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CHAPTER 20 Wind Turbine Noise Measurements and Abatement
CHAPTER 20 Wind turbine noise measurements and abatement methods Panagiota Pantazopoulou BRE, Watford, UK. This chapter presents an overview of the types, the measurements and the potential acoustic solutions for the noise emitted from wind turbines. It describes the fre- quency and the acoustic signature of the sound waves generated by the rotating blades and explains how they propagate in the atmosphere. In addition, the avail- able noise measurement techniques are being presented with special focus on the technical challenges that may occur in the measurement process. Finally, a discus- sion on the noise treatment methods from wind turbines referring to a range of the existing abatement methods is being presented. 1 Introduction Wind turbines generate two types of noise: aerodynamic and mechanical. A tur- bine’s sound power is the combined power of both. Aerodynamic noise is gener- ated by the blades passing through the air. The power of aerodynamic noise is related to the ratio of the blade tip speed to wind speed. The mechanical noise is associated with the relevant motion between the various parts inside the nacelle. The compartments move or rotate in order to convert kinetic energy to electricity with the expense of generating sound waves and vibration which is transmitted through the structural parts of the turbine. Depending on the turbine model and the wind speed, the aerodynamic noise may seem like buzzing, whooshing, pulsing, and even sizzling. Downwind tur- bines with their blades downwind of the tower cause impulsive noise which can travel far and become very annoying for people. The low frequency noise gener- ated from a wind turbine is primarily the result of the interaction of the aerody- namic lift on the blades and the atmospheric turbulence in the wind. -
Chapter 10. Thermohaline Circulation
Chapter 10. Thermohaline Circulation Main References: Schloesser, F., R. Furue, J. P. McCreary, and A. Timmermann, 2012: Dynamics of the Atlantic meridional overturning circulation. Part 1: Buoyancy-forced response. Progress in Oceanography, 101, 33-62. F. Schloesser, R. Furue, J. P. McCreary, A. Timmermann, 2014: Dynamics of the Atlantic meridional overturning circulation. Part 2: forcing by winds and buoyancy. Progress in Oceanography, 120, 154-176. Other references: Bryan, F., 1987. On the parameter sensitivity of primitive equation ocean general circulation models. Journal of Physical Oceanography 17, 970–985. Kawase, M., 1987. Establishment of deep ocean circulation driven by deep water production. Journal of Physical Oceanography 17, 2294–2317. Stommel, H., Arons, A.B., 1960. On the abyssal circulation of the world ocean—I Stationary planetary flow pattern on a sphere. Deep-Sea Research 6, 140–154. Toggweiler, J.R., Samuels, B., 1995. Effect of Drake Passage on the global thermohaline circulation. Deep-Sea Research 42, 477–500. Vallis, G.K., 2000. Large-scale circulation and production of stratification: effects of wind, geometry and diffusion. Journal of Physical Oceanography 30, 933–954. 10.1 The Thermohaline Circulation (THC): Concept, Structure and Climatic Effect 10.1.1 Concept and structure The Thermohaline Circulation (THC) is a global-scale ocean circulation driven by the equator-to-pole surface density differences of seawater. The equator-to-pole density contrast, in turn, is controlled by temperature (thermal) and salinity (haline) variations. In the Atlantic Ocean where North Atlantic Deep Water (NADW) forms, the THC is often referred to as the Atlantic Meridional Overturning Circulation (AMOC). -
Atmospheric Effects on Traffic Noise Propagation
TRANSPORTATION RESEARCH RECORD 1255 59 Atmospheric Effects on Traffic Noise Propagation ROGER L. WAYSON AND WILLIAM BOWLBY Atmospheric effects on traffic noise propagation have largely L 0 sound level at a reference distance, been ignored during measurements and modeling, even though Ageo attenuation due to geometric spreading, it has generally been accepted that the effects may produce large Ab insertion loss due to diffraction, changes in receiver noise levels. Measurement of traffic noise at L, level increases due to reflection, and multiple locations concurrently with measurement of meteoro Ac attenuation due to ground characteristics and envi logical data is described. Statistical methods were used to evaluate the data. Atmospheric effects on traffic noise levels were shown ronmental effects. to be significant, even at very short distances; parallel components It should be noted that all levels in dB in this paper are of the wind (which are usually ignored) were important at second 2 row receivers; turbulent scattering increased noise levels near the referenced to 2 x 10-s N/m • ground more than refractive ray bending for short-distance prop The last term on the right side of Equation 1, A,, consists agation; and temperature lapse rates were not as important as of three parameters: ground attenuation, attenuation due to wind shear very near the highway. A statistical model was devel atmospheric absorption, and attenuation due to atmospheric oped to predict excess attenuations due to atmospheric effects. refraction. (2) Outdoor noise propagation has been studied since the time of the Greek philosopher Chrysippus (240 B. C.). Modern where prediction models have become accurate, and the advent of computers has increased the capabilities of models. -
Ocean Wind and Current Retrievals Based on Satellite SAR Measurements in Conjunction with Buoy and HF Radar Data
remote sensing Article Ocean Wind and Current Retrievals Based on Satellite SAR Measurements in Conjunction with Buoy and HF Radar Data He Fang 1, Tao Xie 1,* ID , William Perrie 2, Li Zhao 1, Jingsong Yang 3 and Yijun He 1 ID 1 School of Marine Sciences, Nanjing University of Information Science and Technology, Nanjing 210044, Jiangsu, China; [email protected] (H.F.); [email protected] (L.Z.); [email protected] (Y.H.) 2 Fisheries & Oceans Canada, Bedford Institute of Oceanography, Dartmouth, NS B2Y 4A2, Canada; [email protected] 3 State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, Zhejiang, China; [email protected] * Correspondence: [email protected]; Tel.: +86-255-869-5697 Received: 22 September 2017; Accepted: 13 December 2017; Published: 15 December 2017 Abstract: A total of 168 fully polarimetric synthetic-aperture radar (SAR) images are selected together with the buoy measurements of ocean surface wind fields and high-frequency radar measurements of ocean surface currents. Our objective is to investigate the effect of the ocean currents on the retrieved SAR ocean surface wind fields. The results show that, compared to SAR wind fields that are retrieved without taking into account the ocean currents, the accuracy of the winds obtained when ocean currents are taken into account is increased by 0.2–0.3 m/s; the accuracy of the wind direction is improved by 3–4◦. Based on these results, a semi-empirical formula for the errors in the winds and the ocean currents is derived. -
Industrial Aerodynamics
INDUSTRIAL AERODYNAMICS Unit I Wind Energy Collectors INTRODUCTION Air Movement Wind Air Current Circulation The horizontal movement of air along the earth’s surface is called a Wind. The vertical movement of the air is known as an air current. Winds and air current together comprise a system of circulation in the atmosphere. TYPES OF WINDS On the earth’s surface, certain winds blow constantly in a particular direction throughout the year. These are known as the ‘Prevailing Winds’. They are also called the Permanent or the Planetary Winds. Certain winds blow in one direction in one season and in the opposite direction in another. They are known as Periodic Winds. Then, there are Local Winds in different parts of the world. 1. Planetary Winds: There are three main planetary winds that constantly blow in the same direction all around the world. They are also called prevailing or permanent winds. 1.Trade Winds: Blow from the subtropical high pressure belt towards the Equator. They are called the north-east trades in the northern hemisphere and south-east trades in the southern hemisphere. 2.Westerly winds: Blow from the same subtropical high pressure belts, towards 60˚ S and 60˚ N latitude. They are called the sought Westerly wind sin the northern hemisphere and North Westerly winds in the southern hemispheres. 3.Polar Winds Blow from the polar high pressure to the sub polar low pressure area. In the northern hemisphere, their direction is from the north-east. In the southern hemisphere, they blow from the south-east. 2. Periodic Winds These winds are known to blow for a certain time in a certain direction - it may be for a part of a day or a particular season of the year. -
Small Lightweight Aircraft Navigation in the Presence of Wind Cornel-Alexandru Brezoescu
Small lightweight aircraft navigation in the presence of wind Cornel-Alexandru Brezoescu To cite this version: Cornel-Alexandru Brezoescu. Small lightweight aircraft navigation in the presence of wind. Other. Université de Technologie de Compiègne, 2013. English. NNT : 2013COMP2105. tel-01060415 HAL Id: tel-01060415 https://tel.archives-ouvertes.fr/tel-01060415 Submitted on 3 Sep 2014 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Par Cornel-Alexandru BREZOESCU Navigation d’un avion miniature de surveillance aérienne en présence de vent Thèse présentée pour l’obtention du grade de Docteur de l’UTC Soutenue le 28 octobre 2013 Spécialité : Laboratoire HEUDIASYC D2105 Navigation d'un avion miniature de surveillance a´erienneen pr´esencede vent Student: BREZOESCU Cornel Alexandru PHD advisors : LOZANO Rogelio CASTILLO Pedro i ii Contents 1 Introduction 1 1.1 Motivation and objectives . .1 1.2 Challenges . .2 1.3 Approach . .3 1.4 Thesis outline . .4 2 Modeling for control 5 2.1 Basic principles of flight . .5 2.1.1 The forces of flight . .6 2.1.2 Parts of an airplane . .7 2.1.3 Misleading lift theories . 10 2.1.4 Lift generated by airflow deflection . -
Ocean Circulation and Climate: an Overview
ocean-climate.org Bertrand Delorme Ocean Circulation and Yassir Eddebbar and Climate: an Overview Ocean circulation plays a central role in regulating climate and supporting marine life by transporting heat, carbon, oxygen, and nutrients throughout the world’s ocean. As human-emitted greenhouse gases continue to accumulate in the atmosphere, the Meridional Overturning Circulation (MOC) plays an increasingly important role in sequestering anthropogenic heat and carbon into the deep ocean, thus modulating the course of climate change. Anthropogenic warming, in turn, can influence global ocean circulation through enhancing ocean stratification by warming and freshening the high latitude upper oceans, rendering it an integral part in understanding and predicting climate over the 21st century. The interactions between the MOC and climate are poorly understood and underscore the need for enhanced observations, improved process understanding, and proper model representation of ocean circulation on several spatial and temporal scales. The ocean is in perpetual motion. Through its DRIVING MECHANISMS transport of heat, carbon, plankton, nutrients, and oxygen around the world, ocean circulation regulates Global ocean circulation can be divided into global climate and maintains primary productivity and two major components: i) the fast, wind-driven, marine ecosystems, with widespread implications upper ocean circulation, and ii) the slow, deep for global fisheries, tourism, and the shipping ocean circulation. These two components act industry. Surface and subsurface currents, upwelling, simultaneously to drive the MOC, the movement of downwelling, surface and internal waves, mixing, seawater across basins and depths. eddies, convection, and several other forms of motion act jointly to shape the observed circulation As the name suggests, the wind-driven circulation is of the world’s ocean. -
Coastal Upwelling Revisited: Ekman, Bakun, and Improved 10.1029/2018JC014187 Upwelling Indices for the U.S
Journal of Geophysical Research: Oceans RESEARCH ARTICLE Coastal Upwelling Revisited: Ekman, Bakun, and Improved 10.1029/2018JC014187 Upwelling Indices for the U.S. West Coast Key Points: Michael G. Jacox1,2 , Christopher A. Edwards3 , Elliott L. Hazen1 , and Steven J. Bograd1 • New upwelling indices are presented – for the U.S. West Coast (31 47°N) to 1NOAA Southwest Fisheries Science Center, Monterey, CA, USA, 2NOAA Earth System Research Laboratory, Boulder, CO, address shortcomings in historical 3 indices USA, University of California, Santa Cruz, CA, USA • The Coastal Upwelling Transport Index (CUTI) estimates vertical volume transport (i.e., Abstract Coastal upwelling is responsible for thriving marine ecosystems and fisheries that are upwelling/downwelling) disproportionately productive relative to their surface area, particularly in the world’s major eastern • The Biologically Effective Upwelling ’ Transport Index (BEUTI) estimates boundary upwelling systems. Along oceanic eastern boundaries, equatorward wind stress and the Earth s vertical nitrate flux rotation combine to drive a near-surface layer of water offshore, a process called Ekman transport. Similarly, positive wind stress curl drives divergence in the surface Ekman layer and consequently upwelling from Supporting Information: below, a process known as Ekman suction. In both cases, displaced water is replaced by upwelling of relatively • Supporting Information S1 nutrient-rich water from below, which stimulates the growth of microscopic phytoplankton that form the base of the marine food web. Ekman theory is foundational and underlies the calculation of upwelling indices Correspondence to: such as the “Bakun Index” that are ubiquitous in eastern boundary upwelling system studies. While generally M. G. Jacox, fi [email protected] valuable rst-order descriptions, these indices and their underlying theory provide an incomplete picture of coastal upwelling. -
Pheriponf-01A Introduction to Physical Oceanography for Minors Module
pherIPOnf-01a Introduction to Physical Oceanography for Minors Module Name Modul Code Introduction to Physical Oceanography for Minors pherIPOnf-01a Module Coordinator Prof. Dr. Peter Brandt Organizer GEOMAR Helmholtz Centre for Ocean Research Kiel Fakulty Faculty of Mathematics and Natural Sciences Examination Office Examination Office Geosciences Status (C / CE / O) C ECTS Credits 5 Evaluation graded Duration one Semester Frequency every summer semester Workload per ECTS Credit 30 hours Total Workload 150 hours Contact Time 26 hours Independent Study 124 hours Teaching Language English Entry Requirements as Stated in the none Examination Regulations Recommended Requirements* Module Course(s) Compulsory/Compulsory Credit Course Type Course Name elective/Optional hours Introduction to Physical Lecture Compulsory 2 Oceanography Further Information on the Course(s)* Prerequisits for Admission to the Examination(s)* Examination(s) Type of Compulsory/Compulsory Examination Name Evaluation Weighting Examination elective/Optional Introduction to Physical Written Graded Compulsory 100% Oceanography Examination Further Information on the Examination(s)* Short Summary* Course Content Topography of the sea bed, composition and physical properties of sea water and sea ice, sound, heat budget, mean sea salt stratification, characteristic water masses, wind induced ocean currents, geostrophic currents, thermohaline circulation, regional oceanography, tides, ocean currents Learning Outcomes The students have developed a basic knowledge of the structure and dynamics of the ocean. They are able to understand the most important physical mechanisms in the ocean and to apply this knowledge in the study of subject-specific topics of the continuing modules of meteorology and physical oceanography. Reading List Talley, L.D., G.L. Pickard, W.J. Emery, J.H. -
Oceanography of the Pacific Northwest Coastal Ocean and Estuaries with Application to Coastal Ecosystems
Oceanography of the Pacific Northwest Coastal Ocean and Estuaries with Application to Coastal Ecosystems Barbara M. Hickey1 and Neil S. Banas School of Oceanography Box 355351 University of Washington, Seattle, WA 98195-7940 Tel.: 206 543 4737 e-mail: [email protected] Submitted to Estuaries May 2002 1Corresponding author. Hickey and Banas 2 Abstract This paper reviews and synthesizes recent results on both the coastal zone of the U.S. Pacific Northwest (PNW) and several of its estuaries, as well as presenting new data from the PNCERS program on links between the inner shelf and the estuaries, and smaller-scale estuarine processes. In general ocean processes are large-scale on this coast: this is true of both seasonal variations and event-scale upwelling-downwelling fluctuations, which are highly energetic. Upwelling supplies most of the nutrients available for production, although the intensity of upwelling increases southward while primary production is higher in the north, off the Washington coast. This discrepancy is attributable to mesoscale features: variations in shelf width and shape, submarine canyons, and the Columbia River plume. These and other mesoscale features (banks, the Juan de Fuca eddy) are important as well in transport and retention of planktonic larvae and harmful algae blooms. The coastal-plain estuaries, with the exception of the Columbia River, are relatively small, with large tidal forcing and highly seasonal direct river inputs that are low-to-negligible during the growing season. As a result primary production in the estuaries is controlled principally not by river-driven stratification but by coastal upwelling and bulk exchange with the ocean. -
Intercomparison of Planetary Boundary-Layer Parametrizations in the WRF Model for a Single Day from CASES-99
Boundary-Layer Meteorol (2011) 139:261–281 DOI 10.1007/s10546-010-9583-z ARTICLE Intercomparison of Planetary Boundary-Layer Parametrizations in the WRF Model for a Single Day from CASES-99 Hyeyum Hailey Shin · Song-You Hong Received: 5 June 2010 / Accepted: 22 December 2010 / Published online: 20 January 2011 © Springer Science+Business Media B.V. 2011 Abstract This study compares five planetary boundary-layer (PBL) parametrizations in the Weather Research and Forecasting (WRF) numerical model for a single day from the Coop- erative Atmosphere-Surface Exchange Study (CASES-99) field program. The five schemes include two first-order closure schemes—the Yonsei University (YSU) PBL and Asymmet- ric Convective Model version 2 (ACM2), and three turbulent kinetic energy (TKE) closure schemes—the Mellor–Yamada–Janji´c (MYJ), quasi-normal scale elimination (QNSE), and Bougeault–Lacarrére (BouLac) PBL. The comparison results reveal that discrepancies among thermodynamic surface variables from different schemes are large at daytime, while the vari- ables converge at nighttime with large deviations from those observed. On the other hand, wind components are more divergent at nighttime with significant biases. Regarding PBL structures, a non-local scheme with the entrainment flux proportional to the surface flux is favourable in unstable conditions. In stable conditions, the local TKE closure schemes show better performance. The sensitivity of simulated variables to surface-layer parametrizations is also investigated to assess relative contributions of the surface-layer parametrizations to typical features of each PBL scheme. In the surface layer, temperature and moisture are more strongly influenced by surface-layer formulations than by PBL mixing algorithms in both convective and stable regimes, while wind speed depends on vertical diffusion formulations in the convective regime. -
Syllabus Physical Oceanography OEAS 405/505/604 Fall 2021
Syllabus Physical Oceanography OEAS 405/505/604 Fall 2021 Instructor: Tal Ezer (683-5631; [email protected]) Office: CCPO, Innovation Research Park I, 4111 Monarch Way, Room 3217 Office Hours: Monday, Wednesday 09:00am-11:00am (email to schedule any other time) Class time: Tuesday, Thursday, 9:15am-10:30pm. First class: Tuesday, August 31. Place: Room 3200, CCPO, Research Bldg. I, 4111 Monarch Way Web page for class notes: http://www.ccpo.odu.edu/~tezer/405_604/ Learning Outcomes: Students will acquire a broad knowledge of the field of Physical Oceanography and learn how scientists in this field collect, analyze and present data for their research. Students will learn about ocean measurements, seawater properties, and the equations of motion that can help us study ocean currents, ocean circulation patterns, waves, tides and other oceanic processes. Prerequisites: One semester of calculus and two semesters of physics, hydraulics or similar courses. Official Textbook – Knauss and Garfield, 2017: Introduction to Physical Oceanography, Third Edition. or Knauss, 1997: Introduction to Physical Oceanography, Second Edition. Other useful books- Stewart, (electronic version, 2008): Introduction to Physical Oceanography (available online) Pickard & Emery, 1982: Descriptive Physical Oceanography More advanced- Pond & Pickard, 1983: Introductory Dynamic Oceanography Mellor, 1996: Introduction to Physical Oceanography Supporting resources: online data, journal articles, computer models, satellite remote sensing, etc. Grading: • Homework assignments: 50%