scholarly journals Europe's offshore winds assessed with synthetic aperture radar, ASCAT and WRF

2020 ◽  
Vol 5 (1) ◽  
pp. 375-390 ◽  
Author(s):  
Charlotte B. Hasager ◽  
Andrea N. Hahmann ◽  
Tobias Ahsbahs ◽  
Ioanna Karagali ◽  
Tija Sile ◽  
...  
Keyword(s):  
Synthetic Aperture Radar ◽  
Wrf Model ◽  
Offshore Wind ◽  
Synthetic Aperture ◽  
Grid Spacing ◽  
North West ◽  
Wind Retrieval ◽  
The North ◽  
Ocean Wind ◽  
Aperture Radar

Abstract. Europe's offshore wind resource mapping is part of the New European Wind Atlas (NEWA) international consortium effort. This study presents the results of analysis of synthetic aperture radar (SAR) ocean wind maps based on Envisat and Sentinel-1 with a brief description of the wind retrieval process and Advanced Scatterometer (ASCAT) ocean wind maps. The wind statistics at 10 and 100 m above mean sea level (a.m.s.l.) height using an extrapolation procedure involving simulated long-term stability over oceans are presented for both SAR and ASCAT. Furthermore, the Weather Research and Forecasting (WRF) offshore wind atlas of NEWA is presented. This has 3 km grid spacing with data every 30 min for 30 years from 1989 to 2018, while ASCAT has 12.5 km and SAR has 2 km grid spacing. Offshore mean wind speed maps at 100 m a.m.s.l. height from ASCAT, SAR, WRF and ERA5 at a European scale are compared. A case study on offshore winds near Crete compares SAR and WRF for flow from the north, west and all directions. The paper highlights the ability of the WRF model to simulate the overall European wind climatology and the near-coastal winds constrained by the resolution of the coastal topography in the WRF model simulations.

REASSESSING POTENTIAL ORIGINS OF SYNTHETIC APERTURE RADAR (SAR) SLICKS FROM THE TIMOR SEA REGION OF THE NORTH WEST SHELF ON THE BASIS OF FIELD AND ANCILLARY DATA

2005 ◽  
Vol 45 (1) ◽  
pp. 311 ◽  
Author(s):  
A.T. Jones ◽  
G.A. Logan ◽  
J.M. Kennard ◽  
N. Rollet
Keyword(s):  
Synthetic Aperture Radar ◽  
Transition Zone ◽  
Environmental Data ◽  
Synthetic Aperture ◽  
Shelf Area ◽  
North West ◽  
The North ◽  
Timor Sea ◽  
Natural Hydrocarbon ◽  
Aperture Radar

The Timor Sea region of the North West Shelf is one of natural hydrocarbon accumulation and seepage, which has been investigated by integrated remote sensing studies in the past 10 years. One of the primary tools incorporated in these studies has been Synthetic Aperture Radar (SAR). During a recent Geoscience Australia marine survey to the Yampi Shelf area, active hydrocarbon seepage was directly observed in the form of gas plumes rising from the sea-floor. Active seepage was not observed in areas associated with dense clusters of elongated to irregularshaped features in the SAR data, which have previously been interpreted as natural hydrocarbon seepage slicks. These slicks, and another dense cluster of slicks across the Browse–Bonaparte Basin Transition Zone, are reassessed in the context of alternative formational processes.Mapping of bathymetric channels directly beneath the SAR slicks using multi-beam swath bathymetry and measurement of tidal currents using an acoustic doppler current profiler indicates that tidal current flows may have contributed to slick formation over the Yampi Shelf headland. In contrast, coral spawning may have contributed to the formation of annular to crescent-shaped SAR slicks associated with submerged reefs and shoals over the nearby transition zone. Subsequent to identifying potential alternative origins for these two types of SAR features, the remaining slicks across the area were re-categorised on the basis of their size and shape in the context of ancillary hydrographic and environmental data. An alternative nonseepage origin was established for most of the 381 SAR slicks previously identified as being related to natural hydrocarbon seepage. This may necessitate a significant downgrading of the extent and frequency of active hydrocarbon (particularly oil) seepage in the region.

Assessments of Ocean Wind Retrieval Schemes Used for Chinese Gaofen-3 Synthetic Aperture Radar Co-Polarized Data

2019 ◽  
Vol 57 (9) ◽  
pp. 7075-7085 ◽  
Author(s):  
Lin Ren ◽  
Jingsong Yang ◽  
Alexis A. Mouche ◽  
He Wang ◽  
Gang Zheng ◽  
...  
Keyword(s):  
Synthetic Aperture Radar ◽  
Synthetic Aperture ◽  
Wind Retrieval ◽  
Ocean Wind ◽  
Aperture Radar

Extreme wind conditions observed by satellite synthetic aperture radar in the North West Pacific

2008 ◽  
Vol 29 (21) ◽  
pp. 6129-6144 ◽  
Author(s):  
A. Reppucci ◽  
S. Lehner ◽  
J. Schulz‐Stellenfleth ◽  
C. S. Yang
Keyword(s):  
Synthetic Aperture Radar ◽  
Synthetic Aperture ◽  
West Pacific ◽  
North West ◽  
The North ◽  
Extreme Wind ◽  
Aperture Radar

scholarly journals US East Coast synthetic aperture radar wind atlas for offshore wind energy

2019 ◽  
Author(s):  
Tobias Ahsbahs ◽  
Galen Maclaurin ◽  
Caroline Draxl ◽  
Christopher Jackson ◽  
Frank Monaldo ◽  
...  
Keyword(s):  
Wind Speed ◽  
Synthetic Aperture Radar ◽  
East Coast ◽  
Mesoscale Model ◽  
Wrf Model ◽  
Offshore Wind ◽  
Synthetic Aperture ◽  
Wind Resources ◽  
Us East Coast ◽  
Aperture Radar

Abstract. We present the first synthetic aperture radar (SAR)-based offshore wind atlas of the US East Coast from Georgia to the Canadian border. Images from Radarsat-1, Envisat, Sentinel-1A, and Sentinel-1B are processed to wind maps using the Geophysical Model Function (GMF) CMOD5.N. Extensive comparisons with 6,008 collocated buoy observations revealed that biases of the individual system range from −0.8 to 0.6 m/s. Unbiased wind retrievals are crucial for producing an accurate wind atlas and intercalibration for correcting these biases by adjusting the normalized radar cross section is applied. The intercalibrated SAR observations show biases in the range of to −0.2 to 0.0 m/s, while at the same time improving the root mean squared error from 1.67 to 1.46 m/s. These intercalibrated SAR observations are, for the first time, aggregated to create a wind atlas. Monthly averages are used to correct artefacts from seasonal biases. The SAR wind atlas is used as a reference to study wind resources derived from the Weather Research and Forecasting (WRF) model. Comparisons focus on the spatial variation of wind resources and show that model results estimate lower coastal wind speed gradients than those from SAR. At sites designated for offshore wind development by the Bureau of Ocean Energy Management, mean wind speeds typically vary between 0.3 and 0.5 m/s for SAR and less than 0.2 m/s for the WRF model within each site. Findings indicate that wind speed gradients and variation might be underestimated in mesoscale model outputs along US East Coast.

scholarly journals Europe’s offshore winds assessed from SAR, ASCAT and WRF

2019 ◽  
Author(s):  
Charlotte B. Hasager ◽  
Andrea N. Hahmann ◽  
Tobias Ahsbahs ◽  
Ioanna Karagali ◽  
Tija Sile ◽  
...  
Keyword(s):  
Wrf Model ◽  
Offshore Wind ◽  
North West ◽  
Wind Retrieval ◽  
Long Term Stability ◽  
Mean Wind Speed ◽  
Coastal Winds ◽  
Wind Statistics ◽  
Ocean Wind ◽  
Wind Resource

Abstract. Europe’s offshore wind resource mapping is part of the New European Wind Atlas (NEWA) international consortium effort. This study presents the results of analysis of Synthetic Aperture Radar (SAR) ocean wind maps based on Envisat and Sentinel-1 with a brief description of the wind retrieval process and Advanced SCATterometer (ASCAT) ocean wind maps. The wind statistics at 10m and 100m height using an extrapolation procedure involving simulated long-term stability over oceans is presented for both SAR and ASCAT. Furthermore, the Weather Research and Forecasting (WRF) offshore wind atlas of NEWA is presented. This has 3 km grid resolution with data every 30 minutes during 30 years from 1989 to 2018, while ASCAT has 12.5 km and SAR has 2 km resolution. Offshore mean wind speed maps at 100 m height from ASCAT, SAR, WRF and ERA5 at a European scale are compared. A case study on offshore winds near Crete compares SAR and WRF for flow from north, west and all directions. The paper highlights the ability of the WRF model to simulate the overall European wind climatology and the near coastal winds constrained by the resolution of the coastal topography in the WRF model simulations.

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.

The Application of PS-InSAR Technology on Land Subsidence in Cangzhou Region

2011 ◽  
Vol 268-270 ◽  
pp. 1934-1939
Author(s):  
Kun Chao Lei ◽  
Hui Li Gong ◽  
Xiao Juan Li ◽  
Bei Bei Chen ◽  
Ji Wei Li ◽  
...  
Keyword(s):  
Synthetic Aperture Radar ◽  
Land Subsidence ◽  
Radar Data ◽  
Ground Movement ◽  
Synthetic Aperture ◽  
Interferometric Synthetic Aperture Radar ◽  
The North ◽  
Permanent Scatterers ◽  
Satellite Radar ◽  
Aperture Radar

Land subsidence in Cangzhou of the North China Plain, has been an ongoing problem for the past four decades (since the later 1970s). With the development of new synthetic aperture radar(SAR)sensors and interferometric synthetic aperture radar(InSAR) techniques, the application of satellite Radar data have enhanced capabilities to detect and monitor ground displacements with centimeter to millimeter precision at greater spatial detail and higher temporal resolution. We use Permanent Scatterers interferometric synthetic aperture radar（PS-InSAR）technology (Hooper, A.2004) to detect and measure ground movement in this area（from2004 to 2007）. Results of the cangzhou region study are reported and the utility of the InSAR methodology is discussed.

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