IGARSS 2022 - 2022 IEEE International Geoscience and Remote Sensing Symposium, Jul 17, 2022
In this work, the 2D parametric-solver algorithm [1] used to assess atmospheric stability from fl... more In this work, the 2D parametric-solver algorithm [1] used to assess atmospheric stability from floating Doppler wind lidar (FDWL) measurements is revisited. The algorithm performance is studied using data This research is part of the projects PGC2018-094132-B-I00 and MDM-2016-0600 ("CommSensLab" Excellence Unit) funded by Ministerio de Ciencia e Investigación (MCIN)/ Agencia Estatal de Investigación (AEI)/ 10.13039/501100011033/ FEDER "Una manera de hacer Europa". The work of M.P Araújo da Silva was supported under Grant PRE2018-086054 funded by MCIN/AEI/10.13039/501100011033 and FSE "El FSE invierte en tu futuro". The work of A. Salcedo-Bosch was supported under grant 2020 FISDU 00455 funded by Generalitat de Catalunya-AGAUR. The European Commission collaborated under projects H2020 ACTRIS-IMP (GA-871115) and H2020 ATMO-ACCESS (GA-101008004).
IGARSS 2022 - 2022 IEEE International Geoscience and Remote Sensing Symposium, Jul 17, 2022
This work studies the influence of the number of lidar measurement heights on the performance of ... more This work studies the influence of the number of lidar measurement heights on the performance of the floating Doppler wind lidar motion-correction algorithm, recently published by the authors. The work is in the context of offshore wind energy and continuous-wave focusable Zephir T M 300 lidar. A down-sampling technique applied over the lidar-measured wind speed time-series is used to simulate different height-sounding configurations. The operation of the filter under one, three, and five measurement heights of the lidar is studied by using data from El Pont del Petroli measurement campaign. The filter is proved to remove apparent turbulence addition in all three cases, showing a deterioration of statistical indicators as the number of sounding heights increase.
IGARSS 2022 - 2022 IEEE International Geoscience and Remote Sensing Symposium
We present preliminary research on a method to estimate Vertical Air Motion (VAM) at a particular... more We present preliminary research on a method to estimate Vertical Air Motion (VAM) at a particular height by comparing the measured rain-rate (RR) by a vertically-pointing S-band Frequency-Modulated Continuous-Wave (FMCW) radar with that of a ground-based disdrometer. The method is based on a constrained parametric solver, assuming high correlation between 5-min averaged rain rates measured by the radar and disdrometer. The method is tested over disdrometer and radar observations during the Verification of the ORigins Tornado EXperiment in South East US (VORTEX-SE) project. Finally, the results are partially validated by means of fitting a gamma distribution to the VAM-corrected DSD profiles and studying its parameters.
We revisit two recent methodologies based on Monin–Obukhov Similarity Theory (MOST), the 2D metho... more We revisit two recent methodologies based on Monin–Obukhov Similarity Theory (MOST), the 2D method and Hybrid-Wind (HW), which are aimed at estimation of the Obukhov length, friction velocity and kinematic heat flux within the surface layer. Both methods use wind-speed profile measurements only and their comparative performance requires assessment. Synthetic and observational data are used for their quantitative assessment. We also present a procedure to generate synthetic noise-corrupted wind profiles based on estimation of the probability density functions for MOST-related variables (e.g., friction velocity) and the statistics of the noise-corrupting perturbational amplitude found during an 82-day IJmuiden observational campaign. In the observational part of the study, 2D and HW parameter retrievals from floating Doppler wind lidar measurements are compared against those from a reference mast. Overall, the 2D algorithm outperformed the HW in the estimation of all the three paramet...
IGARSS 2020 - 2020 IEEE International Geoscience and Remote Sensing Symposium
This paper tackles atmospheric stability typing using a Zephyr TM 300 offshore Doppler Wind Lidar... more This paper tackles atmospheric stability typing using a Zephyr TM 300 offshore Doppler Wind Lidar in the context of its progressive acceptance in the offshore wind-energy industry. The lidar-retrieved wind-shear exponent, which is used as a proxy atmospheric stability, is compared against the wind-shear exponent and the potential temperature gradient both retrieved from reference metmast. A total sample of 4319 measurements is analysed from IJmuiden's test campaign, in the North Sea, from This work was supported via Spanish Government-European Regional Development Funds project PGC2018-094132-B-I00 and EU H2020 ACTRIS-2 (GA 654109). The European Institute of Innovation and Technology (EIT), KIC InnoEnergy project NEPTUNE (Offshore Metocean Data Measuring Equipment and Wind, Wave and Current Analysis and Forecasting Software, call FP7) supported measurements campaigns. CommSensLab is a Maríade-Maeztu Unit of Excellence funded by the Agencia Estatal de Investigación (Spanish National Science Foundation) that also funded the project MDM-2016-0600-18-1. Spanish NSF
This work presents an analytical formulation to assess the six-degrees-of-freedom-motion-induced ... more This work presents an analytical formulation to assess the six-degrees-of-freedom-motion-induced error in floating Doppler wind LiDARs (FDWLs). The error products derive from the horizontal wind speed bias and apparent turbulence intensity. Departing from a geometrical formulation of the FDWL attitude and of the LiDAR retrieval algorithm, the contributions of the rotational and translational motion to the FDWL-measured total error are computed. Central to this process is the interpretation of the velocity–azimuth display retrieval algorithm in terms of a first-order Fourier series. The obtained 6 DoF formulation is validated numerically by means of a floating LiDAR motion simulator and experimentally in nearshore and open-sea scenarios in the framework of the Pont del Petroli and IJmuiden campaigns, respectively. Both measurement campaigns involved a fixed and a floating ZephIRTM 300 LiDAR. The proposed formulation proved capable of estimating the motion-induced FDWL horizontal wind...
An enhanced filter for floating Doppler wind lidar motion correction is presented. The filter rel... more An enhanced filter for floating Doppler wind lidar motion correction is presented. The filter relies on an unscented Kalman filter prototype for floating-lidar motion correction without access to the internal line-of-sight measurements of the lidar. In the present work, we implement a new architecture based on two cooperative estimation filters and study the impact of different wind and initial scan phase models on the filter performance in the coastal environment of Barcelona. Two model combinations are considered: (i) a basic random walk model for both the wind turbulence and the initial scan phase and (ii) an auto-regressive model for wind turbulence along with a uniform circular motion model for the scan phase. The filter motion-correction performance using each of the above models was evaluated with reference to a fixed lidar in different wind and motion scenarios (low- and high-frequency turbulence cases) recorded during a 25-day campaign at “Pont del Petroli”, Barcelona, by c...
<p>In this work, we revisit the 2D parametric-solver algorithm [1] to estim... more <p>In this work, we revisit the 2D parametric-solver algorithm [1] to estimate the Obukhov length, and hence, determine atmospheric stability from floating Doppler wind lidar (FDWL) wind profiles. The algorithm fits the wind-profile model derived from Monin-Obukhov similarity theory to the FDWL-measured wind profile by means of a constrained non-linear least squares optimisation. Observational data were gathered at the IJmuiden test site in the North Sea (52.848 N, 3.436 E) between March and June of 2015. The reference Obukhov length was obtained via bulk Richardson number, which was estimated from IJmuiden-mast observations. Comparisons with the reference stability are performed by using a simplified atmospheric stability classification consisting of only three types, namely stable, neutral and unstable. Fairly similar results were obtained from the 2D-estimated and the mast-derived reference stability classifications for the stability behaviour during the time of day as well as for horizontal-wind-speed dependence on the stability type.</p><p>This research is part of the projects PGC2018-094132-B-I00 and MDM-2016-0600 (“CommSensLab” Excellence Unit) funded by Ministerio de Ciencia e Investigación (MCIN)/ Agencia Estatal de Investigación (AEI)/ 10.13039/501100011033/ FEDER “Una manera de hacer Europa”. The work of M.P Araujo da Silva was supported under Grant PRE2018-086054 funded by MCIN/AEI/ 10.13039/501100011033 and FSE “El FSE invierte en tu futuro. The work of A. Salcedo-Bosch was supported under grant 2020 FISDU 00455 funded by Generalitat de Catalunya—AGAUR. The European Commission collaborated under projects H2020 ACTRIS-IMP (GA-871115) and H2020 ATMO-ACCESS (GA-101008004).</p><p>[1] M. P. Araujo da Silva, F. Rocadenbosch, J. Farré-Guarné, A. Salcedo-Bosch, D. González-Marco, and A. Peña, “Assessing obukhov length and friction velocity from floating lidar observations: A data screening and sensitivity computation approach,” Remote Sensing, 2022, submitted.</p>
This work presents a parametric-solver algorithm for estimating atmospheric stability and frictio... more This work presents a parametric-solver algorithm for estimating atmospheric stability and friction velocity from floating Doppler wind lidar (FDWL) observations close to the mast of IJmuiden in the North Sea. The focus of the study was two-fold: (i) to examine the sensitivity of the computational algorithm to the retrieved variables and derived stability classes (the latter through confusion-matrix theory), and (ii) to present data screening procedures for FDWLs and fixed reference instrumentation. The performance of the stability estimation algorithm was assessed with reference to wind speed and temperature observations from the mast. A fixed-to-mast Doppler wind lidar (DWL) was also available, which provides a reference for wind-speed observations free from sea-motion perturbations. When comparing FDWL- and mast-derived mean wind speeds, the obtained determination coefficient was as high as that of the fixed-to-mast DWL against the mast (ρ2=0.996) with a root mean square error (RM...
IGARSS 2020 - 2020 IEEE International Geoscience and Remote Sensing Symposium, 2020
This paper proposes two methods to estimate the so-called “characteristic motional period” of a f... more This paper proposes two methods to estimate the so-called “characteristic motional period” of a floating wind-lidar buoy. These techniques aim to characterise the buoy's pitch and roll tilting as simple harmonic motions by estimating their period. The “peak method” (PM) and the “3-dB method” are introduced as two different aproaches to study the multi-modality of the wave motion. Additionally, the off-shore wind measurement campaign at Ijmuiden's is briefly introduced to contextualize where data comes from and the added value of this study.
<p>A wind retrieval simulator of a floating Doppler Wind Lidar (DWL) with six Degrees of Fr... more <p>A wind retrieval simulator of a floating Doppler Wind Lidar (DWL) with six Degrees of Freedom (DoF) in its motion is presented. The simulator considers a continuous-wave, conically scanning, floating DWL which retrieves the local wind profile from 50 line of sight (LoS) radial velocity measurements per scan. Rotational and translational motion effects over horizontal wind speed (HWS) measurements are studied parametrically. The 6 DoF motion framework as well as the most important buoy motion equations are based on the model presented in [1].</p><p>Each rotational and translational motion is simulated as 1 second sinusoidal signal defined by an amplitude, frequency and motion phase. In order to study the problem of motion-induced error on the retrieved HWS, a dimension reduction is needed (22 variables). A consideration followed in the literature [2] to alleviate the problem is to set the same motional frequency (f=0.3 Hz) for all DoF, a wind vector with constant HWS and null vertical wind speed (VWS). Moreover, the parametric study is carried out under certain constraints in order to finally reduce the problem dimensionality to three, which enables the generation of tri-dimensional colorplots of the error on the retrieved HWS.</p><p>Simulation results show that in the presence of motion, HWS error has a strong dependency on FDWL initial scan phase. Moreover, the directions of the rotation axis and translational velocity vector (with respect to wind direction, WD) show great impact on HWS error. For translational motion, a 3 DoF superposition principle is corroborated.</p><p>The simulator is as a useful tool for understanding particular lidar motion scenarios and their contributions to HWS measurements error. However, further analysis of the effect of lidar initial scan phase is needed. Additionally, these simulations are conducted under idealized assumptions of horizontally homogeneous wind profiles in the vicinity of the FDWL. Simulations using non-homogeneous wind fields (e.g., turbulence, air mass boundaries) would give insights on how well floating lidars can be expected to retrieve the wind profile in these common scenarios.</p><p><strong>Acknowledgements</strong></p><p>This work was supported via Spanish Government&#8211;European Regional Development Funds project PGC2018-094132-B-I00 and H2020 ACTRIS-IMP (GA-871115). The European Institute of Innovation and Technology (EIT), KIC InnoEnergy project NEPTUNE (Offshore Metocean Data Mea-suring Equipment and Wind, Wave and Current Analysis and ForecastingSoftware, call FP7) supported measurements campaigns. CommSensLab isa Mar&#237;a-de-Maeztu Unit of Excellence funded by the Agencia Estatal de Investigaci&#243;n (Spanish National Science Foundation). The work of Andreu Salcedo-Bosch was supported by the &#8220;Ag&#232;ncia de Gesti&#243; d&#8217;Ajuts Universitaris i de la Recerca (AGAUR)&#8221;, Generalitat de Catalunya, under Grant no. 2020 FISDU 00455.</p><p><strong>References</strong></p><p>[1] F. Kelberlau, V. Neshaug, L. L&#248;nseth, T. Bracchi, and J. Mann, &#8220;Taking the Motion out of Floating Lidar: Turbulence Intensity Estimates with a Continuous-Wave Wind Lidar,&#8221; Remote Sens., vol. 12, no. 898, 2020.</p><p>[2] J. Tiana-Alsina, F. Rocadenbosch, and M. A. Gutierrez-Antunano, &#8220;Vertical Azimuth Display simulator for wind-Doppler lidar error assessment,&#8221; in 2017 IEEE Int. Geosci. Remote. Se. (IGARSS). IEEE, Jul. 2017.</p>
IGARSS 2020 - 2020 IEEE International Geoscience and Remote Sensing Symposium, 2020
The standard deviation of the Horizontal Wind Speed as a proxy of wind turbulence is used to comp... more The standard deviation of the Horizontal Wind Speed as a proxy of wind turbulence is used to compare the apparent wind turbulence measured by an off-shore floating Doppler lidar to the one measured by a fixed lidar on a metmast. We use statistical analysis based on clustering the horizontal wind speed measured by the floating lidar as well as buoy angular amplitude and period under the approximation of harmonic motion. Three scenarios with different wave and wind conditions are discussed from the IJmuiden's test campaign (North Sea.).
This work proposes a new wave-period estimation (L-dB) method based on the power-spectral-density... more This work proposes a new wave-period estimation (L-dB) method based on the power-spectral-density (PSD) estimation of pitch and roll motional time series of a Doppler wind lidar buoy under the assumption of small angles (±22 deg) and slow yaw drifts (1 min), and the neglection of translational motion. We revisit the buoy’s simplified two-degrees-of-freedom (2-DoF) motional model and formulate the PSD associated with the eigenaxis tilt of the lidar buoy, which was modelled as a complex-number random process. From this, we present the L-dB method, which estimates the wave period as the average wavelength associated to the cutoff frequency span at which the spectral components drop off L decibels from the peak level. In the framework of the IJmuiden campaign (North Sea, 29 March–17 June 2015), the L-dB method is compared in reference to most common oceanographic wave-period estimation methods by using a TriaxysTM buoy. Parametric analysis showed good agreement (correlation coefficient,...
2021 IEEE International Geoscience and Remote Sensing Symposium IGARSS, 2021
This study presents a wind retrieval simulator of a floating Doppler Wind Lidar (DWL) with 6 Degr... more This study presents a wind retrieval simulator of a floating Doppler Wind Lidar (DWL) with 6 Degrees of Freedom (DoF) motion. The simulator considers a continuous-wave conical-scanning floating DWL which retrieves the wind vector from 50
This study presents a new method for correcting the six degrees of freedom motion-induced error i... more This study presents a new method for correcting the six degrees of freedom motion-induced error in ZephIR 300 floating Doppler Wind-LiDAR-derived data, based on a Robust Adaptive Unscented Kalman Filter. The filter takes advantage of the known floating Doppler Wind-LiDAR (FDWL) dynamics, a velocity–azimuth display algorithm, and a wind model describing the LiDAR-retrieved wind vector without motion influence. The filter estimates the corrected wind vector by adapting itself to different atmospheric and motion scenarios, and by estimating the covariance matrices of related noise processes. The measured turbulence intensity by the FDWL (with and without correction) was compared against a reference fixed LiDAR over a 25-day period at “El Pont del Petroli”, Barcelona. After correction, the apparent motion-induced turbulence was greatly reduced, and the statistical indicators showed overall improvement. Thus, the Mean Difference improved from −1.70% (uncorrected) to 0.36% (corrected), th...
2019 13th European Conference on Antennas and Propagation (EuCAP), 2019
Twist symmetry provides an additional degree of freedom to control the wave propagation in period... more Twist symmetry provides an additional degree of freedom to control the wave propagation in periodic structures. However, real twist-symmetric structures are cylindrical structures that have a high cost of manufacturing. In addition, they are not compatible with the available, low-cost and flat technologies, such as microstrip technology. Here, we investigate the possibility of mimicking the dispersion properties of twist symmetry in flat structures.
This work presents a new methodology to estimate the motion-induced standard deviation and relate... more This work presents a new methodology to estimate the motion-induced standard deviation and related turbulence intensity on the retrieved horizontal wind speed by means of the velocity-azimuth-display algorithm applied to the conical scanning pattern of a floating Doppler lidar. The method considers a ZephIR™300 continuous-wave focusable Doppler lidar and does not require access to individual line-of-sight radial-wind information along the scanning pattern. The method combines a software-based velocity-azimuth-display and motion simulator and a statistical recursive procedure to estimate the horizontal wind speed standard deviation—as a well as the turbulence intensity—due to floating lidar buoy motion. The motion-induced error is estimated from the simulator’s side by using basic motional parameters, namely, roll/pitch angular amplitude and period of the floating lidar buoy, as well as reference wind speed and direction measurements at the study height. The impact of buoy motion on ...
IGARSS 2022 - 2022 IEEE International Geoscience and Remote Sensing Symposium, Jul 17, 2022
In this work, the 2D parametric-solver algorithm [1] used to assess atmospheric stability from fl... more In this work, the 2D parametric-solver algorithm [1] used to assess atmospheric stability from floating Doppler wind lidar (FDWL) measurements is revisited. The algorithm performance is studied using data This research is part of the projects PGC2018-094132-B-I00 and MDM-2016-0600 ("CommSensLab" Excellence Unit) funded by Ministerio de Ciencia e Investigación (MCIN)/ Agencia Estatal de Investigación (AEI)/ 10.13039/501100011033/ FEDER "Una manera de hacer Europa". The work of M.P Araújo da Silva was supported under Grant PRE2018-086054 funded by MCIN/AEI/10.13039/501100011033 and FSE "El FSE invierte en tu futuro". The work of A. Salcedo-Bosch was supported under grant 2020 FISDU 00455 funded by Generalitat de Catalunya-AGAUR. The European Commission collaborated under projects H2020 ACTRIS-IMP (GA-871115) and H2020 ATMO-ACCESS (GA-101008004).
IGARSS 2022 - 2022 IEEE International Geoscience and Remote Sensing Symposium, Jul 17, 2022
This work studies the influence of the number of lidar measurement heights on the performance of ... more This work studies the influence of the number of lidar measurement heights on the performance of the floating Doppler wind lidar motion-correction algorithm, recently published by the authors. The work is in the context of offshore wind energy and continuous-wave focusable Zephir T M 300 lidar. A down-sampling technique applied over the lidar-measured wind speed time-series is used to simulate different height-sounding configurations. The operation of the filter under one, three, and five measurement heights of the lidar is studied by using data from El Pont del Petroli measurement campaign. The filter is proved to remove apparent turbulence addition in all three cases, showing a deterioration of statistical indicators as the number of sounding heights increase.
IGARSS 2022 - 2022 IEEE International Geoscience and Remote Sensing Symposium
We present preliminary research on a method to estimate Vertical Air Motion (VAM) at a particular... more We present preliminary research on a method to estimate Vertical Air Motion (VAM) at a particular height by comparing the measured rain-rate (RR) by a vertically-pointing S-band Frequency-Modulated Continuous-Wave (FMCW) radar with that of a ground-based disdrometer. The method is based on a constrained parametric solver, assuming high correlation between 5-min averaged rain rates measured by the radar and disdrometer. The method is tested over disdrometer and radar observations during the Verification of the ORigins Tornado EXperiment in South East US (VORTEX-SE) project. Finally, the results are partially validated by means of fitting a gamma distribution to the VAM-corrected DSD profiles and studying its parameters.
We revisit two recent methodologies based on Monin–Obukhov Similarity Theory (MOST), the 2D metho... more We revisit two recent methodologies based on Monin–Obukhov Similarity Theory (MOST), the 2D method and Hybrid-Wind (HW), which are aimed at estimation of the Obukhov length, friction velocity and kinematic heat flux within the surface layer. Both methods use wind-speed profile measurements only and their comparative performance requires assessment. Synthetic and observational data are used for their quantitative assessment. We also present a procedure to generate synthetic noise-corrupted wind profiles based on estimation of the probability density functions for MOST-related variables (e.g., friction velocity) and the statistics of the noise-corrupting perturbational amplitude found during an 82-day IJmuiden observational campaign. In the observational part of the study, 2D and HW parameter retrievals from floating Doppler wind lidar measurements are compared against those from a reference mast. Overall, the 2D algorithm outperformed the HW in the estimation of all the three paramet...
IGARSS 2020 - 2020 IEEE International Geoscience and Remote Sensing Symposium
This paper tackles atmospheric stability typing using a Zephyr TM 300 offshore Doppler Wind Lidar... more This paper tackles atmospheric stability typing using a Zephyr TM 300 offshore Doppler Wind Lidar in the context of its progressive acceptance in the offshore wind-energy industry. The lidar-retrieved wind-shear exponent, which is used as a proxy atmospheric stability, is compared against the wind-shear exponent and the potential temperature gradient both retrieved from reference metmast. A total sample of 4319 measurements is analysed from IJmuiden's test campaign, in the North Sea, from This work was supported via Spanish Government-European Regional Development Funds project PGC2018-094132-B-I00 and EU H2020 ACTRIS-2 (GA 654109). The European Institute of Innovation and Technology (EIT), KIC InnoEnergy project NEPTUNE (Offshore Metocean Data Measuring Equipment and Wind, Wave and Current Analysis and Forecasting Software, call FP7) supported measurements campaigns. CommSensLab is a Maríade-Maeztu Unit of Excellence funded by the Agencia Estatal de Investigación (Spanish National Science Foundation) that also funded the project MDM-2016-0600-18-1. Spanish NSF
This work presents an analytical formulation to assess the six-degrees-of-freedom-motion-induced ... more This work presents an analytical formulation to assess the six-degrees-of-freedom-motion-induced error in floating Doppler wind LiDARs (FDWLs). The error products derive from the horizontal wind speed bias and apparent turbulence intensity. Departing from a geometrical formulation of the FDWL attitude and of the LiDAR retrieval algorithm, the contributions of the rotational and translational motion to the FDWL-measured total error are computed. Central to this process is the interpretation of the velocity–azimuth display retrieval algorithm in terms of a first-order Fourier series. The obtained 6 DoF formulation is validated numerically by means of a floating LiDAR motion simulator and experimentally in nearshore and open-sea scenarios in the framework of the Pont del Petroli and IJmuiden campaigns, respectively. Both measurement campaigns involved a fixed and a floating ZephIRTM 300 LiDAR. The proposed formulation proved capable of estimating the motion-induced FDWL horizontal wind...
An enhanced filter for floating Doppler wind lidar motion correction is presented. The filter rel... more An enhanced filter for floating Doppler wind lidar motion correction is presented. The filter relies on an unscented Kalman filter prototype for floating-lidar motion correction without access to the internal line-of-sight measurements of the lidar. In the present work, we implement a new architecture based on two cooperative estimation filters and study the impact of different wind and initial scan phase models on the filter performance in the coastal environment of Barcelona. Two model combinations are considered: (i) a basic random walk model for both the wind turbulence and the initial scan phase and (ii) an auto-regressive model for wind turbulence along with a uniform circular motion model for the scan phase. The filter motion-correction performance using each of the above models was evaluated with reference to a fixed lidar in different wind and motion scenarios (low- and high-frequency turbulence cases) recorded during a 25-day campaign at “Pont del Petroli”, Barcelona, by c...
&amp;lt;p&amp;gt;In this work, we revisit the 2D parametric-solver algorithm [1] to estim... more &amp;lt;p&amp;gt;In this work, we revisit the 2D parametric-solver algorithm [1] to estimate the Obukhov length, and hence, determine atmospheric stability from floating Doppler wind lidar (FDWL) wind profiles. The algorithm fits the wind-profile model derived from Monin-Obukhov similarity theory to the FDWL-measured wind profile by means of a constrained non-linear least squares optimisation. Observational data were gathered at the IJmuiden test site in the North Sea (52.848 N, 3.436 E) between March and June of 2015. The reference Obukhov length was obtained via bulk Richardson number, which was estimated from IJmuiden-mast observations. Comparisons with the reference stability are performed by using a simplified atmospheric stability classification consisting of only three types, namely stable, neutral and unstable. Fairly similar results were obtained from the 2D-estimated and the mast-derived reference stability classifications for the stability behaviour during the time of day as well as for horizontal-wind-speed dependence on the stability type.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;This research is part of the projects PGC2018-094132-B-I00 and MDM-2016-0600 (&amp;amp;#8220;CommSensLab&amp;amp;#8221; Excellence Unit) funded by Ministerio de Ciencia e Investigaci&amp;amp;#243;n (MCIN)/ Agencia Estatal de Investigaci&amp;amp;#243;n (AEI)/ 10.13039/501100011033/ FEDER &amp;amp;#8220;Una manera de hacer Europa&amp;amp;#8221;. The work of M.P Araujo da Silva was supported under Grant PRE2018-086054 funded by MCIN/AEI/ 10.13039/501100011033 and FSE &amp;amp;#8220;El FSE invierte en tu futuro. The work of A. Salcedo-Bosch was supported under grant 2020 FISDU 00455 funded by Generalitat de Catalunya&amp;amp;#8212;AGAUR. The European Commission collaborated under projects H2020 ACTRIS-IMP (GA-871115) and H2020 ATMO-ACCESS (GA-101008004).&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;[1] M. P. Araujo da Silva, F. Rocadenbosch, J. Farr&amp;amp;#233;-Guarn&amp;amp;#233;, A. Salcedo-Bosch, D. Gonz&amp;amp;#225;lez-Marco, and A. Pe&amp;amp;#241;a, &amp;amp;#8220;Assessing obukhov length and friction velocity from floating lidar observations: A data screening and sensitivity computation approach,&amp;amp;#8221; Remote Sensing, 2022, submitted.&amp;lt;/p&amp;gt;
This work presents a parametric-solver algorithm for estimating atmospheric stability and frictio... more This work presents a parametric-solver algorithm for estimating atmospheric stability and friction velocity from floating Doppler wind lidar (FDWL) observations close to the mast of IJmuiden in the North Sea. The focus of the study was two-fold: (i) to examine the sensitivity of the computational algorithm to the retrieved variables and derived stability classes (the latter through confusion-matrix theory), and (ii) to present data screening procedures for FDWLs and fixed reference instrumentation. The performance of the stability estimation algorithm was assessed with reference to wind speed and temperature observations from the mast. A fixed-to-mast Doppler wind lidar (DWL) was also available, which provides a reference for wind-speed observations free from sea-motion perturbations. When comparing FDWL- and mast-derived mean wind speeds, the obtained determination coefficient was as high as that of the fixed-to-mast DWL against the mast (ρ2=0.996) with a root mean square error (RM...
IGARSS 2020 - 2020 IEEE International Geoscience and Remote Sensing Symposium, 2020
This paper proposes two methods to estimate the so-called “characteristic motional period” of a f... more This paper proposes two methods to estimate the so-called “characteristic motional period” of a floating wind-lidar buoy. These techniques aim to characterise the buoy's pitch and roll tilting as simple harmonic motions by estimating their period. The “peak method” (PM) and the “3-dB method” are introduced as two different aproaches to study the multi-modality of the wave motion. Additionally, the off-shore wind measurement campaign at Ijmuiden's is briefly introduced to contextualize where data comes from and the added value of this study.
<p>A wind retrieval simulator of a floating Doppler Wind Lidar (DWL) with six Degrees of Fr... more <p>A wind retrieval simulator of a floating Doppler Wind Lidar (DWL) with six Degrees of Freedom (DoF) in its motion is presented. The simulator considers a continuous-wave, conically scanning, floating DWL which retrieves the local wind profile from 50 line of sight (LoS) radial velocity measurements per scan. Rotational and translational motion effects over horizontal wind speed (HWS) measurements are studied parametrically. The 6 DoF motion framework as well as the most important buoy motion equations are based on the model presented in [1].</p><p>Each rotational and translational motion is simulated as 1 second sinusoidal signal defined by an amplitude, frequency and motion phase. In order to study the problem of motion-induced error on the retrieved HWS, a dimension reduction is needed (22 variables). A consideration followed in the literature [2] to alleviate the problem is to set the same motional frequency (f=0.3 Hz) for all DoF, a wind vector with constant HWS and null vertical wind speed (VWS). Moreover, the parametric study is carried out under certain constraints in order to finally reduce the problem dimensionality to three, which enables the generation of tri-dimensional colorplots of the error on the retrieved HWS.</p><p>Simulation results show that in the presence of motion, HWS error has a strong dependency on FDWL initial scan phase. Moreover, the directions of the rotation axis and translational velocity vector (with respect to wind direction, WD) show great impact on HWS error. For translational motion, a 3 DoF superposition principle is corroborated.</p><p>The simulator is as a useful tool for understanding particular lidar motion scenarios and their contributions to HWS measurements error. However, further analysis of the effect of lidar initial scan phase is needed. Additionally, these simulations are conducted under idealized assumptions of horizontally homogeneous wind profiles in the vicinity of the FDWL. Simulations using non-homogeneous wind fields (e.g., turbulence, air mass boundaries) would give insights on how well floating lidars can be expected to retrieve the wind profile in these common scenarios.</p><p><strong>Acknowledgements</strong></p><p>This work was supported via Spanish Government&#8211;European Regional Development Funds project PGC2018-094132-B-I00 and H2020 ACTRIS-IMP (GA-871115). The European Institute of Innovation and Technology (EIT), KIC InnoEnergy project NEPTUNE (Offshore Metocean Data Mea-suring Equipment and Wind, Wave and Current Analysis and ForecastingSoftware, call FP7) supported measurements campaigns. CommSensLab isa Mar&#237;a-de-Maeztu Unit of Excellence funded by the Agencia Estatal de Investigaci&#243;n (Spanish National Science Foundation). The work of Andreu Salcedo-Bosch was supported by the &#8220;Ag&#232;ncia de Gesti&#243; d&#8217;Ajuts Universitaris i de la Recerca (AGAUR)&#8221;, Generalitat de Catalunya, under Grant no. 2020 FISDU 00455.</p><p><strong>References</strong></p><p>[1] F. Kelberlau, V. Neshaug, L. L&#248;nseth, T. Bracchi, and J. Mann, &#8220;Taking the Motion out of Floating Lidar: Turbulence Intensity Estimates with a Continuous-Wave Wind Lidar,&#8221; Remote Sens., vol. 12, no. 898, 2020.</p><p>[2] J. Tiana-Alsina, F. Rocadenbosch, and M. A. Gutierrez-Antunano, &#8220;Vertical Azimuth Display simulator for wind-Doppler lidar error assessment,&#8221; in 2017 IEEE Int. Geosci. Remote. Se. (IGARSS). IEEE, Jul. 2017.</p>
IGARSS 2020 - 2020 IEEE International Geoscience and Remote Sensing Symposium, 2020
The standard deviation of the Horizontal Wind Speed as a proxy of wind turbulence is used to comp... more The standard deviation of the Horizontal Wind Speed as a proxy of wind turbulence is used to compare the apparent wind turbulence measured by an off-shore floating Doppler lidar to the one measured by a fixed lidar on a metmast. We use statistical analysis based on clustering the horizontal wind speed measured by the floating lidar as well as buoy angular amplitude and period under the approximation of harmonic motion. Three scenarios with different wave and wind conditions are discussed from the IJmuiden's test campaign (North Sea.).
This work proposes a new wave-period estimation (L-dB) method based on the power-spectral-density... more This work proposes a new wave-period estimation (L-dB) method based on the power-spectral-density (PSD) estimation of pitch and roll motional time series of a Doppler wind lidar buoy under the assumption of small angles (±22 deg) and slow yaw drifts (1 min), and the neglection of translational motion. We revisit the buoy’s simplified two-degrees-of-freedom (2-DoF) motional model and formulate the PSD associated with the eigenaxis tilt of the lidar buoy, which was modelled as a complex-number random process. From this, we present the L-dB method, which estimates the wave period as the average wavelength associated to the cutoff frequency span at which the spectral components drop off L decibels from the peak level. In the framework of the IJmuiden campaign (North Sea, 29 March–17 June 2015), the L-dB method is compared in reference to most common oceanographic wave-period estimation methods by using a TriaxysTM buoy. Parametric analysis showed good agreement (correlation coefficient,...
2021 IEEE International Geoscience and Remote Sensing Symposium IGARSS, 2021
This study presents a wind retrieval simulator of a floating Doppler Wind Lidar (DWL) with 6 Degr... more This study presents a wind retrieval simulator of a floating Doppler Wind Lidar (DWL) with 6 Degrees of Freedom (DoF) motion. The simulator considers a continuous-wave conical-scanning floating DWL which retrieves the wind vector from 50
This study presents a new method for correcting the six degrees of freedom motion-induced error i... more This study presents a new method for correcting the six degrees of freedom motion-induced error in ZephIR 300 floating Doppler Wind-LiDAR-derived data, based on a Robust Adaptive Unscented Kalman Filter. The filter takes advantage of the known floating Doppler Wind-LiDAR (FDWL) dynamics, a velocity–azimuth display algorithm, and a wind model describing the LiDAR-retrieved wind vector without motion influence. The filter estimates the corrected wind vector by adapting itself to different atmospheric and motion scenarios, and by estimating the covariance matrices of related noise processes. The measured turbulence intensity by the FDWL (with and without correction) was compared against a reference fixed LiDAR over a 25-day period at “El Pont del Petroli”, Barcelona. After correction, the apparent motion-induced turbulence was greatly reduced, and the statistical indicators showed overall improvement. Thus, the Mean Difference improved from −1.70% (uncorrected) to 0.36% (corrected), th...
2019 13th European Conference on Antennas and Propagation (EuCAP), 2019
Twist symmetry provides an additional degree of freedom to control the wave propagation in period... more Twist symmetry provides an additional degree of freedom to control the wave propagation in periodic structures. However, real twist-symmetric structures are cylindrical structures that have a high cost of manufacturing. In addition, they are not compatible with the available, low-cost and flat technologies, such as microstrip technology. Here, we investigate the possibility of mimicking the dispersion properties of twist symmetry in flat structures.
This work presents a new methodology to estimate the motion-induced standard deviation and relate... more This work presents a new methodology to estimate the motion-induced standard deviation and related turbulence intensity on the retrieved horizontal wind speed by means of the velocity-azimuth-display algorithm applied to the conical scanning pattern of a floating Doppler lidar. The method considers a ZephIR™300 continuous-wave focusable Doppler lidar and does not require access to individual line-of-sight radial-wind information along the scanning pattern. The method combines a software-based velocity-azimuth-display and motion simulator and a statistical recursive procedure to estimate the horizontal wind speed standard deviation—as a well as the turbulence intensity—due to floating lidar buoy motion. The motion-induced error is estimated from the simulator’s side by using basic motional parameters, namely, roll/pitch angular amplitude and period of the floating lidar buoy, as well as reference wind speed and direction measurements at the study height. The impact of buoy motion on ...
Uploads
Papers by Andreu Salcedo