Error Estimation of Buoy, Satellite, and Model Wave Height Data

2007 ◽  
Vol 24 (9) ◽  
pp. 1665-1677 ◽  
Author(s):  
Peter A. E. M. Janssen ◽  
Saleh Abdalla ◽  
Hans Hersbach ◽  
Jean-Raymond Bidlot
Keyword(s):  
Collocation Method ◽  
Wave Height ◽  
Wave Model ◽  
Weather Forecasts ◽  
Model Wave ◽  
Analysis Scheme ◽  
Wave Heights ◽  
Forecasting System ◽  
Buoy Data ◽  
Height Data

Abstract Triple collocation is a powerful method to estimate the rms error in each of three collocated datasets, provided the errors are not correlated. Wave height analyses from the operational European Centre for Medium-Range Weather Forecasts (ECMWF) wave forecasting system over a 4-yr period are compared with independent buoy data and dependent European Remote Sensing Satellite-2 (ERS-2) altimeter wave height data, which have been used in the wave analysis. To apply the triple-collocation method, a fourth, independent dataset is obtained from a wave model hindcast without assimilation of altimeter wave observations. The seasonal dependence of the respective errors is discussed and, while in agreement with the properties of the analysis scheme, the wave height analysis is found to have the smallest error. In this comparison the altimeter wave height data have been obtained from an average over N individual observations. By comparing model wave height with the altimeter superobservations for different values of N, alternative estimates of altimeter and model error are obtained. There is only agreement with the estimates from the triple collocation when the correlation between individual altimeter observations is taken into account. The collocation method is also applied to estimate the error in Environmental Satellite (ENVISAT), ERS-2 altimeter, buoy, model first-guess, and analyzed wave heights. It is shown that there is a high correlation between ENVISAT and ERS-2 wave height error, while the quality of ENVISAT altimeter wave height is high.

scholarly journals Wave Height Distributions and Rogue Waves in the Eastern Mediterranean

2021 ◽  
Vol 9 (6) ◽  
pp. 660
Author(s):  
Sagi Knobler ◽  
Daniel Bar ◽  
Rotem Cohen ◽  
Dan Liberzon
Keyword(s):  
Wave Height ◽  
Eastern Mediterranean ◽  
Rogue Waves ◽  
Distribution Model ◽  
Storm Events ◽  
Order Model ◽  
Deep Seawater ◽  
Wave Heights ◽  
Storm Characteristics ◽  
Buoy Data

There is a lack of scientific knowledge about the physical sea characteristics of the eastern part of the Mediterranean Sea. The current work offers a comprehensive view of wave fields in southern Israel waters covering a period between January 2017 and June 2018. The analyzed data were collected by a meteorological buoy providing wind and waves parameters. As expected for this area, the strongest storm events occurred throughout October–April. In this paper, we analyze the buoy data following two main objectives—identifying the most appropriate statistical distribution model and examining wave data in search of rogue wave presence. The objectives were accomplished by comparing a number of models suitable for deep seawater waves. The Tayfun—Fedele 3rd order model showed the best agreement with the tail of the empirical wave heights distribution. Examination of different statistical thresholds for the identification of rogue waves resulted in the detection of 99 unique waves, all of relatively low height, except for one wave that reached 12.2 m in height which was detected during a powerful January 2018 storm. Characteristics of the detected rogue waves were examined, revealing the majority of them presenting crest to trough symmetry. This finding calls for a reevaluation of the crest amplitude being equal to or above 1.25 the significant wave height threshold which assumes rogue waves carry most of their energy in the crest.

A Method to Implement the Random Signals for Time Varying Offshore Wave Height During Storm Condition in an Intra-Wave Period Wave Model

2006 ◽  
Author(s):  
Yuliang Zhu ◽  
Shunqi Pan ◽  
Premanandan T. Fernando ◽  
Xiaoyan Zhou
Keyword(s):  
Wave Height ◽  
Wave Model ◽  
Peak Frequency ◽  
Wave Period ◽  
Storm Event ◽  
Time Varying ◽  
Wave Heights ◽  
Offshore Wave ◽  
Storm Condition ◽  
Period Wave

In this paper, a method to implement the surface elevation at the offshore boundary during storm conditions is presented in the intra-wave period wave model. At storm condition, the offshore incident significant wave height is time varying. In the case of time varying incident wave height, the JONSWAP energy spectrum can be manipulated as follows: H1/32s(f). s(f) is the energy density function for a unit wave height. During a storm event not only the offshore boundary significant wave heights but also the peak frequency varies. If we choose a mean peak frequency during a storm event, s(f) can be calculated for the mean peak frequency for the storm event. The amplitudes of the component waves for the random signals are calculated from the unit energy density function s(f), and the phase angle of the component wave, So we can numerically generate surface elevation time series for the time varying offshore wave heights. The method was verified in the intra-wave period wave model using field measurements at Sea Palling site Norfolk UK.

scholarly journals Global simulations of the atmosphere at 1.45 km grid-spacing with the Integrated Forecasting System

2020 ◽  
Author(s):  
Peter Düben ◽  
Nils Wedi ◽  
Sami Saarinen ◽  
Christian Zeman
Keyword(s):  
Initial Conditions ◽  
Weather Forecast ◽  
Wave Model ◽  
Shallow Convection ◽  
Grid Spacing ◽  
Time Step ◽  
Weather Forecasts ◽  
Forecasting System ◽  
Diabatic Forcing ◽  
Physical Phenomena

<p>Global simulations with 1.45 km grid-spacing are presented that were performed with the Integrated Forecasting System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF). Simulations are uncoupled (without ocean, sea-ice or wave model), using 62 or 137 vertical levels and the full complexity of weather forecast simulations including recent date initial conditions, real-world topography, and state-of-the-art physical parametrizations and diabatic forcing including shallow convection, turbulent diffusion, radiation and five categories for the water substance (vapour, liquid, ice, rain, snow). Simulations are evaluated with regard to computational efficiency and model fidelity. Scaling results are presented that were performed on the fastest supercomputer in Europe - Piz Daint (Top 500, Nov 2018). Important choices for the model configuration at this unprecedented resolution for the IFS are discussed such as the use of hydrostatic and non-hydrostatic equations or the time resolution of physical phenomena which is defined by the length of the time step. </p><p>Our simulations indicate that the IFS model — based on spectral transforms with a semi-implicit, semi-Lagrangian time-stepping scheme in contrast to more local discretization techniques — can provide a meaningful baseline reference for O(1) km global simulations.</p>

scholarly journals Wave climate in the Arkona Basin, the Baltic Sea

Ocean Science ◽  
2012 ◽  
Vol 8 (2) ◽  
pp. 287-300 ◽  
Author(s):  
T. Soomere ◽  
R. Weisse ◽  
A. Behrens
Keyword(s):  
Baltic Sea ◽  
Wave Height ◽  
Wave Model ◽  
Wave Climate ◽  
Wind Fields ◽  
The Baltic Sea ◽  
Wave Heights ◽  
The Baltic ◽  
Basic Features

Abstract. The basic features of the wave climate in the Southwestern Baltic Sea (such as the average and typical wave conditions, frequency of occurrence of different wave parameters, variations in wave heights from weekly to decadal scales) are established based on waverider measurements at the Darss Sill in 1991–2010. The measured climate is compared with two numerical simulations with the WAM wave model driven by downscaled reanalysis of wind fields for 1958–2002 and by adjusted geostrophic winds for 1970–2007. The wave climate in this region is typical for semi-enclosed basins of the Baltic Sea. The maximum wave heights are about half of those in the Baltic Proper. The maximum recorded significant wave height HS =4.46 m occurred on 3 November 1995. The wave height exhibits no long-term trend but reveals modest interannual (about 12 % of the long-term mean of 0.76 m) and substantial seasonal variation. The wave periods are mostly concentrated in a narrow range of 2.6–4 s. Their distribution is almost constant over decades. The role of remote swell is very small.

scholarly journals THỬ NGHIỆM ĐỒNG HOÁ SỐ LIỆU ĐỘ CAO SÓNG TRONG KHU VỰC BIỂN ĐÔNG BẰNG PHƯƠNG PHÁP LỌC KALMAN TỔ HỢP

2019 ◽  
Vol 18 (4) ◽  
pp. 358-367
Author(s):  
Nguyen Trung Thanh ◽  
Nguyen Minh Huan ◽  
Tran Quang Tien
Keyword(s):  
Probability Theory ◽  
Kalman Filter ◽  
Data Assimilation ◽  
Wave Height ◽  
Ensemble Kalman Filter ◽  
Wave Model ◽  
The Past ◽  
Ocean Data Assimilation ◽  
The World ◽  
Height Data

Advances in ocean data assimilation have been improved with the power of computers over the past 30 years, but the theory of data assimilation has a long history with the probability, theory of mathematical simulation, and traditional numerical calculations. Therefore, the research and application of data assimilation technology in oceanography have been widely carried out in the world and have gotten considerable achievements. In Vietnam, the study of data assimilation has also been applied in the meteorology and has attracted the increasing interest in oceanography. This paper presents the results of the study to calculate the wave height data from satellites combined with measured wave height data at MSP1 station of Vietsovpetro using the Ensemble Kalman Filter (EnKF) method associated with SWAN wave model in the Eastern Vietnam Sea.

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.

scholarly journals Operational numerical wind-wave model for the Black Sea

2000 ◽  
Vol 1 (1) ◽  
pp. 65
Author(s):  
A. KORTCHEVA ◽  
G. KORTCHEV ◽  
J. M. LEFEVRE
Keyword(s):  
Shallow Water ◽  
Real Time ◽  
Wave Height ◽  
Black Sea ◽  
Water Wave ◽  
Wind Wave ◽  
Wave Model ◽  
The Black Sea ◽  
Sea State ◽  
Height Data

In this paper the discrete spectral shallow water wave model named VAGBUHL1 is presented. This model is used for real-time Black Sea state forecasting. The model was verified against satellite ERS-2 altimeter wave height data.

Climatology, Variability and Extrema of Ocean Waves: The Web-Based KNMI/ERA-40 Wave Atlas

2006 ◽  
Author(s):  
Andreas Sterl ◽  
Sofia Caires
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Wave Model ◽  
Ocean Waves ◽  
Wave Period ◽  
Web Based ◽  
Significant Wave ◽  
Wave Parameters ◽  
Wave Heights ◽  
The Web

The European Centre for Medium Range Weather Forecasts (ECMWF) has recently finished ERA-40, a reanalysis covering the period September 1957 to August 2002. One of the products of ERA-40 consists of 6-hourly global fields of wave parameters like significant wave height and wave period. These data have been generated with the Centre’s WAM wave model. From these results the authors have derived climatologies of important wave parameters, including significant wave height, mean wave period, and extreme significant wave heights. Particular emphasis is on the variability of these parameters, both in space and time. Besides for scientists studying climate change, these results are also important for engineers who have to design maritime constructions. This paper describes the ERA-40 data and gives an overview of the results derived. The results are available on a global 1.5° × 1.5° grid. They are accessible from the web-based KNMI/ERA-40 Wave Atlas at http://www.knmi.nl/waveatlas.

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