New Publications are available for Winds and their effects in the lower atmosphere
http://dl-live.theiet.org
New Publications are available now online for this publication.
Please follow the links to view the publication.Integrated design approach - urban design for sustainability
http://dl-live.theiet.org/content/conferences/10.1049/cp.2010.0441
This paper proposes new quantitative research methods with computational fluid dynamics (CFD) tools for a sustainable urban design project. This research study is sponsored by Research Councils UK (RCUK) China office. This project is part of the Caofeidian International Eco-town development in North-Eastern China. The research programme addresses the main aspects of good practice in terms of eco-design and sustainability. These aspects include wind flow analysis around buildings, pollutant dispersion in water systems and noise control on urban highways. This programme aims to explore a range of research methods in order to enhance the performance of integrated design with a comprehensive planning stage. The pros and cons, alongside other deficiencies in current forms of comprehensive plan are to be explored further. This project evaluates the Chinese Planning System and introduces new ways of achieving sustainable urban design. The integration in assessment and evaluation across professions and subject boundaries is emphasised to identify the key gaps between sustainability and design.Depolarization effect by wind incidence on vegetation at 40 GHz
http://dl-live.theiet.org/content/conferences/10.1049/ic.2007.1554
A measurement campaign was developed for determining the power attenuation due to individual plants placed inside an anechoic chamber. Measurements of copolar and crosspolar components were conducted to study the depolarization of the incident wave produced by propagation through trees. An analysis of signal strength and depolarization in long- and short-terms, due to wind incidence on individual trees, is presented. Cumulative distribution functions (CDF) for the slow fading component, were obtained, and correlation coefficients were estimated, between the copolar and the crosspolar power levels measured for the different wind speeds and fan positions, to analyze the influence of the wind speed on the depolarization. (6 pages)Detection of ducts by wind profiler radar
http://dl-live.theiet.org/content/conferences/10.1049/cp_20030015
Propagation of radar signals through the atmosphere is strongly dependent on local meteorological conditions, especially in the atmospheric boundary layer. A rapid change in air temperature and humidity with height leads to the generation of tropospheric ducts. Electromagnetic energy can propagate over large distances within a duct and can cause interference on terrestrial and satellite communication links. Duct detection is therefore desirable to predict such interference and influence on radar coverage. Anomalous variations in radiosonde measured temperature and humidity gradient, yield negative values of modified refractive index, M, gradient profiles. These profiles are indicators of ducting conditions in the lower troposphere. However, radiosonde measurements are sparsely distributed in time. Autonomous systems such as wind profiler radars, which operate continuously 24 hours a day could provide continuous monitoring of duct occurrence with height. The 915 MHz wind profiler (operated by the UK Meteorological Office at Camborne) and radiosonde data from Camborne were analysed for the month of June 2000. The data analyses showed that the wind profiler is able to detect ducting conditions through (i) strong correlation of increase in the turbulence structure function parameter, C<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">n</sub><sup xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sup>, with negative values of dM/dz and (ii) agreement in increase in potential refractive index (estimated from radar data) with increase in potential refractive index obtained from radiosonde data, within the duct region.Observed effects of wind on the intensity and spectrum of scintillation
http://dl-live.theiet.org/content/conferences/10.1049/cp_20010347
This paper investigates the observed effect of cross-path wind on the corner frequency of the scintillation power spectrum. Propagation data from ITALSAT satellite were used in this investigation, a satellite beacon operating at 18.68 GHz, 39.59 GHz and 49.49 GHz and covering two months, June and July 1997. The data were obtained at Sparsholt (51.5850° N, 1.5033°W), UK, at an elevation angle thetas=29.9° and at a sampling rate of 1 Hz, using a Cassegrain antenna of diameter 1.22 m for the 18.68 GHz and 0.61 m for the 39.59 GHz and 49.49 GHz. The results show some correlation between the corner frequency and transverse wind speed, a weaker correlation with over-all wind speed and a poor correlation between scintillation intensity and wind speed.Influence of tropical monsoon and local wind circulation to lightning discharge over Indonesia
http://dl-live.theiet.org/content/conferences/10.1049/cp_19990626
Monsoon and local wind circulation have a significant effect on the lightning discharge characteristics in tropical area especially in coastal and mountainous areas of the West Jawa region in Indonesia. Lightning characteristics derived from local measurements and lightning data recorded by the Indonesia lightning location system in the region of Mnt. Tangkuban Perahu were compared and evaluated. Lightning ground flash density through the year in the West Jawa region were introduced to show the significant influence of local and regional correlation to the lightning discharge characteristic. (4 pages)Optimisation of the terminal Doppler weather radar in a cluttered marine environment
http://dl-live.theiet.org/content/conferences/10.1049/cp_19971697
Discusses the Terminal Doppler Weather Radar (TDWR) for the new airport at Chek Lap Kok (CLK) of Hong Kong. This paper discusses the radar characteristics that ensure that the TDWR is able to meet its mission requirements while working in the highly cluttered marine environment of Hong Kong. The Terminal Doppler Weather Radar (TDWR) system, developed by Raytheon Company for the US Federal Aviation Administration (FAA), provides automatic detection of microbursts and low-level wind shear. The second major function of TDWR is to improve air traffic management through forecasts of wind shifts, precipitation and other weather hazards. The TDWR system generates meteorological base data and wind shear products and automatically prepares warning messages for the air traffic controllers, through the timely detection and reporting of hazardous wind shear. It collects low altitude meteorological data and performs reliably in the terminal area environment characterized by natural and man-made ground clutter. The TDWR design specifically addresses the extraction of weather information in the presence of radar returns from severe ground clutter. The TDWR radar utilizes the Doppler effect to measure the radial velocity of rain or airborne microparticulates. This paper addresses the characteristics of the TDWR system design, siting, and signal processing techniques that are critical to optimal performance in the Hong Kong environment, and discusses observations during the optimisation of the TDWR.Measurement of wind velocities and refractivity turbulence structure constant using Indian MST radar
http://dl-live.theiet.org/content/conferences/10.1049/cp_19950447
In this paper an intercomparison of vertical profiles of horizontal velocity observed with MST radar and radiosonde is presented. A gross agreement is seen generally between the radar and balloon measured wind profiles. Vertical profile of the refractivity turbulence structure constant, Cn<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sup> is compared with a model computation of Cn<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sup> based on radiosonde observations. The radar reflectivity and the theoretical model provide good estimates of the 2 vertical profiles of Cn<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sup>. Profiles of Cn<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sup> (model) agree well with the measured profiles of Cn<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sup> (radar). (4 pages)Acoustic sounder applications: remote sensing of sea breeze and radio propagation studies over tropical India
http://dl-live.theiet.org/content/conferences/10.1049/cp_19950448
Acoustic sounding is one of the remote sensing techniques that can give continuous information about some of the micro-meteorological parameters of the lower atmosphere. Microwave propagation is strongly influenced by the atmospheric boundary layer where radioclimatological phenomena such as temperature inversions, fronts, and thunderstorms cause steep refractivity gradients. An important parameter in the study of tropospheric propagation is the refractive index which causes reflection, refraction, diffraction and scattering of radio waves. In an effort to identify the causes of fading over LOS microwave links a monostatic sodar was installed at Tirupati (receiving end of the links) to probe the dynamic behavior of lower atmospheric effects on LOS propagation. The observational study has provided some basic understanding of the boundary layer characteristics affecting propagation and benefitted the development of a climatological model. The authors present some observed significant episodes pertinent to the classification of fading characteristics associated with each of the various atmospheric conditions. In addition, possibilities for the causes of fading are also discussed. It is concluded that severe fading in the early morning and late evening hours is caused due to temperature inversions observed over this region. (4 pages)A moored ‘surface-following’ buoy for spectral wind measurements with satellite and VHF data telemetry
http://dl-live.theiet.org/content/conferences/10.1049/cp_19940581
Discusses the development of a Sonic Buoy. The high quality of the results from the SWALES deployment vindicates the decision to develop the Sonic Buoy. The relation between the calculated wind stress and wind speed is much more clearly defined than in previous ship-based measurements. On the technical side, the buoy design has been proved with respect to survivability, and the redundancy built into the data logging and telemetry has proved its worth.EM models for evaluating rain perturbation on the NRCS of the sea surface observed near nadir
http://dl-live.theiet.org/content/journals/10.1049/ip-rsn_19981901
The authors address the problem of evaluating the normalised radar cross-section (NRCS) of the sea surface perturbed by the joint effect of rain and wind, when observed close to nadir. They present a model, based on the full wave theory, for evaluating such an NRCS when varying polarisation, frequency and incidence angle (not far from nadir) for different values of wind velocity and of the root mean square height of the corrugation induced by rainfall. Some comparisons are made with the integral equation model results in the case of rain-induced corrugation alone. The two models are found to be in good agreement. In addition, partial comparisons made with experimental data suggest that the proposed model is well grounded and exploitable for application. It is indeed expected that the model can be exploited to improve precipitation measurements over the sea through spaceborne rain radar and to improve wind measurements using scatterometers in the presence of rain.Characterisation of wind field with high resolution in time and space by the use of electromagnetic and acoustic waves
http://dl-live.theiet.org/content/journals/10.1049/ip-rsn_20010095
The authors present a bistatic radio–acoustic system where a Bragg grid produced by a spherical pressure wave enhances the forward scattering capability by some 40 dB when matched to the EM phase front. The system is used to measure 3-D wind, turbulence and vortex parameters as wind phenomena alter the scattering characteristics of the acoustic Bragg grid. The criterion for Bragg scattering is only valid over a limited height interval in this system. This confines the scattering volume to the limits of the radio beam and the acoustic beam in the horizontal direction and the Bragg-criteria limitations in the vertical direction. This scattering volume can be shifted vertically by tuning the acoustic frequency to give spatial resolution. Illuminating the acoustic Bragg grid with a CW EM signal gives a continuously received signal from a small scattering volume at a given height. It is possible to continuously measure the real-time cross-path wind component and at the same time perform coherent integration over longer time intervals in investigating turbulence phenomena. Experimental verification supports the theoretical models and underlines the system's capacity to measure wind phenomena, vortex structures and turbulence parameters.Approach for satellite slant path remote sensing
http://dl-live.theiet.org/content/journals/10.1049/el_19980812
It is theoretically and experimentally shown how angular smoothing of the sky brightness temperature caused by the radiometer antenna pattern can be used in conjunction with the spectral characteristics of the amplitude scintillations of a beacon receiver to allow unambiguous determination of the wind speed of a turbulent layer and its height, helping in the estimation of the refractive index structure constant (<i xmlns="http://pub2web.metastore.ingenta.com/ns/">C<sub>n</sub></i><sup xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sup>).Measurements and inferences of raindrop canting angles
http://dl-live.theiet.org/content/journals/10.1049/el_20082899
The canting angle distribution of raindrops derived separately from a 2-D video disdrometer and from an S-band advanced polarimetric radar are presented. In the former case, measurements were made in both natural and artificial rain. The canting angles showed a symmetric distribution about 0° with a standard deviation (σ<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">β</sub>) of 7°–8° in low wind conditions and 12° in moderate wind conditions. In the radar-based estimates, the histogram of σ<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">β</sub> derived from data obtained during a light stratiform rain event with embedded convection shows the mode to be around 7°, with a significant positive skewness. Around 16% of occurrences exceeded 10° and 3.3% exceeded 15°.Extension of Kirchhoff method under stationary phase approximation to determination of polarimetric thermal emission of the sea
http://dl-live.theiet.org/content/journals/10.1049/el_19981055
Wind direction over the sea can be determined from radiometric measurements of the third Stokes parameter (<i xmlns="http://pub2web.metastore.ingenta.com/ns/">T<sub>U</sub></i>). The Kirchhoff method is extended under the stationary phase approximation to compute the dependence of <i xmlns="http://pub2web.metastore.ingenta.com/ns/">T<sub>U</sub></i> on frequency, wind speed and incidence angle. Numerical predictions, in agreement with experimental measurements, are presented.An electrical method of resolving true wind velocity aboard ship
http://dl-live.theiet.org/content/journals/10.1049/jiee-2.1951.0115
Wind- and gust-measuring instruments developed for a wind-power survey
http://dl-live.theiet.org/content/journals/10.1049/jiee-2.1951.0114
The development of electrical anemometers
http://dl-live.theiet.org/content/journals/10.1049/jiee-2.1951.0113
Mean-wind-velocity instruments for use on naval craft
http://dl-live.theiet.org/content/journals/10.1049/jiee-2.1951.0116
Wind- and gust-measuring instruments developed for a wind-power survey
http://dl-live.theiet.org/content/journals/10.1049/pi-2.1951.0124
A description is given of two recorders and an anemometer for measuring gusts, which were developed for use in a survey of the available wind-power in Great Britain. The essential feature of the recorders is that they operate unattended for a period of one week. The first instrument is a photographic recorder which shows, at intervals of half an hour, the wind direction and the run of wind past four standard cup contact anemometers. The second instrument records a mark for each two miles of wind, and will make up to four simultaneous records. The anemometer for measuring gusts uses a perforated aluminium sphere as the detecting element and a mechanoelectronic transducer valve to convert the mechanical response to an electrical output. It is compensated for changes of temperature and for the static effects of atmospheric pressure. When used with an amplifier-driven recording voltmeter, the response of the prototype instrument to an instantaneous change of wind speed from 65 to 85 m.p.h., was completed in about 0.07 sec. Modified forms of the instrument are described which measure, respectively, the horizontal components of the wind in two directions at right angles and the vertical component.The development of electrical anemometers
http://dl-live.theiet.org/content/journals/10.1049/pi-3.1951.0098
Wind- and gust-measuring instruments developed for a wind-power survey
http://dl-live.theiet.org/content/journals/10.1049/pi-3.1951.0100
The development of electrical anemometers
http://dl-live.theiet.org/content/journals/10.1049/pi-2.1951.0123
The paper outlines the development of instruments for measuring and recording wind speed and direction by various electrical means. Methods of calibration and standardization are discussed in relation to the accuracy and speed of response of standard instruments, and some further models which were made for special investigations, or which are still in the development stage, are described. For general use in the Meteorological Office, the most suitable combination of instruments is a cup anemometer of the generator type with an autographic recorder consisting of some form of recording voltmeter and a remote-recording wind vane connected by a self-synchronous a.c. transmission system to a recorder which is capable of being operated by a small torque. The cup anemometer will record the speed of the wind and the wind vane will record its direction.An electrical method of resolving true wind velocity aboard ship
http://dl-live.theiet.org/content/journals/10.1049/pi-2.1951.0126
A knowledge of the behaviour of the true wind aboard ship is essential in modern meteorological practices. The true wind velocity can be resolved from the measured speed and direction of the relative wind and of the ship. A method of polar resolution by alternating current representation of force vectors is shown, together with an outline of the apparatus needed for primary measurement and resolution. The accuracy of the original resolving gear under practical conditions is indicated.Mean-wind-velocity instruments for use on naval craft
http://dl-live.theiet.org/content/journals/10.1049/pi-2.1951.0125
The paper describes two instruments made for use on naval craft during the 1939–45 War. The first was fitted to auxiliary aircraft carriers, and indicated the mean wind direction, so that the vessel might be steered correctly for the take-off and landing of aircraft. The second instrument was fitted on larger naval craft, for meteorological purposes. Its function was to indicate, in various positions in the ship, the direction and speed of both the mean true and the mean apparent winds.The components used in both instruments are magslip transmission elements and electrical computing devices, which were developed for fire-control purposes and subsequently adopted for the meteorological applications.Mean-wind-velocity instruments for use on naval craft
http://dl-live.theiet.org/content/journals/10.1049/pi-3.1951.0101
An electrical method of resolving true wind velocity aboard ship
http://dl-live.theiet.org/content/journals/10.1049/pi-3.1951.0099
Estimation of low-level winds from upper-air data
http://dl-live.theiet.org/content/journals/10.1049/ip-a-1.1983.0079
Estimates of winds at heights of around 100 m are required for the siting of large wind turbines. Because of uncertainties often attached to the normal method of extrapolating from data at 10 m, a method of extrapolating from upper-air data has been developed. The predictions of this method are compared with measurements at several stations on land and one offshore.Dual frequency scintillation measurement for remote sensing
http://dl-live.theiet.org/content/journals/10.1049/el_19951378
A scheme is proposed for utilising measurements of radiowave amplitude scintillation at two frequencies for remote sensing of wind speed and atmospheric turbulence parameters. The main advantage of the method is that all quantities are estimated solely from measured scintillation parameters without the need for secondary measurements. It is shown that the method yields results which compare well with other measurements.