Wind speed and direction estimation from wave spectra using deep learning

High-frequency parts of ocean wave spectra are strongly coupled to the local wind. Measurements of ocean wave spectra can be used to estimate sea surface winds. In this study, two deep neural networks (DNNs) were used to estimate the wind speed and direction from the first five Fourier coefficients from buoys. The DNNs were trained by wind and wave measurements from more than 100 meteorological buoys during 2014–2018. It is found that the wave measurements can best represent the wind information about 40 min previously because the high-frequency portion of the wave spectrum integrates preceding wind conditions. The overall root-mean-square error (RMSE) of estimated wind speed is ∼1.1 m s−1, and the RMSE of the wind direction is ∼ 14∘ when wind speed is 7–25 m s−1. This model can be used not only for the wind estimation for compact wave buoys but also for the quality control of wind and wave measurements from meteorological buoys.

Analysis of Material Susceptibility in Silicon on Insulator Waveguides With Combined Simulation of Four-Wave Mixing and Linear Mode Coupling

We derive propagation equations modeling third-order susceptibility-induced nonlinear interaction and linear mode coupling in waveguides. We model material susceptibility with Raman and electronic response which include approximations suited for optical communications. We validate our model by comparing numerical integration of the propagation equations to continuous wave measurements of a silicon on insulator waveguide.

Wave height and period on 16 March, 21 April, and 22 September 2019, in the Ujung Batee coastal waters and Lampanah coastal waters, Aceh Besar District, Indonesia

Waves are one of the sea parameters that affect the rate of retreat of the coastline. This research investigation was carried out in the coastal waters of Ujong Batee and Lampanah, Aceh Besar District on 16 March, 21 April, and 22 September 2019, with the aim of examining wave parameters, namely wave height and period. Then the wave measurement data sampled at the research station location was carried out by purposive random sampling method. Sea wave data were taken using a scale board that has been labeled with numbers and a stopwatch. Wave measurements were carried out approximately 1000 times. Then the sea wave data is processed to obtain the wave height and period and then analyzed. The results obtained that the wave heights on 16 March, 21 April, and 22 September 2019 were 67 cm, 83 cm, and 80 cm in Ujong Batee and 55 cm, 67 cm, and 66 cm in Lampanah. While the wave period is 12 seconds on March 16, April 21, and September 22 in Ujong Batee and Lampanah. Thus, the wave height and period at both locations ranged from 50 cm to 80 cm and 12 s.

Monitoring of Recovery Process at Yeongildae Beach, South Korea, Using a Video System

Once a beach is eroded by storm waves, it is generally recovered under milder wave conditions. To prevent or reduce damage, it is therefore important to understand the characteristics of the site-specific recovery process. Here, we present the results, based on a data set from a video monitoring system and wave measurements, of the recovery process in a pocketed beach located inside a bay where the shoreline retreated harshly (~12 m, on average, of beach width) during Typhoon TAPAH (T1917) in September 2019. It took about 1.5 years for the beach to be recovered to the level before the typhoon. During this period, the erosion and accretion were repeated, with the pattern highly related to the wave power (Pw); most of the erosion occurred when Pw became greater than 30 kWatt/m, whereas the accretion prevailed when Pw was no greater than 10 kWatt/m. The recovery pattern showed discrepancies between different parts of the beach. The erosion during storm events was most severe in the southern part, whereas the northern shoreline did not significantly change even during TAPAH (T1917). In contrast, the recovery process occurred almost equally at all locations. This discrepancy in the erosion/accretion process was likely due to human intervention, as a shadow zone was formed in the northern end due to the breakwaters, causing disequilibrium in the sediment transport gradient along the shore. The results in this study could be applied in designing the protection plans from severe wave attacks by effectively estimating the size of coastal structures and by correctly arranging the horizontal placement of such interventions or beach nourishment. Although the application of these results should be confined to this specific site, the method using wave energy parameters as criteria can be considered in other areas with similar environments, for future planning of beach protection.

Gender and Childhood Victimization: A Longitudinal Study of Heavy Drinking in Young Adulthood

The present longitudinal study, for 12 years, followed a group of young adults, examining (1) whether/how victimization in childhood increased the likelihood of heavy drinking; (2) whether depression mediated the strain–heavy drinking relationship; and (3) whether/how relationships among strain, depression, and heavy drinking differed across two gender groups. Data came from the National Longitudinal Survey of Youth 1997 cohort, dating 2004–2015 (5 interview waves and 22,549 person-wave measurements total). We linked consumption of 5+ drinks (during the month prior) to four discrete measures of violent victimization, to one measure of stressful events, and to depression. We needed to consider repeat measures of the same variables over time, so we used generalized estimating equations (GEE) to analyze data. Depression was found to increase heavy drinking uniformly. Empirical evidence confirmed that in the strain–heavy drinking relationship, depression plays a minor mediating role. Gender moderated heavy drinking’s associations. Specifically, bullying in childhood raised risk for female respondents. The current strain was associated with a higher risk of heavy drinking among male respondents. Childhood victimization, as well as current life stress, play an important role in depression and heavy drinking. Future research should focus on the development of specific, targeted care to reduce heavy drinking’s harm and promote equity among Americans.

Offshore Wind and Wave Energy Complementarity in the Greek Seas Based on ERA5 Data

In this work, 20 years (2000–2019) of ERA5 wave and wind data are analyzed and evaluated for the Greek Seas by means of in-situ measurements derived from the POSEIDON marine monitoring system. Four different statistical measures were used at six locations, where in-situ wind and wave measurements are available from oceanographic buoys. Furthermore, the ERA5 wind and wave datasets were utilized for the estimation of the available wind and wave energy potential for the Greek Seas, as well as for the assessment of complementarity and synergy between the two resources. In this respect, an event-based approach was adopted. The spatial distribution of the available wind and wave energy potential resembles qualitatively and quantitatively the distributions derived from other reanalysis datasets. Locations with high synergy and complementarity indices were identified taking into account water depth. Finally, taking into consideration a particular offshore wind turbine power curve and the power matrix of the PELAMIS wave energy converter, the estimation of the combined energy potential on a mean annual basis is performed.