A new Doppler frequency anomaly algorithm for surface current measurement with SAR

2021 ◽  
Author(s):  
Lihua Wang ◽  
Yanghua Gao ◽  
Peng Lu ◽  
Li Fan ◽  
Yunxuan Zhou
Keyword(s):  
Surface Current ◽  
Doppler Frequency ◽  
Current Measurement

Assessment of the sea surface wind and current retrieval from ALOS-2 and Sentinel-1 SAR data over coastal areas

2021 ◽  
Author(s):  
Anis Elyouncha ◽  
Leif E. B. Eriksson
Keyword(s):  
Wind Speed ◽  
Frequency Shift ◽  
Doppler Shift ◽  
Surface Wind ◽  
Surface Current ◽  
Doppler Frequency ◽  
Doppler Frequency Shift ◽  
Sea Surface ◽  
Surface Velocity ◽  
L Band

<p><span>Synthetic aperture radar (SAR) has become an essential component in ocean remote sensing due it’s </span><span>high</span> <span>sensitivity</span><span> to sea surface dynamics and its high spatial resolution. </span><span>The ALOS-</span><span>2 SAR</span><span> data are </span> underutilized <span>for</span><span> ocean surface wind and current retrieval. Althou</span><span>g</span><span>h the primary goals of the </span><span>ALOS-2</span><span> mission are focused on land applications, the extension of the satellite scenes over the coast</span><span>al areas</span><span> offers an opportunity for ocean applications. Th</span><span>e</span><span> underutilization </span><span>of ALOS-2 data </span><span>is mainly due to the fact that at low radar frequencies, e.g. L-band, the sensitivity of the radar scattering coefficient to wind speed and the sensitivity of the Doppler frequency shift to sea surface velocity is lower than at higher frequencies, e.g. C- </span><span>and</span><span> X-</span><span>band</span><span>. </span><span>This is also due to the fact that most of ALOS-2 images are acquired in HH or HV polarization while the VV polarization is often preferred in ocean applications due the higher signal to noise ratio. </span></p><p>The wind speed is retrieved from Sentinel-1 and ALOS-2 using the existing empirical C- and L-band geophysical model functions. For Sentinel-1, the Doppler frequency shift provided in the OCN product is used. For ALOS-2, the Doppler frequency shift is estimated from the single look complex data using the pulse-pair processing method. The estimated Doppler shift converted to the surface radial velocity and the velocity is calibrated using land as a reference. The estimated L-band Doppler shift and surface velocity is compared to the C-band Doppler shift provided in the Sentinel-1 OCN product. Due the difference in the local time of ascending node (about 6 hours at the equator) of the two satellites, a direct pixel-by-pixel comparison is not possible, i.e. the wind and surface current can not be assumed to be constant during such a large time difference. Thus, the retrieved wind from each sensor is compared separately to model data and in-situ observations.</p><p>In this paper, the quality of the wind speed retrieved from the L-band SAR (ALOS-2) in coastal areas is assessed and compared to the C-band SAR (Sentinel-1). In addition, the feasibility of the surface current retrieval from the L-band Doppler frequency shift is investigated and also compared to Sentinel-1. Examples will be shown and discussed. This opens an opportunity for synergy between L-band and C-band SAR missions to increase the spatial and temporal coverage, which is one of the main limitations of SAR application in ocean remote sensing.</p>

Near-surface current measurement from a surface following data buoy (DB1)—I

1978 ◽  
Vol 5 (3) ◽  
pp. 181-196 ◽  
Author(s):  
P.G. Collar
Keyword(s):  
Surface Current ◽  
Current Measurement ◽  
Near Surface

Wave and surface current measurement with HF radar in the central east coast of Korea

2014 ◽  
Vol 38 (6) ◽  
pp. 771-780
Author(s):  
Moo-Hong Kim ◽  
Gyung-Soo Kim ◽  
Hyeon-Seong Kim
Keyword(s):  
East Coast ◽  
Surface Current ◽  
Current Measurement ◽  
Hf Radar

Enhancement of the normalized scalar product method for surface current measurement using nautical radar

2012 Oceans ◽  
2012 ◽  
Author(s):  
Weimin Huang ◽  
Eric W. Gill ◽  
Zhifeng Zhong
Keyword(s):  
Scalar Product ◽  
Surface Current ◽  
Current Measurement ◽  
Product Method

A New Azimuth Ambiguity Suppression Algorithm for Surface Current Measurement in Coastal Waters and Rivers With Along-track InSAR

2019 ◽  
Vol 57 (6) ◽  
pp. 3148-3165
Author(s):  
Baochang Liu ◽  
Yijun He ◽  
Yongkang Li ◽  
Heyang Duan ◽  
Xin Song
Keyword(s):  
Coastal Waters ◽  
Surface Current ◽  
Current Measurement ◽  
Along Track

Sea surface current measurement with Ku-band SAR along-track interferometry

2011 ◽  
Author(s):  
Nobuo Kumagae ◽  
Kazuo Kawamura ◽  
Kenji Tatsumi ◽  
Masatada Furuhata ◽  
Masayoshi Tsuchida ◽  
...  
Keyword(s):  
Surface Current ◽  
Current Measurement ◽  
Sea Surface ◽  
Along Track ◽  
Ku Band

scholarly journals Ocean Surface Current Observation with a Dual Monopole-Cross-Loop Antenna Array

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Yeping Lai ◽  
Hao Zhou ◽  
Yuming Zeng ◽  
Biyang Wen
Keyword(s):  
Antenna Array ◽  
Surface Current ◽  
Ocean Surface ◽  
Antenna System ◽  
Current Measurement ◽  
Current Profile ◽  
Current Observation ◽  
Ocean Surface Currents ◽  
Ocean Surface Current

The high-frequency radars (HFRs) receiving the sea echoes backscattered from the fluctuating ocean surface to remotely sense ocean surface currents are a popular and powerful tool in oceanic observation. Dominant error source in current measurement for HFR systems has been recognized to be the direction of arrival (DOA) determination of the sea echoes. To eliminate this error and therefore improve the performance of direction-finding HFR system in current measurement, we have investigated a dual monopole-cross-loop (MCL) antenna array in current observation. Simulations indicated that the dual MCL antenna array has a better performance than the conventional single MCL antenna system in current mapping, especially for the complex current profile. And comparisons of radar field data and buoy measurements suggested that the RMSE value was larger than 15 cm/s for the conventional MCL antenna. But it decreased to 12.64 cm/s for the dual MCL antenna array. Moreover, the temporal coverage rate also showed the benefit of using this antenna system in current mapping. The results demonstrated that it is advisable to adopt the dual MCL antenna array in operational applications.

The Feasibility of Ocean Surface Current Measurement Using Pencil-Beam Rotating Scatterometer

2015 ◽  
Vol 8 (7) ◽  
pp. 3441-3451 ◽  
Author(s):  
Qingliu Bao ◽  
Xiaolong Dong ◽  
Di Zhu ◽  
Shuyan Lang ◽  
Xingou Xu
Keyword(s):  
Surface Current ◽  
Ocean Surface ◽  
Current Measurement ◽  
Pencil Beam ◽  
Ocean Surface Current
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