The INCOIS-GODAS (Indian National Centre for Ocean Information Services-Global Ocean Data Assimilation System), a modified version of NCEP-GODAS (National Centre for Environmental Prediction-Global Ocean Data Assimilation System), is an Ocean General Circulation Model (OGCM) with assimilation capabilities. The OGCM is Modular Ocean Model-4.0 (MOM-4.0). The assimilation schemes used in INCOIS-GODAS is 3DVAR and Newtonian relaxation (Nudging). The 3DVAR assimilation scheme is used to assimilate observed temperature and salinity profiles, in the top 700m, from observational platforms like Argo, Moored buoys (RAMA, PIRATA/TRITON, TAO, NIOT buoys etc.), and ship-based (XBT, CTD, XCTD, etc.). Using the Newtonian relaxation scheme the model SST is nudged towards satellite blended gridded fields of SST.
Major differences between NCEP-GODAS and INCOIS-GODAS
Modular Ocean Model 3
Modular Ocean Model 4.0
Observed In-situ Temperature and Synthetic Salinity
Observed In-Situ Temperature and observed In-situ salinity
T&S profiles for assimilation
GTS + NDBP moorings
Inter-annual monthly river discharge (derived from datasets provided by Dai et al. 2009 and Papa et al. 2010)
Radiation, momentum, and Freshwater Fluxes
Daily averaged NCEP-R2 fluxes on coarse resolution (1.8º X 1.8º near equator)
4 times daily NCMRWF-T574L64 fluxes on high spatial resolution (0.25º X 0.25º)
10-15 day delayed pentadal averaged ocean analysis
The INCOIS-GODAS runs every day to provide global ocean analysis of temperature, salinity, sea surface height, and currents from the surface to the bottom of the ocean on real time basis (products are available with just 1-day delay). Various tailor made products (ElNino indices, Global maps of monthly SST anomalies, depth-wise distribution of temperature anomalies, TCHP, etc.) are also being made available using these INCOIS-GODAS ocean analysis.Ocean analysis data from INCOIS-GODAS is available for free from 2003 to till date on INCOIS ftp server (ftpser.incois.gov.in) and also on INCOIS Live Access Server (las.incois.gov.in ; under ocean analysis folder). For data access, users are requested to contact
Mukherjee, A., Shankar, D., Fernando, V., Amol, P., Aparna, S. G.., Fernandes, R., Michael, G. S., Khalap, S. T., Satelkar, N. P., Agarvadekar, Y., Gaonkar, M. G., Tari, A. P., Kankonkar, A., and Vernekar, S. (2014) Observed seasonal and intraseasonal variability of the East India Coastal Current on the continental slope. Journal of Earth System Science, 1-36.
Pandey, V.K., and Kurtakoti, P. (2014) Evaluation of GODAS using RAMA mooring observations from the Indian Ocean. Marine Geodesy, 37, no. 1, 14-31.
Sengupta, S., Anant Parekh, Chakraborty, S., Ravikumar, K., and Bose, T. (2013) Vertical variation of oxygen isotope in Bay of Bengal and its relationships with water masses. Journal of Geophysical Research: Oceans 118, no. 12, 6411-6424.
Ravichandran, M., Behringer, D., Sivareddy, S., Girishkumar, M.S., Neethu Chacko., and Harikumar, R. (2013) Evaluation of the Global Ocean Data Assimilation System at INCOIS: The Tropical Indian Ocean. Ocean modelling, 69, p123-135, , doi:http://dx.doi.org/10.1016/j.oceamod.2013.05.003
Ramu, V., Patnaik, K. V. K. R., Prasad, K. V. S. R., Arunkumar, S. V. V., and Acharyulu, P. S. N. (2012) Upper Ocean thermal features during Tropical Cyclones over Bay of Bengal. Int. J. Innovative Research and Development, 1, 10.
Ravichandran, M., Behringer, D., Sivareddy, S., Girishkumar, M.S., Neethu Chacko., and Harikumar, R. (2011) INCOIS-GODAS-MOM: Ocean Analysis for the Indian Ocean: Configuration, Validation and Product Dissemination. INCOIS tech. report, No. INCOIS-MOG-TR-2011-06.