scholarly journals Observations of Typhoon Waves in a Reef Lagoon of the South China Sea

2020 ◽  
Vol 50 (1) ◽  
pp. 161-173 ◽  
Author(s):  
Z. W. Cai ◽  
W. W. Chen ◽  
X. L. Liu ◽  
Z. Sun
Keyword(s):  
Wind Speed ◽  
South China Sea ◽  
Wave Height ◽  
South China ◽  
Wind Waves ◽  
The South China Sea ◽  
The South ◽  
China Sea ◽  
Open Sea ◽  
The Waves

AbstractBased on wave measurements lasting three and a half years, typhoon wave characteristics in a lagoon of the South China Sea are discussed in this paper. According to the upper boundaries of wind speed and significant wave height Hs, the maximum wave height has a similar rate of change as the maximum wind speed. The peak frequencies decrease in the approaching stage and are concentrated with an average of 0.1415 Hz in the leaving stage. The distributions of the wind and wave directions indicate that the local wind waves and the waves from the open sea propagated to the site in the approaching and leaving stages, respectively. Wind waves generated inside the lagoon are fetch-trapped, and the spectra can be described by αf(−4) or βk(−2.5) when f > fp. In addition, the measurements show that the nondimensional maximum spectrum can be estimated by the nondimensional fetch. The spectra of the waves from the open sea can be described by . Parameters a and c are determined by the nondimensional peak frequency. In addition, it is found that the peak energy density S(fp) is a linear function of for all waves.

How HY-2A/GM altimeter performs in marine gravity derivation: assessment in the South China Sea

2019 ◽  
Vol 219 (2) ◽  
pp. 1056-1064 ◽  
Author(s):  
Chengcheng Zhu ◽  
Jinyun Guo ◽  
Cheinway Hwang ◽  
Jinyao Gao ◽  
Jiajia Yuan ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Gravity Anomalies ◽  
The South China Sea ◽  
The South ◽  
China Sea ◽  
Open Sea ◽  
Marine Gravity ◽  
Sea Surface Heights ◽  
The Difference

SUMMARY HY-2A is China's first satellite altimeter mission, launched in Aug. 2011. Its geodetic mission (GM) started from 2016 March 30 till present, collecting sea surface heights for about five 168-d cycles. To test how the HY-2A altimeter performs in marine gravity derivation, we use the least-squares collocation method to determine marine gravity anomalies on 1′ × 1′ grids around the South China Sea (covering 0°–30°N, 105°E–125°E) from the HY-2A/GM-measured geoid gradients. We assess the qualities of the HY-2A/GM-derived gravity over different depths and areas using the bias and tilt-adjusted ship-borne gravity anomalies from the U.S. National Centers for Environmental Information (NCEI) and the Second Institute of Oceanography, Ministry of Natural Resources (MNR) of P. R. China. The RMS difference between the HY-2A/GM-derived and the NCEI ship-borne gravity is 5.91 mGal, and is 5.33 mGal when replacing the HY-2A value from the Scripps Institution of Oceanography (SIO) V23.1 value. The RMS difference between the HY-2A/GM-derived and the MNR ship-borne gravity is 2.90 mGal, and is 2.76 mGal when replacing the HY-2A value from the SIO V23.1 value. The RMS difference between the HY-2A and SIO V23.1 value is 3.57 mGal in open sea areas at least 20 km far away from the coast. In general, the difference between the HY-2A/GM-derived gravity and ship-borne gravity decreases with decreasing gravity field roughness and increasing depth. HY-2A results in the lowest gravity accuracy in areas with islands or reefs. Our assessment result suggests that HY-2A can compete with other Ku-band altimeter missions in marine gravity derivation.

scholarly journals Kinematic parameters of internal waves of the second mode in the South China Sea

2017 ◽  
Author(s):  
Oxana Kurkina ◽  
Tatyana Talipova ◽  
Tarmo Soomere ◽  
Ayrat Giniyatullin ◽  
Andrey Kurkin
Keyword(s):  
South China Sea ◽  
Internal Waves ◽  
South China ◽  
Phase Speed ◽  
The South China Sea ◽  
The South ◽  
Gardner Equation ◽  
China Sea ◽  
Second Mode ◽  
The Waves

Abstract. Spatial distributions of the main properties of the mode function and kinematic and nonlinear parameters of internal waves of the second mode are derived for the South China Sea for typical summer conditions in July. The calculations are based on the Generalized Digital Environmental Model (GDEM) climatology of hydrological variables. The focus is on the phase speed of long internal waves and the coefficients at the dispersive, quadratic and cubic terms of the weakly nonlinear Gardner model. Spatial distributions of these parameters, except for the coefficient at the cubic term, are qualitatively similar for waves of both modes. The dispersive term of Gardner equation and phase speed for internal waves of the second mode are about a quarter and half, respectively, of those for waves of the first mode. Similarly to the waves of the first mode, the coefficients at the quadratic and cubic terms of Gardner equation are practically independent of water depth. In contrast to the waves of the first mode, for waves of the second mode the quadratic term is mostly negative. The results can serve as a basis for express estimates of the expected parameters of internal waves for the South China Sea.

Diversity and biogeography of picoplankton communities from the Straits of Malacca to the South China Sea

2020 ◽  
Vol 49 (1) ◽  
pp. 23-33
Author(s):  
Zhao-Yu Jiang ◽  
Fu-Lin Sun
Keyword(s):  
Community Structure ◽  
South China Sea ◽  
South China ◽  
Marine Ecosystem ◽  
The South China Sea ◽  
Rrna Genes ◽  
The South ◽  
China Sea ◽  
Open Sea ◽  
Straits Of Malacca

AbstractMarine picoplankton, including prokaryotic and eukaryotic picoplankton, drive many biogeochemical processes, such as carbon, nitrogen and sulfur cycles, making them crucial to the marine ecosystem. Despite the fact that picoplankton is prevalent, its diversity and spatial distribution from the Straits of Malacca (SM) to the South China Sea (SCS) remain poorly investigated. This work explores the phylogenetic diversity and community structure of picoplankton in relation to environmental factors from the SM to the SCS. To this end, the Illumina MiSeq sequencing technique was applied to 16S and 18S rRNA genes. The results showed significant differences in the dynamics of picoplankton between the open sea and the strait region. Proteobacteria and Cyanobacteria constituted a larger part of the prokaryotic group. Within Cyanobacteria, the abundance of Prochlorococcus in the open sea was significantly higher than that of Synechococcus, while the opposite trend was observed in the strait. Dinoflagellata, Cnidaria, Retaria, Tunicata, and Arthropoda dominated among the eukaryotic taxa. High-throughput sequencing data indicated that salinity, temperature and NO2-N were the key factors determining the prokaryotic community structure, while temperature and dissolved oxygen determined the eukaryotic community structure in the studied region. The network analysis demonstrated that the cooperation and competition were also important factors affecting the picoplankton community.

Coupling between SST and wind speed over mesoscale eddies in the South China Sea

2016 ◽  
Vol 66 (11) ◽  
pp. 1467-1474 ◽  
Author(s):  
Shuangwen Sun ◽  
Yue Fang ◽  
Baochao Liu ◽  
Tana ᅟ
Keyword(s):  
Wind Speed ◽  
South China Sea ◽  
South China ◽  
Mesoscale Eddies ◽  
The South China Sea ◽  
The South ◽  
China Sea

scholarly journals Observations of Shoaling Internal Wave Transformation Over a Gentle Slope in the South China Sea

2021 ◽  
Author(s):  
Steven R. Ramp ◽  
Yiing Jang Yang ◽  
Ching-Sang Chiu ◽  
D. Benjamin Reeder ◽  
Frederick L. Bahr
Keyword(s):  
Kinetic Energy ◽  
South China Sea ◽  
Energy Flux ◽  
South China ◽  
The South China Sea ◽  
Wave Transformation ◽  
Recent Theory ◽  
The South ◽  
China Sea ◽  
The Waves

Abstract. Four oceanographic moorings were deployed across the South China Sea continental slope near 21.85° N, 117.71° E, from May 30 to July 18, 2014 for the purpose of observing high-frequency nonlinear internal waves (NLIWs) as they shoaled across a rough, gently sloping bottom. Individual waves required just two hours to traverse the array and could thus easily be tracked from mooring-to-mooring. In general, the amplitude of the incoming NLIWs was a good match with the fortnightly tidal envelope in the Luzon Strait, lagged by 48.5 hours, and were smaller than the waves observed 50 km to the southwest near the Dongsha Plateau. The now-familiar type a-waves and b-waves were observed, with the b-waves always leading the a-waves by 6–8 hours. Most of the waves were remotely generated, but a few of the b-waves formed locally via convergence and breaking at the leading edge of the upslope internal tide. Waves incident upon the array with amplitude less than 50 m and energy less than 100 MJ m−1 propagated adiabatically upslope with little change of form. Larger waves formed packets via wave dispersion. For the larger waves, the kinetic energy flux decreased sharply upslope between 342 m to 266 m while the potential energy flux increased slightly, causing an increasing ratio of potential-to-kinetic energy as the waves shoaled. The results are in rough agreement with recent theory and numerical simulations of shoaling waves.

Revisiting the seasonal wave height variability in the South China Sea with merged satellite altimetry observations

2017 ◽  
Vol 36 (11) ◽  
pp. 38-50 ◽  
Author(s):  
Hui Su ◽  
Chunlei Wei ◽  
Shaocai Jiang ◽  
Peiliang Li ◽  
Fangguo Zhai
Keyword(s):  
South China Sea ◽  
Wave Height ◽  
South China ◽  
Satellite Altimetry ◽  
The South China Sea ◽  
The South ◽  
China Sea

scholarly journals Kinematic parameters of internal waves of the second mode in the South China Sea

2017 ◽  
Vol 24 (4) ◽  
pp. 645-660 ◽  
Author(s):  
Oxana Kurkina ◽  
Tatyana Talipova ◽  
Tarmo Soomere ◽  
Ayrat Giniyatullin ◽  
Andrey Kurkin
Keyword(s):  
South China Sea ◽  
Internal Waves ◽  
South China ◽  
Phase Speed ◽  
The South China Sea ◽  
Spatial Distributions ◽  
The South ◽  
China Sea ◽  
Second Mode ◽  
The Waves

Abstract. Spatial distributions of the main properties of the mode function and kinematic and non-linear parameters of internal waves of the second mode are derived for the South China Sea for typical summer conditions in July. The calculations are based on the Generalized Digital Environmental Model (GDEM) climatology of hydrological variables, from which the local stratification is evaluated. The focus is on the phase speed of long internal waves and the coefficients at the dispersive, quadratic and cubic terms of the weakly non-linear Gardner model. Spatial distributions of these parameters, except for the coefficient at the cubic term, are qualitatively similar for waves of both modes. The dispersive term of Gardner's equation and phase speed for internal waves of the second mode are about a quarter and half, respectively, of those for waves of the first mode. Similarly to the waves of the first mode, the coefficients at the quadratic and cubic terms of Gardner's equation are practically independent of water depth. In contrast to the waves of the first mode, for waves of the second mode the quadratic term is mostly negative. The results can serve as a basis for expressing estimates of the expected parameters of internal waves for the South China Sea.

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