Large-scale crop type and crop area mapping across Brazil using synthetic aperture radar and optical imagery

Multi-temporal Interferometric Synthetic Aperture Radar (MT-InSAR) has been widely used for ground motion identification and monitoring over large-scale areas, due to its large spatial coverage and high accuracy. However, automatically locating and assessing the state of the ground motion from the massive Interferometric Synthetic Aperture Radar (InSAR) measurements is not easy. Utilizing the spatial-temporal characteristics of surface deformation on the basis of the Small Baseline Subsets InSAR (SBAS-InSAR) measurements, this study develops an improved method to locate potential unstable or dangerous regions, using the spatial velocity gradation and the temporal evolution trend of surface displacements in large-scale areas. This method is applied to identify the potential geohazard areas in a mountainous region in northwest China (Lajia Town in Qinghai province) using 73 and 71 Sentinel-1 images from the ascending and descending orbits, respectively, and an urban area (Dongguan City in Guangdong province) in south China using 32 Sentinel-1 images from the ascending orbit. In the mountainous area, 23 regions with potential landslide hazards have been identified, most of which have high to very high instability levels. In addition, the instability is the highest at the center and decreases gradually outward. In the urban area, 221 potential hazards have been identified. The moderate to high instability level areas account for the largest proportion, and they are concentrated in the farmland irrigation areas, and construction areas. The experiment results show that the improved method can quickly identify and evaluate geohazards on a large scale. It can be used for disaster prevention and mitigation.

Download Full-text

Mapping potential signs of gas emissions in ice of Lake Neyto, Yamal, Russia, using synthetic aperture radar and multispectral remote sensing data

The Cryosphere ◽

10.5194/tc-15-1907-2021 ◽

2021 ◽

Vol 15 (4) ◽

pp. 1907-1929

Author(s):

Georg Pointner ◽

Annett Bartsch ◽

Yury A. Dvornikov ◽

Alexei V. Kouraev

Keyword(s):

Synthetic Aperture Radar ◽

Synthetic Aperture ◽

The Arctic ◽

Lake Ice ◽

Gas Emissions ◽

L Band ◽

Optical Imagery ◽

Sar Data ◽

Sar Imagery ◽

Aperture Radar

Abstract. Regions of anomalously low backscatter in C-band synthetic aperture radar (SAR) imagery of lake ice of Lake Neyto in northwestern Siberia have been suggested to be caused by emissions of gas (methane from hydrocarbon reservoirs) through the lake’s sediments. However, to assess this connection, only analyses of data from boreholes in the vicinity of Lake Neyto and visual comparisons to medium-resolution optical imagery have been provided due to a lack of in situ observations of the lake ice itself. These observations are impeded due to accessibility and safety issues. Geospatial analyses and innovative combinations of satellite data sources are therefore proposed to advance our understanding of this phenomenon. In this study, we assess the nature of the backscatter anomalies in Sentinel-1 C-band SAR images in combination with very high resolution (VHR) WorldView-2 optical imagery. We present methods to automatically map backscatter anomaly regions from the C-band SAR data (40 m pixel spacing) and holes in lake ice from the VHR data (0.5 m pixel spacing) and examine their spatial relationships. The reliability of the SAR method is evaluated through comparison between different acquisition modes. The results show that the majority of mapped holes (71 %) in the VHR data are clearly related to anomalies in SAR imagery acquired a few days earlier, and similarities to SAR imagery acquired more than a month before are evident, supporting the hypothesis that anomalies may be related to gas emissions. Further, a significant expansion of backscatter anomaly regions in spring is documented and quantified in all analysed years 2015 to 2019. Our study suggests that the backscatter anomalies might be caused by lake ice subsidence and consequent flooding through the holes over the ice top leading to wetting and/or slushing of the snow around the holes, which might also explain outcomes of polarimetric analyses of auxiliary L-band Advanced Land Observing Satellite (ALOS) Phased Array type L-band Synthetic Aperture Radar-2 (PALSAR-2) data. C-band SAR data are considered to be valuable for the identification of lakes showing similar phenomena across larger areas in the Arctic in future studies.

Download Full-text

Analysis of synthetic aperture radar Data collected over the southwestern Greenland ice sheet

Journal of Glaciology ◽

10.1017/s002214300001577x ◽

1993 ◽

Vol 39 (131) ◽

pp. 119-132 ◽

Cited By ~ 46

Author(s):

K. C. Jezek ◽

M. R. Drinkwater ◽

J. P. Crawford ◽

R. Bindschadler ◽

R. Kwok

Keyword(s):

Synthetic Aperture Radar ◽

Large Scale ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Synthetic Aperture ◽

Model Calculations ◽

Synthetic Aperture Radar Data ◽

Surface Patterns ◽

Sar Data ◽

Aperture Radar

AbstractAnalyses of the first aircraft multi-frequency, Polarimetric synthetic aperture radar (SAR) data acquired over the southwestern Greenland ice sheet are presented. Data were collected on 31 August 1989 by the Jet Propulsion Laboratory SAR using the NASA DC-8 aircraft. Along with curvilinear patterns associated with large-scale morphologic features such as crevasses, lakes and streams, frequency and polarization dependencies are observed in the P-, L-and C-band image products. Model calculations that include firn grain-size and volumetric water content suggest that tonal variations in and between the images are attributable to large-scale variations in the snow-and ice-surface characteristics, especially snow wetness. In particular, systematic trends in back-scatter strength observed at C-band across regions of changing snow wetness are suggestive of a capability to delineate boundaries between snow facies. Ice lenses and ice pipes are the speculated cause for similar trends in P-band back-scatter. Finally, comparison between SEASAT SAR data collected in 1978 and these airborne data collected in 1989 indicate a remarkable stability of surface patterns associated with the locations of supraglacial lake and stream systems.

Download Full-text

Synthetic Aperture Radar Interferometry for Disaster Monitoring of Harbor Facilities

Journal of Disaster Research ◽

10.20965/jdr.2017.p0526 ◽

2017 ◽

Vol 12 (3) ◽

pp. 526-535 ◽

Cited By ~ 2

Author(s):

Ryo Natsuaki ◽

◽

Takuma Anahara ◽

Tsuyoshi Kotoura ◽

Yuudai Iwatsuka ◽

...

Keyword(s):

Synthetic Aperture Radar ◽

Large Scale ◽

Ground Deformation ◽

Volcanic Eruptions ◽

Radar Interferometry ◽

Synthetic Aperture ◽

Synthetic Aperture Radar Interferometry ◽

Disaster Monitoring ◽

Hyogo Prefecture ◽

Aperture Radar

In this paper, we present experimental results of the disaster monitoring of harbor facilities using spaceborne synthetic aperture radar interferometry (InSAR). The Advanced Land Observing Satellite-2 (ALOS-2 or DAICHI-2), operated by the Japan Aerospace Exploration Agency (JAXA), carries the Phased Array type L-band Synthetic Aperture Radar-2 (PALSAR-2). PALSAR-2 can observe disaster areas day and night, in any weather, at a resolution of approximately 3 m. ALOS-2 PALSAR-2 has been used to measure large-scale ground deformation e.g., after earthquakes and volcanic eruptions. However, its robustness for smaller targets, such as harbor facilities, has not yet been substantiated. Here, we measured the uplift of a breakwater model made of concrete armor units, and confirmed the sensor accuracy to be better than 2 cm standard deviation. We also analyzed the damage to the Nagata and Suma ports in Kobe city, Hyogo prefecture, Japan hit by the 11th Typhoon in 2014, and detected the damaged area using interferometric coherence analysis.

Download Full-text

High Accuracy Algorithm of Airborne Interferometric Synthetic Aperture Radar

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.128-129.138 ◽

2011 ◽

Vol 128-129 ◽

pp. 138-141

Author(s):

Song Tao Han ◽

Ge Shi Tang ◽

Yong Fei Mao ◽

Lue Chen ◽

Mei Wang

Keyword(s):

Data Processing ◽

Synthetic Aperture Radar ◽

Large Scale ◽

Synthetic Aperture ◽

Interferometric Synthetic Aperture Radar ◽

Processing Methods ◽

X Band ◽

System Data ◽

Data Processing Methods ◽

Aperture Radar

Interferometric Synthetic Aperture Radar is one of the most important technologies for topographic mapping. The DEM quality of airborne InSAR system depends on both system hardware performance and data processing methods. To derive large scale topographic and thematic maps up to scale 1:50000 and 1:10000, the whole data processing methods were presented. The methods included SAR imaging, interferometric processing and cartographic processing. Special methods were induced to resolve the problems encountered in project applications. Results using X-band airborne InSAR system data showed validity of the algorithm.

Download Full-text