Impact of the objective analysis on the assimilation of satellite altimetric data into ocean model
© Boukthir Moncef, Abdennadher Jihène
In this paper, we attempt to quantify the possible ability of the interpolated altimetric data to better constrain the simulated fields towards the observations. Some tests of assimilation of the altimetric data into ocean model are then realised. The model is quasigeostrophic, eddy resolving and multi-layered, and is applied to the prognostic description of the mid-latitude ocean circulation in a schematic box ocean. In the first experiment (ASStr), the altimeter data are assimilated in the real time along the satellite track. In the second (ASSao), these data are objectively analysed and then assimilated in each grid point of the model. In both experiments, the insertion of the altimeter data into the model is able to constrain strongly the simulated circulation towards the real ocean circulation. The main structures of the reference fields are correctly reproduced in both experiments, particularly in the upper layer. Nevertheless, a comparison between the ASStr and ASSao fields shows that the assimilation under the tracks do better than the assimilation of the interpolated data, particularly in the bottom layers. This result is strongly related to the nature of the ocean dynamics and the knowledge of its main statistics.