An evaluation of sea surface height assimilation using along-track and gridded products based on the Regional Ocean Mode
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An evaluation of sea surface height assimilation using along-track and gridded products based on the Regional Ocean Modeling System (ROMS) and the four-dimensional variational data assimilation ZHOU Chaojie1, 2, DING Xiaohua1, ZHANG Jie2, YANG Jungang2*, MA Qiang1 1 Department of Mathematics, Harbin Institute of Technology at Weihai, Weihai 264209, China 2 The First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China
Received 8 March 2018; accepted 27 March 2018 © Chinese Society for Oceanography and Springer-Verlag GmbH Germany, part of Springer Nature 2018
Abstract
Remote sensing products are significant in the data assimilation of an ocean model. Considering the resolution and space coverage of different remote sensing data, two types of sea surface height (SSH) product are employed in the assimilation, including the gridded products from AVISO and the original along-track observations used in the generation. To explore their impact on the assimilation results, an experiment focus on the South China Sea (SCS) is conducted based on the Regional Ocean Modeling System (ROMS) and the four-dimensional variational data assimilation (4DVAR) technology. The comparison with EN4 data set and Argo profile indicates that, the along-track SSH assimilation result presents to be more accurate than the gridded SSH assimilation, because some noises may have been introduced in the merging process. Moreover, the mesoscale eddy detection capability of the assimilation results is analyzed by a vector geometry–based algorithm. It is verified that, the assimilation of the gridded SSH shows superiority in describing the eddy’s characteristics, since the complete structure of the ocean surface has been reconstructed by the original data merging. Key words: ROMS, 4DVAR, sea surface height assimilation, along-track, gridded product Citation: Zhou Chaojie, Ding Xiaohua, Zhang Jie, Yang Jungang, Ma Qiang. 2018. An evaluation of sea surface height assimilation using along-track and gridded products based on the Regional Ocean Modeling System (ROMS) and the four-dimensional variational data assimilation. Acta Oceanologica Sinica, 37(9): 50–58, doi: 10.1007/s13131-018-1225-1
1 Introduction An efficient simulation of ocean could make a significant contribution to the prediction of oceanic dynamic progress and climate change. Using the consistency constraints with laws of time evolution and physical properties, the estimation of an ocean model state could be enhanced, when the observed information is accumulated into the oceanic model states by data assimilation technology (Bouttier and Courtier, 2002). Remote sensing has collected large mount observations with high temporal and spatial coverages, such as sea surface temperature (SST) and sea surface height (SSH). According to the research of Kurapov et al. (2011) and O’Dea et al. (2012), the accuracy of model simulation could be enhanced when the remote sensing products, such as SSH and SST, are assimilated in the model. Therefore, an excellent assimilation strateg
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