scholarly journals In situ hyperspectral characteristics and the discriminative ability of remote sensing to coral species in the South China Sea

2022 ◽  
pp. 1-23
Author(s):  
Kai Zeng ◽  
Zhantang Xu ◽  
Yuezhong Yang ◽  
Yongming Liu ◽  
Hongwuyi Zhao ◽  
...  
2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Shih-Jen Huang ◽  
Chen-Chih Lin

The satellite-derived aerosol optical depth (AOD) data is used to investigate the distribution of aerosol over the South China Sea (SCS). High correlation coefficients are found between in situ AERONET data and satellite AOD measurements around the SCS with the highest coefficient of 0.9 on the Dongsha Island (i.e., Pratas Island). The empirical orthogonal function (EOF) analysis of AOD over the SCS shows that high AOD is always found around offshore areas of China, Indochina, Sumatra, and Borneo. Besides, spring is the major season of occurring coarse aerosol particles (AOT_C) but fine aerosol particles (AOT_F) occur yearly. The biomass burning is found in Indochina during March and April, and so it is in Sumatra and Borneo from August to October. The results also show that the AOT_F are higher during El Niño events, but higher AOT_C are found in La Niña years.


2021 ◽  
Author(s):  
Qiumei Quan ◽  
Yong Liu ◽  
Teng Wang ◽  
Chunhou Li

Abstract Based on the key ecological processes of parrotfish in coral reefs, we compiled species presence-absence data across 51 sites in the South China Sea to identify the distribution and composition of parrotfish and explore the relationship between species distribution and environmental factors, and 50 species (the Pacific: 57 species) of parrotfish were record. Nansha islands had the highest abundance with 41 parrotfish species. Nestedness analysis indicated parrotfish community had statistically significant nested patterns in the South China Sea and Nansha islands was the topmost site of nested matrix rank. Scleractinian coral species richness and Log(reef area) both had a significant effect on sites nested matrix rank (P < 0.05), which supports habitat nestedness hypothesis in the South China Sea. Scrapers were the most important functional group composition while the browser had a greater contribution on species nested matrix rank. Linear regression model showed parrotfish species richness increased with increasing longitude, scleractinian coral species richness and reef area. Variations in the parrotfish species richness in longitude was related to distance from the biodiversity hotspot in the Indo-Australian Archipelago. Parrotfish was mainly distributed in the range of 26-29℃, which was almost the same as the optimum temperature for coral growth. Nansha islands should be as biodiversity conservation priority areas, which could provide important reference significance for conservation efforts of parrotfish in degraded coral reefs habitats, especially in the context of increasing natural variability and anthropogenic disturbance.


2020 ◽  
Author(s):  
Guizhi Wang ◽  
Samuel S. P. Shen ◽  
Yao Chen ◽  
Yan Bai ◽  
Huan Qin ◽  
...  

Abstract. Sea surface partial pressure of CO2 (pCO2) data with high spatial-temporal resolution are important in studying the global carbon cycle and assessing the oceanic carbon uptake capacity. However, the observed sea surface pCO2 data are usually limited in spatial and temporal coverage, especially in marginal seas. This study provides an approach to reconstruct the complete sea surface pCO2 field in the South China Sea (SCS) with a grid resolution of 0.5º × 0.5º over the period of 2000–2017 using both remote-sensing derived pCO2 and observed pCO2. Empirical orthogonal functions (EOFs) were computed from the remote sensing derived pCO2. Then, a multilinear regression was applied to the observed pCO2 as the response variable with the EOFs as the explanatory variables. EOF1 explains the general spatial pattern of pCO2 in the SCS. EOF2 shows the pattern influenced by the Pearl River plume on the northern shelf and slope. EOF3 is consistent with the pattern influenced by coastal upwelling along the north coast of the SCS. The reconstructions always agree with observations. When pCO2 observations cover a sufficiently large area, the reconstructed fields successfully display a pattern of relatively high pCO2 in the mid-and-southern basin. The rate of sea surface pCO2 increase in the SCS is 2.383 μatm per year based on the spatial average of the reconstructed pCO2 over the period of 2000–2017. All the data for this paper are openly and freely available at PANGAEA under the link https://doi.pangaea.de/10.1594/PANGAEA.921210 (Wang et al., 2020).


2021 ◽  
Vol 13 (16) ◽  
pp. 3223
Author(s):  
Bing Yang ◽  
Po Hu ◽  
Yijun Hou

Characteristics of near-inertial waves (NIWs) induced by the tropical storm Noul in the South China Sea are analyzed based on in situ observations, remote sensing, and analysis data. Remote sensing sea level anomaly data suggests that the NIWs were influenced by a southwestward moving anticyclonic eddy. The NIWs had comparable spectral density with internal tides, with a horizontal velocity of 0.14–0.21 m/s. The near-inertial kinetic energy had a maximum value of 7.5 J/m3 and propagated downward with vertical group speed of 10 m/day. Downward propagation of near-inertial energy concentrated in smaller wavenumber bands overwhelmed upward propagation energy. The e-folding time of NIWs ranged from 4 to 11 days, and the larger e-folding time resulted from the mesoscale eddies with negative vorticity. Modified by background relative vorticity, the observed NIWs had both red-shifted and blue-shifted frequencies. The upward propagating NIWs had larger vertical phase speeds and wavelengths than downward propagating NIWs. There was energy transfer from the mesoscale field to NIWs with a maximum value of 8.5 × 10−9 m2 s−3 when total shear and relative vorticity of geostrophic currents were commensurate. Our results suggest that mesoscale eddies are a significant factor influencing the generation and propagation of NIWs in the South China Sea.


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