Research

23 pages, 9863 KiB

Open AccessArticle

An Improved Approach to Wave Energy Resource Characterization for Sea States with Multiple Wave Systems

by Xingjie Jiang, Dalu Gao, Feng Hua, Yongzeng Yang and Zeyu Wang

J. Mar. Sci. Eng. 2022, 10(10), 1362; https://doi.org/10.3390/jmse10101362 - 23 Sep 2022

Cited by 2 | Viewed by 1192

Generally, wave energy resource assessment and characterization are performed based on an entire wave spectrum, ignoring the detailed energy features that belong to wave systems, i.e., wind waves and swells. In reality, the energy is separately possessed by multiple wave systems, propagating at [...] Read more.

Generally, wave energy resource assessment and characterization are performed based on an entire wave spectrum, ignoring the detailed energy features that belong to wave systems, i.e., wind waves and swells. In reality, the energy is separately possessed by multiple wave systems, propagating at different directions and velocities. Therefore, it is the wave system that is the most fundamental unit of the wave energy resource. Although detailed analyses of wind waves and swells can be conducted via wave system partitioning, operational assessment methods that can reveal the detailed wave energy characteristics of wave systems still deserve further development. Following a two-step partitioning procedure, this paper presents an improved approach to the characterization of wave energy resources based on grouped wave systems. Wave systems classified as the same group are consistent in terms of propagation direction, velocity, and other characteristics of wave energy, but these characteristics between the groups are obviously different. Therefore, in comparison with the traditional method, the new approach can reveal more comprehensive and more detailed characteristics of the wave energy resource in terms of (i) wind-sea and swell components, (ii) directionality, and (iii) wave conditions; details that represent valuable information for the improvement of the performance of wave energy converter devices and the optimization of the layout of device arrays in wave farms. Full article

(This article belongs to the Special Issue Data Modelling for Coastal-Ocean Environments and Disasters)

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20 pages, 6723 KiB

Open AccessArticle

Prediction of Significant Wave Height in Offshore China Based on the Machine Learning Method

by Zhijie Feng, Po Hu, Shuiqing Li and Dongxue Mo

J. Mar. Sci. Eng. 2022, 10(6), 836; https://doi.org/10.3390/jmse10060836 - 20 Jun 2022

Cited by 22 | Viewed by 2717

Abstract

Accurate wave prediction can help avoid disasters. In this study, the significant wave height (SWH) prediction performances of the recurrent neural network (RNN), long short-term memory network (LSTM), and gated recurrent unit network (GRU) were compared. The 10 m u-component of wind (U10), [...] Read more.

Accurate wave prediction can help avoid disasters. In this study, the significant wave height (SWH) prediction performances of the recurrent neural network (RNN), long short-term memory network (LSTM), and gated recurrent unit network (GRU) were compared. The 10 m u-component of wind (U10), 10 m v-component of wind (V10), and SWH of the previous 24 h were used as input parameters to predict the SWHs of the future 1, 3, 6, 12, and 24 h. The SWH prediction model was established at three different sites located in the Bohai Sea, the East China Sea, and the South China Sea, separately. The experimental results show that the performance of LSTM and GRU networks based on the gating mechanism was better than that of traditional RNNs, and the performances of the LSTM and GRU networks were comparable. The EMD method was found to be useful in the improvement of the LSTM network to forecast the significant wave heights of 12 and 24 h. Full article

(This article belongs to the Special Issue Data Modelling for Coastal-Ocean Environments and Disasters)

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12 pages, 4177 KiB

Open AccessArticle

Numerical Study on the Influence of Tropical Cyclone Characteristics on the Sea State and Sea Surface Roughness inside the Tropical Cyclones

by Shuiqing Li, Rui Li, Yanjun Wang and Jiuyou Lu

J. Mar. Sci. Eng. 2022, 10(5), 609; https://doi.org/10.3390/jmse10050609 - 29 Apr 2022

Viewed by 1453

Abstract

The development of wind wave (i.e., sea state) inside an intense tropical cyclone (TC) is the dominant contributor to the sea surface roughness and thus significantly impacts the air–sea interaction. The sea state is known to vary with TC characteristics (intensity, size, and [...] Read more.

The development of wind wave (i.e., sea state) inside an intense tropical cyclone (TC) is the dominant contributor to the sea surface roughness and thus significantly impacts the air–sea interaction. The sea state is known to vary with TC characteristics (intensity, size, and translation speed); however, comprehensive knowledge of the influence of TC characteristics on the sea state and sea surface roughness is quite limited, largely because of the lack of observations. In this study, numerical experiments are performed to investigate the influence of TC characteristics on the sea state and the sea surface roughness under a range of idealized TCs. The numerical results indicate that the sea states are systematically younger for a more intense or smaller TC, and their azimuthal variation is predominantly determined by the TC translation. The dependence of the sea surface roughness on wind speed shows systematic variations with the TC characteristics, which are most significant for a moderately moving TC. Full article

(This article belongs to the Special Issue Data Modelling for Coastal-Ocean Environments and Disasters)

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24 pages, 4667 KiB

Open AccessArticle

Different Types of Near-Inertial Internal Waves Observed by Lander in the Intermediate-Deep Layers of the South China Sea and Their Generation Mechanisms

by Huaqian Hou, Tengfei Xu, Bin Li, Bing Yang, Zexun Wei and Fei Yu

J. Mar. Sci. Eng. 2022, 10(5), 594; https://doi.org/10.3390/jmse10050594 - 28 Apr 2022

Cited by 2 | Viewed by 1308

Abstract

We report the direct and quantitative measurement of five significant near-inertial waves (NIWs) events observed by Lander at water depths of 600 m to 1100 m at 119°17′ E and 22°06′ N in the northern South China Sea from July to November 2017. [...] Read more.

We report the direct and quantitative measurement of five significant near-inertial waves (NIWs) events observed by Lander at water depths of 600 m to 1100 m at 119°17′ E and 22°06′ N in the northern South China Sea from July to November 2017. We found that these five NIWs events lead to strong shearing, which plays an important role in deep water mixing. Each event corresponds to several different NIWs generation mechanisms. The results show that the NIWs events generated by typhoons were the most regular. This was caused by dispersive NIWs propagation over long periods of time and over long distances. NIWs formed by spontaneous generation do not have this feature. The strongest NIWs events during the observation period were caused by a combination of shelf wave attenuation and monsoon. This time, the signal was transmitted to the seabed, and the upward signal reflected in the meridional direction was found. The reflected signal was anisotropically affected by the seabed topography. A horizontally propagated NIWs event with relatively weak dispersion was also found in this study. Based on the topography, we suspect it was formed by the Lee wave, but we cannot provide any more useful evidence. Full article

(This article belongs to the Special Issue Data Modelling for Coastal-Ocean Environments and Disasters)

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23 pages, 4981 KiB

Open AccessArticle

Establishing a Risk Assessment Framework for Marine Assets and Assessing Typhoon Lekima Storm Surge for the Laizhou Bay Coastal Area of the Bohai Sea, China

by Jian Li, Dongxue Mo, Rui Li, Yijun Hou and Qingrong Liu

J. Mar. Sci. Eng. 2022, 10(2), 298; https://doi.org/10.3390/jmse10020298 - 21 Feb 2022

Cited by 1 | Viewed by 1688

Abstract

Effective risk assessment can reduce the economic losses and physical damage caused by marine dynamic processes, such as storm surges. Most risk assessments of marine disasters are based on regional parameters and discrete hazard grades. Targeted, multilevel, and multiangle risk assessments are urgently [...] Read more.

Effective risk assessment can reduce the economic losses and physical damage caused by marine dynamic processes, such as storm surges. Most risk assessments of marine disasters are based on regional parameters and discrete hazard grades. Targeted, multilevel, and multiangle risk assessments are urgently needed. This study focuses on specific types of affected infrastructure. We established a sensitivity matrix by considering the effects of different disaster causal factors on different types of affected infrastructure. Through this matrix, hazards, vulnerability, and emergency response and recovery capability were effectively combined in a risk assessment framework. We completed the risk calculation for multiple concurrent effects of disasters in areas with superimposed key infrastructure using complementary risk superposition. The hazard grade, vulnerability grade, and coefficient of emergency response and recovery capability were established based on the means of return period, characteristics of disaster distribution, types of affected infrastructure and disaster relief distance, and were continuous by solving functions, normal cumulative distributions, and analytic functions. On the basis of reasonable MIKE21 numerical simulation and abstract spatial distribution of vulnerable assets, we tested the rationality of the assessment system in the Lekima typhoon storm surge process. The results showed that the assessment system accurately reflected the risk of damage to the important infrastructure in terms of spatial distribution. Therefore, this risk assessment framework was suitable for the assessment of a marine dynamic disaster process in the lower Laizhou Bay coastal area of the Bohai Sea, China. Moreover, it provided a reference for disaster prevention and reduction, guided the way for decision making, and effectively reduced disaster losses. Full article

(This article belongs to the Special Issue Data Modelling for Coastal-Ocean Environments and Disasters)

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25 pages, 16566 KiB

Open AccessArticle

Observation of Near-Inertial Waves Induced by Typhoon Mitag (2019) on the Southwestern East China Sea Continental Slope

by Zhiling Ouyang, Ze Liu, Yunfei Sun, Bing Yang and Yijun Hou

J. Mar. Sci. Eng. 2022, 10(2), 202; https://doi.org/10.3390/jmse10020202 - 01 Feb 2022

Cited by 6 | Viewed by 1764

Abstract

Based on horizontal velocity data recorded by a moored acoustic Doppler current profiler (ADCP) deployed on the southwestern continental slope of the East China Sea (ECS), this study investigates the characteristics of near-inertial waves (NIWs) induced by typhoon Mitag in October 2019. The [...] Read more.

Based on horizontal velocity data recorded by a moored acoustic Doppler current profiler (ADCP) deployed on the southwestern continental slope of the East China Sea (ECS), this study investigates the characteristics of near-inertial waves (NIWs) induced by typhoon Mitag in October 2019. The results indicated that Mitag-induced near-inertial kinetic energy (NIKE) was mainly concentrated above 290 m and was subsurface-intensified; both the maximum velocity and kinetic energy of the NIWs occurred at a depth of 100 m and were 0.21 m/s and 23.01 J/m³, respectively. The rotary vertical wavenumber spectra suggested that both downward and upward energy propagation existed. However, upward energy propagation was much smaller than downward energy propagation, mainly in the 0.007–0.014 cpm wavenumber band. The NIWs had an e-folding timescale of 9.5 days and were red-shifted as a result of the Doppler shift of the Kuroshio. Normal mode analysis suggested that the NIWs were dominated by the first and fourth baroclinic modes, which together accounted for 76.7% of the total NIKE. Spectral analysis showed that although the spectral density of the semidiurnal internal tide (M₂) peak overwhelmed that of the NIWs by a factor of approximately 30, the shear strength generated by the NIWs was comparable to that of the semidiurnal internal tide (M₂), which plays an important role in upper ocean mixing on the southwestern continental slope of the ECS. In addition, the bicoherence analysis suggested that a harmonic wave (M₂–f) was generated via the nonlinear interaction between the NIWs and semidiurnal internal tide (M₂), which reflects the energy dissipation mechanism of semidiurnal tides and NIWs on the southwestern continental slope of the ECS. Full article

(This article belongs to the Special Issue Data Modelling for Coastal-Ocean Environments and Disasters)

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26 pages, 10443 KiB

Open AccessArticle

The Impact of Typhoon Intensity on Wave Height and Storm Surge in the Northern East China Sea: A Comparative Case Study of Typhoon Muifa and Typhoon Lekima

by Junyan Wang, Dongxue Mo, Yijun Hou, Shuiqing Li, Jian Li, Mei Du and Baoshu Yin

J. Mar. Sci. Eng. 2022, 10(2), 192; https://doi.org/10.3390/jmse10020192 - 31 Jan 2022

Cited by 4 | Viewed by 2834

Abstract

A comparative study was conducted on typhoon intensity factors affecting the marine environment using two representative cases: Typhoon Lekima, which made landfall at Shandong Peninsula, the Northern East China Sea, and Typhoon Muifa, which did not. Using the ADCIRC and SWAN models, we [...] Read more.

A comparative study was conducted on typhoon intensity factors affecting the marine environment using two representative cases: Typhoon Lekima, which made landfall at Shandong Peninsula, the Northern East China Sea, and Typhoon Muifa, which did not. Using the ADCIRC and SWAN models, we developed a coupled numerical model and applied it to simulate the storm surge and destructive waves caused by typhoons. Three typhoon parameters—maximum wind speed, radius of maximum wind speed, and translation speed—were investigated through sensitivity experiments. The storm surge during the typhoon that made landfall showed a positive correlation with the distance of the typhoon’s center. The maximum significant wave height and storm surge had near-linear growth with a maximum wind speed but decreased with the growth rate of the radius of maximum wind. A rapid typhoon translation speed from 47 km/h to 60 km/h could cause a storm surge resonance phenomenon at the northern coast of the East China Sea. Full article

(This article belongs to the Special Issue Data Modelling for Coastal-Ocean Environments and Disasters)

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15 pages, 5069 KiB

Open AccessArticle

On the Genesis of the South China Sea Mesoscale Eddies

by Yuhui Zhao, Yang Yang, Longjiang Mao and Yuanzhi Zhang

J. Mar. Sci. Eng. 2022, 10(2), 188; https://doi.org/10.3390/jmse10020188 - 31 Jan 2022

Cited by 2 | Viewed by 2324

Abstract

The climatology of the mesoscale eddies in the upper layer of the South China Sea (SCS) is investigated for an understanding of its genesis using the outputs from a 1/12.5° ocean reanalysis. Employed is a recently developed multiscale energetics formalism on the basis [...] Read more.

The climatology of the mesoscale eddies in the upper layer of the South China Sea (SCS) is investigated for an understanding of its genesis using the outputs from a 1/12.5° ocean reanalysis. Employed is a recently developed multiscale energetics formalism on the basis of a multiscale window transform (MWT) and the theory of canonical transfer. Three scale windows, namely, background flow, mesoscale eddy and synoptic eddy, are differentiated, and fields on different scales are reconstructed henceforth. Diagnosis of the mesoscale eddy energy budget reveals that barotropic and baroclinic instabilities, wind work, advection and pressure work are essential ingredients of the eddy energy sources and sinks in the SCS, but their contributions vary from region to region. In the southwestern part of the SCS, the regional mesoscale eddy energy is mainly generated by barotropic instability, while in the northeastern SCS, baroclinic instability and the wind working directly on the eddies are the two dominant eddy generation processes. The eddies southwest of Taiwan are damped by outward energy transport via advection, while the decay of those southeast of Vietnam is due to pressure work. The three-scale framework also reveals that the interaction between the mesoscale eddies and higher-frequency synoptic eddies mainly serves as a sink for the mesoscale eddy energy in the SCS, except for the northeastern SCS, where significant inverse cascade of kinetic energy is found. Full article

(This article belongs to the Special Issue Data Modelling for Coastal-Ocean Environments and Disasters)

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23 pages, 6761 KiB

Open AccessArticle

Investigating Spatial Distribution of Green-Tide in the Yellow Sea in 2021 Using Combined Optical and SAR Images

by Yufei Ma, Kapo Wong, Jin Yeu Tsou and Yuanzhi Zhang

J. Mar. Sci. Eng. 2022, 10(2), 127; https://doi.org/10.3390/jmse10020127 - 19 Jan 2022

Cited by 18 | Viewed by 2005

Abstract

Optical remote sensing is limited to clouds and rain. It is difficult to obtain ground object images in severe weather. Microwave remote sensing can penetrate clouds and rain to obtain ground object images. Therefore, this paper combines optical and microwave data to analyze [...] Read more.

Optical remote sensing is limited to clouds and rain. It is difficult to obtain ground object images in severe weather. Microwave remote sensing can penetrate clouds and rain to obtain ground object images. Therefore, this paper combines optical and microwave data to analyze the time and space of the green-tide in the Yellow Sea in 2021. Compared with a single data source, the distribution characteristics increase the frequency of time observation and show the green-tide changes in more detail. The continuous remote sensing observation time is 80 days. Ulva prolifera has experienced discovery (mid-late May), development (mid-late May to early June), outbreak (early June to mid-late June), decline (late June to mid-July), and extinction (late July to mid-August) in five stages; the development period drifts along the northeast direction, the outbreak period drifts along the northwest direction, the decline and extinction periods are mainly in the Rizhao and Qingdao waters. Ulva prolifera has a tendency to drift northward as a whole, drifting through Yancheng, Lianyungang, Linyi, Rizhao and Qingdao waters eventually landing on the coast of Qingdao and gradually disappearing. Full article

(This article belongs to the Special Issue Data Modelling for Coastal-Ocean Environments and Disasters)

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16 pages, 5762 KiB

Open AccessArticle

Estimation of Wave-Breaking Index by Learning Nonlinear Relation Using Multilayer Neural Network

by Miyoung Yun, Jinah Kim and Kideok Do

J. Mar. Sci. Eng. 2022, 10(1), 50; https://doi.org/10.3390/jmse10010050 - 03 Jan 2022

Cited by 2 | Viewed by 4315

Abstract

Estimating wave-breaking indexes such as wave height and water depth is essential to understanding the location and scale of the breaking wave. Therefore, numerous wave-flume laboratory experiments have been conducted to develop empirical wave-breaking formulas. However, the nonlinearity between the parameters has not [...] Read more.

Estimating wave-breaking indexes such as wave height and water depth is essential to understanding the location and scale of the breaking wave. Therefore, numerous wave-flume laboratory experiments have been conducted to develop empirical wave-breaking formulas. However, the nonlinearity between the parameters has not been fully incorporated into the empirical equations. Thus, this study proposes a multilayer neural network utilizing the nonlinear activation function and backpropagation to extract nonlinear relationships. Existing laboratory experiment data for the monochromatic regular wave are used to train the proposed network. Specifically, the bottom slope, deep-water wave height and wave period are plugged in as the input values that simultaneously estimate the breaking-wave height and wave-breaking location. Typical empirical equations employ deep-water wave height and length as input variables to predict the breaking-wave height and water depth. A newly proposed model directly utilizes breaking-wave height and water depth without nondimensionalization. Thus, the applicability can be significantly improved. The estimated wave-breaking index is statistically verified using the bias, root-mean-square errors, and Pearson correlation coefficient. The performance of the proposed model is better than existing breaking-wave-index formulas as well as having robust applicability to laboratory experiment conditions, such as wave condition, bottom slope, and experimental scale. Full article

(This article belongs to the Special Issue Data Modelling for Coastal-Ocean Environments and Disasters)

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20 pages, 6827 KiB

Open AccessArticle

Interannual to Interdecadal Variability of the Southern Yellow Sea Cold Water Mass and Establishment of “Forcing Mechanism Bridge”

by Yunxia Guo, Dongxue Mo and Yijun Hou

J. Mar. Sci. Eng. 2021, 9(12), 1316; https://doi.org/10.3390/jmse9121316 - 23 Nov 2021

Cited by 5 | Viewed by 2177

Abstract

The Yellow Sea cold water mass (YSCWM) occupies a wide region below the Yellow Sea (YS) thermocline in summer which is the most conservative water and may contain clearer climate signals than any other water masses in the YS. This study investigated the [...] Read more.

The Yellow Sea cold water mass (YSCWM) occupies a wide region below the Yellow Sea (YS) thermocline in summer which is the most conservative water and may contain clearer climate signals than any other water masses in the YS. This study investigated the low-frequency variability of the southern YSCWM (SYSCWM) and established the “forcing mechanism bridge” using correlation analysis and singular value decomposition. On the interannual timescale, the southern oscillation can affect the SYSCWM through both the local winter monsoon (WM) and the sea surface net heat flux. On the decadal timescale, the Pacific decadal oscillation (PDO) can affect the SYSCWM via two “bridges”. First, the PDO affects the SYSCWM intensity by Aleutian low (AL), WM, and surface air temperature (SAT). Second, the PDO affects the SYSCWM by AL, WM, Kuroshio heat transport, and Yellow Sea warm current. The Arctic oscillation (AO) affects the SYSCWM by the Mongolian high, WM, and SAT. Before and after the 1980s, the consistent phase change of the PDO and the AO contributed to the significant decadal variability of the SYSCWM. Finally, one simple formula for predicting the decadal variability of SYSCWM intensity was established using key influencing factors. Full article

(This article belongs to the Special Issue Data Modelling for Coastal-Ocean Environments and Disasters)

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22 pages, 5666 KiB

Open AccessArticle

Assessment of Extreme Storm Surges over the Changjiang River Estuary from a Wave-Current Coupled Model

by Yutao Chi and Zengrui Rong

J. Mar. Sci. Eng. 2021, 9(11), 1222; https://doi.org/10.3390/jmse9111222 - 05 Nov 2021

Cited by 7 | Viewed by 2003

Abstract

Disastrous storm surges and waves caused by typhoons are major marine dynamic disasters affecting the east China coast and the Changjiang River Estuary, especially when they occur coincidentally. In this study, a high-resolution wave–current coupled model consisting of ADCIRC (Advanced Circulation) and SWAN [...] Read more.

Disastrous storm surges and waves caused by typhoons are major marine dynamic disasters affecting the east China coast and the Changjiang River Estuary, especially when they occur coincidentally. In this study, a high-resolution wave–current coupled model consisting of ADCIRC (Advanced Circulation) and SWAN (Simulating Waves Nearshore) was established and validated. The model shows reasonable skills in reproducing the surge levels and waves. The storm surges and associated waves are then simulated for 98 typhoons affecting the Changjiang River Estuary over the past 32 years (1987–2018). Two different wind fields, the ERA reanalysis and the ERA-based synthetic wind with a theoretical typhoon model, were adopted to discern the potential uncertainties associated with winds. Model results forced by the ERA reanalysis show comparative skills with the synthetic winds, but differences may be relatively large in specific stations. The extreme surge levels with a 50-year return period are then presented based on the coupled model results and the Gumbel distribution model. Higher risk is presented in Hangzhou Bay and the nearshore region along the coast of Zhejiang. Comparative runs with and without wave effects were conducted to discern the impact of waves on the extreme surge levels. The wave setup contributes to 2–12.5% of the 50-year extreme surge level. Furthermore, the joint exceedance probabilities of high surge levels and high wave height were evaluated with the Gumbel–logistic statistic model. Given the same joint return period, the nearshore region along the coast of Zhejiang is more vulnerable with high surges and large waves than the Changjiang River Estuary with large waves and moderate surges. Full article

(This article belongs to the Special Issue Data Modelling for Coastal-Ocean Environments and Disasters)

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23 pages, 23802 KiB

Open AccessArticle

Variation and Episodes of Near-Inertial Internal Waves on the Continental Slope of the Southeastern East China Sea

by Bing Yang, Po Hu and Yijun Hou

J. Mar. Sci. Eng. 2021, 9(8), 916; https://doi.org/10.3390/jmse9080916 - 23 Aug 2021

Cited by 6 | Viewed by 2605

Abstract

Based on in situ observations, six episodes of near-inertial internal waves (NIWs) were detected on the East China Sea (ECS) continental slope, and the mechanisms and characteristics of them were examined. The generation mechanisms of the observed NIWs included typhoon, wind burst, lateral [...] Read more.

Based on in situ observations, six episodes of near-inertial internal waves (NIWs) were detected on the East China Sea (ECS) continental slope, and the mechanisms and characteristics of them were examined. The generation mechanisms of the observed NIWs included typhoon, wind burst, lateral propagation, and energy transfer from low-frequency flow. The depth-integrated near-inertial kinetic energy (NIKE) showed no significant seasonal variation, and the annual mean NIKE and near-inertial currents were 400 J/m² and 3.50 cm/s, respectively. Downward propagation of NIKE was evident in the small wavenumber band according to the rotary vertical wavenumber spectra. The NIKE was subsurface-intensified, and the near-inertial vertical shear reached 0.01 s⁻¹. The vertical phase speeds of the NIWs ranged from 5 to 19 m/h. The frequencies of the NIWs were mostly red-shifted, however, blue-shift also existed. One episode had both blue- and red-shifted frequencies vertically, and had both upward and downward propagating vertical phase speeds. The e-folding times of the observed NIWs ranged from 4 to 11 days, which were influenced by successive wind bursts and background vorticity. On the left-hand side of Kuroshio, the background vorticity is usually positive; however, the NIWs were almost red-shifted, which resulted from the Doppler shift of the Kuroshio. Full article

(This article belongs to the Special Issue Data Modelling for Coastal-Ocean Environments and Disasters)

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24 pages, 5094 KiB

Open AccessFeature PaperArticle

Energy Sources Generation and Energy Cascades along the Kuroshio East of Taiwan Island and the East China Sea

by Ru Wang, Yijun Hou and Ze Liu

J. Mar. Sci. Eng. 2021, 9(7), 692; https://doi.org/10.3390/jmse9070692 - 24 Jun 2021

Cited by 2 | Viewed by 2116

Abstract

There are multi-spatial-scale ocean dynamic processes in the western boundary current region, so the budget of energy source and sink in the Kuroshio Current area can describe the oceanic energy cycle and transformation more accurately. The slope of the one-dimensional spectral energy density [...] Read more.

There are multi-spatial-scale ocean dynamic processes in the western boundary current region, so the budget of energy source and sink in the Kuroshio Current area can describe the oceanic energy cycle and transformation more accurately. The slope of the one-dimensional spectral energy density varies between −5/3 and −3 in the wavenumber range of 0.02–0.1 cpkm, indicating an inverse energy cascade in the Kuroshio of Taiwan Island and the East China Sea. According to the steady-state energy evolution, an energy source must be present. The locations of energy sources were identified using the spectral energy transfer calculated by 24 years of Ocean General Circulation Model for the Earth Simulator (OFES) data. At the sea surface, the kinetic energy (KE) sources are mainly within 23.2°–25.6° Nand 28°–29° N at less than 0.02 cpkm and within 23.2°–25° N and 26°–30° N at 0.02–0.1 cpkm. The available potential energy (APE) sources are mainly within 22°–28° N and 28.6°–30° N at less than 0.02 cpkm and within 22.6°–24.6° N, 25.4°–28° N and 29.2°–30° N at 0.02–0.1 cpkm. Beneath the sea surface, the energy sources are mainly above 400 m depth. Wind stress and density differences are primarily responsible for the KE and APE sources, respectively. Once an energy source is formed, to maintain a steady state, energy cascades (mainly inverse cascades by calculating spectral energy flux) will be engendered. By calculating the energy flux at 600 m depth, KE changes from inflow (sink) to outflow (source), and the conversion depth of source and sink is 380 m. However, outflow of the APE behaves as the source. Full article

(This article belongs to the Special Issue Data Modelling for Coastal-Ocean Environments and Disasters)

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