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Author: Aditya Choukulkar Publisher: ISBN: Category : Boundary layer (Meteorology) Languages : en Pages : 157
Book Description
This thesis outlines the development of a vector retrieval technique, based on data assimilation, for a coherent Doppler LIDAR (Light Detection and Ranging). A detailed analysis of the Optimal Interpolation (OI) technique for vector retrieval is presented. Through several modifications to the OI technique, it is shown that the modified technique results in significant improvement in velocity retrieval accuracy. These modifications include changes to innovation covariance portioning, covariance binning, and analysis increment calculation. It is observed that the modified technique is able to make retrievals with better accuracy, preserves local information better, and compares well with tower measurements. In order to study the error of representativeness and vector retrieval error, a lidar simulator was constructed. Using the lidar simulator a thorough sensitivity analysis of the lidar measurement process and vector retrieval is carried out. The error of representativeness as a function of scales of motion and sensitivity of vector retrieval to look angle is quantified. Using the modified OI technique, study of nocturnal flow in Owens' Valley, CA was carried out to identify and understand uncharacteristic events on the night of March 27th 2006. Observations from 1030 UTC to 1230 UTC (0230 hr local time to 0430 hr local time) on March 27 2006 are presented. Lidar observations show complex and uncharacteristic flows such as sudden bursts of westerly cross-valley wind mixing with the dominant up-valley wind. Model results from Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS®) and other in-situ instrumentations are used to corroborate and complement these observations. The modified OI technique is used to identify uncharacteristic and extreme flow events at a wind development site. Estimates of turbulence and shear from this technique are compared to tower measurements. A formulation for equivalent wind speed in the presence of variations in wind speed and direction, combined with shear is developed and used to determine wind energy content in presence of turbulence.
Author: Aditya Choukulkar Publisher: ISBN: Category : Boundary layer (Meteorology) Languages : en Pages : 157
Book Description
This thesis outlines the development of a vector retrieval technique, based on data assimilation, for a coherent Doppler LIDAR (Light Detection and Ranging). A detailed analysis of the Optimal Interpolation (OI) technique for vector retrieval is presented. Through several modifications to the OI technique, it is shown that the modified technique results in significant improvement in velocity retrieval accuracy. These modifications include changes to innovation covariance portioning, covariance binning, and analysis increment calculation. It is observed that the modified technique is able to make retrievals with better accuracy, preserves local information better, and compares well with tower measurements. In order to study the error of representativeness and vector retrieval error, a lidar simulator was constructed. Using the lidar simulator a thorough sensitivity analysis of the lidar measurement process and vector retrieval is carried out. The error of representativeness as a function of scales of motion and sensitivity of vector retrieval to look angle is quantified. Using the modified OI technique, study of nocturnal flow in Owens' Valley, CA was carried out to identify and understand uncharacteristic events on the night of March 27th 2006. Observations from 1030 UTC to 1230 UTC (0230 hr local time to 0430 hr local time) on March 27 2006 are presented. Lidar observations show complex and uncharacteristic flows such as sudden bursts of westerly cross-valley wind mixing with the dominant up-valley wind. Model results from Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS®) and other in-situ instrumentations are used to corroborate and complement these observations. The modified OI technique is used to identify uncharacteristic and extreme flow events at a wind development site. Estimates of turbulence and shear from this technique are compared to tower measurements. A formulation for equivalent wind speed in the presence of variations in wind speed and direction, combined with shear is developed and used to determine wind energy content in presence of turbulence.
Author: Viktor Banakh Publisher: Artech House ISBN: 1608076679 Category : Technology & Engineering Languages : en Pages : 277
Book Description
Radiophysical tools for measuring atmospheric dynamics include sodars, Doppler radars, and Doppler lidars. Among these, coherent Doppler lidars (CDLs) have been considered the best for remote measurement of wind turbulence. This is important not only for understanding the exchange processes in the boundary layer, but also in the applied aspect, such as aviation safety. CDLs significantly extend possibilities of experimental investigation of not only wind turbulence, but also coherent structures such as aircraft wake vortices. The authors of this book conducted field tests of the developed methods of lidar measurements of the wind velocity, atmospheric turbulence parameters, and aircraft wake vortices. This valuable resource, containing over 500 equations based on original results from the authors’ work, gives professionals a comprehensive description of the operating principles of continuous wave and pulsed coherent Doppler lidars. This book studies the possibilities of obtaining information about wind turbulence from data measured by continuous wave and pulsed CDLs. The procedures for estimation are described, as well as algorithms for numerical simulation. Results on the vortex behavior and evolution are then presented.
Author: Mithu Debnath Publisher: ISBN: Category : Optical radar Languages : en Pages :
Book Description
Wind turbine wakes undergo complex dynamics varying as a function of the incoming wind conditions, which are modulated by the atmospheric static stability and terrain characteristics. Accurate evaluation of the wind velocity components over the rotor disc represent the relevant input for the wind turbine aerodynamics. Power extraction exerted by the turbines on the atmospheric boundary layer leads to the generation of wind turbine wakes, which are flow regions characterized by a velocity deficit and the presence of coherent vorticity structures evolving downstream. Therefore, wind turbulence and dynamics of these vorticity structures produced by utility-scale wind turbines need to be characterized accurately. In this work, a field measurement campaign is described where different remote sensing instruments were assessed to retrieve the wind velocity components with different levels of accuracy. This campaign provided an unique opportunity to retrieve the wind velocity components with different technologies and perform inter-comparison studies in terms of both first and second order turbulent statistics. The results show that Doppler LiDARs have capability to retrieve mean wind speed with high accuracy and turbulent fluctuations with certain limitations. Besides the development of experimental measurement techniques for probing vorticity dynamics within the atmospheric boundary layer, research endeavors were focused in performing analyses based on Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) to identify coherent structures within wind turbine wakes. Different data-sets, which include Large Eddy Simulation (LES) of single wind turbine with and without tower and nacelle were analyzed. Careful analysis enabled the detection of different instability modes of the helicoidal tip vortices, namely elliptical instability and leap-frogging due to the self rotation and mutual induction among the vortex cores.
Author: Charlotte Bay Hasager Publisher: MDPI ISBN: 3038979422 Category : Technology & Engineering Languages : en Pages : 290
Book Description
This Special Issue “Atmospheric Conditions for Wind Energy Applications” hosts papers on aspects of remote sensing for atmospheric conditions for wind energy applications. Wind lidar technology is presented from a theoretical view on the coherent focused Doppler lidar principles. Furthermore, wind lidar for applied use for wind turbine control, wind farm wake, and gust characterizations is presented, as well as methods to reduce uncertainty when using lidar in complex terrain. Wind lidar observations are used to validate numerical model results. Wind Doppler lidar mounted on aircraft used for observing winds in hurricane conditions and Doppler radar on the ground used for very short-term wind forecasting are presented. For the offshore environment, floating lidar data processing is presented as well as an experiment with wind-profiling lidar on a ferry for model validation. Assessments of wind resources in the coastal zone using wind-profiling lidar and global wind maps using satellite data are presented.
Author: Roland B. Stull Publisher: Springer Science & Business Media ISBN: 9789027727695 Category : Science Languages : en Pages : 688
Book Description
Part of the excitement in boundary-layer meteorology is the challenge associated with turbulent flow - one of the unsolved problems in classical physics. An additional attraction of the filed is the rich diversity of topics and research methods that are collected under the umbrella-term of boundary-layer meteorology. The flavor of the challenges and the excitement associated with the study of the atmospheric boundary layer are captured in this textbook. Fundamental concepts and mathematics are presented prior to their use, physical interpretations of the terms in equations are given, sample data are shown, examples are solved, and exercises are included. The work should also be considered as a major reference and as a review of the literature, since it includes tables of parameterizatlons, procedures, filed experiments, useful constants, and graphs of various phenomena under a variety of conditions. It is assumed that the work will be used at the beginning graduate level for students with an undergraduate background in meteorology, but the author envisions, and has catered for, a heterogeneity in the background and experience of his readers.
Author: Stawiarski, Christina Publisher: KIT Scientific Publishing ISBN: 373150197X Category : Science Languages : en Pages : 262
Book Description
Coherent structures are patterns in the wind field of the atmospheric boundary layer. The deployment of two scanning Doppler lidars facilitates the measurement of the horizontal wind field, but the inherent averaging processes complicate an interpretation of the results. To assess the suitability of this technique for coherent structure detection large-eddy simulations are used as a basis for virtual measurements, and the effects of the lidar technique on the wind field structure are analyzed.
Author: Publisher: ISBN: Category : Languages : en Pages : 24
Book Description
Wind speed and direction, together with pressure, temperature, and relative humidity, are the most fundamental atmospheric state parameters. Accurate measurement of these parameters is crucial for numerical weather prediction. Vertically resolved wind measurements in the atmospheric boundary layer are particularly important for modeling pollutant and aerosol transport. Raw data from a scanning coherent Doppler lidar system can be processed to generate accurate height-resolved measurements of wind speed and direction in the atmospheric boundary layer.
Author: J. C. Kaimal Publisher: Oxford University Press, USA ISBN: 0195062396 Category : Nature Languages : en Pages : 304
Book Description
This text gives a simple view of the structure of the boundary layer, the instruments available for measuring its mean and turbulent properties, how best to make the measurements, and ways to process and analyze the data.
Author: Christina Stawiarski Publisher: ISBN: 9781013283666 Category : Science Languages : en Pages : 258
Book Description
Coherent structures are patterns in the wind field of the atmospheric boundary layer. The deployment of two scanning Doppler lidars facilitates the measurement of the horizontal wind field, but the inherent averaging processes complicate an interpretation of the results. To assess the suitability of this technique for coherent structure detection large-eddy simulations are used as a basis for virtual measurements, and the effects of the lidar technique on the wind field structure are analyzed. This work was published by Saint Philip Street Press pursuant to a Creative Commons license permitting commercial use. All rights not granted by the work's license are retained by the author or authors.
Author: Aditya Choukulkar
Author: Aditya Choukulkar
Author: Viktor Banakh 
Author: Mithu Debnath
Author: Charlotte Bay Hasager
Author: Roland B. Stull
Author: Stawiarski, Christina
Author: 
Author: J. C. Kaimal
Author: 
Author: Christina Stawiarski