Extraction of ocean wave height and dominant wavelength from Geos 3 altimeter data

1979 ◽  
Vol 84 (B8) ◽  
pp. 4003 ◽  
Author(s):  
Edward J. Walsh
Keyword(s):  
Wave Height ◽  
Ocean Wave ◽  
Altimeter Data ◽  
Dominant Wavelength

scholarly journals Comparison of Envisat ASAR Ocean Wave Spectra with Buoy and Altimeter Data via a Wave Model

2009 ◽  
Vol 26 (3) ◽  
pp. 593-614 ◽  
Author(s):  
Jian-Guo Li ◽  
Martin Holt
Keyword(s):  
Wave Height ◽  
Spectral Characteristics ◽  
Wave Model ◽  
Ocean Wave ◽  
Global Ocean ◽  
Altimeter Data ◽  
Wave Spectra ◽  
Envisat Asar ◽  
Comparison Results ◽  
Wave Heights

Abstract The Advanced Synthetic Aperture Radar (ASAR) on board the Envisat satellite is an important resource for observation of global ocean surface wave spectra. However, assessment of this valuable dataset is not straightforward as a result of a lack of other independent ocean wave spectral observations. The radar altimeter (RA-2) on board the same satellite measures ocean wave height at the same time as the ASAR but at a location about 200 km distant. A small number of moored buoys produce one-dimensional (1D) ocean wave spectra but few ASAR spectra fall on the buoy positions in a given period. Indirect comparison of the Envisat ASAR 2D wave spectra with the RA-2 wave heights and 1D spectra of three selected buoys from July 2004 to February 2006 is facilitated by a wave model, which provides coherent spatial and temporal links between these observations. In addition to the conventional significant wave height (SWH), four spectral subrange wave heights (SRWHs) are used to illustrate the spectral characteristics of these observations. A comparison of three Envisat ASAR 2D spectra with the closest model and buoy spectra is also attempted to illustrate the qualities of these different observations and to demonstrate the restrictions to their direct comparison. Results indicate that these three independent observations are in good agreement in terms of SWH, though the Envisat ASAR shows the largest variance. Comparison of SRWHs indicates that the ASAR spectra agree well with buoy and model in moderately long waves, but the ASAR instrument does not resolve high-frequency waves, especially along the satellite track.

scholarly journals Accuracy Evaluation of CFOSAT SWIM L2 Products Based on NDBC Buoy and Jason-3 Altimeter Data

2021 ◽  
Vol 13 (5) ◽  
pp. 887
Author(s):  
Guozhou Liang ◽  
Jungang Yang ◽  
Jichao Wang
Keyword(s):  
Wave Height ◽  
Wave Spectrum ◽  
Data Accuracy ◽  
Ocean Wave ◽  
Global Ocean ◽  
Altimeter Data ◽  
Accuracy Evaluation ◽  
Wave Direction ◽  
Dominant Wave ◽  
Better Than

Chinese-French Oceanography Satellite (CFOSAT), the first satellite which can observe global ocean wave and wind synchronously, was successfully launched On 29 October 2018. The CFOSAT carries SWIM that can observe ocean wave on a global scale. Based on National Data Buoy Center (NDBC) buoys and Jason-3 altimeter data, this study evaluated the accuracy of L2 level products of CFOSAT SWIM from August 2019 to September 2020. The results show that the accuracy of the nadir Significant Wave Height (SWH) data of the SWIM wave spectrometer is good. Compared with the data of the NDBC buoys and Jason-3 altimeter, the RMSE of the nadir box SWH were 0.39 and 0.21 m, respectively. The variation trend of SWH were first increasing and then decreasing with the increasing of the wave height. The precision of off-nadir wave spectrum SWH is not better than nadir box SWH data. Accuracy was evaluated for off-nadir data from August 2019 to June 2020 and after June 2020, respectively. After linear regression correction, the accuracy of off-nadir wave spectrum SWH was improved. The data accuracy evaluation and comparison of different time period showed that the off-nadir wave spectrum SWH accuracy was improved after the data version was updated in June 2020, especially for 6° and 8° wave spectrum. The precision of off-nadir wave spectrum SWH decreases with the increasing of wave height. The accuracy of the dominant wave direction of each wave spectrum is also not very good, and the accuracy of the dominant wave direction of 10° wave spectrum is slightly better than the others. In general, the accuracy of SWIM nadir beam SWH data reaches the high data accuracy of traditional altimeter, while the accuracy of off-nadir wave spectrum SWH is less than that of nadir beam SWH data. The off-nadir SWH data accuracy after June 2020 has been greatly improved.

Prediction of Ocean Wave Height Suitable for Ship Autopilot

2021 ◽  
pp. 1-10
Author(s):  
Ranran Lou ◽  
Wen Wang ◽  
Xinfang Li ◽  
Yuchao Zheng ◽  
Zhihan Lv
Keyword(s):  
Wave Height ◽  
Ocean Wave ◽  
Ship Autopilot

Two tests of real-time ocean wave-height mapping with HF skywave radar

1986 ◽  
Vol 11 (2) ◽  
pp. 180-186 ◽  
Author(s):  
J. Maresca ◽  
T. Georges ◽  
C. Carlson ◽  
J. Riley
Keyword(s):  
Real Time ◽  
Wave Height ◽  
Ocean Wave

scholarly journals Wave Transformation for International Hub Port Planning (Transformasi Gelombang untuk Perencanaan Pelabuhan Hub Internasional)

2015 ◽  
Vol 20 (1) ◽  
pp. 9
Author(s):  
Denny Nugroho Sugianto ◽  
Purwanto Purwanto ◽  
Andika B Candra
Keyword(s):  
Wave Height ◽  
Vital Role ◽  
Ocean Wave ◽  
Wave Transformation ◽  
Wave Refraction ◽  
Wave Characteristics ◽  
Maximum Period ◽  
Wave Patterns ◽  
Port Planning ◽  
North Sumatra

Indonesia merupakan salah satu negara kepulauan terbesar di dunia sehingga peran pelabuhan sangat vital dalam pembangunan ekonomi. Pelabuhan bukan hanya sekedar sebagai pelengkap infrastruktur, melainkan harus direncanakan dan dikelola dengan baik serta memperhatikan fenomena dinamika perairan laut seperti pola gelombang laut. Data gelombang laut menjadi faktor penting dalam perencanaan tata letak dan tipe bangunan pantai karena dipengaruhi oleh tinggi gelombang signifikan, tunggang pasang surut dan transformasi gelombang. Penelitian ini mengalisis karaketristrik dan bentuk transformasi gelombang untuk perencanaan Pelabuhan Hub Internasional, sebagai studi kasus adalah pelabuhan di Kuala Tanjung, Kabupaten Batu Bara. Pelabuhan di Kuala Tanjung merupakan salah satu dari 2 pelabuhan hub internasional yang direncanakan akan dibangun oleh pemerintah Indonesia. Metode yang digunakan adalah metode kuantitatif yang dilakukan dengan perhitungan statistik dan pemodelan matematik dengan modul hydrodinamic dan spectral wave untuk mengetahui arah penjalaran dan transformasi gelombang. Hasil dari data ECMWF selama 1999–Juni 2014, diketahui tinggi gelombang signifikan (Hs) maksimum mencapai 1,69 m dan periode maksimum 8 detik. Karakteristik gelombang termasuk klasifikasi gelombang laut transisi dengan nilai d.L-1 berkisar anrata 0,27–0,48 dan berdasarkan periodenya diklasifikasikan sebagai gelombang gravitasi.Transformasi gelombang terjadi akibat pendangkalan dengan koefesian pendangkalan Ks 0,93–0,98 dan proses refraksi gelombang dengan koefesien Kr 0,97–0,99. Tinggi gelombang pecah Hb sebesar 1,24 meter dengan kedalaman gelombang pecah db sebesar 1,82 meter. Efektifitas desain bangunan terminal di Pelabuhan Kuala Tanjung secara keseluruhan untuk sepanjang musim sebesar 79,8% atau dapat dikatakan cukup efektif dalam meredam gelombang. Kata kunci: transformasi gelombang, tinggi dan periode gelombang, pelabuhan Indonesia is one of the largest archipelagic countries in the world, therefore port has vital role in economic development. Port is not just as a complement to the infrastructure, but it must be planned and managed properly and attention to the dynamics of marine phenomena such as ocean wave patterns. Ocean wave data become important factors in planning coastal building, since it is influenced by wave height, tides and waves transformation. The purpose of this study was to analyse characteristic and forms wave transformations for planning of international hub port at Kuala Tanjung, Baru Bara District North Sumatra. This port is one of two Indonesian government's plan in the development of international hub port. Quantitative method was used in this study by statistical calculations and mathematical modeling with hydrodinamic modules and spectral wave to determine the direction of wave propagation and transformation. Results show that based on ECMWF data during 1999-June 2014, known significant wave height (Hs) maximum of 1.69 m and maximum period (Ts) of 8 secs. The classification wave characteristics iswave transition (d.L-1: 0.27–0.48) and by the period are classified as gravitational waves. Wave transformation occurs due to the soaling, withKs 0.93–0.98 and the wave refraction Kr 0.97–0.99. Whereas Hb of 1.24 meters anddb 1.82 meters. The effectiveness of the design of the terminal building at the Port of Kuala Tanjung overall for the season amounted to 79.8%, which is quite effective in reducing the wave. Keywords: wave transformation, wave height and period, Port of Kuala Tanjung

scholarly journals Reliability of Extreme Significant Wave Height Estimation from Satellite Altimetry and In Situ Measurements in the Coastal Zone

2020 ◽  
Vol 8 (12) ◽  
pp. 1039
Author(s):  
Ben Timmermans ◽  
Andrew G. P. Shaw ◽  
Christine Gommenginger
Keyword(s):  
Coastal Zone ◽  
Wave Height ◽  
Satellite Data ◽  
Significant Wave Height ◽  
Wave Climate ◽  
In Situ Measurements ◽  
Altimeter Data ◽  
Sea State ◽  
Significant Wave

Measurements of significant wave height from satellite altimeter missions are finding increasing application in investigations of wave climate, sea state variability and trends, in particular as the means to mitigate the general sparsity of in situ measurements. However, many questions remain over the suitability of altimeter data for the representation of extreme sea states and applications in the coastal zone. In this paper, the limitations of altimeter data to estimate coastal Hs extremes (<10 km from shore) are investigated using the European Space Agency Sea State Climate Change Initiative L2P altimeter data v1.1 product recently released. This Sea State CCI product provides near complete global coverage and a continuous record of 28 years. It is used here together with in situ data from moored wave buoys at six sites around the coast of the United States. The limitations of estimating extreme values based on satellite data are quantified and linked to several factors including the impact of data corruption nearshore, the influence of coastline morphology and local wave climate dynamics, and the spatio-temporal sampling achieved by altimeters. The factors combine to lead to considerable underestimation of estimated Hs 10-yr return levels. Sensitivity to these factors is evaluated at specific sites, leading to recommendations about the use of satellite data to estimate extremes and their temporal evolution in coastal environments.

Nonstationary Extreme-Value Predictions in the Gulf of Mexico

2007 ◽  
Author(s):  
Christos N. Stefanakos
Keyword(s):  
Time Series ◽  
Gulf Of Mexico ◽  
Wave Height ◽  
Missing Values ◽  
Extreme Value ◽  
Altimeter Data ◽  
Dependence Structure ◽  
Measured Time ◽  
Definition Of

In the present work, return periods of various level values of significant wave height in the Gulf of Mexico are given. The predictions are based on a new method for nonstationary extreme-value calculations that have recently been published. This enhanced method exploits efficiently the nonstationary modeling of wind or wave time series and a new definition of return period using the MEan Number of Upcrossings of the level value x* (MENU method). The whole procedure is applied to long-term measurements of wave height in the Gulf of Mexico. Two kinds of data have been used: long-term time series of buoy measurements, and satellite altimeter data. Measured time series are incomplete and a novel procedure for filling in of missing values is applied before proceeding with the extreme-value calculations. Results are compared with several variants of traditional methods, giving more realistic estimates than the traditional predictions. This is in accordance with the results of other methods that take also into account the dependence structure of the examined time series.

scholarly journals Marine Wind and Wave Height Trends at Different ERA-Interim Forecast Ranges

2015 ◽  
Vol 28 (2) ◽  
pp. 819-837 ◽  
Author(s):  
Ole Johan Aarnes ◽  
Saleh Abdalla ◽  
Jean-Raymond Bidlot ◽  
Øyvind Breivik
Keyword(s):  
Wind Speed ◽  
Wave Height ◽  
North Atlantic ◽  
Wave Model ◽  
Altimeter Data ◽  
The North ◽  
The Impact ◽  
Global Reanalysis ◽  
Made In

Abstract Trends in marine wind speed and significant wave height are investigated using the global reanalysis ERA-Interim over the period 1979–2012, based on monthly-mean and monthly-maximum data. Besides the traditional reanalysis, the authors include trends obtained at different forecast range, available up to 10 days ahead. Any model biases that are corrected differently over time are likely to introduce spurious trends of variable magnitude. However, at increased forecast range the model tends to relax, being less affected by assimilation. Still, there is a trade-off between removing the impact of data assimilation at longer forecast range and getting a lower level of uncertainty in the predictions at shorter forecast range. Because of the sheer amount of assimilations made in ERA-Interim, directly and indirectly affecting the data, it is difficult, if not impossible, to distinguish effects imposed by all updates. Here, special emphasis is put on the introduction of wave altimeter data in August 1991, the only type of data directly affecting the wave field. From this, it is shown that areas of higher model bias introduce quite different trends depending on forecast range, most apparent in the North Atlantic and eastern tropical Pacific. Results are compared with 23 in situ measurements, Envisat altimeter winds, and two stand-alone ECMWF operational wave model (EC-WAM) runs with and without wave altimeter assimilation. Here, the 48-h forecast is suggested to be a better candidate for trend estimates of wave height, mainly due to the step change imposed by altimeter observations. Even though wind speed seems less affected by undesirable step changes, the authors believe that the 24–48-h forecast more effectively filters out any unwanted effects.

scholarly journals Monstrous ocean waves during typhoon Krosa

2008 ◽  
Vol 26 (6) ◽  
pp. 1327-1329 ◽  
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.

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