Jakob Mann
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View article: Squeezing turbulence statistics out of a pulsed Doppler lidar
Squeezing turbulence statistics out of a pulsed Doppler lidar Open
Accurate estimation of second-order turbulence statistics using pulsed Doppler lidar has been a challenge for a long time, mainly due to the negative influence of probe volume averaging. The present study aims to investigate a novel approa…
View article: The LOLland offshore Lidar EXperiment (LOLLEX): A novel observational approach for the study of wind farm flow and entrainment
The LOLland offshore Lidar EXperiment (LOLLEX): A novel observational approach for the study of wind farm flow and entrainment Open
Vertical momentum entrainment above offshore wind farms plays a key role in the recovery of wind turbine and wind farm wakes but remains poorly documented by field measurements. The LOLland offshore Lidar EXperiment (LOLLEX) campaign intro…
View article: Measurement of turbulence energy dissipation rate by a standalone high-resolution Doppler lidar
Measurement of turbulence energy dissipation rate by a standalone high-resolution Doppler lidar Open
A second-order structure function model for the lidar line of sight (LOS) velocities is proposed. This structure function model corrects for the turbulence filtering due to the probe volume averaging effect using a Gaussian weighting funct…
View article: Aerodynamic admittance and dynamics of an open-grown tree
Aerodynamic admittance and dynamics of an open-grown tree Open
View article: Improving Wind Speed Availability of a Six-Beam Doppler Lidar
Improving Wind Speed Availability of a Six-Beam Doppler Lidar Open
A simple adaptive variant of the Doppler Beam Swinging (DBS) method is presented to enhance the availability of wind velocity measurements in profiling lidars. The adaptive method dynamically selects beams with sufficient signal-to-noise r…
View article: Squeezing Turbulence Statistics out of a Pulsed Lidar
Squeezing Turbulence Statistics out of a Pulsed Lidar Open
Accurate estimation of second-order turbulence statistics using pulsed Doppler lidar has been a challenge for a long time, mainly due to the negative influence of probe volume averaging. The present study aims to investigate a novel approa…
View article: A perspective on lessons learned and future needs for wind energy field campaigns
A perspective on lessons learned and future needs for wind energy field campaigns Open
This perspective paper provides motivation and guidance to the wind energy community for suggested future investments and a long-term strategy for wind-energy-related field campaigns that will provide much-needed observations for improving…
View article: Exploring dual-lidar mean and turbulence measurements over Perdigão's complex terrain
Exploring dual-lidar mean and turbulence measurements over Perdigão's complex terrain Open
To assess the accuracy of lidars in measuring mean wind speed and turbulence at large distances above the ground as an alternative to tall and expensive meteorological towers, we evaluated three dual-lidar measurements in virtual-mast (VM)…
View article: Aerodynamic Admittance and Dynamics of an Open-Grown Tree
Aerodynamic Admittance and Dynamics of an Open-Grown Tree Open
View article: Simulating low-frequency wind fluctuations
Simulating low-frequency wind fluctuations Open
Large-scale flow structures are vital in influencing the dynamic response of floating wind turbines and wake meandering behind large offshore wind turbines. It is imperative that we develop an inflow wind turbulence model capable of replic…
View article: Uncertainty and bias on velocities determined from an arc-scanning lidar
Uncertainty and bias on velocities determined from an arc-scanning lidar Open
Accurate determination of wind speed offshore is important for the progression of offshore wind energy. Arc-scanning lidars offer precise measurements of both wind speed and direction. They can be placed on a fixed footing, such as a trans…
View article: Impact of floating turbine motion on nacelle lidar turbulence measurements
Impact of floating turbine motion on nacelle lidar turbulence measurements Open
We determine the impact of floating turbine motion on turbulence measurements from a four-beam lidar by emulating its scanning configuration and retrievals within atmospheric turbulence boxes. Since the elevation angle of the lidar beams i…
View article: Impact of low-frequency fluctuations on loads of a fixed-bottom offshore reference wind turbine
Impact of low-frequency fluctuations on loads of a fixed-bottom offshore reference wind turbine Open
Marine atmospheric turbulence is predominantly characterized by large-scale structures associated with low-frequency wind turbulence. However, conventional turbulence models for assessing wind turbine loads often fall short of adequately i…
View article: Rotary-wing drone-induced flow – comparison of simulations with lidar measurements
Rotary-wing drone-induced flow – comparison of simulations with lidar measurements Open
Ultrasonic anemometers mounted on rotary-wing drones have the potential to provide a cost-efficient alternative to the classical meteorological mast-mounted counterpart for atmospheric boundary layer research. However, the propeller-induce…
View article: Exploring dual-lidar mean and turbulence measurements over complex terrain
Exploring dual-lidar mean and turbulence measurements over complex terrain Open
To assess the accuracy of lidars in measuring mean wind speed and turbulence at large distances above the ground as an alternative to tall and expensive meteorological towers, we evaluated three dual-lidar measurements in virtual mast (VM)…
View article: Comment on wes-2023-142
Comment on wes-2023-142 Open
Abstract. Large-scale flow structures are vital in influencing the dynamic response of floating wind turbines and wake meandering behind large offshore wind turbines. It is imperative that we develop an inflow wind turbule…
View article: A Model for Low-Frequency, Anisotropic Wind Fluctuations and Coherences in the Marine Atmosphere
A Model for Low-Frequency, Anisotropic Wind Fluctuations and Coherences in the Marine Atmosphere Open
View article: Suppression of precipitation bias in wind velocities from continuous-wave Doppler lidars
Suppression of precipitation bias in wind velocities from continuous-wave Doppler lidars Open
In moderate to heavy precipitation, raindrops may deteriorate the accuracy of Doppler lidar measurements of the line-of-sight wind velocity because their projected velocity in the beam direction differs greatly from that of air. Therefore,…
View article: Simulating low-frequency wind fluctuations
Simulating low-frequency wind fluctuations Open
Large-scale flow structures are vital in influencing the dynamic response of floating wind turbines and wake meandering behind large offshore wind turbines. It is imperative that we develop an inflow wind turbulence model capable of replic…
View article: Rotary-wing drone-induced flow – comparison of simulations with lidar measurements
Rotary-wing drone-induced flow – comparison of simulations with lidar measurements Open
Ultrasonic anemometers mounted on rotary-wing drones have the potential to provide a cost-efficient alternative to the classical meteorological mast-mounted counterpart for wind energy applications. However, the propeller-induced flow may …
View article: Revealing inflow and wake conditions of a 6 MW floating turbine
Revealing inflow and wake conditions of a 6 MW floating turbine Open
We investigate the characteristics of the inflow and the wake of a 6 MW floating wind turbine from the Hywind Scotland offshore wind farm, the world's first floating wind farm. We use two commercial nacelle-mounted lidars to measure the up…
View article: Triple-lidar measurements of wind across a virtual rotor plane over a sea surface
Triple-lidar measurements of wind across a virtual rotor plane over a sea surface Open
An improved understanding of the spatiotemporal characteristics of the wind velocity field above the sea surface will benefit the design of modern offshore wind turbines. This study examines wind velocity data recorded on a bow-tie-like me…
View article: A model for low-frequency, anisotropic wind fluctuations and coherences in the marine atmosphere
A model for low-frequency, anisotropic wind fluctuations and coherences in the marine atmosphere Open
To assess dynamic loads, large offshore wind turbines need detailed and reliable statistical information on the inflow turbulence. We present a model that includes low frequencies down to $\sim 1$ hr$^{-1}$ using the observed $S(f) \propto…
View article: Lidar measurements of wake around a bridge deck
Lidar measurements of wake around a bridge deck Open
Remote wind sensing technologies allow for measurements in a spatial domain beyond the one accessible by anemometers fixed to a mast. Remote optical wind sensors installed at an existing bridge site can both provide new information on the …
View article: Comment on egusphere-2023-464
Comment on egusphere-2023-464 Open
Abstract. In moderate to heavy precipitation, rain droplets may deteriorate Doppler lidars' accuracy for measuring the line-of-sight wind velocity because their projected velocity on the beam direction differs greatly from…
View article: Comment on egusphere-2023-464
Comment on egusphere-2023-464 Open
Abstract. In moderate to heavy precipitation, rain droplets may deteriorate Doppler lidars' accuracy for measuring the line-of-sight wind velocity because their projected velocity on the beam direction differs greatly from…
View article: Comment on wes-2023-37
Comment on wes-2023-37 Open
Abstract. We investigate the characteristics of the inflow and the wake of a 6MW floating wind turbine from the Hywind Scotland offshore wind farm, the world's first floating wind farm. We use two commercial nacel…
View article: Comment on egusphere-2023-464
Comment on egusphere-2023-464 Open
Abstract. In moderate to heavy precipitation, rain droplets may deteriorate Doppler lidars' accuracy for measuring the line-of-sight wind velocity because their projected velocity on the beam direction differs greatly from…
View article: Dependence of turbulence estimations on nacelle lidar scanning strategies
Dependence of turbulence estimations on nacelle lidar scanning strategies Open
Through numerical simulations and the analysis of field measurements, we investigate the dependence of the accuracy and uncertainty of turbulence estimations on the main features of the nacelle lidars' scanning strategy, i.e., the number o…
View article: Comment on wes-2023-37
Comment on wes-2023-37 Open
Abstract. We investigate the characteristics of the inflow and the wake of a 6MW floating wind turbine from the Hywind Scotland offshore wind farm, the world's first floating wind farm. We use two commercial nacel…