Towards the Sea Wind Measurement with the Airborne Scatterometer Having the Rotating-Beam Antenna Mounted over Fuselage

Nekrasov, Alexey; Khachaturian, Alena B.

doi:10.3390/rs13245165

Cited by 6 publications

(6 citation statements)

References 34 publications

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“…This scheme supports normalized radar cross sections (NRCSs) of the underlying surface with an entire azimuth observation from 0° to 360° at an incidence angle of interest that reveals its azimuthal features and enables reliable sea wind retrieval using an appropriate sea water geophysical model function (GMF) [12,13,15]. In previous research, we evaluated sea wind retrieval capability with a circular measurement scheme at incidence angles of 30° to 60° by airborne rotating beam scatterometers in rectilinear flight [16][17][18] and in circular flight by an FM-CW (Frequency Modulated Continuous Wave) millimeter wave demonstrator system [19], Doppler navigation system [20,21], and airborne weather radar [22,23]. These earlier studies proved the feasibility of the circular observation scheme for retrieval of sea surface winds by airborne scatterometer instruments and the scheme's applicability.…”

mentioning

confidence: 79%

Using Semicircular Sampling to Increase Sea Water/Ice Discrimination Altitude

Nekrasov,

Khachaturian,

Fidge

2024

Emerg Sci J

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The rapid development of aircraft and unmanned aerial vehicles (UAV) increases their use, including in polar areas, which are characterized by their remoteness and rather harsh conditions. The dominant trends in airborne radar development are expanding their functionality and increasing the altitude of their applicability. Our study focuses on the functionality enhancement of airborne high-altitude conical scanning radars currently used for circular clouds and precipitation observations as well as for sea wind measurements. Recently, we showed how a semicircular observation scheme, instead of a circular one, can double the maximum applicable altitude of sea wind measurements made with such radars. Here we apply this approach to show how an airborne high-altitude conical scanning radar’s functionality can also be expanded for sea water/ice discrimination within a semicircular observation scheme, again doubling the maximum discrimination altitude compared to circular observations. The discrimination is performed in scatterometer mode using the minimum statistical distance of the measured normalized radar cross sections (NRCSs) to the geophysical model functions (GMFs) of the sea water and ice underlying surfaces. However, as no sea ice GMF is available for the considered horizontal transmit and receive polarization at the Ku band, we instead used a substitute sea ice GMF having the same azimuth isotropic property setting for its NRCSs as the averaged value of the measured azimuth NRCSs within the semicircular observations scheme. Our analysis found that incidence angles of 30°, 45°, and 60° are well suited to our sea water/ice discrimination method, and that incidence angles higher than 30° are preferable as they provide a higher difference in the statistical distance of the measured NRCSs to the sea ice and water GMFs, whereas an incidence angle of 30° provides the highest applicable altitude for sea water/ice discrimination and wind retrieval. We also demonstrated the ability of the sea water/ice discrimination procedure’s implementation for any airborne wind scatterometer or multimode radar operated in scatterometer mode over freezing seas to avoid entirely erroneous sea wind measurement results when a sea ice surface is observed. The obtained results can also be used for enhancing aircraft and UAV radars and for developing new remote sensing systems. Doi: 10.28991/ESJ-2024-08-02-07 Full Text: PDF

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confidence: 79%

Using Semicircular Sampling to Increase Sea Water/Ice Discrimination Altitude

Nekrasov,

Khachaturian,

Fidge

2024

Emerg Sci J

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“…Airborne scatterometers (or multimode radars with a scatterometer mode) have a fixed-beam antenna [ 17 , 18 , 19 , 20 ], scanning antenna [ 21 , 22 , 23 ], or rotating-beam antenna [ 12 , 24 , 25 , 26 , 27 , 28 ]. Mostly, antennas rotating in the horizontal plane are installed on the bottom or under the fuselage.…”

Section: Introductionmentioning

confidence: 99%

“…Scatterometers with a fixed-beam antenna require the measurements to be on a circular ground track [ 19 , 20 , 29 ]. On the contrary, scatterometers with scanning [ 30 , 31 , 32 ] or rotating-beam [ 12 , 27 ] antennas require the measurements to be on a rectilinear ground track.…”

Section: Introductionmentioning

confidence: 99%

Optimization of the NRCS Sampling at the Sea Wind Retrieval by the Airborne Rotating-Beam Scatterometer Mounted under Fuselage

Nekrasov

Khachaturian

Vorobev

2022

Sensors

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The optimization of normalized radar cross-section (NRCS) sampling by a scatterometer allows an increase in the accuracy of the wind retrieval over the water surface and a decrease in the time of the measurement. Here, we investigate the possibility of improving wind vector measurement with an airborne rotating-beam scatterometer mounted under the fuselage. For this purpose, we investigated NRCS sampling at various incidence angles, and the possibility of using NRCS samples obtained during simultaneous measurement at different incidence angles to perform wind retrieval. The proposed wind algorithms are based on a geophysical model function (GMF). Sea wind retrieval was carried out using Monte Carlo simulations with consideration of a single incidence angle or combinations of several incidence angles. The incidence angles of interest were 30°, 35°, 40°, 45°, 50°, 55°, and 60°. The simulation showed that the wind speed error decreased with an increase in the incidence angle, and the wind direction error tended to decrease with an increase in the incidence angle. The single incidence angle case is characterized by higher maximum wind retrieval errors but allows for a higher maximum altitude of the wind retrieval method’s applicability to be achieved. The use of several neighboring incidence angles allows a better wind vector retrieval accuracy to be achieved. The combinations of three and four incidence angles provided the lowest maximum wind speed and direction errors in the range of the incidence angles from 45° to 60° but, unfortunately, provide the lowest maximum altitude of applicability of the wind retrieval method. At the same time, the combination of two incidence angles is characterized by slightly higher maximum wind retrieval errors than in the cases of three and four incidence angles, but they are lower than in the case of the single incidence angle. Moreover, the two incidence angles’ combination is a simpler way to decrease the wind retrieval errors, especially for measurement near an incidence angle of 30°, providing nearly the highest maximum altitude of the wind retrieval method applicability. The results obtained can be used to enhance existing airborne radars and in the development of new remote sensing systems.

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“…In previous literature, the beam axis is considered collinear to the rotation center [10,11]. Since their potential engineering background may be helicopter rotor blades [12], aircraft engine [13], robotic manipulators, and turbine blades [14,15]. For the machine gun system, considering the rotating beam with an axis eccentricity is more appropriate.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of a multi-pulse excited rotating beam system

Hua

2022

Preprint

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The periodic motion characteristic is crucial for the firing accuracy of the machine gun system. In this study, a demonstrated machine gun system is simplified as a rotating beam system to study its periodic motion characteristic under a multi-pulsed excitation. Unlike the previously rotating beam model, the beam axis and the rotation center are non-collinear. The nonlinear coupled dynamic model of the system is derived by Rayleigh-Ritz method and Lagrange equation, and the dynamic responses are analyzed using Runge-Kutta method. Based on the computed responses, the effect of rotating radius, beam length, torsional stiffness and damping on system dynamic behavior are analyzed and discussed. Results reveal that increasing the rotating radius and beam length could affect the periodic motion of the system gradually. Increasing the torsional stiffness could enhance the periodic motion characteristic of the rotating beam system. The quasi-periodic motion characterized of the system could be dominated by matching the torsional damping.

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Towards the Sea Wind Measurement with the Airborne Scatterometer Having the Rotating-Beam Antenna Mounted over Fuselage

Cited by 6 publications

References 34 publications

Using Semicircular Sampling to Increase Sea Water/Ice Discrimination Altitude

Using Semicircular Sampling to Increase Sea Water/Ice Discrimination Altitude

Optimization of the NRCS Sampling at the Sea Wind Retrieval by the Airborne Rotating-Beam Scatterometer Mounted under Fuselage

Dynamics of a multi-pulse excited rotating beam system

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