Wave Disturbance Transport Caused by Rocket Launches Accompanied by Solar Terminator

2016 ◽  
pp. 77-110
Keyword(s):  
Wave Disturbance ◽  
Solar Terminator

scholarly journals An Underwater Quadrotor Control with Wave-disturbance Compensation by a UKF

2020 ◽  
Vol 53 (2) ◽  
pp. 9017-9022
Author(s):  
T. Ohhira ◽  
A. Kawamura ◽  
A. Shimada ◽  
T. Murakami
Keyword(s):  
Wave Disturbance ◽  
Disturbance Compensation ◽  
Quadrotor Control

scholarly journals On the Relationship between Low Latitude Scintillation Onset and Sunset Terminator over Africa

2021 ◽  
Vol 13 (11) ◽  
pp. 2087
Author(s):  
Mogese Wassaie Mersha ◽  
Elias Lewi ◽  
Norbert Jakowski ◽  
Volker Wilken ◽  
Jens Berdermann ◽  
...  
Keyword(s):  
Moving Boundary ◽  
Occurrence Rate ◽  
Scintillation Index ◽  
Small Scale ◽  
Bahir Dar ◽  
Remarkable Change ◽  
Equatorial Africa ◽  
Night Side ◽  
Solar Terminator ◽  
First Time

The solar terminator is a moving boundary between day-side and night-side regions on the Earth, which is a substantial source of perturbations in the ionosphere. In the vicinity of the solar terminator, essential parameters like S4 index measurements are widely analyzed in order to monitor and predict perturbations in the ionosphere. The utilization of the scintillation index S4 is a well-accepted approach to describe the amplitude/intensity fluctuation of a received signal, predominantly caused by small-scale irregularities of the ionospheric plasma. We report on the longitudinal daily and seasonal occurrence of GNSS signal scintillations, using the data derived from the GNSS stations in Bahir Dar, Ethiopia, Lomé, Togo and Dakar, Senegal. The observed seasonal climatology of GNSS signal scintillations in equatorial Africa is adequately explained by the alignment of the solar terminator and local geomagnetic declination line. It should be pointed out that the strongest scintillations are most frequently observed during the time when the solar terminator is best aligned with the geomagnetic declination line. At all three stations, the comparison of computational and observational results indicated that the scintillation activity culminated around equinoxes in the years 2014, 2015 and 2016. Comparatively, the western equatorial Africa sector has the most intense, longest-lasting, and highest scintillation occurrence rate in equinoctial seasons in all three years. For the first time, we show that the seasonal variation of the scintillation peaks changes systematically from west to east at equatorial GNSS stations over Africa. A detailed analysis of the solar day–night terminator azimuth at ionospheric heights including the time equation shows that the scintillation intensity has a maximum if the azimuth of the terminator coincides with the declination line of the geomagnetic field. Due to the remarkable change of the declination by about 10° at the considered GNSS stations, the distance between scintillation peaks increases by 46 days when moving westward from the Bahir Dar to the Dakar GNSS station. The observations agree quite well with the computational results, thus confirming Tsunoda’s theory.

Tidal excitation of hydromagnetic waves and their damping in the Earth

1994 ◽  
Vol 274 ◽  
pp. 219-241 ◽  
Author(s):  
R. R. Kerswell
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Outer Core ◽  
Decay Rates ◽  
Wave Disturbance ◽  
Instability Mechanism ◽  
The Earth ◽  
Elliptical Instability ◽  
Hydromagnetic Waves

We examine the possibility that the Earth's outer core, as a tidally distorted fluid-filled rotating spheroid, may be the seat of an elliptical instability. The instability mechanism is described within the framework of a simple Earth-like model. The preferred forms of wave disturbance are explored and a likely growth rate supremum deduced. Estimates are made of the Ohmic and viscous decay rates of such hydromagnetic waves in the outer core. Rather than a conclusive disparity of scales, we find that typical elliptical growth rates, Ohmic decay rates and viscous decay rates all have the same order for plausible core fields and core-to-mantle conductivities. This study is all the more timely considering the recent realization that the Earth's precession may also drive similar instabilities at comparable strengths in the outer core.

scholarly journals Minor Structures for the Improvement of Wave Disturbance in a Small Harbor

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
A. Sulis
Keyword(s):  
Boussinesq Equations ◽  
Wave Disturbance ◽  
Comprehensive Description ◽  
New Energy ◽  
Efficient Alternative ◽  
Operational Activities ◽  
Traditional Structures ◽  
Energy Absorbing ◽  
Incident Waves ◽  
Large Research

A very important aspect in the planning, design, and maintenance of a harbor is to determine the response of the harbor basin to incident waves. The Saras harbor in South Sardinia (Italy) has been experiencing significant wave disturbance that affects the safety of mooring and operational activities. In the framework of a large research, this paper summarises a comprehensive description of new energy absorbing structures that can be seen as an efficient alternative to more traditional structures when limited by economic or technical constraints. Specifically, the paper presents the results of a graphical preliminary approach and a numerical modelling that solves the enhanced Boussinesq equations in two horizontal dimensions.

Timing of Wave Disturbance and the Resistance and Recovery of a Freshwater Epilithic Microalgal Community

1990 ◽  
Vol 9 (1) ◽  
pp. 54-67 ◽  
Author(s):  
Christopher G. Peterson ◽  
Kyle D. Hoagland ◽  
R. Jan Stevenson
Keyword(s):  
Wave Disturbance ◽  
Microalgal Community

Influence of Water Surface Wave Disturbance on Wireless Optical Communication

2021 ◽  
Vol 41 (7) ◽  
pp. 0706005
Author(s):  
李军 Li Jun ◽  
罗江华 Luo Jianghua ◽  
元秀华 Yuan Xiuhua
Keyword(s):  
Surface Wave ◽  
Optical Communication ◽  
Water Surface ◽  
Wave Disturbance ◽  
Wireless Optical Communication ◽  
Influence Of Water

Nonlinear Wave Disturbance Around a Vertical Circular Column

2002 ◽  
Author(s):  
C. T. Stansberg ◽  
H. Braaten
Keyword(s):  
Linear Prediction ◽  
Harmonic Component ◽  
Nonlinear Effects ◽  
Second Order ◽  
Wave Disturbance ◽  
Difference Frequency ◽  
Irregular Waves ◽  
Order Effects ◽  
Sum Frequency ◽  
Circular Column

The wave disturbance close to vertical columns is analysed. In particular, the deviations from linear predictions are investigated, by experimental as well as by numerical methods. Thus a second-order numerical diffraction model is established by means of a diffraction analysis code (WAMIT) and compared to model tests with a single, fixed column with diameter 16m. Tests in regular, bi-chromatic as well as irregular waves are run. Significant nonlinear effects are observed, especially in steep waves, with the maximum elevation in front of the column increasing from 11.5m in a linear prediction to around 19m, in a 12s regular wave with 22m wave height. The main nonlinear effects in front of the column are identified as second-order sum-frequency and difference-frequency terms, plus a significant nonlinear increase in the first harmonic component. The WAMIT prediction of the second-order effects agrees fairly well with the measurements, although with some overprediction and underprediction, respectively, of the sum-frequency and difference-frequency (LF and mean set-up) terms in the steepest waves. For the underprediction of the first harmonic, however, a theory beyond second order is required.

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