Investigating sound speed profile assimilation: An experiment in the Philippine Sea

•A method to find the optimal SSP assimilation radius is proposed.•The optimal SSP assimilation radius for Philippine Sea in certain environment is found.•The optimal SSP assimilation radius is proved useful for future use.•An SSP inversion mehtod is proposed.

In this paper, a single datum assimilation method is described for constructing the sound speed profile (SSP) in the ocean. Our method's key is assimilation radius, where various radii provide different SSPs. By means of the Bellhop acoustic model and acoustic data, we calculated the optimal SSP assimilation radius. Due to the lack of proper in-situ observations, an SSP inversion method is proposed. Inverted SSP compared to assimilated SSP indicates close correlation, showing that both methods yield reliable results. Historical data analysis indicates a stable correlation structure under certain conditions, implying the optimal assimilation radius would measure SSP effectively under similar conditions.