scholarly journals Multi-lidar wind resource mapping in complex terrain

2019 ◽  
Author(s):  
Robert Menke ◽  
Nikola Vasiljević ◽  
Johannes Wagner ◽  
Steven P. Oncley ◽  
Jakob Mann
Keyword(s):  
Complex Terrain ◽  
Forest Canopy ◽  
Ground Level ◽  
Atmospheric Conditions ◽  
Surface Drag ◽  
Wind Speeds ◽  
Forest Distribution ◽  
Aerodynamic Roughness ◽  
Wind Resource ◽  
Wind Resources

Abstract. Scanning Doppler lidars have great potential for reducing uncertainty of wind resource estimation in complex terrain. Due to their scanning capabilities, they can measure at multiple locations over large areas. We demonstrate this ability using dual-Doppler lidar measurements of flow over two parallel ridges. The data have been collected using two pairs of long-range WindScanner systems operated in a dual-Doppler mode during the Perdigão 2017 measurement campaign. The lidars mapped the flow along the southwest and northeast ridges 80 m above ground level. By analyzing the collected data, we found that for different flow conditions on average wind speeds are 10 % higher over the southwest ridge compared to the northeast ridge. At the southwest ridge, the data shows, depending on the atmospheric conditions, a change of 20 % in wind speed along the ridge. For the measurement period, we have simulated the flow over the site using WRF-LES to compare how well the model can capture wind resources along the ridges. We used two model configurations. In the first configuration, surface drag is based purely on aerodynamic roughness whereas in the second configuration forest canopy drag is also considered. We found that simulated winds are underestimated in WRF-LES runs with forest drag due to an unrealistic forest distribution on the ridge tops. The correlation of simulated and observed winds is, however, improved when the forest parameterization is applied. WRF-LES results without forest drag overestimated the wind resources over the southwest and northeast ridges by 6.5 % and 4.5 % respectively. Overall, this study demonstrates the ability of scanning lidars to map wind resources in complex terrain.

scholarly journals Multi-lidar wind resource mapping in complex terrain

2020 ◽  
Vol 5 (3) ◽  
pp. 1059-1073 ◽  
Author(s):  
Robert Menke ◽  
Nikola Vasiljević ◽  
Johannes Wagner ◽  
Steven P. Oncley ◽  
Jakob Mann
Keyword(s):  
Complex Terrain ◽  
Forest Canopy ◽  
Ground Level ◽  
Surface Drag ◽  
Flow Models ◽  
Wind Speeds ◽  
Eddy Simulation ◽  
Lidar Measurements ◽  
Wind Resource ◽  
Wind Resources

Abstract. Scanning Doppler lidars have great potential for reducing uncertainty of wind resource estimation in complex terrain. Due to their scanning capabilities, they can measure at multiple locations over large areas. We demonstrate this ability with dual-Doppler lidar measurements of flow over two parallel ridges. The data have been collected using two pairs of scanning lidars operated in a dual-Doppler mode during the Perdigão 2017 measurement campaign. There the scanning lidars mapped the flow 80 m above ground level along two ridges, which are considered favorable for wind turbine siting. The measurements are validated with sonic wind measurements at each ridge. By analyzing the collected data, we found that wind speeds are on average 10 % higher over the southwest ridge compared to the northeast ridge. At the southwest ridge, the data show, for approach flow normal to the ridge, a change of 20 % in wind speed along the ridge. Fine differences like these are difficult to reproduce with computational flow models, as we demonstrate by comparing the lidar measurements with Weather Research and Forecasting large-eddy simulation (WRF-LES) results. For the measurement period, we have simulated the flow over the site using WRF-LES to compare how well the model can capture wind resources along the ridges. We used two model configurations. In the first configuration, surface drag is based purely on aerodynamic roughness, whereas in the second configuration forest canopy drag is also considered. We found that simulated winds are underestimated in WRF-LES runs with forest drag due to an unrealistic forest distribution on the ridge tops. The correlation of simulated and observed winds is, however, improved when the forest parameterization is applied. WRF-LES results without forest drag overestimated the wind resources over the southwest and northeast ridges by 6.5 % and 4.5 %, respectively. Overall, this study demonstrates the ability of scanning lidars to map wind resources in complex terrain.

scholarly journals Characterization of flow recirculation zones in complex terrain using multi-lidar measurements

2018 ◽  
Author(s):  
Robert Menke ◽  
Nikola Vasiljević ◽  
Jakob Mann ◽  
Julie K. Lundquist
Keyword(s):  
Complex Terrain ◽  
Reverse Flow ◽  
Atmospheric Stability ◽  
Resource Assessment ◽  
Atmospheric Conditions ◽  
Recirculation Flow ◽  
Flow Recirculation ◽  
Wind Speeds ◽  
Recirculation Zones ◽  
Wind Resource

Abstract. Because flow recirculation can generate significant amounts of turbulence, it can impact the success of wind energy projects. This study uses unique Doppler lidar observations to quantify occurrences of flow recirculation on lee sides of ridges. An extensive dataset of observations of flow over complex terrain is available from the Perdigão-2017 field campaign over a period of three months. The campaign site was selected because of the unique terrain feature of two nearly parallel ridges with a valley-to-ridge-top height difference of about 200 m and a ridge-to-ridge distance of 1.4 km. Six scanning Doppler lidars probed the flow field in several vertical planes orthogonal to the ridges using range-height-indicator scans. With this lidar setup, we achieved vertical scans of the recirculation zone at three positions along two parallel ridges. We construct a method to identify flow recirculation zones in the scans, as well as define characteristics of these zones. According to our data analysis, flow recirculation, with reverse flow wind speeds greater than 0.5 m s−1, occurs over 50 % of the time when the wind direction is perpendicular to the direction of the ridges. Atmospheric conditions, such as atmospheric stability and wind speed, affect the occurrence of flow recirculation. Flow recirculation occurs more frequently during periods with wind speeds above 8 m s−1. Recirculation within the valley affects the mean wind and turbulence fields at turbine heights on the downwind ridge in magnitudes significant for wind resource assessment.

scholarly journals Assessment of Resource and Forecast Modeling of Wind Speed through An Evolutionary Programming Approach for the North of Tehuantepec Isthmus (Cuauhtemotzin, Mexico)

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3197 ◽  
Author(s):  
Luis López-Manrique ◽  
E. Macias-Melo ◽  
O. May Tzuc ◽  
A. Bassam ◽  
K. Aguilar-Castro ◽  
...  
Keyword(s):  
Wind Speed ◽  
Computation Time ◽  
Ground Level ◽  
Bimodal Distribution ◽  
Programming Approach ◽  
Climatic Data ◽  
Wind Speeds ◽  
Availability Analysis ◽  
The North ◽  
Wind Resource

This work studies the characteristics of the wind resource for a location in the north zone of Tehuantepec isthmus. The study was conducted using climatic data from Cuauhtemotzin, Mexico, measured at different altitudes above the ground level. The measured data allowed establishing the profile of wind speeds as well as the analysis of its availability. Analysis results conclude that the behavior of the wind speed presents a bimodal distribution with dominant northeast wind direction (wind flow of sea–land). In addition, the area was identified as feasible for the use of low speed power wind turbines. On the other hand, the application of a new approach for very short-term wind speed forecast (10 min) applying multi-gene genetic programming and global sensitivity analysis is also presented. Using a computational methodology, an exogenous time series with fast computation time and good accuracy was developed for the forecast of the wind speed. The results presented in this work complement the panorama for the evaluation of the resource in an area recognized worldwide for its vast potential for wind power.

scholarly journals Small wind turbines study and integration in a peri-urban microgrid

2021 ◽  
Author(s):  
Paula Peña-Carro ◽  
Óscar Izquierdo-Monge ◽  
Luis Hernández-Callejo ◽  
Gonzalo Martín-Jiménez
Keyword(s):  
Wind Turbines ◽  
Urban Environments ◽  
Wind Speeds ◽  
Small Wind Turbines ◽  
Micro Power ◽  
The Cost ◽  
Wind Resource ◽  
Wind Resources ◽  
Selection Of ◽  
Instantaneous Control

The use of wind resources has always gone hand in hand with high wind speeds in open fields. This paper develops the decisions to be taken for the selection, installation, and connection of small wind turbines in peri-urban environments, where wind speeds are medium or low. The guidelines are detailed throughout the document, starting with the study of the wind resource, the selection of the turbine, installation, and real-time monitoring of production for integration into a micro power grid. The installation of small wind systems in places as close as possible to the point of demand makes it possible to achieve a reduction in the cost of the electricity bill. This is thanks to the instantaneous control of generation and demand at a particular level through the installation of software, in this case, Home Assistant. The novelty of this paper is the use of this software Home Assistant to integrate of a small wind turbine in a microgrid and its control system.

scholarly journals Vertical characterization of Highly Oxygenated Molecules (HOMs) below and above a boreal forest canopy

2017 ◽  
Author(s):  
Qiaozhi Zha ◽  
Chao Yan ◽  
Heikki Junninen ◽  
Matthieu Riva ◽  
Juho Aalto ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Boreal Forest ◽  
Forest Canopy ◽  
Mixed Boundary ◽  
Ground Level ◽  
Atmospheric Conditions ◽  
Research Attention ◽  
Significant Research ◽  
First Time

Abstract. While the role of highly oxygenated molecules (HOMs) in new particle formation (NPF) and secondary organic aerosol (SOA) formation is not in dispute, the interplay between HOM chemistry and atmospheric conditions continues to draw significant research attention. During the Influence of Biosphere-Atmosphere Interactions on the Reactive Nitrogen budget (IBAIRN) campaign, profile measurements of neutral HOM molecules below and above the forest canopy were performed for the first time in the boreal forest SMEAR II station during September 2016. The HOM concentrations and composition distributions below and above the canopy were similar, supporting a well-mixed boundary layer approximation during daytime. However, much lower HOM concentration were frequently observed at ground level due to the formation of a shallow decoupled layer below the canopy attached to the forest floor. Near ground HOMs were influenced by the changes in the precursors and oxidants, and enhancement of the loss on surfaces in this layer, while the HOMs above the canopy top were not significantly affected. Our findings also illustrate that near-ground HOM measurements conducted in strong stably stratified conditions might only be representative of a small fraction of the entire nocturnal boundary layer. This might, in turn, influence the growth of newly formed particles and SOA formation below the canopy where a large majority of measurements are typically conducted.

Exploring fire response to high wind speeds: fire rate of spread, energy release and flame residence time from fires burned in pine needle beds under winds up to 27 ms−1

2020 ◽  
Vol 29 (1) ◽  
pp. 81
Author(s):  
Bret Butler ◽  
Steve Quarles ◽  
Christine Standohar-Alfano ◽  
Murray Morrison ◽  
Daniel Jimenez ◽  
...  
Keyword(s):  
Wind Speed ◽  
Energy Release ◽  
Residence Time ◽  
Wildland Fire ◽  
Ground Level ◽  
Fire Spread ◽  
Convective Heating ◽  
Atmospheric Conditions ◽  
Wind Speeds ◽  
Rate Of Spread

The relationship between wildland fire spread rate and wind has been a topic of study for over a century, but few laboratory studies report measurements in controlled winds exceeding 5ms−1. In this study, measurements of fire rate of spread, flame residence time and energy release are reported for fires burning under controlled atmospheric conditions in shallow beds of pine needles subject to winds ranging from 0 to 27ms−1 (measured 5m above ground level). The data suggested that under constant flow conditions when winds are less than 10ms−1, fire rate of spread increases linearly at a rate of ~3% of the wind speed, which generally agrees with other laboratory-based models. When wind speed exceeds 10ms−1, the fire rate of spread response to wind remains linear but with a much stronger dependence, spreading at a rate of ~13% of the wind speed. Radiative and convective heating correlated directly to wind speed, with radiant heating increasing approximately three-fold as much as convective heating over the range of winds explored. The data suggested that residence time is inversely related to wind speed and appeared to approach a lower limit of ~20s as wind exceeded 15ms−1. Average flame residence time over the range of wind speeds was nominally 26s.

scholarly journals Vertical characterization of highly oxygenated molecules (HOMs) below and above a boreal forest canopy

2018 ◽  
Vol 18 (23) ◽  
pp. 17437-17450 ◽  
Author(s):  
Qiaozhi Zha ◽  
Chao Yan ◽  
Heikki Junninen ◽  
Matthieu Riva ◽  
Nina Sarnela ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Boreal Forest ◽  
Forest Canopy ◽  
Mixed Boundary ◽  
Ground Level ◽  
Atmospheric Conditions ◽  
Research Attention ◽  
Significant Research ◽  
First Time

Abstract. While the role of highly oxygenated molecules (HOMs) in new particle formation (NPF) and secondary organic aerosol (SOA) formation is not in dispute, the interplay between HOM chemistry and atmospheric conditions continues to draw significant research attention. During the Influence of Biosphere-Atmosphere Interactions on the Reactive Nitrogen budget (IBAIRN) campaign in September 2016, profile measurements of neutral HOMs below and above the forest canopy were performed for the first time at the boreal forest SMEAR II station. The HOM concentrations and composition distributions below and above the canopy were similar during daytime, supporting a well-mixed boundary layer approximation. However, much lower nighttime HOM concentrations were frequently observed at ground level, which was likely due to the formation of a shallow decoupled layer below the canopy. Near the ground HOMs were influenced by the changes in the precursors and oxidants and enhancement of the loss on surfaces in this layer, while the HOMs above the canopy top were not significantly affected. Our findings clearly illustrate that near-ground HOM measurements conducted under stably stratified conditions at this site might only be representative of a small fraction of the entire nocturnal boundary layer. This could, in turn, influence the growth of newly formed particles and SOA formation below the canopy where the large majority of measurements are typically conducted.

scholarly journals Advancing Wind Resource Assessment in Complex Terrain with Scanning Lidar Measurements

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3280
Author(s):  
Julia Gottschall ◽  
Alkistis Papetta ◽  
Hassan Kassem ◽  
Paul Julian Meyer ◽  
Linda Schrempf ◽  
...  
Keyword(s):  
Complex Terrain ◽  
Numerical Models ◽  
Numerical Data ◽  
Resource Assessment ◽  
Flow Models ◽  
Wind Speeds ◽  
Starting Point ◽  
Scanning Lidar ◽  
Wind Lidar ◽  
Wind Resource

The planning and realization of wind energy projects requires an as accurate and precise wind resource estimation as possible. Standard procedures combine shorter on-site measurements with the application of numerical models. The uncertainties of the numerical data generated from these models are, particularly in complex onshore terrain, not just rather high but typically not well quantified. In this article we propose a methodology for using a single scanning Doppler wind lidar device to calibrate the output data of a numerical flow model and with this not just quantify but potentially also reduce the uncertainties of the final wind resource estimate. The scanning lidar is configured to perform Plan Position Indicator (PPI) scans and the numerical flow data are projected onto this geometry. Deviations of the derived from the recorded line-of-sight wind speeds are used to identify deficiencies of the model and as starting point for an improvement and tuning. The developed methodology is demonstrated based on a study for a site in moderately complex terrain in central Germany and using two rather different types of numerical flow models. The findings suggest that the use of the methodology and the introduced scanning wind lidar technology offers a promising opportunity to control the uncertainty of the applied flow models, which can otherwise only be estimated very roughly.

scholarly journals Air Pollution Scenario over China during COVID-19

2020 ◽  
Vol 12 (13) ◽  
pp. 2100 ◽  
Author(s):  
Janet E. Nichol ◽  
Muhammad Bilal ◽  
Md. Arfan Ali ◽  
Zhongfeng Qiu
Keyword(s):  
Ground Level ◽  
Central China ◽  
Quality Data ◽  
Satellite Monitoring ◽  
Atmospheric Conditions ◽  
Ozone Monitoring Instrument ◽  
Wind Speeds ◽  
Enhanced Production ◽  
Low Wind Speeds ◽  
Peripheral Regions

The unprecedented slowdown in China during the COVID-19 period of November 2019 to April 2020 should have reduced pollution in smog-laden cities. However, moderate resolution imaging spectrometer (MODIS) satellite retrievals of aerosol optical depth (AOD) show a marked increase in aerosols over the Beijing–Tianjin–Hebei (BHT) region and most of Northeast and Central China, compared with the previous winter. Fine particulate (PM2.5) data from ground monitoring stations show an increase of 19.5% in Beijing during January and February 2020, and no reduction for Tianjin. In March and April 2020, a different spatial pattern emerges, with very high AOD levels observed over 50% of the Chinese mainland, and including peripheral regions in the northwest and southwest. At the same time, ozone monitoring instrument (OMI) satellite-derived NO2 concentrations fell drastically across China. The increase in PM2.5 while NO2 decreased in BTH and across China is likely due to enhanced production of secondary particulates. These are formed when reductions in NOx result in increased ozone formation, thus increasing the oxidizing capacity of the atmosphere. Support for this explanation is provided by ground level air quality data showing increased volume of fine mode aerosols throughout February and March 2020, and increased levels of PM2.5, relative humidity (RH), and ozone during haze episodes in the COVID-19 lockdown period. Backward trajectories show the origin of air masses affecting industrial centers of North and East China to be local. Other contributors to increased atmospheric particulates may include inflated industrial production in peripheral regions to compensate loss in the main population and industrial centers, and low wind speeds. Satellite monitoring of the extraordinary atmospheric conditions resulting from the COVID-19 shutdown could enhance understanding of smog formation and attempts to control it.

scholarly journals Assessment of wind energy potential for Tuvalu with accurate estimation of Weibull parameters

2020 ◽  
Vol 38 (5) ◽  
pp. 1742-1773
Author(s):  
Fatonga Talama ◽  
Saiyad S Kutty ◽  
Ajal Kumar ◽  
MGM Khan ◽  
M Rafiuddin Ahmed
Keyword(s):  
Maximum Likelihood ◽  
Wind Power ◽  
Power Density ◽  
Maximum Likelihood Method ◽  
Ground Level ◽  
Empirical Method ◽  
Likelihood Method ◽  
Above Ground Level ◽  
Wind Speeds ◽  
Wind Resource

Wind resource assessments are carried out for two sites in Tuvalu: Funafuti and Nukufetau. The wind speeds at 34 and 20 m above ground level were recorded for approximately 12 months and analyzed. The averages of each site are computed as the overall, daily, monthly, annual, and seasonal averages. The overall average wind speeds for Funafuti and Nukufetau at 34 m above ground level were estimated to be 6.19 and 5.36 m/s, respectively. The turbulence intensities at the two sites were also analyzed. The turbulence intensity is also computed for windy and low-wind days. Wind shear analysis was carried out and correlated with temperature variation. Ten different methods: median and quartiles method, the empirical method of Lysen, the empirical method of Justus, the moments method, the least squares method, the maximum likelihood method, the modified maximum likelihood method, the energy pattern factor method, method of multi-objective moments, and the wind atlas analysis and application program method were used to find the Weibull parameters. From these methods, the best method is used to determine the wind power density for the site. The wind power density for Funafuti is 228.18 W/m2 and for Nukufetau is 145.1 W/m2. The site maps were digitized and with the WAsP software, five potential locations were selected for each site from the wind resource map. The annual energy production for the sites was computed using wind atlas analysis and application program to be 2921.34 and 1848.49 MWh. The payback periods of installing the turbines for each site are calculated by performing an economic analysis, which showed payback periods of between 3.13 and 4.21 years for Funafuti and between 4.83 to 6.72 years for Nukufetau.

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