scholarly journals Ocean Optical Profiling in South China Sea Using Airborne LiDAR

2019 ◽  
Vol 11 (15) ◽  
pp. 1826 ◽  
Author(s):  
Peng Chen ◽  
Delu Pan
Keyword(s):  
South China Sea ◽  
South China ◽  
Vertical Structure ◽  
Airborne Lidar ◽  
Scattering Function ◽  
Retrieval Method ◽  
China Sea ◽  
Absolute Relative Error ◽  
The Mean ◽  
Optical Structure

Increasingly, LiDAR has more and more applications. However, so far, there are no relevant publications on using airborne LiDAR for ocean optical profiling in the South China Sea (SCS). The applicability of airborne LiDAR for optical profiling in the SCS will be presented. A total of four airborne LiDAR flight experiments were conducted over autumn 2017 and spring 2018 in the SCS. A hybrid retrieval method will be presented here, which incorporates a Klett method to obtain LiDAR attenuation coefficient and a perturbation retrieval method for a volume scattering function at 180°. The correlation coefficient between the LiDAR-derived results and the traditional measurements was 0.7. The mean absolute relative error (MAE) and the normalized root mean square deviation (NRMSD) between the two are both between 10% and 12%. Subsequently, the vertical structure of the LiDAR-retrieved attenuation and backscattering along airborne LiDAR flight tracks was mapped. In addition to this, ocean subsurface phytoplankton layers were detected between 10 to 20 m depths along the flight track in Sanya Bay. Primary results demonstrated that our airborne LiDAR has an independent ability to survey and characterize ocean optical structure.

scholarly journals The impact of the planetary β-effect on the tilting vertical structure of a mesoscale eddy

2018 ◽  
Author(s):  
Shengmu Yang ◽  
Jiuxing Xing ◽  
Shengli Chen ◽  
Jiwei Tian ◽  
Daoyi Chen
Keyword(s):  
South China Sea ◽  
South China ◽  
General Circulation ◽  
Vertical Structure ◽  
Mesoscale Eddy ◽  
Maximum Velocity ◽  
Circulation Model ◽  
Mesoscale Eddies ◽  
China Sea ◽  
The Impact

Abstract. Tilting mesoscale eddies in the South China Sea have been reported recently from observed field data. The mechanism of the dynamic process of the tilt, however, is not well understood. In this study, the influence of planetary β on the vertical structure of mesoscale eddies and its mechanism is investigated using theoretical analysis and numerical model experiments based on the MIT General Circulation Model (MITgcm). The results of the both approaches show that vertical motion due to the planetary β effect and nonlinear dynamics causes a pressure anomaly in the horizontal domain which triggers the tilt of the eddy axis. The tilting distance extends to be the radius of the eddy maximum velocity. In addition, the vertical stratification is another key factor in controlling the tilt of a mesoscale eddy. External forcings such as wind and inflow current are not considered in this study, and topography is included only in a realistic South China Sea model. Therefore, mesoscale eddies with large vertical depth should have the similar axis tilt character in open oceans under the β-effect.

scholarly journals On The Simulation of Northeast Monsoon Rainfall Over Southern Peninsular India in CMIP5 Models

2021 ◽  
Author(s):  
P.P. Sree ◽  
C. A. Babu ◽  
S. Vijaya Bhaskara Rao
Keyword(s):  
Pacific Ocean ◽  
Indian Ocean ◽  
South China Sea ◽  
South China ◽  
Cmip5 Models ◽  
Northeast Monsoon ◽  
Peninsular India ◽  
China Sea ◽  
Sst Bias ◽  
The Mean

Abstract The skill of 34 CMIP5 models to simulate the mean state and interannual variability of Northeast Monsoon Rainfall (NEMR) is studied here. The mean (1979-2005) NEMR over southern Peninsular India (SPIRF), Indian Ocean and Maritime continents (10°S-30°N,40°E- 120°E) is simulated reasonably well by CMIP5 models with pattern correlation ranges from 0.6 to 0.93. Diverse behaviour in the simulation of Indian and Pacific Ocean SST is observed in the CMIP5 models. A set of models (high skill models: HSM), which shows a Negative Indian Ocean Dipole (NIOD) like mean (1979-2005) SST bias in Indian Ocean and strong La Nina like mean SST bias in the Pacific Ocean, are able to simulate the mean NEMR more realistically. Another set of models (low skill models: LSM) which shows a Positive IOD (PIOD) like mean SST bias in the Indian Ocean and weak La Nina like mean SST bias in the Pacific Ocean are not able to simulate the observed equatorial Indian Ocean westerlies, which leads to an abnormal ascending motion and unrealistic wet bias over the western Indian Ocean and dry bias over the southern Peninsular India, southeast Asia and southeast Indian Ocean. The observation analysis reveals that the establishment of South China Sea anticyclone and Bay of Bengal anticyclone during El Nino and PIOD are strongly related with the ascending motion over south peninsular India and enhances the south Peninsular Indian rainfall during NEM season. Around 70% of the CMIP5 models were not able to capture the observed positive correlation that exist between SPIRF and Nino3.4 SST as well as SPIRF and DMI. Unrealistic westward extension of South China Sea anticyclone and Bay of Bengal anticyclone (up to 70°E) in the low skill models (LSM-IAV) manifested as the abnormal descending anomalies and unrealistic dry bias over the southern Peninsular India. This leads to a negative Correlation coefficient (CC) between SPIRF and Nino 3.4 SST as well as SPIRF and DMI in the low skill models. The descending anomalies over South China Sea and ascending anomalies over the western Indian Ocean and southern Peninsular India (50°E-80°E) is well captured but with lower intensity in the high skill models (HSM-IAV) and hence it captures the observed positive CC between SPIRF and Nino3.4 SST as well as SPIRF and DMI.

Rediscovery and elaborate description of Platycephalus cultellatus Richardson, 1846 collected from the coastal waters of South China Sea

2018 ◽  
Vol 31 ◽  
pp. 32 ◽  
Author(s):  
Zhi Chen ◽  
Na Song ◽  
Jianwei Zou ◽  
Tianxiang Gao
Keyword(s):  
South China Sea ◽  
Genetic Distance ◽  
South China ◽  
Coastal Waters ◽  
Coi Gene ◽  
China Sea ◽  
Dorsal Fin ◽  
Meristic Counts ◽  
The Mean

Platycephalus cultellatus Richardson, 1846 was originally found and named in its type locality, Canton, Guangdong Province, China. However, this species was very rare in the coastal waters of China. Except that Qin et al. simply mentioned the original literature records of this species in 2013, no Chinese taxonomy books or publications have ever recorded or described local P. cultellatus. We collected P. cultellatus individuals from the coastal waters of South China Sea and gave valid identification and detailed descriptions of this species. The diacritically meristic counts were listed as follows: first dorsal fin usually with two small isolated spine anteriorly; second dorsal-fin and anal-fin usually with 13 soft rays; pectoral fin usually with 17–19 soft rays and without very small dark spots; caudal fin with 3–6 horizontal blackish bands, but without yellow marking on the middle when fresh; gill rakers 7–10 and pored lateral line scales 65–76. These conclusive characters were consistent with typical P. cultellatus individuals and could thoroughly separate them from other Platycephalus species. The fragment of cytochrome oxidase subunit I (COI) gene of mitochondrial DNA was also sequenced for the classification of specimens. The mean genetic distance within P. cultellatus was 0.25%, net genetic distance between P. cultellatus and other 14 species of the genus Platycephalus ranged from 11.59 to 25.48%. The phylogenetic analysis supported the validity of P. cultellatus existed in the coastal waters of South China Sea. This study will contribute to species identification within this genus distributed in Chinese seas.

The impact of the planetary β-effect on the vertical structure of a coherent vortex in the South China Sea

2020 ◽  
Vol 70 (7) ◽  
pp. 879-896
Author(s):  
Shengmu Yang ◽  
Jiuxing Xing ◽  
Jinyu Sheng ◽  
Shengli Chen ◽  
Jiwei Tian ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Vertical Structure ◽  
The South China Sea ◽  
The South ◽  
China Sea ◽  
Coherent Vortex ◽  
The Impact

Effects of the Pearl River plume on the vertical structure of coastal currents in the Northern South China Sea during summer 2008

2014 ◽  
Vol 64 (12) ◽  
pp. 1743-1752 ◽  
Author(s):  
Yeqiang Shu ◽  
Ju Chen ◽  
Jinglong Yao ◽  
Jiayi Pan ◽  
Weiwen Wang ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Vertical Structure ◽  
Northern South China Sea ◽  
River Plume ◽  
Pearl River ◽  
Coastal Currents ◽  
China Sea ◽  
The Pearl River

scholarly journals FECUNDITY OF BLUE SWIMMING CRAB, Portunus pelagicus LINNAEUS, 1758 FROM SEMATAN FISHING DISTRICT, SARAWAK COASTAL WATER OF SOUTH CHINA SEA

2016 ◽  
Vol 1 (1) ◽  
pp. 46-51 ◽  
Author(s):  
Ikhwanuddin Abdullah@Polity ◽  
Juariah Hafsya Muhamad ◽  
Shabdin Mohd Long ◽  
Abol-Munafi Ambok Bolong
Keyword(s):  
Linear Regression ◽  
South China Sea ◽  
Coastal Water ◽  
South China ◽  
Egg Size ◽  
Carapace Width ◽  
Swimming Crab ◽  
Portunus Pelagicus ◽  
China Sea ◽  
The Mean

A total of 57 pieces of ovigerous females were sampled through the study period of 14 months from the commercial catches that were made at the Sematan Fishing District, Sarawak coastal water. These ovigerous females were used to determine the crab fecundity through mean number of egg per crab. The present study shows that the mean number of egg is 2,132,924 with mean egg size (volume) 9.3×10-6 ml and mean egg size (diameter) 383.6 μm measured using volumetric sub sampling. Fecundity was significantly related to crab size with larger crabs producing a greater number of eggs through linear regression of the fecundity – carapace width relationship. The fecundity-carapace width relationship for P. pelagicus was estimated as follows; y = 106804x + 375319 (R2=0.0229; n=57). The study shows that the egg size is significantly larger (P < 0.05) as the eggs nearly about to hatch which is black in colour.

scholarly journals Poleward Propagation of Typhoon-Induced Near-Inertial Waves in the Northern South China Sea

2021 ◽  
Vol 8 ◽  
Author(s):  
Ruhui Huang ◽  
Xiaohui Xie ◽  
Jianyu Hu ◽  
Zhenyu Sun
Keyword(s):  
South China Sea ◽  
South China ◽  
Northern South China Sea ◽  
Subsurface Layer ◽  
Inertial Waves ◽  
Background Flow ◽  
China Sea ◽  
Short Period ◽  
The Mean ◽  
Baroclinic Modes

One of the main responses of the ocean to typhoons is the generation of near-inertial waves (NIWs), whose intrinsic frequency is close to the local inertial frequency. Based on the mooring observations, we carefully investigated the spatial–temporal variations in NIWs in the northern South China Sea (SCS) after Typhoon “Haima,” which passed through the northern SCS from October 20 to 21, 2016, with its track parallel to the mooring array on its northeast side. Moorings in different locations responded differently to this typhoon, with stronger NIWs found on the continental slope to the shelf break and relatively weak NIWs found on the shallow continental shelf. Strong NIWs appeared twice within a short period and showed different characteristics and frequencies. The first NIWs were generated locally with blue-shifted (super-inertial) frequencies. These initial NIWs were dominated by the first three baroclinic modes and rapidly weakened due to their propagation away and local dissipation. However, the second NIWs mainly consisted of higher baroclinic modes with red-shifted (sub-inertial) frequencies. The analysis of the mean background flow revealed that these red-shifted NIWs were excited at low latitudes, and subsequently advected by the poleward background flow to moorings whose latitudes were higher than their critical latitudes. Higher-mode (n &gt; 3) NIWs were more easily carried away by mean background flow, and, at the same time, high-mode NIWs propagated downward to the subsurface layer, leading to the significant elevation of velocity shear therein. Given these findings, the mean background flow may provide an important route to redistributing the energy of the upper ocean imported from typhoons.

scholarly journals Subsurface plankton layers observed from airborne lidar in Sanya Bay, South China Sea

2018 ◽  
Vol 26 (22) ◽  
pp. 29134 ◽  
Author(s):  
Hang Liu ◽  
Peng Chen ◽  
Zhihua Mao ◽  
Delu Pan ◽  
Yan He
Keyword(s):  
South China Sea ◽  
South China ◽  
Airborne Lidar ◽  
China Sea ◽  
Sanya Bay
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