Evaluation of the Global Ocean Data Assimilation System at INCOIS: The Tropical Indian Ocean

Representation of Bay of Bengal Upper-Ocean Salinity in General Circulation Models

“…Temperature and salinity profiles from Argo, TAO/TRITON, RAMA, PIRATA, XBT, CTD, and NDPB (Ravichandran et al, 2013) …”

“…is an improved version of NCEP-GODAS (ocean model is MOM3) with a shorter assimilation window (Ravichandran et al, 2013). Temperature and salinity profiles are assimilated at six-hour intervals using all observations from the 10-day assimilation window, and the 3DVAR assimilation technique is used for data assimilation.…”

“…We note that maintaining such varied observational networks (Venkatesan et al, 2013) is crucial if models are to be substantially constrained by data assimilation. Ravichandran et al (2013) provide more details of INC-GODAS. The model is forced by momentum flux, heat flux, and freshwater flux from the NCEP-DOE atmospheric reanalysis version 2 (Kanamitsu et al, 2002;hereafter, NCEP R2).…”

“…However, factors responsible for such salinity biases in the BoB (both in the surface and in the subsurface) are unclear and need examination. Biases in subsurface salinity and temperature in GCMs can alter the ocean circulation, sea level, vertical mixing, and the coupling between ocean and atmosphere (e.g., Seo et al, 2009;Brown et al, 2013 Ravichandran et al, 2013; a data assimilation product; see Table 1 for details). This article describes details of different models and data sets used in the study, provides insights into salinity biases in the BoB vertical structure and associated processes, and discusses thoughts for future work.…”

An introduction to GODAE OceanView

“…The Indian Ocean Forecast System (INDOFOS [http:// www.incois.gov.in/Incois/indofos_main.jsp]) is currently based on ROMS and GODAS (Ravichandran et al 2013) and uses atmospheric forcing data from the operational atmospheric prediction system of the National Centre for Medium Range Weather Forecast (NCMRWF) in New Delhi. An integrated Indian Ocean forecast system, which consists of a very high resolution configuration of ROMS (1/32°) for coastal waters, a high resolution configuration of HYCOM (1/12°) [http://hycom.org/] for the Indian Ocean region and a coarse resolution configuration of MOM4 [http://www.gfdl.noaa.…”