Consistent Design Criteria for South China Sea With a Large-Scale Extreme Value Model

2016 ◽  
Author(s):  
L. Raghupathi ◽  
D. Randell ◽  
P. Jonathan ◽  
K. C. Ewans
Keyword(s):  
South China Sea ◽  
South China ◽  
Large Scale ◽  
Extreme Value ◽  
Design Criteria ◽  
China Sea ◽  
Extreme Value Model ◽  
Value Model

Topographic Rossby Waves in the Abyssal South China Sea

2021 ◽  
Author(s):  
QI QUAN ◽  
ZHONGYA CAI ◽  
GUANGZHEN JIN ◽  
ZHIQIANG LIU
Keyword(s):  
South China Sea ◽  
Group Velocity ◽  
South China ◽  
Large Scale ◽  
Rossby Waves ◽  
Western Boundary ◽  
Horizontal Shear ◽  
Boundary Current ◽  
China Sea ◽  
Topographic Rossby Waves

AbstractTopographic Rossby waves (TRWs) in the abyssal South China Sea (SCS) are investigated using observations and high-resolution numerical simulations. These energetic waves can account for over 40% of the kinetic energy (KE) variability in the deep western boundary current and seamount region in the central SCS. This proportion can even reach 70% over slopes in the northern and southern SCS. The TRW-induced currents exhibit columnar (i.e., in-phase) structure in which the speed increases downward. Wave properties such as the period (5–60 days), wavelength (100–500 km), and vertical trapping scale (102–103 m) vary significantly depending on environmental parameters of the SCS. The TRW energy propagates along steep topography with phase propagation offshore. TRWs with high frequencies exhibit a stronger climbing effect than low-frequency ones and hence can move further upslope. For TRWs with a certain frequency, the wavelength and trapping scale are dominated by the topographic beta, whereas the group velocity is more sensitive to the internal Rossby deformation radius. Background circulation with horizontal shear can change the wavelength and direction of TRWs if the flow velocity is comparable to the group velocity, particularly in the central, southern, and eastern SCS. A case study suggests two possible energy sources for TRWs: mesoscale perturbation in the upper layer and large-scale background circulation in the deep layer. The former provides KE by pressure work, whereas the latter transfers the available potential energy (APE) through baroclinic instability.

scholarly journals Eddy characteristics in the northern South China Sea as inferred from Lagrangian drifter data

Ocean Science ◽  
2011 ◽  
Vol 7 (5) ◽  
pp. 661-669 ◽  
Author(s):  
◽  
◽  
Keyword(s):  
South China Sea ◽  
South China ◽  
Large Scale ◽  
Northern South China Sea ◽  
Temporal Distribution ◽  
Height Anomaly ◽  
Spatial And Temporal Patterns ◽  
China Sea ◽  
Eddy Characteristics ◽  
Anticyclonic Eddies

Abstract. Cyclonic and anticyclonic eddies from large scale to submesoscale in the northern South China Sea (NSCS) have been statistically characterized based on the satellite-tracked Lagrangian drifters using our developed geometric eddy identification method. There are in total 2208 eddies identified, 70% of which are anticyclonic eddies. If the submesoscale eddies are eliminated, the other eddies in the NSCS will show a 1.2:1 ratio of the number of anticyclones (210) to the number of cyclones (171). The spatial distribution of the eddies is regional: in southwest of Taiwan, the number of anticyclones dominates the number of cyclones, and most of them are the submesoscale anticyclones with small radii; in contrast, the large and medium cyclonic eddies are a little more than the same scale anticyclonic eddies in northwest of Luzon. The temporal distribution of eddy number in the NSCS has a close relation with the Asian monsoon. The number of the large and medium eddies peaks during the winter monsoon, while the submesoscale eddies are apt to generate in the summer monsoon. The spatial and temporal patterns have a good agreement with the results of the sea surface height anomaly (SSHA). The maximum and mean tangential velocities of anticyclones (cyclones) are 40 (30) cm s−1 and 25 (15) cm s−1, respectively. The calculated normalized vorticities from drifters suggest that although the mesoscale eddies may be considered in geostrophic balance, ageostrophic dynamics and centrifugal effects may play an important role for the growth and decay of the mesoscale cores.

scholarly journals Analysis of Severe Droughts in Taiwan and its Related Atmospheric and Oceanic Environments

Atmosphere ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 159 ◽  
Author(s):  
Chih-wen Hung ◽  
Ming-Fu Shih
Keyword(s):  
South China Sea ◽  
South China ◽  
Large Scale ◽  
Drought Index ◽  
The South China Sea ◽  
Severe Drought ◽  
The South ◽  
China Sea ◽  
Dry Conditions ◽  
Oceanic Environments

Drought is one of the important issues in climate studies. A drought index, Taiwan Meteorological Drought index (TMD index), was previously proposed and is applied here to identify historical severe droughts in Taiwan in order to clarify the corresponding large-scale backgrounds as a potential alert to the society in future. Through the TMD index, several historical severe drought cases in Taiwan are detected and characterized by significant seasonal variability in the annual cycle. Composites for large-scale atmospheric and oceanic environments over different periods within the dry season are conducted. From October to December, the colder sea surface temperature (SST) pattern of Pacific Meridional Mode (PMM) and the PMM-induced local anomalous anticyclones over the South China Sea are both in charge of the extremely dry conditions in Taiwan. From January to February, cold SST in the South China Sea and its adjacent oceans dominates local atmospheric conditions above these regions and creates an unfavorable environment for convection systems. From March to May, a massive anomalous anticyclonic circulation centering beside Alaska and extending its properties to East Asia and Taiwan generates a descending environment and in turn suppresses convection systems to develop. Therefore, the extremely dry conditions under this system are expected.

Partitioning between strike-slip and orthogonal extension in the western South China Sea

2020 ◽  
Author(s):  
Pan Luo ◽  
Jianye Ren ◽  
Xi He ◽  
Chao Lei ◽  
Junjie Xu ◽  
...  
Keyword(s):  
South China Sea ◽  
Continental Crust ◽  
South China ◽  
Large Scale ◽  
Strike Slip ◽  
Fault System ◽  
Relative Role ◽  
China Sea ◽  
Kinematic Evolution ◽  
Mantle Exhumation

<p>Our study focuses on the Zhongjianna (ZJN) (Phu Kham) Basin, located at the western termination of the South China Sea (SCS) and separated from the Indochina continent by the N-S striking East Vietnam Boundary Fault Zone, which is a large scale strike-slip fault system. The sedimentary infill history of the ZJN basin records the complete evolution and interaction of the Indochina-SCS system and allows the tectonic and kinematic evolution of the basin to be understood.. The discovery of hyper-extended continental crust and mantle exhumation in this basin leads to the question of what is the relative role of large-scale strike-slip and orthogonal faulting in controlling crustal thinning in the ZJN basin.  </p><p>  Our preliminary results confirm the existence of hyperextended continental crust flooring the ZJN basin. Two different types of structures can be identified in this area: extension related deformation in the eastern part and strike-slip related deformation in the western part. The analysis of fault geometries and kinematics linked to timing and subsidence rates suggest that the N-S-orientated strike-slip structures dominated the continental shelf and slope area on the west side of the basin. In the basin, however, most faults strike NE-SW and are parallel to the mid-ocean ridge. Thus, it appears that the ZJN basin resulted from the partitioning between strike-slip and orthogonal extension.</p><p>In our presentation we show the results of our seismic interpretation, strain and subsidence analysis and discuss the interaction between strike-slip and orthogonal extension in setting up the hyper-extended ZJN basin and its implications for the large scale tectonic and geodynamic framework.</p>

scholarly journals Formalin-Fixed Fish Larvae Could Be Effectively Identified by DNA Barcodes: A Case Study on Thousands of Specimens in South China Sea

2021 ◽  
Vol 8 ◽  
Author(s):  
Gang Hou ◽  
Yanying Chen ◽  
Sijin Wang ◽  
Jinrun Wang ◽  
Weitao Chen ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Large Scale ◽  
Fish Larvae ◽  
Morphological Characters ◽  
Dna Barcodes ◽  
High Quality ◽  
China Sea ◽  
Early Stages ◽  
Formalin Fixed

Delimiting ichthyoplankton is fundamental work for monitoring the recruitment process and identifying the spawning and nursing grounds of fishes. Nevertheless, it is extremely difficult to identify the fish during the early stages at the species level based on morphological characters because of the paucity of diagnostic features. In this study, we investigated the fish larval community through large-scale ecosystemic sampling in South China Sea (SCS) during 2013 and 2017 using DNA barcodes. To maintain the morphologies of fish larvae, we preserved the larvae in formalin and developed a technique to recover their DNA. Among the 3,500 chosen larvae, we successfully extracted DNA from 2,787 larval samples and obtained 1,006 high-quality sequences. Blast searches showed that 408 larvae (i.e., 40.5%) could be unambiguously identified to species, 413 larvae (i.e., 41.1%) were ambiguously species delimitation, and 185 larvae (i.e., 18.4%) showed a low match similarity with target sequences. A total of 101 species were identified, among which 38 and 33 species corresponded to demersal and reef-associated species, whereas the remaining 30 species corresponded to benthopelagic, pelagic-oceanic, bathypelagic, and pelagic-neritic species. High-quality larval photographs of the 101 diagnosed species showed intact morphological characters and thus provided a reference for identifying fish species during the early stages based on morphological characters. Our study highlighted the possibility of recovering and amplifying DNA from formalin-fixed samples and provided new insight into the fish larval community in the SCS.

scholarly journals Spatial and Seasonal Variability of Metocean Design Criteria in the Southern South China Sea From Covariate Extreme Value Analysis

2019 ◽  
Author(s):  
Vadim Anokhin ◽  
Emma Ross ◽  
David Randell ◽  
Philip Jonathan
Keyword(s):  
Wind Speed ◽  
South China Sea ◽  
South China ◽  
Upper Bound ◽  
Shape Parameter ◽  
Extreme Value ◽  
Extreme Value Analysis ◽  
Design Criteria ◽  
Southern South China Sea ◽  
Value Analysis

Abstract This paper describes spatial and seasonal variability of metocean design criteria in the southern South China Sea. Non-stationary extreme value analysis was performed using the CEVA approach (Covariate Extreme Value Analysis,[1]) for a 59-year long SEAFINE hindcast of winds and waves, estimating metocean design criteria up to 10,000-year return period. Wind design criteria are mostly driven by large-scale monsoonal events; at higher return periods infrequent cyclonic events have strong influence on the tail of the extreme value distribution but confined to a limited geographical area. The CEVA analysis of waves showed much less dependence on the tropical cyclone events; the spatial metocean design criteria were smoother, mostly influenced by the monsoonal wind strength, fetch and local bathymetry. Return value estimates illustrate the strong seasonality of metocean design criteria, with boreal winter (December-February, Northeasterly monsoon) contributing most to the extremes, while April and May are the mildest months. Estimates for the ratio of 10,000/100-year return values are also presented, both for winds and waves. There is empirical evidence that the range of “typical” values of generalised Pareto shape parameter observed for Hs is different to that observed for wind speed. For this reason, an upper bound of +0.2 for generalised Pareto shape was specified for wind speed analysis, compared to 0.0 for Hs. In some cases, increase of upper bound for waves to 0.1 is justified, leading to slightly more conservative Hs values. We confirmed that the upper end point constraint was not too influential on the distributions of generalised Pareto shape parameter estimated. Nevertheless, it is apparent that specification of bounds for generalised Pareto shape is a critical, but problematic choice in metocean applications.

scholarly journals Arctic and Antarctic Oscillation signatures in tropical coral proxies over the South China Sea

2009 ◽  
Vol 27 (5) ◽  
pp. 1979-1988 ◽  
Author(s):  
D.-Y. Gong ◽  
S.-J. Kim ◽  
C.-H. Ho
Keyword(s):  
South China Sea ◽  
South China ◽  
Large Scale ◽  
Horizontal Wind ◽  
Time Lags ◽  
Antarctic Oscillation ◽  
Similar Time ◽  
Sea Level Pressure ◽  
Tropical Regions ◽  
China Sea

Abstract. Arctic Oscillation (AO) and Antarctic Oscillation (AAO) are the leading modes of atmospheric circulation in mid-high latitudes. Previous studies have revealed that the climatic influences of the two modes are dominant in extra-tropical regions. This study finds that AO and AAO signals are also well recorded in coral proxies in the tropical South China Sea. There are significant interannual signals of AO and AAO in the strontium (Sr) content, which represents the sea surface temperature (SST). Among all the seasons, the most significant correlation occurs during winter in both hemispheres: the strongest AO-Sr and AAO-Sr coral correlations occur in January and August, respectively. This study also determined that the Sr content lags behind AO and AAO by 1–3 months. Large-scale anomalies in sea level pressure and horizontal wind at 850 hPa level support the strength of AO/AAO-coral teleconnections. In addition, a comparison with oxygen isotope records from two coral sites in neighboring oceans yields significant AO and AAO signatures with similar time lags. These results help to better understand monsoon climates and their teleconnection to high-latitude climate changes.

Large scale distribution patterns of taxonomic diversity of fish in coral reef waters, South China Sea

2013 ◽  
Vol 18 (3) ◽  
pp. 619-628
Author(s):  
Yongzhen LI ◽  
Yunrong SHI ◽  
Hong AI ◽  
Lina DONG ◽  
Nana LI ◽  
...  
Keyword(s):  
Coral Reef ◽  
South China Sea ◽  
South China ◽  
Large Scale ◽  
Distribution Patterns ◽  
Taxonomic Diversity ◽  
China Sea

Genetic diversity and large-scale connectivity of the scleractinian coral Porites lutea in the South China Sea

Coral Reefs ◽  
2018 ◽  
Vol 37 (4) ◽  
pp. 1259-1271 ◽  
Author(s):  
Wen Huang ◽  
Ming Li ◽  
Kefu Yu ◽  
Yinghui Wang ◽  
Jingjing Li ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
South China Sea ◽  
South China ◽  
Scleractinian Coral ◽  
Large Scale ◽  
The South China Sea ◽  
The South ◽  
Porites Lutea ◽  
China Sea
Sign in / Sign up

Export Citation Format

Share Document