scholarly journals Influence of winds on temporally varying short and long period gravity waves in the near shore regions of the eastern Arabian Sea

Ocean Science ◽  
2013 ◽  
Vol 9 (2) ◽  
pp. 343-353 ◽  
Author(s):  
J. Glejin ◽  
V. Sanil Kumar ◽  
T. M. Balakrishnan Nair ◽  
J. Singh
Keyword(s):  
Southern Ocean ◽  
Wave Height ◽  
Arabian Sea ◽  
Sea Breeze ◽  
Land Breeze ◽  
Wind System ◽  
Near Surface ◽  
Maximum Wave Height ◽  
Long Period ◽  
Wave Data

Abstract. Wave data collected off Ratnagiri, west coast of India, during 1 May 2010 to 30 April 2012 are used in this study. Seasonal and annual variations in wave data controlled by the local wind system such as sea breeze and land breeze, and remote wind generated long period waves are also studied. The role of sea breeze on the sea state during pre- and postmonsoon seasons is studied and it is found that the maximum wave height is observed at 15:00 UTC during the premonsoon season, with an estimated difference in time lag of 1–2 h in maximum wave height between premonsoon and postmonsoon seasons. Observed waves are classified in to (i) short waves (Tp < 8 s), (ii) intermediate waves (8 < Tp < 13 s), and (iii) long waves (Tp> 13 s) based on peak period (Tp) and the percentages of occurrence of each category are estimated. Long period waves are observed mainly during the pre- and the postmonsoon seasons. During the southwest monsoon period, the waves with period > 13 s are a minimum. An event during 2011 is identified as swells propagated from the Southern Ocean with an estimated travelling time of 5–6 days. The swells reaching the Arabian Sea from the south Indian Ocean and Southern Ocean, due to storms during the pre- and postmonsoon periods, modify the near surface winds due to higher phase wave celerity than the wind speed. Estimation of inverse wave age using large-scale winds such as NCEP (National Centers for Environmental Prediction) reflects the presence of cyclonic activity during pre- and postmonsoon seasons but not the effect of the local sea breeze/land breeze wind system.

scholarly journals Changes in nearshore waves during the active sea/land breeze period off Vengurla, central west coast of India

2016 ◽  
Vol 34 (2) ◽  
pp. 215-226 ◽  
Author(s):  
M. M. Amrutha ◽  
V. Sanil Kumar ◽  
J. Singh
Keyword(s):  
Wave Height ◽  
Water Depth ◽  
West Coast ◽  
Unique Feature ◽  
Sea Breeze ◽  
Wave Transformation ◽  
Land Breeze ◽  
West Coast Of India ◽  
Nearshore Waves ◽  
Wind Sea

Abstract. A unique feature observed in the tropical and subtropical coastal area is the diurnal sea-breeze/land-breeze cycle. We examined the nearshore waves at 5 and 15 m water depth during the active sea/land breeze period (January–April) in the year 2015 based on the data measured using the waverider buoys moored in the eastern Arabian sea off Vengurla, central west coast of India. Temporal variability of diurnal wave response is examined. Numerical model Delft3D is used to study the nearshore wave transformation. The wave height increased due to the sea breeze and reached its peak at  ∼ 13:00 UTC at 15 m water depth, whereas the peak significant wave height is at 12:00 UTC at 5 m water depth. Due to the influence of the land/sea breeze system, the range of the peak wave period in 1 day varied up to 8 s. Reduction in the wave height of wind-sea is around 20 % and that of the swell is around 10 % from 15 to 5 m water depth.

Observed and Modeled Urban Heat Island and Sea Breeze Circulation Interactions: a Shanghai Case Study

2021 ◽  
Keyword(s):  
Urban Heat Island ◽  
Time Scales ◽  
Single Layer ◽  
Sea Breeze ◽  
Accurate Estimation ◽  
Land Breeze ◽  
Heat Island ◽  
Near Surface ◽  
Low Level ◽  
Urban Heat

Abstract Urban heat island (UHI) and sea-land breeze systems are well-known and important characteristics of the climate of coastal cities. To model these, the accurate estimation of the surface energy balance (SEB) is a key factor needed to improve local scale simulations of thermodynamic and dynamic boundary circulations. The Weather Research and Forecasting model with a single layer urban model (WRF/SLUCM), with parameters derived from MODIS and local GIS information, is used to investigate the UHI and sea breeze circulations (SBC) in the megacity of Shanghai. The WRF/SLUCM can reproduce observed urban radiation and SEB fluxes, near-surface meteorological variables, and the evolution of the UHI and SBC. Simulations for an August period show the maximum UHI tends to drift northwest in the afternoon, driven by the prevailing southeast wind. The sea breeze lasts for about 4-h and is strongest between 1200 and 1400 Local Time (UTC+8 h). The interaction between UHI and SBC is evident with low-level convergence, upward motion and moisture transport from the sea and urban breezes simulated. An urban circulation (horizontal/vertical/time scales: ∼20-km/ ∼1.5-km/ ∼3-h) with thermal vertical motions (∼1.5 m s−1) above the urban area and a SBC (horizontal/vertical/time scales: 6 - 7 km/ ∼1 km/ 2 - 3-h) above the northern coastal suburb occur. Combined the sea breeze and southerly winds form a low-level wind shear (convergence zone) ∼5 km from the coast that penetrates ∼20 km inland to the urban center. Using the WRF/SLUCM simulations we improve understanding of the complex spatial dynamics of summer-time urban heating in coastal megacities, such as Shanghai.

scholarly journals Temporal variations in the wind and wave climate at a location in the eastern Arabian Sea based on ERA-Interim reanalysis data

2013 ◽  
Vol 1 (6) ◽  
pp. 7239-7269 ◽  
Author(s):  
P. R. Shanas ◽  
V. Sanil Kumar
Keyword(s):  
Wind Speed ◽  
Wave Height ◽  
Arabian Sea ◽  
Temporal Variations ◽  
Reanalysis Data ◽  
Annual Maximum ◽  
Upward Trend ◽  
Maximum Wave Height ◽  
South West Monsoon ◽  
Eastern Arabian Sea

Abstract. Temporal variations of wind speed and significant wave height (SWH) at a location in the eastern Arabian Sea is studied using ERA-Interim reanalysis data during 1979–2012. A Shallow water location is selected for the study since measured buoy data is available close to the location for comparison of the reanalysis data. Annual mean wind speed shows a statistically significant decreasing trend of 1.5 cm s-1 yr-1. Weakening of SWH during one of the peak monsoon month (August) is identified from the monthly analysis of SWH, which shows higher upward trend in SWH during south west monsoon period with an exception during August. The annual mean SWH shows slight upward trend (0.012 cm yr-1), whereas larger upward trend (1.4 cm yr-1) is observed for annual maximum SWH. The influence of tropical cyclone activity is also studied and found that the maximum SWH and wind speed during 1996 is directly related to the cyclonic event. The relationship between annual maximum wave height and wind speed with ENSO and Indian Ocean Dipole (IOD) are tested and found that larger waves are reported during strong El-Niño and negative IOD year, whereas decrease in maximum wave height and wind speed is observed during strong La-Niña and positive IOD year.

scholarly journals Structure Analysis of the Sea Breeze Based on Doppler Lidar and Its Impact on Pollutants

2022 ◽  
Vol 14 (2) ◽  
pp. 324
Author(s):  
Jiaxin Liu ◽  
Xiaoquan Song ◽  
Wenrui Long ◽  
Yiyuan Fu ◽  
Long Yun ◽  
...  
Keyword(s):  
Dissipation Rate ◽  
Sea Breeze ◽  
Turbulent Intensity ◽  
Horizontal Wind ◽  
Land Breeze ◽  
Doppler Lidar ◽  
Helmholtz Instability ◽  
Spatiotemporal Resolution ◽  
Near Surface ◽  
Wind Profiles

The Doppler lidar system can accurately obtain wind profiles with high spatiotemporal resolution, which plays an increasingly important role in the research of atmospheric boundary layers and sea–land breeze. In September 2019, Doppler lidars were used to carry out observation experiments of the atmospheric wind field and pollutants in Shenzhen. Weather Research and Forecasting showed that the topography of Hongkong affected the sea breeze to produce the circumfluence flow at low altitudes. Two sea breezes from the Pearl River Estuary and the northeast of Hong Kong arrived at the observation site in succession, changing the wind direction from northeast to southeast. Based on the wind profiles, the structural and turbulent characteristics of the sea breeze were analyzed. The sea breeze front was accurately captured by the algorithm based on fuzzy logic, and its arrival time was 17:30 on 25 September. The boundary between the sea breeze and the return flow was separated by the edge enhancement algorithm. From this, the height of the sea breeze head (about 1100 m) and the thickness of the sea breeze layer (about 700 m) can be obtained. The fluctuated height of the boundary and the spiral airflow nearby revealed the Kelvin–Helmholtz instability. The influence of the Kelvin–Helmholtz instability could be delivered to the near-surface, which was verified by the spatiotemporal change of the horizontal wind speed and momentum flux. The intensity of the turbulence under the control of the sea breeze was significantly lower than that under the land breeze. The turbulent intensity was almost 0.1, and the dissipation rate was between 10−4 and 10−2 m2·s−3 under the land breeze. The turbulent intensity was below 0.05, and the dissipation rate was between 10−5 and 10−3 m2·s−3 under the sea breeze. The turbulent parameters showed peaks and large gradients at the boundary and the sea breeze front. The peak value of the turbulent intensity was around 0.3, and the dissipation rate was around 0.1 m2·s−3. The round-trip effect of sea–land breeze caused circulate pollutants. The recirculation factor was maintained at 0.5–0.6 at heights where the sea and land breeze alternately controlled (below 600 m), as well as increasing with a decreasing duration of the sea breeze. The factor exceeded 0.9 under the control of the high-altitude breeze (above 750 m). The convergence and rise of the airflow at the front led to collect pollutants, causing a sharp decrease in air quality when the sea breeze front passed.

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

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.

On the Accuracy of the Simple Ocean Data Assimilation Analysis for Estimating Heat Budgets of the Near-Surface Arabian Sea and Bay of Bengal*

2005 ◽  
Vol 35 (3) ◽  
pp. 395-400 ◽  
Author(s):  
S S C. Shenoi ◽  
D. Shankar ◽  
S. R. Shetye
Keyword(s):  
Data Assimilation ◽  
Bay Of Bengal ◽  
Arabian Sea ◽  
Heat Budget ◽  
Heat Content ◽  
Heat Fluxes ◽  
Simple Ocean Data Assimilation ◽  
Near Surface ◽  
Surface Heat Fluxes ◽  
Ocean Data Assimilation

Abstract The accuracy of data from the Simple Ocean Data Assimilation (SODA) model for estimating the heat budget of the upper ocean is tested in the Arabian Sea and the Bay of Bengal. SODA is able to reproduce the changes in heat content when they are forced more by the winds, as in wind-forced mixing, upwelling, and advection, but not when they are forced exclusively by surface heat fluxes, as in the warming before the summer monsoon.

Searching for Factors that Limit Observed Extreme Maximum Wave Height Distributions in the North Sea

2008 ◽  
pp. 127-138 ◽  
Author(s):  
Gerrit Burgers ◽  
Frits Koek ◽  
Hans de Vries ◽  
Martin Stam
Keyword(s):  
Wave Height ◽  
North Sea ◽  
Maximum Wave Height ◽  
The North ◽  
The North Sea

scholarly journals REPRODUCTION ANALYSIS OF HUMAN DRIFTING BEHAVIOR DURING TSUNAMI USING NUMERICAL CALCULATION

2020 ◽  
pp. 34
Author(s):  
Riko Morita ◽  
Taro Arikawa
Keyword(s):  
Numerical Calculation ◽  
Wave Height ◽  
Prediction Method ◽  
Great East Japan Earthquake ◽  
Numerical Calculations ◽  
Water Tank ◽  
Maximum Wave Height ◽  
Hydraulic Experiment ◽  
Secondary Damage ◽  
Simulation Results

Along with the 2011 Great East Japan Earthquake (Mw 9.0), a huge tsunami exceeding a maximum wave height of 15 m occurred. Many people and objects were destroyed and drifted by the tsunami. In addition, these debris were transported to various places that could not be predicted, resulting in significant secondary damage and increase in the number of missing. Therefore, in order to reduce the amount of damage, it is important to predict the behavior and landing points of person after set adrift in a tsunami. The best way to increase the rescue rate is to predict in advance the area that people will be drifted, and prioritize searching operations at that area. Although there has been considerable number of studies which handle the drifting behavior of containers and ships (e.g., Kaida et al., 2016), the prediction of drifting areas focusing on people has not been conducted. Moreover, a drifting area prediction method has not yet been established. The purpose of this study is to conduct a hydraulic experiment using a flat water tank, and observe the drifting area of the drifting object. Then, we conducted numerical calculations and compared simulation results with the experimental ones.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/1yhKuodhCbg

Effect of Uni- and Bi-Directional Coupling of Ocean-Met Interaction on Significant Wave Height and Local Wind

2017 ◽  
Author(s):  
Adil Rasheed ◽  
Jakob Kristoffer Süld ◽  
Mandar Tabib
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Surface Wind ◽  
Wave Model ◽  
Ocean Surface ◽  
Observation Data ◽  
Local Wind ◽  
Near Surface ◽  
Significant Wave ◽  
Bidirectional Coupling

Accurate prediction of near surface wind and wave height are important for many offshore activities like fishing, boating, surfing, installation and maintenance of marine structures. The current work investigates the use of different methodologies to make accurate predictions of significant wave height and local wind. The methodology consists of coupling an atmospheric code HARMONIE and a wave model WAM. Two different kinds of coupling methodologies: unidirectional and bidirectional coupling are tested. While in Unidirectional coupling only the effects of atmosphere on ocean surface are taken into account, in bidirectional coupling the effects of ocean surface on the atmosphere are also accounted for. The predicted values of wave height and local wind at 10m above the ocean surface using both the methodologies are compared against observation data. The results show that during windy conditions, a bidirectional coupling methodology has better prediction capability.

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