Abstract
A regional ocean reanalysis system of China coastal waters and adjacent seas, called CORA (China ocean reanalysis), has been recently developed at the National Marine Data and Information Service (NMDIS). In this study, based on CORA, the impact of Argo profiles on the regional reanalysis is evaluated using a twin-experiment approach. It is found that, by assimilating Argo observations, the reanalysis quality is much improved: the root mean square (RMS) error of temperature and salinity can be further reduced by about 10% and the RMS error of current can be further reduced by 18%, compared to the case only assimilating conventional in situ temperature and salinity observations. Consistent with the unique feature of Argo observations, the temperature is improved in all levels and the largest improvement of salinity happens in the deep ocean. Argo profile data have a significant impact on the regional ocean reanalysis through improvements of both hydrographic and dynamic fields.
Highlights
With the gradual increasing of global ocean Argo (Array for Real-Time Geostrophic Oceanography) profile [1], a lot of researches on Argo application have been carried out by scientists and many useful results have been achieved
Argo profiles are widely distributed in World Ocean, so the ocean circulation field can be significantly improved by assimilating Argo
In this paper, based on the CORA system, three twin experiments are used to evaluate the impact of Argo data on temperature, salinity, and current reanalysis results
Summary
With the gradual increasing of global ocean Argo (Array for Real-Time Geostrophic Oceanography) profile [1], a lot of researches on Argo application have been carried out by scientists and many useful results have been achieved. Permutations of combinations of the available observation systems are used in an analysis, in which one observational system is excluded from the analysis, so providing an estimate of the impact of the omitted observational system by comparing the analysis with the reference In this field lots of works have been done to evaluate the Argo impact. Dunstone and Smith [15] investigated the impact of assimilating different amounts of atmosphere and ocean data, including Argo profile, on decadal climate prediction skill through a set of idealized model experiments and found that the upper 2000 m temperature and salinity observations currently provided by the Argo array of floats are potentially well suited to initializing decadal climate predictions. In this paper, based on the CORA system, data assimilation identical twin-experiment approach used in OSSE technique is employed to evaluate the impact of Argo data on temperature, salinity, and current reanalysis results of China coastal waters and adjacent seas.
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