[M-GI26] Data assimilation: A fundamental approach in geosciences

[MGI26-P12] The Impact of BGC Argo float array deployment region on state estimation using Estimated Ocean State for Climate Research (ESTOC)

*Toshimasa Doi¹, Satoshi Osafune¹, Shinya Kouketsu¹, Shigeki Hosoda¹, Shuhei Masuda¹ (1.Japan Agency for Marine-Earth Science and Technology)

Keywords:BGC Argo, dissolved oxygen, data assimilation

BGC Argo float array is recognized as an important tool for observing the ocean environment, and efforts are underway to deploy, maintain, and manage it to cover the global ocean. In order to monitor global ocean environmental variations, it is effective to use numerical models in conjunction with such observation networks. We try to estimate both physical and biogeochemical ocean states with integrating various observations including BGC Argo float array through a 4-dimensional variational data synthesis system, which is constructed based on a pelagic lower trophic level ecosystem model and oceanic general circulation model. This data synthesize system can estimate dynamically self-consistent ocean state which integrates available ocean observations. In this study, we focused on the dissolved oxygen observation accumulated by BGC Argo, and examined the effectiveness of BGC Argo observations in ocean state estimation by using the data synthesis system. We conducted the data synthesis by estimate the optimal model parameters for the atmospheric exchange coefficient of oxygen at sea-surface and the rate of oxygen consumption by biogeochemical activity with Green’s function approach for five basins (Atlantic, Pacific, Indian, Southern Ocean, and Arctic Ocean) of the global ocean. By comparing the results based on obtained optimized parameters between with and without BGC Argo observations, we evaluate the observation impacts on our ocean state estimation. This result is an assessment of the impact on data synthesis for each ocean region where the BGC Argo is deployed, and contribute to clarify the importance of the deployment of BGC Argo to the global ocean.