Marine gravity determined from multi-satellite GM/ERM altimeter data over the South China Sea: SCSGA V1.0

2020 ◽  
Vol 94 (5) ◽  
Author(s):  
Chengcheng Zhu ◽  
Jinyun Guo ◽  
Jinyao Gao ◽  
Xin Liu ◽  
Cheinway Hwang ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
The South China Sea ◽  
Altimeter Data ◽  
The South ◽  
China Sea ◽  
Marine Gravity

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 A simple predictive model for the eddy propagation trajectory in the South China Sea

2018 ◽  
Author(s):  
Jiaxun Li ◽  
Guihua Wang ◽  
Huijie Xue ◽  
Huizan Wang
Keyword(s):  
South China Sea ◽  
Predictive Model ◽  
South China ◽  
Forecast Accuracy ◽  
The South China Sea ◽  
Altimeter Data ◽  
Linear Regression Method ◽  
Mean Flow ◽  
The South ◽  
China Sea

Abstract. A novel predictive model is built for eddy propagation trajectory using the multiple linear regression method. This simple model has related various oceanic parameters to eddy propagation position changes in the South China Sea (SCS). These oceanic parameters mainly represent the effects of planetary β and mean flow advection on the eddy propagation. The performance of the proposed model is examined in the SCS based on twenty years of satellite altimeter data, and demonstrates its significant forecast skills over a 4-week forecast window comparing to the traditional persistence method. It is also found that the model forecast accuracy is sensitive to eddy polarity and forecast season.

Impact of assimilating altimeter data on eddy characteristics in the South China Sea

2020 ◽  
Vol 155 ◽  
pp. 101704
Author(s):  
J. Xie ◽  
M. De Vos ◽  
L. Bertino ◽  
J. Zhu ◽  
F. Counillon
Keyword(s):  
South China Sea ◽  
South China ◽  
The South China Sea ◽  
Altimeter Data ◽  
The South ◽  
China Sea ◽  
Eddy Characteristics

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.

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