Relation between ocean wave activity and wavefield of the ambient noise recorded in northern Poland

AbstractThe temporal and spatial variations of the wavefield of ambient noise recorded at ‘13 BB star’ array located in northern Poland were related to the activity of high, long-period ocean waves generated by strong storms in the Northern Indian Ocean, the Atlantic Ocean, and the Northern Pacific Ocean between 2013 and 2016. Once pre-processed, the raw noise records in time- and frequency-domains, and spectral analysis and high-resolution three-component beamforming techniques were applied to the broadband noise data. The power spectral density was analysed to quantify the noise wavefield, observing the primary (0.04–0.1 Hz) microseism peak and the splitting of the secondary microseism into long-period (0.2–0.3 Hz) and short-period (0.3–0.8 Hz) peaks. The beam-power analysis allowed to determine the changes in the azimuth of noise sources and the velocity of surface waves. The significant wave height, obtained by combining observed data and forecast model results for wave height and period, was analysed to characterise ocean wave activity during strong storms. The comparison of wave activity and beam-power led to distinguish the sources of Rayleigh and Love waves associated to long-period microseisms, of short-period microseisms, and of primary microseisms. High, long-period ocean waves hitting the coastline were found to be the main source of noise wavefield. The source of long-period microseisms was correlated to such waves in the open sea able to reach the shore, whereas the source of primary microseisms was tied to waves interacting with the seafloor very close to the coastlines. The source of short-period microseisms was attributed to strong storms constituted of short-period waves not reaching the coast.

Download Full-text

Analysis of Peak Mooring Forces Caused by Slow Vessel Drift Oscillations in Random Seas

Society of Petroleum Engineers Journal ◽

10.2118/3256-pa ◽

1972 ◽

Vol 12 (04) ◽

pp. 329-344 ◽

Cited By ~ 6

Author(s):

F.H. Hsu ◽

K.A. Blenkarn

Keyword(s):

Wave Height ◽

Ocean Waves ◽

Irregular Waves ◽

Mooring Line ◽

Financial Loss ◽

Slow Oscillations ◽

Long Period ◽

Random Seas ◽

Short Period ◽

Large Vessels

Abstract A procedure for calculation of peak mooring force caused by the long-period vessel drift oscillation is described. The long-period drift oscillation is induced by the action of groups of high waves in random seas. The procedure is developed from consideration of momentum flux change in ocean waves. Introduction The demand on the offshore petroleum industry for mooring under trying conditions has created the need for a clearer understanding of the physical phenomena involved in mooring large vessels under phenomena involved in mooring large vessels under severe conditions in the open ocean. The offshore industry has experienced major difficulties in mooring under storm conditions and has suffered extensive financial loss. Over the years, attempts have been made to solve offshore mooring problems, utilizing a variety of vessels and mooring techniques. Results of experience and practice offer conflicting indications of the relative merits of various mooring systems. Various engineering and scientific studies have contributed toward an understanding of many factors influencing forces; however, it appears that previous studies have, for the most part, ignored an important phenomenon, which under certain situations is the governing factor to be considered in design of mooring systems. Specifically, there has been little attention devoted to the effects of slow vessel drift oscillations in random or irregular seas. It is this phenomenon that is the prime subject of the present phenomenon that is the prime subject of the present paper. paper. Fig. 1 illustrates results obtained from model tests of a moored vessel in irregular waves. Shown in the figure, as a function of time, are the variations of wave height and period, the surge or drift position of the vessel, and the tension in the primary mooring line. It will be noted that the surge primary mooring line. It will be noted that the surge motion of the vessel involves both a direct wave-induced short-period surge and a gradual long-period drift oscillation taking place over a period of 1 minute or more in prototype time. This type of drift motion is also found in the motion records of moored ships in an actual ocean storm environment. Moreover, the basic behavior of slow oscillations is not unique to moored vessels. For instance, such behavior has been observed in tests involving vessels towed through irregular waves with a constant towing force. In such case, it has been observed that the vessel velocity exhibits slow oscillations with periods in the range of 1 to 2 minutes. When an ocean wave is propagated toward a moored vessel, part of the wave is reflected, the remainder being transmitted on beyond the vessel The conservation of wave momentum results in a net force applied to the vessel for each wave. For regular waves the consequence is a steady drift force resulting in a static shift of the average position of the moored vessel. For irregular waves, position of the moored vessel. For irregular waves, on the other hand, a varying sequence of drift forces arises in correspondence to changes in wave height and period. Investigations leading to this paper show that the ensuing long period drift oscillation of the vessel can, for many cases, be the completely dominating influence in determining maximum mooring line tension. SPEJ P. 329

Download Full-text

Wave Force Characteristics of Large-Sized Offshore Wind Support Structures to Sea Levels and Wave Conditions

Applied Sciences ◽

10.3390/app9091855 ◽

2019 ◽

Vol 9 (9) ◽

pp. 1855

Author(s):

Youn-Ju Jeong ◽

Min-Su Park ◽

Jeongsoo Kim ◽

Sung-Hoon Song

Keyword(s):

Shallow Water ◽

Wave Height ◽

Wave Force ◽

Diffraction Effect ◽

Support Structures ◽

Sea Levels ◽

Irregular Wave ◽

Long Period ◽

Short Period ◽

Period Wave

This paper presents the results of wave force tests conducted on three types of offshore support structures considering eight waves and three sea levels to investigate the corresponding wave forces. As a result of this study, it is found that the occurrence of shoaling in shallow water induces a significant increase of the wave force. Most of the test models at the shallow water undergo a nonlinear increase of the wave force with higher wave height increasing. In addition, the larger the diameter of the support structure within the range of this study, the larger the diffraction effect is, and the increase in wave force due to shoaling is suppressed. Under an irregular wave at the shallow water, the wave force to the long-period wave tends to be slightly higher than that of the short period wave since the higher wave height component included in the irregular wave has an influence on the shoaling. In addition, it is found that the influence of shoaling under irregular wave becomes more apparent in the long period.

Download Full-text

Coupling between the ocean and an ice shelf

Annals of Glaciology ◽

10.3189/1991aog15-1-101-108 ◽

1991 ◽

Vol 15 ◽

pp. 101-108 ◽

Cited By ~ 6

Author(s):

Colin Fox ◽

Vernon A. Squire

Keyword(s):

Elastic Plate ◽

Velocity Potential ◽

Open Water ◽

Ocean Waves ◽

Ocean Wave ◽

Single Frequency ◽

Plate Model ◽

Ice Shelf ◽

Long Period ◽

Set Up

The possibility of long-period ocean waves coupling to an ice shelf is investigated. A thick elastic plate model is used for the ice shelf with comparisons made to the simpler thin-plate model. The strain set up on the ice shelf by a normally incident single frequency ocean wave is calculated by completely solving the equations governing the velocity potential for such a system. In the absence of measurements on an ice shelf, existing measurements of long-period strain on an ice tongue are used to estimate the required incident amplitude in the open water to induce the observed oscillations. It is found that the height of seas required indicates that ocean wave driving is a plausible forcing mechanism for observed oscillations.

Download Full-text

Monstrous ocean waves during typhoon Krosa

Annales Geophysicae ◽

10.5194/angeo-26-1327-2008 ◽

2008 ◽

Vol 26 (6) ◽

pp. 1327-1329 ◽

Cited By ~ 16

Author(s):

P. C. Liu ◽

H. S. Chen ◽

D.-J. Doong ◽

C. C. Kao ◽

Y.-J. G. Hsu

Keyword(s):

Time Series ◽

Wave Height ◽

Time Series Data ◽

Ocean Waves ◽

Western Pacific ◽

Ocean Wave ◽

Series Data

Abstract. This paper presents a set of ocean wave time series data recorded from a discus buoy deployed near northeast Taiwan in western Pacific that was operating during the passage of Typhoon Krosa on 6 October 2007. The maximum trough-to-crest wave height was measured to be 32.3 m, which could be the largest Hmax ever recorded.

Download Full-text

Measuring Global Ocean Wave Skewness by Retracking RA-2 Envisat Waveforms

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech2014.1 ◽

2007 ◽

Vol 24 (6) ◽

pp. 1102-1116 ◽

Cited By ~ 8

Author(s):

J. Gómez-Enri ◽

C. P. Gommenginger ◽

M. A. Srokosz ◽

P. G. Challenor ◽

J. Benveniste

Keyword(s):

Wave Height ◽

Significant Wave Height ◽

Likelihood Estimation ◽

Ocean Waves ◽

Ocean Wave ◽

Global Ocean ◽

Radar Altimeter ◽

Significant Wave ◽

Linear And Nonlinear ◽

The Impact

For early satellite altimeters, the retrieval of geophysical information (e.g., range, significant wave height) from altimeter ocean waveforms was performed on board the satellite, but this was restricted by computational constraints that limited how much processing could be performed. Today, ground-based retracking of averaged waveforms transmitted to the earth is less restrictive, especially with respect to assumptions about the statistics of ocean waves. In this paper, a theoretical maximum likelihood estimation (MLE) ocean waveform retracker is applied tothe Envisat Radar Altimeter system (RA-2) 18-Hz averaged waveforms under both linear (Gaussian) and nonlinear ocean wave statistics assumptions, to determine whether ocean wave skewness can be sensibly retrieved from Envisat RA-2 waveforms. Results from the MLE retracker used in nonlinear mode provide the first estimates of global ocean wave skewness based on RA-2 Envisat averaged waveforms. These results show for the first time geographically coherent skewness fields and confirm the notion that large values of skewness occur primarily in regions of large significant wave height. Results from the MLE retracker run in linear and nonlinear modes are compared with each other and with the RA-2 Level 2 Sensor Geophysical Data Records (SGDR) products to evaluate the impact of retrieving skewness on other geophysical parameters. Good agreement is obtained between the linear and nonlinear MLE results for both significant wave height and epoch (range), except in areas of high-wave-height conditions.

Download Full-text

Possible Linkages between Microseisms in the Andaman-Nicobar Region and Swells in the South Indian Ocean

Seismological Research Letters ◽

10.1785/0220200193 ◽

2020 ◽

Author(s):

Telluri Ramakrushna Reddy ◽

Pawan Dewangan ◽

Prasad Kumar Bhaskaran ◽

Paresh Nath Singha Roy

Keyword(s):

Indian Ocean ◽

Ocean Wave ◽

Ocean Bottom ◽

Source Characterization ◽

The South ◽

South Indian Ocean ◽

Long Period ◽

Wave Parameters ◽

South Indian ◽

Short Period

Abstract Microseism source characterization and its genesis play a key role in linking microseism records to prevailing atmospheric and oceanic conditions. In the present study, we analyzed the spatial and temporal distribution of microseisms in the Andaman-Nicobar region using ocean-bottom seismometers and nearby continental stations data for the deployment period of January–April 2014. We attempted to establish a linkage between microseisms and ocean wave parameters derived from the ERA5 dataset. The short-period secondary microseisms (2–5 s) show a marked difference compared with long-period secondary microseisms (6–10 s) and are associated with local climatology and geomorphology. In contrast, long-period microseisms are related to distant sources in the South Indian Ocean. The primary microseisms (11–20 s) are weak in the Andaman region and do not correlate with any ocean wave parameters.

Download Full-text

Coupling between the ocean and an ice shelf

Annals of Glaciology ◽

10.1017/s0260305500009605 ◽

1991 ◽

Vol 15 ◽

pp. 101-108 ◽

Cited By ~ 27

Author(s):

Colin Fox ◽

Vernon A. Squire

Keyword(s):

Elastic Plate ◽

Velocity Potential ◽

Open Water ◽

Ocean Waves ◽

Ocean Wave ◽

Single Frequency ◽

Plate Model ◽

Ice Shelf ◽

Long Period ◽

Set Up

Download Full-text

Discussion following the presentation by F. Deubner

International Astronomical Union Colloquium ◽

10.1017/s0252921100053240 ◽

1977 ◽

Vol 36 ◽

pp. 69-74

Keyword(s):

List Type ◽

The Sun ◽

Type Number ◽

Harmonic Motion ◽

Locally Excited ◽

Long Period ◽

Coherent Wave ◽

Short Period ◽

Global Modes

The discussion was separated into 3 different topics according to the separation made by the reviewer between the different periods of waves observed in the sun :1) global modes (long period oscillations) with predominantly radial harmonic motion.2) modes with large coherent - wave systems but not necessarily global excitation (300 s oscillation).3) locally excited - short period waves.

Download Full-text

Isolation and Analysis of Six timeless Alleles That Cause Short- or Long-Period Circadian Rhythms in Drosophila

Genetics ◽

10.1093/genetics/156.2.665 ◽

2000 ◽

Vol 156 (2) ◽

pp. 665-675

Author(s):

Adrian Rothenfluh ◽

Marla Abodeely ◽

Jeffrey L Price ◽

Michael W Young

Keyword(s):

Nuclear Translocation ◽

Phase Response Curve ◽

Fixed Number ◽

Constant Darkness ◽

Genetic Screens ◽

Protein Levels ◽

Long Period ◽

Short Period ◽

Molecular Oscillation ◽

New Alleles

Abstract In genetic screens for Drosophila mutations affecting circadian locomotion rhythms, we have isolated six new alleles of the timeless (tim) gene. Two of these mutations cause short-period rhythms of 21–22 hr in constant darkness, and four result in long-period cycles of 26–28 hr. All alleles are semidominant. Studies of the genetic interactions of some of the tim alleles with period-altering period (per) mutations indicate that these interactions are close to multiplicative; a given allele changes the period length of the genetic background by a fixed percentage, rather than by a fixed number of hours. The timL1 allele was studied in molecular detail. The long behavioral period of timL1 is reflected in a lengthened molecular oscillation of per and tim RNA and protein levels. The lengthened period is partly caused by delayed nuclear translocation of TIML1 protein, shown directly by immunocytochemistry and indirectly by an analysis of the phase response curve of timL1 flies.

Download Full-text

Estimation of Significant Wave Heights from ASCAT Scatterometer Data via Deep Learning Network

Remote Sensing ◽

10.3390/rs13020195 ◽

2021 ◽

Vol 13 (2) ◽

pp. 195

Author(s):

He Wang ◽

Jingsong Yang ◽

Jianhua Zhu ◽

Lin Ren ◽

Yahao Liu ◽

...

Keyword(s):

Deep Learning ◽

Wave Height ◽

Significant Wave Height ◽

Incidence Angle ◽

Ocean Waves ◽

Global Scale ◽

Learning Technology ◽

Sea State ◽

Significant Wave ◽

Wave Heights

Sea state estimation from wide-swath and frequent-revisit scatterometers, which are providing ocean winds in the routine, is an attractive challenge. In this study, state-of-the-art deep learning technology is successfully adopted to develop an algorithm for deriving significant wave height from Advanced Scatterometer (ASCAT) aboard MetOp-A. By collocating three years (2016–2018) of ASCAT measurements and WaveWatch III sea state hindcasts at a global scale, huge amount data points (>8 million) were employed to train the multi-hidden-layer deep learning model, which has been established to map the inputs of thirteen sea state related ASCAT observables into the wave heights. The ASCAT significant wave height estimates were validated against hindcast dataset independent on training, showing good consistency in terms of root mean square error of 0.5 m under moderate sea condition (1.0–5.0 m). Additionally, reasonable agreement is also found between ASCAT derived wave heights and buoy observations from National Data Buoy Center for the proposed algorithm. Results are further discussed with respect to sea state maturity, radar incidence angle along with the limitations of the model. Our work demonstrates the capability of scatterometers for monitoring sea state, thus would advance the use of scatterometers, which were originally designed for winds, in studies of ocean waves.

Download Full-text