Achim Roth

Achim Roth
German Aerospace Center (DLR) | DLR · Department of Land Surface

About

324
Publications
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7,390
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Publications

Publications (324)
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...
Conference Paper
Digital elevation models (DEMs) hold a key role as the main input data for a large variety of applications as they provide an accurate representation of the Earth’s surface and its corresponding topographic parameters. Scientific applications require current, reliable and precise elevation information to be implemented in research to generate corre...
Article
Rivers are the arteries of the planet, providing vital resources as they flow and pulse across landscapes in a vast global network. Rivers and streams convey sediments and nutrients to fertile valleys and river deltas, create habitat corridors and transportation routes, and deliver life-sustaining fresh water to aquatic and riparian ecosystems and...
Article
Full-text available
Settlements, and in particular cities, are at the center of key future challenges related to global change and sustainable development. Widely used indicators to assess the efficiency and sustainability of settlement development are the compactness and density of the built-up area. However, at global scale, a temporally consistent and spatially det...
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
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...
Conference Paper
The increased availability and accuracy of recent remote sensing data accelerates the development of data products for hydrological modelling. Most hydrological models rely on the accurate representation of the Earth’s terrestrial surface including all waterways from small mountain streams to great lowland rivers in order to compute discharge. In l...
Article
Full-text available
Due to the remote location and the extreme climate, monitoring stations in Arctic rivers such as Lena in Siberia have been decreasing through time. Every year, after a long harsh winter, the accumulated snow on the Lena watershed melts, leading to the major annual spring flood event causing heavy transport of sediments, organic carbon, and trace me...
Article
Full-text available
We present the generation and validation of an updated version of the TanDEM-X Digital Elevation Model (DEM) of Antarctica: the TanDEM-X PolarDEM 90 m of Antarctica. Improvements compared to the global TanDEM-X DEM version include filling of gaps with newer acquisitions, interpolating of smaller voids, smoothing of noisy areas and replacing frozen...
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
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...
Article
Full-text available
This work analyzes the potential synergies between the two German satellites of the TerraSAR-X/TanDEM-X mission and the Spanish PAZ satellite. Since both platforms are almost identical and they were launched in the same orbital plane, comparable images of the same area under the same geometry may be regularly acquired by both systems. This allows t...
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...
Preprint
Full-text available
We present the generation and validation of an updated version of the TanDEM-X Digital Elevation Model (DEM) of Antarctica: the TanDEM-X PolarDEM 90 m of Antarctica. Improvements compared to the global TanDEM-X DEM version include filling of gaps with newer acquisitions, interpolating of smaller voids, smoothing of noisy areas and replacing frozen...
Conference Paper
The high latitudes of the Northern Hemisphere have experienced the largest regional warming over the last decades. On the Greenland ice sheet, rapid changes are observed in response to temperature increase, with the amount of liquid water at the surface particularly increasing. Understanding Greenland’s ice sheet hydrology is essential to assess it...
Conference Paper
In this study we present the digital elevation model (DEM) for Antarctica produced by the TanDEM-X (TerraSAR add-on for digital elevation measurement) mission. The TanDEM-X Polar DEM 90 is a reduced version of the global TanDEM-X DEM with special adaptations. Holes were filled with additional acquisitions and water areas were flattened to avoid noi...
Article
Full-text available
Continental to global scale mapping of the human settlement extent based on earth observation satellite data has made considerable progress. Nevertheless, the current approaches only provide a two-dimensional representation of the built environment. Therewith, a full characterization is restricted in terms of the urban morphology and built-up densi...
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...
Conference Paper
Arctic watersheds heavily influence the oceans and the mean global temperature. They are the largest source of freshwater to the Arctic Ocean and affecting the sea ice cover and the ocean conveyor belt. An example of these impacts is the 7% rise of the average annual freshwater discharge from the six largest Eurasian rivers to the Arctic Ocean over...
Conference Paper
River runoff is the single largest contributor to the Arctic Ocean's freshwater budget. The Lena River in Eastern Siberia is one of the major rivers flowing into the Arctic Ocean. More than 50% of the total runoff from the mainland originates from the four large rivers Ob, Yenisei, Lena and Mackenzie. Global warming is expected to significantly inf...
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
Mackenzie Rive located in Yukon and Northwest Territories is the longest river system in Canada and an important transportation link. During the ice free season it is used for shipping transportation, while during freeze up time it serves as an ice road for trucks. Therefore, knowledge of ice conditions is essential to enable save navigation. Due t...
Conference Paper
Remotely sensed surface elevation datasets are key to study mass balance and dynamic behaviours of glaciers, ice caps, and ice sheets. Digital elevation models (DEMs) generated from the TanDEM-X mission from single-pass synthetic aperture radar interferometry (InSAR) at X-band provide an excellent potential resource for this purpose. However, they...
Conference Paper
In this study we present the digital elevation model (DEM) for Antarctica produced by the TanDEM-X (TerraSAR add-on for digital elevation measurement) mission. It is composed of more than 41,000 interferometric synthetic aperture radar (InSAR) DEM scenes. The DEM presented here is a reduced version of the TanDEM-X global DEM in a 90m universal pola...
Conference Paper
The Greenland ice sheet represents the world’s largest ice mass outside Antarctica covering an area of approximately 1.7 million km2. During the last decades, observations reveal dramatic changes, which can be attributed to anthropogenic induced global warming with considerable implications for environment and human society. The melting of the enti...
Conference Paper
River runoff is the single largest contributor to the Arctic Ocean's freshwater budget.. The Lena River in Eastern Siberia is one of the major rivers flowing into the Arctic Ocean. More than 50% of the total runoff from the mainland originates from the four large rivers Ob, Yenisei, Lena and Mackenzie. Global warming is expected to significantly in...
Article
Full-text available
This paper presents the first comprehensive review on the scientific utilization of earth observation data provided by the German TerraSAR-X mission. It considers the different application fields and technical capabilities to identify the key applications and the preferred technical capabilities of this high-resolution SAR satellite system from a s...
Article
Full-text available
The timing of snowmelt is an important turning point in the seasonal cycle of small Arctic catchments. The TerraSAR-X (TSX) satellite mission is a synthetic aperture radar system (SAR) with high potential to measure the high spatiotemporal variability of snow cover extent (SCE) and fractional snow cover (FSC) on the small catchment scale. We invest...
Conference Paper
This study demonstrates the potential of TanDEM-X SAR imagery to analyze glacial elevation changes across entire Greenland. TanDEM-X time series data between 2010 and 2017 allow for consistent and high-resolution delineation of DEM at unprecedented quality. The first analysis reveal major elevation changes at the outlet and peripheral glaciers up t...
Conference Paper
Permafrost is an essential element of the cryosphere, which will be strongly affected by global warming. Although permafrost cannot be measured directly with remote sensing, many permafrost features are observable. Polarimetric information can be used in this context. Polarimetric data of TerraSAR -X is the basis for a local landcover classificatio...
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 Greenland ice sheet. In particular, the relation of backscatter intens...
Article
Full-text available
Three synthetic aperture radar (SAR) data classification methodologies were used to assess the ability of single-polarization and dual-polarization TerraSAR-X (TSX) data to classify surface water, including open water, ice, and flooded vegetation. Multi-polarization SAR observations contain more information than single-polarization SAR, but the ava...
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
Full-text available
The TerraSAR-X (TSX) mission provides a distinguished collection of high resolution satellite images that shows great promise for a global monitoring of human settlements. Hence, the German Aerospace Center (DLR) has developed the Urban Footprint Processor (UFP) that represents an operational framework for the mapping of built-up areas based on a m...
Article
Full-text available
The primary goal of the German TanDEM-X mission is the generation of a highly accurate and global Digital Elevation Model (DEM) with global accuracies of at least 10 m absolute height error (linear 90% error). The global TanDEM-X DEM acquired with single-pass SAR interferometry was finished in September 2016. This paper provides a unique accuracy a...
Article
Arctic warming is leading to substantial changes to permafrost including rapid Degradation of ice and ice-rich coasts and riverbanks. In this study, we present and evaluate a high spatiotemporal resolution three-year time series of X-Band microwave satellite data from the TerraSAR-X (TSX) satellite to quantify cliff-top erosion (CTE) of an ice-rich...
Conference Paper
The joint use of TerraSAR-X and TanDEM-X SAR sensors gains more and more interest. As each sensor has operationally only dual-polarization acquisition capabilities, this contribution presents a way of image combination by joining co- and cross-polarized SAR images of TerraSAR-X and TanDEM-X. The problem of co-registration of two complex data sets i...
Conference Paper
Polar regions pass through dramatic changes caused by ongoing climate warming. In many areas, rapid retreat of glaciers and ice sheets has been observed within the past decades, which leads to significant consequences globally. In order to understand and predict these complex processes and their impacts on the environment as well as on human system...
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...
Article
Full-text available
Arctic warming is leading to substantial changes to permafrost including rapid degradation of ice and ice-rich coasts and riverbanks. In this study, we present and evaluate a high spatiotemporal resolution three-year time series of X-Band microwave satellite data from the TerraSAR-X (TSX) satellite to quantify cliff-top erosion (CTE) of an ice-rich...
Conference Paper
In this presentation we analyze three digital elevation models (DEM) of Greenland produced with data recorded by the TanDEM-X (TerraSAR add-on for digital elevation measurement) mission. During the TanDEM-X mission several area-wide coverages of Greenland were acquired. From this data we produce three DEMs with distinct temporal coverage: one captu...
Article
Full-text available
Today 7.2 billion people inhabit the Earth and by 2050 this number will have risen to around nine billion, of which about 70 percent will be living in cities. Hence, it is essential to understand drivers, dynamics, and impacts of the human settlements development. A key component in this context is the availability of an up-to-date and spatially co...