standing vegetation, and...
Conference Paper
Conventional studies to assess the annual mass balance for glaciers rely on single point observations in combination with model and interpolation approaches. Just recently, airborne and spaceborne data is used to support such mass balance determinations. Here, we present an approach to map temporal changes of the snow cover in glaciated regions of...
Article
Full-text available
As the number of space-borne SAR sensors increases, a rising number of different SAR acquisition modes is in use, resulting in a higher variation within the image products. This variability in acquisition geometry, radiometry, and last but not least polarimetry raises the need for a consistent SAR image description incorporating all available senso...
Article
Full-text available
Conventional studies to assess the annual mass balance for glaciers rely on single point observations in combination with model and interpolation approaches. Just recently, airborne and spaceborne data is used to support such mass balance determinations. Here, we present an approach to map temporal changes of the snow cover in glaciated regions of...
Conference Paper
Full-text available
Monitoring of wetlands is a very important task for water management as well as for wetland ecology. Water bodies and wetlands in semi-arid African areas show strong seasonal dynamics throughout the year that require time series imagery with narrow temporal intervals for satellite-based monitoring. The study site for this work is Lac Bam, which is...
Conference Paper
The monitoring of wetlands and water extents plays more and more an important key role with respect to climate change. In this paper, a novel technique of SAR image pre-processing using multi-temporal, multi-polarized and multi-sensor data is described. This technique bases on the Kennaugh element framework which is a very versatile polarimetric de...
Conference Paper
In September 2013 the production of TanDEM-X digital elevation model (DEM) started. As the data acquisition for difficult terrain lasted until April 2014, final DEM production started for flat to moderate terrain regions where two final coverages surfice. This paper focuses on a first validation of moderate terrain to prove the absolute height accu...
Conference Paper
Our technique containing the Kennaugh decomposition, ortho-rectification, radiometric enhancement and normalization is universal applicable for multi-sensor, multi-polarization and multi-temporal processing provides important and meaningful information for the monitoring of arctic environments. The calibrated and ortho-rectified imagery, i.e. the i...
Article
Full-text available
The TanDEM-X mission will derive a global digital elevation model (DEM) with satellite SAR interferometry. Two radar satellites (TerraSAR-X and TanDEM-X) will map the Earth in a resolution and accuracy with an absolute height error of 10m and a relative height error of 2m for 90% of the data. In order to fulfill the height requirements in general t...
Conference Paper
The TanDEM-X mission will derive a global digital elevation model (DEM) with satellite SAR interferometry. Two radar satellites (TerraSAR-X and TanDEM-X) will map the Earth in a resolution and accuracy with an absolute height error of 10m and a relative height error of 2m for 90% of the data. In order to fulfill the height requirements in general t...