A new climatology of temperature and salinity for the North Indian Ocean
The most used temperature and salinity climatology for the world ocean, including the Indian Ocean, is the World Ocean Atlas (WOA) because of the vast amount of data used in its preparation. The WOA climatology does not, however, include all the avail able hydrographic data from the Indian Exclusive Economic Zone (EEZ), leading to the potential for improvement if the data from this region are included to prepare a new climatology. This new climatology is called the North Indian Ocean Atlas (NIOA) and the climatology files are available for download.
We derive an improved annual, seasonal, and monthly climatology for the Indian Ocean (30°E-120°E and 30°S-40°N) using all the data that went into the preparation of the WOA, but add considerable data from Indian sources. The main source of data was the National Oceanographic Data Center (NODC); additional data were obtained from the Japanese Oceanographic Data Center (JODC), the Indian National Oceanographic Data Centre (INODC) at the CSIR National Institute of Oceanography, the Central Marine Fisheries Research Institute (CMFRI) at Kochi, the Indian National Centre for Ocean Information Services (INCOIS) at Hyderabad, and Centre for Marine Living Resources and Ecology (CMLRE) at Kochi.
A total of 517772 temperature profiles and 229258 salinity profiles were obtained from the above sources. After all quality control checks, 415160 temperature profiles and 157264 salinity profiles were used for the annual climatology. The number of profiles added to the WOA database are 58401 for temperature and 49032 for salinity.
The addition of data improves the climatology considerably in the Indian EEZ, the differences between the NIOA and WOA being most significant in the Bay of Bengal, where the patchiness seen in WOA, an artifact of the sparsity of data, was eliminated in NIOA. The significance of the new climatology is that it presents a more stable climatological value for the temperature and salinity fields in the Indian EEZ.
For more information, you may download the paper by Chatterjee et al. (2012) from SpringerLink (http://www.springerlink.com/) or the Indian Academy of Sciences (http://www.ias.ac.in/jess/). If you use these
data, please cite this paper as follows.
Chatterjee, A,; Shankar, D,; Shenoi, S.S.C.; Reddy, G.V.; Michael, G.S.; Ravichandran, M.; Gopalkrishna, V.V.; Rao, E.P.R.; Bhaskar, T.V.S.U.; Sanjeevan, V.N. A new atlas of temperature and salinity for the North Indian Ocean. Journal of Earth System Science, 121, No.3, 2012, pp. 559-593; doi: 10.1007/s12040-012-0191-9.
Currently, the datasets are available as NetCDF files. Climatologies are derived based on two different seasonal definition. First, as Levitus definitions (WOA) of seasons, i.e. winter (Janauary-February-March), spring (April-May-June), summer (July-August-September), and fall (October-November-December). The second definition is to suite Indian Ocean monsoonal cycle, i.e. winter monsoon (December-January-February), spring intermonsoon (March-April-May), summer monsoon (June-July-August-September), and fall intermonsoon (October-November).
Climatologies with Levitus definition of seasons consists two sets of files. One set of files (for annual, seasonal, and monthly climatologies) contain just the NIOA and are restricted to the Indian Ocean. In the second set of files (for annual, seasonal, and monthly climatologies), the NIOA climatology has been merged with the global WOA climatology, there being a smooth transition over 20°S-30°S at the southern boundary and 115°E-120°E at the eastern boundary.
Climatologies (annual, seasonal, and monthly) are also available for a "monsoon definition" of seasons; these data are restricted to the Indian Ocean.
For feedback/suggestions please contact:
Abhisek Chatterjee (email@example.com) or Dr. D. Shankar (firstname.lastname@example.org).