scholarly journals KARAKTERISTIK GELOMBANG DI BEBERAPA KAWASAN PERAIRAN SEKITAR SEMENANJUNG MINAHASA

2021 ◽  
Vol 9 (2) ◽  
pp. 1
Author(s):  
Intanta Br Ginting ◽  
Ping Astony Angmalisang ◽  
Royke M Rampengan ◽  
Rignolda Djamaluddin ◽  
Hermanto WK Manengkey ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Wave Height ◽  
Significant Wave Height ◽  
Wave Parameter ◽  
Weather Forecasts ◽  
Wave Characteristics ◽  
The North ◽  
Medium Range ◽  
The Waves ◽  
The Rose

The waters surrounding the Minahasa Peninsula are important areas of various activities by use of coastal and marine space. This research aims, firstly to describe direction, period and height of waves at several water areas around the Minahasa Peninsula in various season. Secondly to analyze the characteristic of daily and seasonal waves. The wave parameter, which reanalysis by ECMWF for 5 years (September 2014 to august 2019) were used in this research.  By the analysis spasial-temporal, the results are presented by the rose grapich waves direction and stock chart. The wave propagation in the north season and transition season I, is dominated by the northeasterly wave. While the wave propagation in the southern season and the transitional season II, is more diverse directions. The characteristics of the waves formed in the southeast Minahasa waters in the north season and transitional season I, show that the wave period is greater than in the waters of Manado Bay and Bitung waters. Furthermore, the wave characteristics formed in the waters of the Minahasa Peninsula show a significant wave height in Bitung waters which is higher than the waters of Manado Bay and Southeast Minahasa waters.Keywords: Waves, ECMWF, Minahasa Peninsula Waters Perairan sekitar Semenanjung Minahasa merupakan kawasan penting dalam berbagai aktivitas pemanfaatan ruang pantai dan laut. Penelitian ini bertujuan, pertama untuk mendeskripsikan arah, periode, dan tinggi gelombang di beberapa kawasan perairan sekitar Semenanjung Minahasa dalam berbagai musim yang berlangsung. Kedua adalah menganalisis karakteristik gelombang harian dan musiman pada perairan sekitar Semenanjung Minahasa.  Data yang digunakan dalam penelitian adalah data reanalysis ECMWF (European Centre for Medium-Range Weather Forecasts) parameter gelombang selama 5 tahun mulai bulan September 2014 sampai Agustus 2019.  Dengan metode analisis spasial-temporal hasilnya disajikan dalam bentuk grafik mawar arah datang gelombang dan grafik kotak (stock chart). Rambatan gelombang pada musim Utara dan musim Peralihan I, arah datangnya didominasi dari arah Timur Laut.  Sedangkan rambatan gelombang pada musim Selatan dan musim Peralihan II, arah datangnya lebih beragam.  Karakteristik gelombang yang terbentuk di perairan Minahasa Tenggara pada musim Utara dan musim Peralihan I memperlihatkan periode gelombangnya lebih besar dari pada perairan Teluk Manado dan Perairan Bitung. Selanjutnya karakteristik gelombang yang terbentuk di perairan Semenanjung Minahasa memperlihatkan tinggi gelombang signifikan di perairan Bitung lebih tinggi dari pada perairan Teluk Manado dan perairan Minahasa Tenggara.Kata kunci: Gelombang, ECMWF, Perairan Semenanjung Minahasa

scholarly journals Long-Term and Seasonal Trends in Global Wave Height Extremes Derived from ERA-5 Reanalysis Data

2020 ◽  
Vol 8 (12) ◽  
pp. 1015
Author(s):  
Alicia Takbash ◽  
Ian R. Young
Keyword(s):  
Southern Hemisphere ◽  
Wave Height ◽  
Significant Wave Height ◽  
Reanalysis Data ◽  
Extreme Value Analysis ◽  
Winter Storms ◽  
Value Analysis ◽  
Weather Forecasts ◽  
Significant Wave

A non-stationary extreme value analysis of 41 years (1979–2019) of global ERA5 (European Centre for Medium-Range Weather Forecasts Reanalysis) significant wave height data is undertaken to investigate trends in the values of 100-year significant wave height, Hs100. The analysis shows that there has been a statistically significant increase in the value of Hs100 over large regions of the Southern Hemisphere. There have also been smaller decreases in Hs100 in the Northern Hemisphere, although the related trends are generally not statistically significant. The increases in the Southern Hemisphere are a result of an increase in either the frequency or intensity of winter storms, particularly in the Southern Ocean.

Comparison of Bivariate Models of the Distribution of Significant Wave Height and Peak Wave Period

2007 ◽  
Author(s):  
Catarina S. Soares ◽  
C. Guedes Soares
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Bivariate Normal Distribution ◽  
Wave Period ◽  
Peak Period ◽  
Data Set ◽  
Significant Wave ◽  
The North ◽  
Bivariate Models ◽  
The North Sea

This paper presents the results of a comparison of the fit of three bivariate models to a set of 14 years of significant wave height and peak wave period data from the North Sea. One of the methods defines the joint distribution from a marginal distribution of significant wave height and a set of distributions of peak period conditional on significant wave height. Other method applies the Plackett model to the data and the third one applies the Box-Cox transformation to the data in order to make it approximately normal and then fits a bivariate normal distribution to the transformed data set. It is shown that all methods provide a good fit but each one have its own strengths and weaknesses, being the choice dependent on the data available and applications in mind.

Comparison Between a Fatigue Model for Voyage Planning and Measurements of a Container Vessel

2009 ◽  
Author(s):  
Wengang Mao ◽  
Jonas W. Ringsberg ◽  
Igor Rychlik ◽  
Gaute Storhaug
Keyword(s):  
Fatigue Damage ◽  
Wave Height ◽  
Significant Wave Height ◽  
Route Planning ◽  
Estimation Model ◽  
Ongoing Research ◽  
Significant Wave ◽  
The North ◽  
Fatigue Damage Accumulation ◽  
Fatigue Model

This paper presents results from an ongoing research project which aims at developing a numerical tool for route planning of container ships. The objective with the tool is to be able to schedule a route that causes minimum fatigue damage to a vessel before it leaves port. Therefore a new simple fatigue estimation model, only using encountered significant wave height, is proposed for predicting fatigue accumulation of a vessel during a voyage. The formulation of the model is developed based on narrow-band approximation. The significant response height hs, is shown to have a linear relationship with its encountered significant wave height Hs. The zero up-crossing response frequency fz, is represented as the corresponding encountered wave frequency and is expressed as a function of Hs. The capacity and accuracy of the model is illustrated by application on one container vessel’s fatigue damage accumulation, for different voyages, operating in the North Atlantic during 2008. For this vessel, all the necessary data needed in the fatigue model, and for verification of it, was obtained by measurements. The results from the proposed fatigue model are compared with the well-known and accurate rain-flow estimation. The conclusion is that the estimations made using the current fatigue model agree well with the rain-flow method for almost all of the voyages.

Uncertainties in Extreme Wave Height Estimates for Hurricane-Dominated Regions

2007 ◽  
Vol 129 (4) ◽  
pp. 300-305 ◽  
Author(s):  
Philip Jonathan ◽  
Kevin Ewans
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Small Data ◽  
Extreme Wave ◽  
Significant Wave ◽  
Wave Characteristics ◽  
Height Estimates ◽  
Wave Heights ◽  
Using Data ◽  
High Percentile

Inherent uncertainties in estimation of extreme wave heights in hurricane-dominated regions are explored using data from the GOMOS Gulf of Mexico hindcast for 1900–2005. In particular, the effect of combining correlated values from a neighborhood of 72 grid locations on extreme wave height estimation is quantified. We show that, based on small data samples, extreme wave heights are underestimated and site averaging usually improves estimates. We present a bootstrapping approach to evaluate uncertainty in extreme wave height estimates. We also argue in favor of modeling supplementary indicators for extreme wave characteristics, such as a high percentile (95%) of the distribution of 100-year significant wave height, in addition to its most probable value, especially for environments where the distribution of 100-year significant wave height is strongly skewed.

scholarly journals Variability of the Winter Wind Waves and Swell in the North Atlantic and North Pacific as Revealed by the Voluntary Observing Ship Data

2006 ◽  
Vol 19 (21) ◽  
pp. 5667-5685 ◽  
Author(s):  
Sergey K. Gulev ◽  
Vika Grigorieva
Keyword(s):  
Interannual Variability ◽  
Wave Height ◽  
North Atlantic ◽  
North Pacific ◽  
Significant Wave Height ◽  
Wind Wave ◽  
Significant Wave ◽  
The North ◽  
The North Atlantic ◽  
Wind Sea

Abstract This paper analyses secular changes and interannual variability in the wind wave, swell, and significant wave height (SWH) characteristics over the North Atlantic and North Pacific on the basis of wind wave climatology derived from the visual wave observations of voluntary observing ship (VOS) officers. These data are available from the International Comprehensive Ocean–Atmosphere Data Set (ICOADS) collection of surface meteorological observations for 1958–2002, but require much more complicated preprocessing than standard meteorological variables such as sea level pressure, temperature, and wind. Visual VOS data allow for separate analysis of changes in wind sea and swell, as well as in significant wave height, which has been derived from wind sea and swell estimates. In both North Atlantic and North Pacific midlatitudes winter significant wave height shows a secular increase from 10 to 40 cm decade−1 during the last 45 yr. However, in the North Atlantic the patterns of trend changes for wind sea and swell are quite different from each other, showing opposite signs of changes in the northeast Atlantic. Trend patterns of wind sea, swell, and SWH in the North Pacific are more consistent with each other. Qualitatively the same conclusions hold for the analysis of interannual variability whose leading modes demonstrate noticeable differences for wind sea and swell. Statistical analysis shows that variability in wind sea is closely associated with the local wind speed, while swell changes can be driven by the variations in the cyclone counts, implying the importance of forcing frequency for the resulting changes in significant wave height. This mechanism of differences in variability patterns of wind sea and swell is likely more realistic than the northeastward propagation of swells from the regions from which the wind sea signal originates.

scholarly journals A Multifaceted Climatology of Atmospheric Blocking and Its Recent Linear Trend

2007 ◽  
Vol 20 (4) ◽  
pp. 633-649 ◽  
Author(s):  
M. Croci-Maspoli ◽  
C. Schwierz ◽  
H. C. Davies
Keyword(s):  
North Pacific ◽  
Linear Trend ◽  
Age Distribution ◽  
Atmospheric Blocking ◽  
Weather Forecasts ◽  
The North ◽  
Four Seasons ◽  
Medium Range ◽  
The Mean ◽  
The North Pacific

Abstract A dynamically based climatology is derived for Northern Hemisphere atmospheric blocking events. Blocks are viewed as large amplitude, long-lasting, and negative potential vorticity (PV) anomalies located beneath the dynamical tropopause. The derived climatology [based on the 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40)] provides a concise, coherent, and illuminating description of the main physical characteristics of blocks and the accompanying linear trends. The latitude–longitude distribution of blocking frequency captures the standard bimodal geographical distribution with major peaks over the North Atlantic and eastern North Pacific in all four seasons. The accompanying pattern for the age distribution, the genesis–lysis regions, and the track of blocks reveals that 1) younger blocks (1–4 days) are more prevalent at lower latitudes whereas significantly older blocks (up to 12 days) are located at higher latitudes; 2) genesis is confined predominantly to the two major ocean basins and in a zonal band between 40° and 50°N latitude, whereas lysis is more dispersed but with clear preference to higher latitudes; and 3) the general northeastward–west-northwest movement of blocks in the genesis–lysis phase also exhibits subtle seasonal and intra- and interbasin differences. Examination of the intensity and spatial-scale changes during the blocking life cycle suggests that in the mean a block’s evolution is independent of the genesis region and its eventual duration. A novel analysis of blocking trends reveals significant negative trends in winter over Greenland and in spring over the North Pacific. It is shown that the changes over Greenland are linked to the number of blocking episodes, whereas a neighboring trend signal to the south is linked to higher-frequency anticyclonic systems. Furthermore, evidence is adduced that changes in blocking frequency contribute seminally to tropopause height trends.

scholarly journals The Condition of Significant Wave Height and Wind Velocity in Makassar Strait during 2017

2019 ◽  
Vol 3 (1) ◽  
pp. 179-189
Author(s):  
Hanah Khoirunnisa ◽  
Shofia Karima
Keyword(s):  
Energy Spectrum ◽  
Wind Velocity ◽  
Wave Height ◽  
Significant Wave Height ◽  
Secondary Data ◽  
Weather Forecasts ◽  
Significant Wave ◽  
A Value ◽  
One Year ◽  
Height Data

This study aims to look at the conditions and characteristics of significant wave height and its relationship to wind velocity in the Makassar Strait in 2017. The data used in this study are bathymetry data from GEBCO with a resolution of 30 seconds, significant wave height data (Hs) with a resolution of 0.25 x 0.25 as well as wind velocity and direction with a resolution of 0.25 x 0.25 which are secondary data results from the European Center for Medium-Range Weather Forecasts (ECMWF) with a span of one year in 2017. The method used in this research is an analysis of the energy spectrum of significant wave height using Fast Fourier Transform. In addition, wind velocity and direction are processed by using GrADS software to see the visual conditions. Based on this study, it can be concluded that wind velocity is strongly associated with significant wave height values. This can be seen at each sample point in the Makassar Strait, where when the value of wind velocity is high, the value of significant wave height has the same conditions, and vice versa. The wind velocity value has a maximum value in the Makassar Strait during the east season with a value of more than 4.5 m/s. The highest energy spectrum occurs at point 3 in the Makassar Strait, which is 7303 m2 with a period of 6 months.

Relative Motion During Single Blade Installation: Measurements From the North Sea

2020 ◽  
Author(s):  
Aljoscha Sander ◽  
Andreas F. Haselsteiner ◽  
Kader Barat ◽  
Michael Janssen ◽  
Stephan Oelker ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wave Height ◽  
North Sea ◽  
Relative Motion ◽  
Significant Wave Height ◽  
Offshore Wind ◽  
Wave Excitation ◽  
Significant Wave ◽  
The North ◽  
The North Sea

Abstract During single blade installation in offshore wind farms, relative motion between nacelle and blade root due to wind and wave excitation pose a significant challenge. Wave excitation can be modelled considerably well by employing state-of-the-art simulation tools and can, therefore, be included in installation planning. Other phenomena, such as flow-induced vibrations are hard to capture and hence challenging to account for when defining installation procedures and limitations. Here, we present measurements conducted during the installation of an offshore wind farm consisting of multi-megawatt turbines installed on monopile foundations in the North Sea. A custom-built sensor capturing linear & angular acceleration and GPS-data was deployed atop the nacelle. Both partially and fully assembled turbines displayed complex oscillation orbits, swiftly changing amplitude and direction. Mean nacelle deflection correlated strongly with significant wave height as well as mean wind speed. As wind speed and significant wave height showed a strong correlation as well, it is difficult to discern which load drives the observed relative motions. While wind loads are significantly smaller than wave loads on partially assembled turbines under installation conditions, additional momentum induced by vortex shedding may prove sufficient to cause the observed effects.

Potential Temperature and Potential Vorticity Inversion: Complementary Approaches

2010 ◽  
Vol 67 (12) ◽  
pp. 4001-4016 ◽  
Author(s):  
Joseph Egger ◽  
Klaus-Peter Hoinka
Keyword(s):  
North Atlantic ◽  
Potential Vorticity ◽  
Potential Temperature ◽  
Storm Track ◽  
Temperature Inversion ◽  
Weather Forecasts ◽  
The North ◽  
Potential Vorticity Inversion ◽  
Medium Range ◽  
Balanced Flow

Abstract Given the distribution of one atmospheric variable, that of nearly all others can be derived in balanced flow. In particular, potential vorticity inversion (PVI) selects potential vorticity (PV) to derive pressure, winds, and potential temperature θ. Potential temperature inversion (PTI) starts from available θ fields to derive pressure, winds, and PV. While PVI has been applied extensively, PTI has hardly been used as a research tool although the related technical steps are well known and simpler than those needed in PVI. Two idealized examples of PTI and PVI are compared. The 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) datasets are used to determine typical anomalies of PV and θ in the North Atlantic storm-track region. Statistical forms of PVI and PTI are applied to these anomalies. The inversions are equivalent but the results of PTI are generally easier to understand than those of PVI. The issues of attribution and piecewise inversion are discussed.

Sign in / Sign up

Export Citation Format

Share Document