scholarly journals Assimilation of Middepth Velocities from Argo Floats in the Western South China Sea

2020 ◽  
Vol 37 (1) ◽  
pp. 141-157
Author(s):  
Pinqiang Wang ◽  
Weimin Zhang ◽  
Huizan Wang ◽  
Haijin Dai ◽  
Xiaohui Wang
Keyword(s):  
Data Assimilation ◽  
South China Sea ◽  
South China ◽  
Ocean Model ◽  
Trajectory Data ◽  
Argo Float ◽  
Argo Floats ◽  
China Sea ◽  
Regional Ocean Model System ◽  
Regional Ocean Model

AbstractPrevious studies are mainly limited to temperature and salinity (T/S) profiling data assimilation, while data assimilation based on Argo float trajectory information has received less research focus. In this study, a new method was proposed to assimilate Argo trajectory data: the middepth (indicates the parking depth of Argo floats in this study, ~1200 m) velocities are estimated from Argo trajectories and subsequently assimilated into the Regional Ocean Model System (ROMS) using four-dimensional variational data assimilation (4DVAR) method. This method can avoid a complicated float trajectory model in direct position assimilation. The 2-month assimilation experiments in South China Sea (SCS) showed that this proposed method can effectively assimilate Argo trajectory information into the model and improve middepth velocity field by adjusting the unbalanced component in the velocity increments. The assimilation of the Argo trajectory-derived middepth velocity with other observations (satellite observations and T/S profiling data) together yielded the best performance, and the velocity fields at the float parking depth are more consistent with the Argo float trajectories. In addition, this method will not decrease the assimilation performance of other observations [i.e., sea level anomaly (SLA), sea surface temperature (SST), and T/S profiles], which is indicative of compatibility with other observations in the 4DVAR assimilation system.

scholarly journals A GIS-based method for depicting the characteristics of mesoscale eddies: a case study in the Northern South China Sea

2015 ◽  
Vol 52 (9) ◽  
pp. 746-756
Author(s):  
Ce Li ◽  
Yunyan Du ◽  
Fuyuan Liang ◽  
Jiawei Yi ◽  
V. Chris Lakhan
Keyword(s):  
South China Sea ◽  
South China ◽  
Northern South China Sea ◽  
Mesoscale Eddies ◽  
Ocean Model ◽  
Geographical Information ◽  
Naval Research ◽  
Evolutionary Processes ◽  
China Sea ◽  
Internal Structures

The paper presents a geographical information system (GIS)-based method for depicting the characteristics, particularly the internal structures and evolutionary processes, of mesoscale eddies. This was done by examining topologic relations among closed sea surface height (SSH) contours that were reconstructed from the Naval Research Laboratory Navy layered ocean model (NLOM). Different scenarios of the topological relations among the contour lines permitted the identification of the outermost outline of eddies and the depiction of the number of cores in each mesoscale oceanic eddy. With full consideration of the internal structure of the eddies, we then reconstructed the evolutionary processes of these eddies, and the results were compared with empirical observations on three long-lived mesoscale eddies in the northern South China Sea (SCS). Tracking results were similar, thereby validating our method as being efficient and robust in reconstructing mesoscale ocean eddies, especially their evolutionary processes based on their internal structures.

An eddy-borne Argo float measurement experiment in the South China Sea

2020 ◽  
Vol 70 (10) ◽  
pp. 1325-1338
Author(s):  
Chunyong Ma ◽  
Zhanwen Gao ◽  
Siqing Li ◽  
Shuo Li ◽  
Ge Chen
Keyword(s):  
South China Sea ◽  
South China ◽  
The South China Sea ◽  
The South ◽  
Argo Float ◽  
China Sea ◽  
Measurement Experiment

scholarly journals Research on Geospatial Association of the Urban Agglomeration around the South China Sea Based on Marine Traffic Flow

2018 ◽  
Vol 10 (9) ◽  
pp. 3346 ◽  
Author(s):  
Xianzhe Zhang ◽  
Yanming Chen ◽  
Manchun Li
Keyword(s):  
South China Sea ◽  
Traffic Flow ◽  
South China ◽  
The South China Sea ◽  
Urban Agglomeration ◽  
Association Network ◽  
Trajectory Data ◽  
The South ◽  
China Sea ◽  
Marine Traffic

Studying the geospatial association within the urban agglomeration around the South China Sea can provide a basis for understanding the internal development of the China-Association of Southeast Asian Nations (ASEAN) Free Trade Area (CAFTA) and provide ideas for promoting economic and trade cooperation among cities in the region. The purpose of this paper was to reflect the characteristics of the urban agglomeration association network based on big traffic data. Based on trajectory data mining and complex network analysis methods, the automatic identification system (AIS) data was used to construct the traffic flow association network of the urban agglomeration around the South China Sea and then analysis and evaluation were carried out in three aspects: Spatial distribution characteristics of marine traffic flow, analysis of spatial hierarchy and internal difference analysis of the urban agglomeration. The results show the following: (1) The distribution of marine traffic flow within the urban agglomeration around the South China Sea is characterized by polarization and localization and shows a specific power-law distribution; (2) there is a close relationship within the urban agglomeration and the core urban and the marginal urban agglomerations were apparent; (3) subgroup division of urban agglomeration around the South China Sea shows an evident geographic agglomeration phenomenon and there were significant differences between the level of economic development among subgroups; and (4) relative to static factors such as population size and economic aggregate, dynamic flow of information and capital traffic flow plays a more important role in the spatial correlation between cities. Strengthening the links among the three layers of core-intermediate-edge cities through trade and investment means enhancing cooperation among cities within the urban agglomeration and ultimately promoting sustainable regional development.

scholarly journals An eddy resolving tidal-driven model of the South China Sea assimilating along-track SLA data using the EnOI

Ocean Science ◽  
2011 ◽  
Vol 7 (5) ◽  
pp. 609-627 ◽  
Author(s):  
J. Xie ◽  
F. Counillon ◽  
J. Zhu ◽  
L. Bertino
Keyword(s):  
Data Assimilation ◽  
South China Sea ◽  
South China ◽  
The South China Sea ◽  
Optimal Interpolation ◽  
Altimeter Data ◽  
The South ◽  
Validation Data ◽  
China Sea ◽  
Along Track

Abstract. The upper ocean circulation in the South China Sea (SCS) is driven by the Asian monsoon, the Kuroshio intrusion through the Luzon Strait, strong tidal currents, and a complex topography. Here, we demonstrate the benefit of assimilating along-track altimeter data into a nested configuration of the HYbrid Coordinate Ocean Model that includes tides. Including tides in models is important because they interact with the main circulation. However, assimilation of altimetry data into a model including tides is challenging because tides and mesoscale features contribute to the elevation of ocean surface at different time scales and require different corrections. To address this issue, tides are filtered out of the model output and only the mesoscale variability is corrected with a computationally cheap data assimilation method: the Ensemble Optimal Interpolation (EnOI). This method uses a running selection of members to handle the seasonal variability and assimilates the track data asynchronously. The data assimilative system is tested for the period 1994–1995, during which time a large number of validation data are available. Data assimilation reduces the Root Mean Square Error of Sea Level Anomalies from 9.3 to 6.9 cm and improves the representation of the mesoscale features. With respect to the vertical temperature profiles, the data assimilation scheme reduces the errors quantitatively with an improvement at intermediate depth and deterioration at deeper depth. The comparison to surface drifters shows an improvement of surface current by approximately −9% in the Northern SCS and east of Vietnam. Results are improved compared to an assimilative system that does not include tides and a system that does not consider asynchronous assimilation.

Sign in / Sign up

Export Citation Format

Share Document