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XU Dazhi,ZHU Jiang,QI Yiquan,LI Xichen,YAN Youfang. 2012. The impact of mean dynamic topography on a sea-level anomaly assimilation in the South China Sea based on an eddy-resolving model. Acta Oceanologica Sinica, (5):11-25
The impact of mean dynamic topography on a sea-level anomaly assimilation in the South China Sea based on an eddy-resolving model
The impact of mean dynamic topography on a sea-level anomaly assimilation in the South China Sea based on an eddy-resolving model
Received:March 01, 2012  Revised:August 09, 2012
DOI:10.1007/s13131-012-0232-x
Key words:data assimilation  mean dynamic topography  sea level anomaly  South China Sea
中文关键词:  data assimilation  mean dynamic topography  sea level anomaly  South China Sea
基金项目:The National Basic Research Program of China under contract Nos 2012CB417404 and 2011CB403504; the National Natural Science Foundation of China under contract No. 41075064; and the National High Technology Research and Development Program of China under contract No. 2008AA09A404-3.
Author NameAffiliationE-mail
XU Dazhi State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
Graduate School, Chinese Academy of Sciences, Beijing 100049, China 
 
ZHU Jiang Institute of Atmospheric Physics, Chinese Academic of Science, Beijing 100029, China jzhu@mail.iap.ac.cn 
QI Yiquan State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China  
LI Xichen Institute of Atmospheric Physics, Chinese Academic of Science, Beijing 100029, China  
YAN Youfang State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China  
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Abstract:
      The sea-level anomaly (SLA) from a satellite altimeter has a high accuracy and can be used to improve ocean state estimation by assimilation techniques. However, the lack of an accurate mean dynamic topography (MDT) is still a bothersome issue in an ocean data assimilation. The previous studies showed that the errors in MDT have significant impacts on assimilation results, especially on the time-mean components of ocean states and on the time variant parts of states via nonlinear ocean dynamics. The temporal-spatial differences of three MDTs and their impacts on the SLA analysis are focused on in the South China Sea (SCS). The theoretical analysis shows that even for linear models, the errors in MDT have impacts on the SLA analysis using a sequential data assimilation scheme. Assimilation experiments, based on EnOI scheme and HYCOM, with three MDTs from July 2003 to June 2004 also show that the SLA assimilation is very sensitive to the choice of different MDTs in the SCS with obvious differences between the experimental results and observations in the centre of the SCS and in the vicinity of the Philippine Islands. A new MDT for assimilation of SLA data in the SCS was proposed. The results from the assimilation experiment with this new MDT show a marked reduction (increase) in the RMSEs (correlation coefficient) between the experimental and observed SLA. Furthermore, the subsurface temperature field is also improved with this new MDT in the SCS.
中文摘要:
      The sea-level anomaly (SLA) from a satellite altimeter has a high accuracy and can be used to improve ocean state estimation by assimilation techniques. However, the lack of an accurate mean dynamic topography (MDT) is still a bothersome issue in an ocean data assimilation. The previous studies showed that the errors in MDT have significant impacts on assimilation results, especially on the time-mean components of ocean states and on the time variant parts of states via nonlinear ocean dynamics. The temporal-spatial differences of three MDTs and their impacts on the SLA analysis are focused on in the South China Sea (SCS). The theoretical analysis shows that even for linear models, the errors in MDT have impacts on the SLA analysis using a sequential data assimilation scheme. Assimilation experiments, based on EnOI scheme and HYCOM, with three MDTs from July 2003 to June 2004 also show that the SLA assimilation is very sensitive to the choice of different MDTs in the SCS with obvious differences between the experimental results and observations in the centre of the SCS and in the vicinity of the Philippine Islands. A new MDT for assimilation of SLA data in the SCS was proposed. The results from the assimilation experiment with this new MDT show a marked reduction (increase) in the RMSEs (correlation coefficient) between the experimental and observed SLA. Furthermore, the subsurface temperature field is also improved with this new MDT in the SCS.
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