Abstract: Due to the interaction between the river discharge and the tide, as well as the high suspended sediment concentration in the surface water, the optical property of the Yangtze Estuary waters is different from the open sea waters. In a single tidal cycle, the total suspended maters (TSM) concentration can reach 0.5~kg/m{3} or more during spring tide, while in neap tide the maximum TSM concentration is only 1/3 of the spring tides. High TSM concentrations and a greater variation in single tidal cycle make a lot of empirical inversion algorithm unavailable in this region. A new algorithm was developed in the Yangtze Estuary, named improved complex proxy TSM (ICPTSM) model to improve the complex proxy TSM model. Using in situ synchronous optical and TSM concentration data
collected in the survey in May 2014, we analyze the characteristic of sediment concentration changing in the Yangtze Estuary associated within entire tidal cycle. Based on the original seven alternative bands, we introduce two alternative bands, 806~nm and 858 nm, as a supplement. We add a near-infrared peak area index as the fifth index to the complex proxy (CP). Linear relationship between the CP index and TSM concentration is improved into quadratic relationship. For water characteristics of different tidal conditions, individual ICPTSM models have been established. The results show that: ICPTSMmodel is adaptable in the Yangtze Estuary, distinction model toward spring and neap tidal have higher retrieval accuracy than unified model for a whole tide cycle, distinction model can better describe changes of water-leaving radiance, and TSM concentration changes in a tidal cycle