Correcting circulation biases in a lower-resolution global general circulation model with data assimilation

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• 作者：Martin Canter ; Alexander Barth ; Jean-Marie Beckers
• 关键词：Bias correction ; Data assimilation ; Global ocean model ; Stochastic forcing ; NEMOLIM2 ; Ensemble transform Kalman filter ; ETKF ; Ensemble smoother ; Circulation bias ; Parameter estimation
• 刊名：Ocean Dynamics
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：67
• 期：2
• 页码：281-298
• 全文大小：
• 刊物类别：Earth and Environmental Science
• 刊物主题：Oceanography; Geophysics/Geodesy; Atmospheric Sciences; Fluid- and Aerodynamics; Monitoring/Environmental Analysis;
• 出版者：Springer Berlin Heidelberg
• ISSN：1616-7228
• 卷排序：67

文摘

In this study, we aim at developing a new method of bias correction using data assimilation. This method is based on the stochastic forcing of a model to correct bias by directly adding an additional source term into the model equations. This method is presented and tested first with a twin experiment on a fully controlled Lorenz ’96 model. It is then applied to the lower-resolution global circulation NEMO-LIM2 model, with both a twin experiment and a real case experiment. Sea surface height observations are used to create a forcing to correct the poorly located and estimated currents. Validation is then performed throughout the use of other variables such as sea surface temperature and salinity. Results show that the method is able to consistently correct part of the model bias. The bias correction term is presented and is consistent with the limitations of the global circulation model causing bias on the oceanic currents.