Multiparametric Sea State from Spaceborne Synthetic Aperture Radar for Near Real Time Services

2021 ◽  
Author(s):  
Andrey Pleskachevsky ◽  
Björn Tings ◽  
Sven Jacobsen ◽  
Egbert Schwarz ◽  
Detmar Krause
Keyword(s):  
Synthetic Aperture Radar ◽  
Real Time ◽  
Spatial Information ◽  
Surface Wind ◽  
State Parameter ◽  
Synthetic Aperture ◽  
Wide Field ◽  
Atmospheric Conditions ◽  
Sea State ◽  
Aperture Radar

<p>Spaceborne synthetic aperture radar (SAR) is a powerful tool for monitoring marine environmental parameters of the seas. The ability to work independently of sun illumination, cloud coverage and atmospheric conditions, as well as the capability of delivering spatial information, makes SAR one of the most perceptive instruments. The newest methods for processing SAR data with increased precision allow sea state fields to be estimated with local variabilities. For large areas in oceans where no <em>in-situ</em> measurements and only forecast predictions are available, this information is indispensable for global shipping and over human activity. Due to newest developments, the derived meteo-marine parameters can be transferred to weather services and to a ship’s bridge several minutes after acquisition, where the ship route can be optimized.</p> <p>The study presents a method and application for estimating series of integrated sea state parameters from satellite-borne SAR, allow processing of data from different satellites and modes in near real time (NRT). The developed Sea State Processor (SSP) estimates total significant wave height <em>H<sub>s</sub></em>, dominant and secondary swell and windsea wave heights, first, and second moment wave periods, mean wave period and period of wind sea. The algorithm was applied for the Sentinel-1 (S1) C-band Interferometric Wide Swath Mode (IW), Extra Wide (EW) and Wave Mode (WM) Level-1 (L1) products and also extended to the X-band TerraSAR-X (TSX) StripMap (SM) mode. The scenes are processed in raster and result in continuous sea state fields with the exception of S1 WV. Each 20 km × 20 km WV imagette, acquired every 100 km along the orbit, presents averaged values for each sea state parameter.</p> <p>The SSP was tuned and validated using two independent global wave models WAVEWATCH-3 (NOAA) and CMEMS (Copernicus) and NDBC buoys. The accuracy of <em>H<sub>s</sub></em> reaches an RMSE of 0.25  m by comparison with models (S1 WV); comparisons to NDBC worldwide buoys result into an RMSE of 0.31  m. Due to implemented parallelization, a fine rater step for scene processing can be practical applied: for example, S1 IW scene with coverage of 200  km  ×  250  km can be processed using raster step of 1  km (corresponds to ~50.000 subscenes) during minutes.</p> <p>The DLR Ground Station “Neustrelitz” applies SSP as part of a near real-time demonstrator service that involves a fully automated daily provision of surface wind and sea state parameters estimates from S1 IW for the North and Baltic Sea. All results and the presented methods are novel and provide a wide field for applications and implementations in prediction systems.</p>

Ground Based Interferometric Synthetic Aperture Radar Combined With a Critical Slope Monitoring Program Will Provide Early Detection of Slope Movement Along Pipeline Corridors

2019 ◽  
Author(s):  
Steven E. Borron ◽  
Martin P. Derby
Keyword(s):  
Synthetic Aperture Radar ◽  
Real Time ◽  
Visual Presentation ◽  
Slope Movement ◽  
Synthetic Aperture ◽  
Interferometric Synthetic Aperture Radar ◽  
Atmospheric Conditions ◽  
Technical Requirements ◽  
Radar Systems ◽  
Aperture Radar

Abstract The transition of satellite InSAR technology to a ground-based system provides a proven risk reduction technology if combined with a critical slope monitoring (CSM) program. Together the technology with the active engagement of a defined program can detect the onset of slope displacement, acceleration, and provide a method to determine slope collapse. Recently, using the radar software, Guardian, and its ability to document surface velocity in intervals of 24-hours or less has allowed for the development of site-specific levels of rockfall risk. The ground-based InSAR (interferometric synthetic aperture radar) systems and their near real-time capabilities allow for proactive and early warning monitoring. The technical requirements include the ability to operate 24/7 in all weather conditions, acquire data in near real-time, and visually present data in an interpretable format that requires no end user processing. Since slope failure without acceleration is unlikely, the rapid visual presentation of processed data becomes a crucial component for a CSM technology. The definition of the CSM program not only requires short intervals for data acquisition, processing, and visual presentation but also requires a monitoring professional that can interpret and communicate changes in slope movement. A specific CSM technology requirement demands, acquiring data at a continuous interval of 2-minutes or less, 24 hours per day for the duration of the monitoring project. Also, the CSM technology must be able to transmit alarm messages at the moment thresholds are met, visually present data with various time series plots, including displacement, and velocity maps while acquired radar data is continuously updated and with no end-user processing. A site-specific document called a trigger action response plan (TARP) needs to be prepared at the start of any CSM project. Currently, only the IBIS-FM and ArcSAR radars developed by IDS (Ingegneria Dei Sistemi) GeoRadar can meet the technical requirements of the defined CSM technology. During a CSM program, the short interval between each data acquisition provides two specific advantages. First, the short acquisition interval decreases interpolation, which automatically increases data confidence. Second, the short intervals also decrease the effects of atmospheric changes that are a part of all data acquisitions. Although the IBIS-FM and ArcSAR radar systems can operate in nearly all-weather conditions, sudden changes in local atmospheric conditions can still exhibit data effects. Both radar systems include active proprietary algorithms that account for ongoing atmospheric changes during acquisitions. In comparison, some remote sensing data acquired from, LIDAR, and total station technologies can be critically affected by sudden changes in local atmospheric conditions. Combining the near real-time capabilities of an interferometric synthetic aperture radar system with a dedicated professional will decrease risk to people and property by allowing slope movement trends to be identified and observed in near real-time, 24-hours per/day. The paper will discuss the highlights of several successful CSM programs. We describe deployment versatility, the ability to identify the onset of displacement accurately, and the critical identification of the onset of acceleration.

scholarly journals New Algorithm and Processor for Obtaining Maritime Information from Sentinel-1 Radar Imagery for Near Real Time Services

2020 ◽  
Author(s):  
Andrey Pleskachevsky ◽  
Björn Tings ◽  
Sven Jacobsen ◽  
Egbert Schwarz ◽  
Detmar Krause ◽  
...  
Keyword(s):  
High Resolution ◽  
Synthetic Aperture Radar ◽  
Real Time ◽  
Wave Height ◽  
Surface Wind ◽  
Open Ocean ◽  
Synthetic Aperture ◽  
Sea State ◽  
Sar Imagery

<p>The focus of the study is analysing storm peak/center propagation, front movement and arrival of swell using newest remote sensing information, numerical models, <em>in-situ</em> measurements and their combination. For this purposes, a new empirical algorithm for sea state retrieval from satellite borne Sentinel-1 (S1) Synthetic Aperture Radar (SAR) imagery was developed. The algorithm is applied inside a new processor for meteo-marine parameter estimation for Near Real Time (NRT) applications. These NRT-applications include the investigation of geophysical processes using different satellite modes ranging from high resolution modes with small image coverage of ~20km in open ocean to low resolution modes with wide coverage of ~250km in shelf areas.</p><p>The quick developments in satellite techniques, processors, algorithms and ground infrastructures provide new possibilities for series of oceanographic applications in the last years. These new techniques allow estimation of a wide range of oceanographic information including properties of surface waves and internal waves, surface wind speed, sub-meso scale fronts and eddies, ice coverage, oil spills, coastal bathymetry, currents and others. Generally, the new high resolution products from different models allow verification of meteo-marine parameters more accurately. Here, a cross validation with different sea state model results using WWIII (NOAA) and CMEMS (COPERNICUS), with <em>in situ</em> buoy measurements and with satellite estimated parameters allowed an significant improvement of the accuracy of the derived sea state and wind fields. </p><p>The new empirical algorithm allows estimation of total integrated sea state parameters including significant wave height <em>H<sub>s</sub></em>, first moment wave period <em>T<sub>m1</sub></em>, second moment period <em>T<sub>m2</sub></em>, mean period <em>T<sub>m</sub></em> and also partial integrated parameters like swell and windsea wave heights and windsea period. The algorithm allows processing of different S1 Synthetic Aperture Radar (SAR) modes into sea state fields: </p><ul><li>S1 Wave Mode (WV) acquires multiple vignettes with an extent of ~20km×20km and each displaced by 100 km along satellite tracks in open ocean (global). About 60 tracks around the globe have been acquired per day. The relatively high spatial resolution of ~4 m allows estimating wave height with accuracy of ~35cm. This is comparable with the accuracy of satellite altimetry and a new achievement for SAR based techniques. </li> <li>S1 Interferometric Wide Swath Mode (IW) covers area-strips of thousand kilometres of earth and ocean surface in coastal areas with a resolution of ~30m by sequences of multiple images with an approximate size of 200km×250km. The accuracy of ~ 70cm (<em>H<sub>s</sub></em>) for this mode is not as so high as for S1-WV, because the short waves are not visible for S1-IW mode and imaged as noise. However, the accuracy is much higher than state-of-the-art methods for this mode. </li> </ul><p>The algorithm has been integrated into a prototype processor for Sentinel-1 SAR imagery. The DLR Ground Station Neustrelitz applies this prototype as part of a near real-time demonstrator MSA service. The presented scientific service involves daily provision of surface wind and sea state parameters estimated fully automatically from S1 IW images of North and Baltic Sea in and around German territorial waters.</p>

Compact acousto-optic system for real-time synthetic aperture radar image formation

1998 ◽  
Author(s):  
Michael W. Haney ◽  
Marc P. Christensen ◽  
Robert R. Michael, Jr. ◽  
Peter A. Wasilousky ◽  
Dennis R. Pape
Keyword(s):  
Synthetic Aperture Radar ◽  
Real Time ◽  
Image Formation ◽  
Synthetic Aperture Radar Image ◽  
Radar Image ◽  
Synthetic Aperture ◽  
Optic System ◽  
Aperture Radar

Effectiveness of WRF wind direction for retrieving coastal sea surface wind from synthetic aperture radar

Wind Energy ◽  
2012 ◽  
Vol 16 (6) ◽  
pp. 865-878 ◽  
Author(s):  
Yuko Takeyama ◽  
Teruo Ohsawa ◽  
Katsutoshi Kozai ◽  
Charlotte Bay Hasager ◽  
Merete Badger
Keyword(s):  
Synthetic Aperture Radar ◽  
Wind Direction ◽  
Surface Wind ◽  
Sea Surface ◽  
Synthetic Aperture ◽  
Sea Surface Wind ◽  
Coastal Sea ◽  
Aperture Radar

Better Utilization of SAR Dynamic Range

1977 ◽  
Vol 21 (3) ◽  
pp. 235-240
Author(s):  
Edward J. Dragavon
Keyword(s):  
Computer Simulation ◽  
Synthetic Aperture Radar ◽  
Real Time ◽  
Image Enhancement ◽  
Dynamic Range ◽  
Synthetic Aperture ◽  
Analytic Methods ◽  
Sar Imagery ◽  
Gray Shade ◽  
Aperture Radar

Three general classes of image enhancement techniques for synthetic aperture radar (SAR) video were investigated through non-real-time computer simulation. The general categories were 1) monochromatic adaptive gray shade transformations, 2) pseudocolor encoding, and 3) feature analytic methods. The class of feature analytic techniques was found to have the greatest potential for improving the operational utility of SAR imagery.

scholarly journals Capabilities of Chinese Gaofen-3 Synthetic Aperture Radar in Selected Topics for Coastal and Ocean Observations

2018 ◽  
Vol 10 (12) ◽  
pp. 1929 ◽  
Author(s):  
Xiao-Ming Li ◽  
Tianyu Zhang ◽  
Bingqing Huang ◽  
Tong Jia
Keyword(s):  
Synthetic Aperture Radar ◽  
Surface Wind ◽  
Wave Mode ◽  
Sea Surface ◽  
Synthetic Aperture ◽  
Radiometric Calibration ◽  
Sea Surface Wind ◽  
Wind Retrievals ◽  
Sea Surface Wave ◽  
Aperture Radar

Gaofen-3 (GF-3), the first Chinese spaceborne synthetic aperture radar (SAR) in C-band for civil applications, was launched on August 2016. Some studies have examined the use of GF-3 SAR data for ocean and coastal observations, but these studies generally focus on one particular application. As GF-3 has been in operation over two years, it is essential to evaluate its performance in ocean observation, a primary goal of the GF-3 launch. In this paper, we offer an overview demonstrating the capabilities of GF-3 SAR in ocean and coastal observations by presenting several representative cases, i.e., the monitoring of intertidal flats, offshore tidal turbulent wakes and oceanic internal waves, to highlight the GF-3’s full polarimetry, high spatial resolution and wide-swath imaging advantages. Moreover, we also present a detailed analysis of the use of GF-3 quad-polarization data for sea surface wind retrievals and wave mode data for sea surface wave retrievals. The case studies and statistical analysis suggest that GF-3 has good ocean and coastal monitoring capabilities, though further improvements are possible, particularly in radiometric calibration and stable image quality.

scholarly journals Comparison of C-Band Quad-Polarization Synthetic Aperture Radar Wind Retrieval Models

2018 ◽  
Vol 10 (9) ◽  
pp. 1448 ◽  
Author(s):  
He Fang ◽  
Tao Xie ◽  
William Perrie ◽  
Guosheng Zhang ◽  
Jingsong Yang ◽  
...  
Keyword(s):  
Wind Speed ◽  
Synthetic Aperture Radar ◽  
Surface Wind ◽  
Synthetic Aperture ◽  
Northwest Pacific ◽  
Sar Images ◽  
Retrieval Models ◽  
Wind Retrieval ◽  
Wind Speeds ◽  
Aperture Radar

This work discusses the accuracy of C-2PO (C-band cross-polarized ocean backscatter) and CMOD4 (C-band model) geophysical model functions (GMF) for sea surface wind speed retrieval from satellite-born Synthetic Aperture Radar (SAR) images over in the Northwest Pacific off the coast of China. In situ observations are used for comparison of the retrieved wind speed using two established wind retrieval models: C-2PO model and CMOD4 GMF. Using 439 samples from 92 RADARSAT-2 fine quad-polarization SAR images and corresponding reference winds, we created two subset wind speed databases: the training and testing subsets. From the training data subset, we retrieve ocean surface wind speeds (OSWSs) from different models at each polarization and compare with reference wind speeds. The RMSEs of SAR-retrieved wind speeds are: 2.5 m/s: 2.11 m/s (VH-polarized), 2.13 m/s (HV-polarized), 1.86 m/s (VV-polarized) and 2.26 m/s (HH-polarized) and the correlation coefficients are 0.86 (VH-polarized), 0.85(HV-polarized), 0.87(VV-polarized) and 0.83 (HH-polarized), which are statistically significant at the 99.9% significance level. Moreover, we found that OSWSs retrieved using C-2PO model at VH-polarized are most suitable for moderate-to-high winds while CMOD4 GMF at VV-polarized tend to be best for low-to-moderate winds. A hybrid wind retrieval model is put forward composed of the two models, C-2PO and CMOD4 and sets of SAR test data are used in order to establish an appropriate wind speed threshold, to differentiate the wind speed range appropriate for one model from that of the other. The results show that the OSWSs retrieved using our hybrid method has RMSE of 1.66 m/s and the correlation coefficient are 0.9, thereby significantly outperforming both the C-2PO and CMOD4 models.

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