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Beaufort Scale

The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform

Bryan R Kerman – 1st expert on this subject based on the ideXlab platform

  • a multifractal equivalent of the Beaufort Scale for sea state
    Geophysical Research Letters, 1993
    Co-Authors: Bryan R Kerman

    Abstract:

    It is reported here that the ocean surface under a sufficiently high wind is a multi-fractal process, consisting of breaking wave singularities. It has been argued elsewhere that the singularity strength associated with individual breaking waves implies a distinct energy state within a continuum of such states whose entropy is associated with a fractal dimension. When the multi-fractal process is modelled in the simplest, non-trivial multiplicative energy flux cascade – as a Besicovitch-Cantor process – 3 independent variables are required for a full description. It is shown that when a closure assumption is invoked which relates the 2 sub-process energy fluxes as a power-law in their respective receiving areas (the process’ support), the 2 exponents involved are remarkably constant within the experimental variation arising from different aircraft imaging sorties over different sea states. The result is a reduction of complexity from 3 to just 1 independent variable to describe any realization; this parameter is referred to as the multi-fractal equivalent of the Beaufort Scale.

  • A multifractal equivalent of the Beaufort Scale for sea‐state
    Geophysical Research Letters, 1993
    Co-Authors: Bryan R Kerman

    Abstract:

    It is reported here that the ocean surface under a sufficiently high wind is a multi-fractal process, consisting of breaking wave singularities. It has been argued elsewhere that the singularity strength associated with individual breaking waves implies a distinct energy state within a continuum of such states whose entropy is associated with a fractal dimension. When the multi-fractal process is modelled in the simplest, non-trivial multiplicative energy flux cascade – as a Besicovitch-Cantor process – 3 independent variables are required for a full description. It is shown that when a closure assumption is invoked which relates the 2 sub-process energy fluxes as a power-law in their respective receiving areas (the process’ support), the 2 exponents involved are remarkably constant within the experimental variation arising from different aircraft imaging sorties over different sea states. The result is a reduction of complexity from 3 to just 1 independent variable to describe any realization; this parameter is referred to as the multi-fractal equivalent of the Beaufort Scale.

John Tyrrell – 2nd expert on this subject based on the ideXlab platform

  • comparing the theoretical versions of the Beaufort Scale the t Scale and the fujita Scale
    Atmospheric Research, 2007
    Co-Authors: Terence G Meaden, S Kochev, Leszek Kolendowicz, A Kosakiss, Izolda Marcinoniene, Michalis V Sioutas, Heino Tooming, John Tyrrell

    Abstract:

    Abstract 2005 is the bicentenary of the Beaufort Scale and its wind-speed codes: the marine version in 1805 and the land version later. In the 1920s when anemometers had come into general use, the Beaufort Scale was quantified by a formula based on experiment. In the early 1970s two tornado wind-speed Scales were proposed: (1) an International T-Scale based on the Beaufort Scale; and (2) Fujita’s damage Scale developed for North America. The International Beaufort Scale and the T-Scale share a common root in having an integral theoretical relationship with an established scientific basis, whereas Fujita’s Scale introduces criteria that make its intensities non-integral with Beaufort. Forces on the T-Scale, where T stands for Tornado force, span the range 0 to 10 which is highly useful world wide. The shorter range of Fujita’s Scale (0 to 5) is acceptable for American use but less convenient elsewhere. To illustrate the simplicity of the decimal T-Scale, mean hurricane wind speed of Beaufort 12 is T2 on the T-Scale but F1.121 on the F-Scale; while a tornado wind speed of T9 (= B26) becomes F4.761. However, the three wind Scales can be uni-fied by either making F-Scale numbers exactly half the magnitude of T-Scale numbers [i.e. F′half = T / 2 = (B / 4) − 4] or by doubling the numbers of this revised version to give integral equivalence with the T-Scale. The result is a decimal formula F′double = T = (B / 2) − 4 named the TF-Scale where TF stands for Tornado Force. This harmonious 10-digit Scale has all the criteria needed for world-wide practical effectiveness.

Alfredo Renga – 3rd expert on this subject based on the ideXlab platform

  • SAR-Based Vessel Velocity Estimation From Partially Imaged Kelvin Pattern
    IEEE Geoscience and Remote Sensing Letters, 2017
    Co-Authors: Alessandro Panico, Maria Daniela Graziano, Alfredo Renga

    Abstract:

    Spaceborne synthetic aperture radar (SAR) can be considered an operational asset for maritime monitoring applications. Well-assessed approaches exist for ship detection, validated in several maritime surveillance systems. However, measuring vessel velocity from detected single-channel SAR images of ships is in general difficult. This letter contributes to this problem by investigating the possibility of retrieving vessel velocity by wake analysis. An original method for velocity estimation is developed for calm sea (Beaufort Scale 1-2) and applied over seven X-band SAR images, gathered by COSMO-SkyMed mission over the Gulf of Naples, Italy. The algorithm exploits the well-known relation between the wavelength of the waves composing the Kelvin pattern and the ship velocity. But the proposed approach extends the applicability of the existing wake-based techniques since it foresees evaluation of the wavelength along a generic direction in the Kelvin angle. Promising results have been achieved, which are in good agreement with those of more assessed techniques for ship velocity estimation in SAR images.