| A quality-controlled climatological dataset for the Indian Ocean (Indian HydroBase) is produced.The Indian Hydrobase has the following characteristics.(1) It is composed of 1° × 1° gridded data and raw/quality-controlled profile datasets.(2) Most of the original data come from World Ocean Database 1998 version 2.Additional data observed by Japanese ships are collected from other Japanese datasets: MIRC Ocean Dataset 2001 and Far Seas Collection.(3) All the data are checked by visual inspection at least one time.They are then statistically quality-controlled considering local water-mass structure with the similar procedures as Lozier et al. (1995) and Macdonald et al. (2001).(4) Gridded data are produced by averaging along isopycnal surfaces with fairly small smoothing scales, intending not to distort the observed water-mass structure.When the Indian HydroBase is compared with World Ocean Atlas 1998 (WOA98), especially larger differences (exceeding 1°C or 0.15 psu) are found around two regions in the properties on isopycnal surfaces.One is around the Polar Front, where the sharper fronts of temperature, salinity, and isopycnal surface depth appear in the Indian HydroBase.The other is at the boundary of the Indonesian Throughflow Water and the Indian Central Water.The former is colder and less saline and comes from the Pacific, and the latter is warmer and saltier and formed in the southeastern part of the South Indian subtropical gyre.Sharper fronts are also found there; the contrasts between the two water-masses are much clearer.Besides the gridded data, the quality-controlled profiles will be utilized for many purposes.They are currently used for quality control of the data obtained by Argo floats in JAMSTEC/FORSGC.We will make the Indian HydroBase publicly available soon and believe it will greatly contribute to the current/future studies of the Indian Ocean. |
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