scholarly journals ROGUE WAVE ASYMMETRY IN THE DIRECT NUMERICAL SIMULATIONS OF DIRECTIONAL JONSWAP WAVES

2020 ◽  
pp. 48
Author(s):  
Alexey Slunyaev ◽  
Anna Kokorina
Keyword(s):  
Water Wave ◽  
Rogue Wave ◽  
Rogue Waves ◽  
Hydrodynamic Equations ◽  
Laboratory Measurements ◽  
Term Evolution ◽  
Typical Picture ◽  
High Order Spectral Method

The asymmetry between the troughs from the rear and front sides of rogue waves is the particular object of the present study. In our previous simulations of unidirectional waves the typical picture of a rogue waves possesses the trend that most of the rogue waves where characterized by deeper rear troughs. In the present work we broaden the discussion of the rogue wave front-to-crest asymmetry to the directional case. The direct numerical simulation of primitive water equations is an affordable alternative to the in-situ or laboratory measurements, in particularly when the interest is focused on the long-term evolution or on the detailed consideration of the water wave movement in space and time. In this work we simulate irregular surface waves in the hydrodynamic equations using the High-Order Spectral Method, and focus on the so-called rogue waves.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/plseXdjpE6c

Are There Different Kinds of Rogue Waves?

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Paul C. Liu ◽  
Keith R. MacHutchon
Keyword(s):  
Rogue Wave ◽  
Rogue Waves ◽  
Rayleigh Distribution ◽  
The Other ◽  
South Indian Ocean ◽  
Gas Drilling ◽  
Wave Measurements ◽  
South Indian ◽  
Theoretical Considerations

There is clearly no immediate answer to the question posted by the title of this paper. Inasmuch as that there are not much definitively known about rogue waves and that there is still no universally accepted definition for rogue waves in the ocean, we think there might just be even more than one kind of rogue waves to contend with. While the conventional approach has generally designated waves with Hmax∕Hs greater than 2.2 as possible rogue waves, based on Rayleigh distribution considerations, there is conspicuously no provision as to how high the ratio of Hmax∕Hs can be and thus not known how high can a rogue wave be. In our analysis of wave measurements made from a gas-drilling platform in South Indian Ocean, offshore from Mossel Bay, South Africa, we found a number of cases that indicated Hmax∕Hs could be valued in the range between 4 and 10. If this were to be the case, then these records could be considered to be “uncommon” rogue waves, whereas a record of Hmax∕Hs in the range between 2 and 4 could be considered to comprise “typical” rogue waves. On the other hand, the spikes in the Hmax data could have been caused by equipment malfunction or some other phenomenon. Clearly, the question of whether or not there are different kinds of rogue waves cannot be readily answered by theoretical considerations alone and there is a crucial need for long-term wave time-series measurements for studying rogue waves.

scholarly journals Long-term evolution and seasonal modulation of methanol above Jungfraujoch (46.5° N, 8.0° E): optimisation of the retrieval strategy, comparison with model simulations and independent observations

2014 ◽  
Vol 7 (5) ◽  
pp. 4659-4692 ◽  
Author(s):  
W. Bader ◽  
T. Stavrakou ◽  
J.-F. Muller ◽  
S. Reimann ◽  
C. D. Boone ◽  
...  
Keyword(s):  
Peak Amplitude ◽  
Systematic Bias ◽  
Retrieval Strategy ◽  
Model Simulations ◽  
Term Evolution ◽  
Time Period ◽  
Independent Observations ◽  
June July

Abstract. Methanol (CH3OH) is the second most abundant organic compound in the Earth's atmosphere after methane. In this work, we present the first long-term time series of methanol total, lower tropospheric and upper tropospheric-lower stratospheric partial columns derived from the analysis of high resolution Fourier transform infrared solar spectra recorded at the Jungfraujoch station (46.5° N, 3580 m a.s.l.). The retrieval of methanol is very challenging due to strong absorptions of ozone in the region of the selected υ8 band of CH3OH. Two wide spectral intervals have been defined and adjusted in order to maximize the information content. Methanol does not exhibit a significant trend over the 1995–2012 time period, but a strong seasonal modulation characterized by maximum values and variability in June–July, minimum columns in winter and a peak-to-peak amplitude of 130%. In situ measurements performed at the Jungfraujoch and ACE-FTS occultations give similar results for the methanol seasonal variation. The total and lower tropospheric columns are also compared with IMAGESv2 model simulations. There is no systematic bias between the observations and IMAGESv2 but the model underestimates the peak-to-peak amplitude of the seasonal modulations.

scholarly journals A Statistical Analysis of Rogue Waves in the Southern North Sea

2020 ◽  
Author(s):  
Ina Teutsch ◽  
Ralf Weisse ◽  
Jens Moeller ◽  
Oliver Krueger
Keyword(s):  
North Sea ◽  
Rogue Wave ◽  
Rogue Waves ◽  
New Wave ◽  
Radar Measurement ◽  
Southern North Sea ◽  
Monte Carlo Experiments ◽  
Statistical Sense ◽  
Radar Measurements

Abstract. A new wave dataset from the southern North Sea covering the period 2011–2016 and composed of wave buoy and radar measurements sampling the sea surface height at frequencies between 1.28–4 Hz was quality controlled and scanned for the presence of rogue waves. Here rogue waves refer to waves whose height exceeds twice the significant wave height. Rogue wave frequencies were analysed, compared to Rayleigh and Forristall distributions, and spatial, seasonal and long-term variability was assessed. Rogue wave frequency appeared to be relatively constant over the course of the year and uncorrelated among the different measurement sites. While data from buoys basically correspond with expectations from the Forristall distribution, radar measurement showed some deviations in the upper tail pointing towards higher rogue wave frequencies. Number of data available in the upper tail is, however, still limited to allow a robust assessment. Some indications were found that the distribution of waves in samples with and without rogue waves were different in a statistical sense. However, differences were small and deemed not to be relevant as attempts to use them as a criterion for rogue wave detection were not successful in Monte Carlo experiments based on the available data.

scholarly journals Long-term evolution of antibiotic persistence in P. aeruginosa lung infections

2021 ◽  
Author(s):  
Melanie Ghoul ◽  
Sandra B Andersen ◽  
Helle Krogh Johansen ◽  
Lars Jelsbak ◽  
Søren Molin ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Resistance Mechanisms ◽  
Term Evolution ◽  
Bacterial Clone ◽  
Evolution Of Resistance ◽  
Lung Infections

Pathogenic bacteria respond to antibiotic pressure with the evolution of resistance but survival can also depend on their ability to tolerate antibiotic treatment, known as persistence. While a variety of resistance mechanisms and underlying genetics are well characterised in vitro and in vivo, the evolution of persistence, and how it interacts with resistance in situ is less well understood. We assayed for persistence and resistance with three clinically relevant antibiotics: meropenem, ciprofloxacin and tobramycin, in isolates of Pseudomonas aeruginosa from chronic cystic fibrosis lung infections spanning up to forty years of evolution. We find evidence that persistence is under positive selection in the lung and that it can particularly act as an evolutionary stepping stone to resistance. However, this pattern is not universal and depends on the bacterial clone type and antibiotic used, indicating an important role for antibiotic mode of action.

scholarly journals A statistical analysis of rogue waves in the southern North Sea

2020 ◽  
Vol 20 (10) ◽  
pp. 2665-2680
Author(s):  
Ina Teutsch ◽  
Ralf Weisse ◽  
Jens Moeller ◽  
Oliver Krueger
Keyword(s):  
North Sea ◽  
Rogue Wave ◽  
Rogue Waves ◽  
New Wave ◽  
Data Set ◽  
Southern North Sea ◽  
Monte Carlo Experiments ◽  
Statistical Sense ◽  
Radar Measurements

Abstract. A new wave data set from the southern North Sea covering the period 2011–2016 and composed of wave buoy and radar measurements sampling the sea surface height at frequencies between 1.28 and 4 Hz was quality controlled and scanned for the presence of rogue waves. Here, rogue waves refer to waves whose height exceeds twice the significant wave height. Rogue wave frequencies were analyzed and compared to Rayleigh and Forristall distributions, and spatial, seasonal, and long-term variability was assessed. Rogue wave frequency appeared to be relatively constant over the course of the year and uncorrelated among the different measurement sites. While data from buoys basically correspond with expectations from the Forristall distribution, radar measurement showed some deviations in the upper tail pointing towards higher rogue wave frequencies. The amount of data available in the upper tail is, however, still too limited to allow a robust assessment. Some indications were found that the distribution of waves in samples with and without rogue waves was different in a statistical sense. However, differences were small and deemed not to be relevant as attempts to use them as a criterion for rogue wave detection were not successful in Monte Carlo experiments based on the available data.

scholarly journals Rogue waves in a wave tank: experiments and modeling

2013 ◽  
Vol 1 (4) ◽  
pp. 3201-3216 ◽  
Author(s):  
A. Lechuga
Keyword(s):  
Water Wave ◽  
Rogue Wave ◽  
Landau Equation ◽  
Rogue Waves ◽  
Theoretical Studies ◽  
Ginzburg Landau ◽  
Wave Tank ◽  
Sudden Appearance ◽  
Wave Maker ◽  
Symmetric Spectrum

Abstract. In past decades theoretical studies have been carried out with the double aim of improving the knowledge of rogue wave main characteristics and of attempting to predict its sudden appearance. As an effort on this topic we tried the generation of rogue waves in a water wave tank using a symmetric spectrum (Akhmediev et al., 2011a) as input on the wave maker. To go on further the next step has been to apply a theoretical model to the envelope of these waves. After some considerations the best model has been an analogue of the Ginzburg–Landau equation.

‘Pulmonary thrombosis in situ’: risk factors, clinic characteristics and long-term evolution

2020 ◽  
Vol 31 (7) ◽  
pp. 469-475
Author(s):  
Delfina Fletcher-Sanfeliu ◽  
Josep Redón ◽  
Álvaro García-Granero ◽  
Matteo Frasson ◽  
Ignacio Barreira ◽  
...  
Keyword(s):  
Risk Factors ◽  
Long Term Evolution ◽  
Pulmonary Thrombosis ◽  
Term Evolution

scholarly journals In-flight calibration of double-probe electric field measurements on Cluster

2014 ◽  
Vol 3 (2) ◽  
pp. 143-151 ◽  
Author(s):  
Y. V. Khotyaintsev ◽  
P.-A. Lindqvist ◽  
C. M. Cully ◽  
A. I. Eriksson ◽  
M. André
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Field Measurements ◽  
Calibration Procedure ◽  
Double Probe ◽  
Term Evolution ◽  
Electric Field Measurements ◽  
Electric Field Instrument

Abstract. Double-probe electric field instrument with long wire booms is one of the most popular techniques for in situ measurement of electric fields in plasmas on spinning spacecraft platforms, which have been employed on a large number of space missions. Here we present an overview of the calibration procedure used for the Electric Field and Wave (EFW) instrument on Cluster, which involves spin fits of the data and correction of several offsets. We also describe the procedure for the offset determination and present results for the long-term evolution of the offsets.

scholarly journals Spectrometric monitoring of atmospheric carbon tetrafluoride (CF<sub>4</sub>) above the Jungfraujoch station since 1989: evidence of continued increase but at a slowing rate

2014 ◽  
Vol 7 (1) ◽  
pp. 333-344 ◽  
Author(s):  
E. Mahieu ◽  
R. Zander ◽  
G. C. Toon ◽  
M. K. Vollmer ◽  
S. Reimann ◽  
...  
Keyword(s):  
Swiss Alps ◽  
Gas Chromatography Mass Spectrometry ◽  
Anthropogenic Emissions ◽  
Spectrometric Analysis ◽  
Time Intervals ◽  
Vertical Column ◽  
Carbon Tetrafluoride ◽  
Term Evolution

Abstract. The long-term evolution of the vertical column abundance of carbon tetrafluoride (CF4) above the high-altitude Jungfraujoch station (Swiss Alps, 46.5° N, 8.0° E, 3580 m a.s.l.) has been derived from the spectrometric analysis of Fourier transform infrared solar spectra recorded at that site between 1989 and 2012. The investigation is based on a multi-microwindow approach, two encompassing pairs of absorption lines belonging to the R-branch of the strong ν3 band of CF4 centered at 1283 cm−1, and two additional ones to optimally account for weak but overlapping HNO3 interferences. The analysis reveals a steady accumulation of the very long-lived CF4 above the Jungfraujoch at mean rates of (1.38 ± 0.11) × 1013 molec cm−2 yr−1 from 1989 to 1997, and (0.98 ± 0.02) × 1013 molec cm−2 yr−1 from 1998 to 2012, which correspond to linear growth rates of 1.71 ± 0.14 and 1.04 ± 0.02% yr−1 respectively referenced to 1989 and 1998. Related global CF4 anthropogenic emissions required to sustain these mean increases correspond to 15.8 ± 1.3 and 11.1 ± 0.2 Gg yr−1 over the above specified time intervals. Findings reported here are compared and discussed with respect to relevant northern mid-latitude results obtained remotely from space and balloons as well as in situ at the ground, including new gas chromatography mass spectrometry measurements performed at the Jungfraujoch since 2010.

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