A Report on implementation of operational Global and Indian Ocean HYCOM at INCOIS

A state of the art operational forecasting system with data assimilation (DA) is established at INCOIS, which is the first of it's kind in the country. The Indian Ocean model is the highest resolution operational system with DA available for the basin compared to any operational agency in the world. The core of the system is a 1/16th eddy resolving Indian ocean Hybrid Coordinate Model (HYCOM), nested to a 1/4th Global HYCOM which provides lateral boundary conditions to the high-resolution model. The system uses data assimilation scheme based on Tentral Statistical Interpolation (T-SIS) scheme. A five-year hindcast for the period 2012 to 2016 has been carried out using both setups. This report presents a detailed evaluation of both global and Indian ocean models in comparison with observations and two other established systems, NRL HYCOM and GODAS from INCOIS. The five-year hindcast results show that both Indian Ocean and global model simulated SST, SSS, SLA, currents and vertical structure of the ocean favourably when compared with observations and other models. Bias, RMSD, correlation and skill score compared to observations from each of the four models for selected parameters are evaluated as part of this exercise. Sea-level and currents, show a notable better performance for the new setups at INCOIS over NRL-HYCOM and INCOIS-GODA